weldtech

CO2 welding :An introduction of Metal active gas

2022-06-23T23:30:00.009+05:30

CO2 welding

CO2 (Carbon-dioxide) welding is nothing but a variation of the standard MIG welding process.

Introduction

In this process, carbon dioxide is used as active gas, hence it is also known as a metal active gas process.

CO2 is basically a semi-automatic process, in which the arc length and electrode wire feeding into the arc are automatically controlled.

Difference between CO2 and Mig Process

Typically in the MIG process, argon, helium, or their mixtures are used to protect the molten weld pool, while in the CO2 welding process carbon dioxide is used as the shielding gas.

In this process, carbon dioxide is used as active gas, hence it is also known as a metal active gas(MAG) process.

Benefits of CO2 welding

Although argon and helium are used for MIG welding of most metals, providing reliable and robust welding, carbon dioxide has become widely popular for arc shielding in the welding of steels.

Some of the main reasons for its popularity are as follows:

CO2 overcomes the restriction of using short lengths of electrodes as in the Shielded metal arc welding (stick welding) process.
The CO2 process overcomes the inability of the submerged arc welding process to weld in several welding positions.
CO2 welding requires less skill than TIG or shield metal ARC welding.

Welding equipment for CO2 welding

Following is the list of equipment used in CO2 welding:

A constant potential DC power source and controls.

DCRP(electrode positive) current is used in CO 2 process as it always facilitates smooth metal transfer with stable arc and minimum spatter. The use of DCSP and AC current is unsuitable as this makes the arc erratic and unstable.

In the CO2 process, a welding generator or a constant voltage type transformer-rectifier is used for the power source. A constant voltage power source with a constant speed wire feeder provides a self-correcting arc length system.

Wire feeder

The wire feeder pulls the wire electrode from the spool and pushes it through the welding gun at the required speed.

Along with this, a DC motor, speed-reducing gearbox, rule drive gas solenoid valve, and potentiometer are fitted to adjust the speed, which helps in providing a constant speed to the wire.

Welding gun

Welding guns are of two types Lightweight types which are air-cooled with shielding gas

While the other heavy type is water-cooled, it is used for more than 400 amperes current or heavy-duty.

Review some of the weld tech blog's most popular articles.

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Best welding for beginners

2022-05-19T12:38:00.006+05:30

Best welding for beginners

If you are thinking of starting your career as a welding operator, then the first question will obviously arise in your mind “what is the best welding for beginners?”

Choice of welding for a beginner

The choice of welding for a beginner mainly depends on which field he wants to make his career. Some notable fields in which various welding processes are used are as follows:

Aircraft and Automobile Construction, Bridges and Buildings, Pressure vessels and Tanks, Pipings and pipelines, Ships, and many others.

What is the best welding for beginners?

MIG Welding, TIG Welding, and Stic Welding are more popular in the welding industry, for a beginner These processes are popular due to the factors of efficiency, simplicity, and cost-effectiveness.

What is the easiest type of welding to learn?

MIG, TIG, and Stick Welding are easier than other processes for a beginner welder, due to ease of welding, portability, cost-effectiveness, and flexibility.

1-MIG or GMAW( Gas metal arc welding) is a Sami automatic welding process that is demandable in Aircraft and Automobile Construction and easy to learn also.

photo credit weldworld

2- TIG or GTAW (Gas tungsten arc welding )

This is the most commonly used process in-plant piping and pipeline. It is widely used in industry as it allows small joints to be joined quickly and firmly.

Photo credit weldworld

3- Stick welding or SMAWShielded metal arc welding)

-The reason for the high popularity of stick welding is because of its simple technology, ease of learning, and cost-effectiveness. All the equipment required for the stick welding process is easily available anywhere. And metals can be joined together at a low cost.

What should I weld as a beginner?

Beginners can choose between tig, Mig, or stick in the initial round. But if you want to select one of these three processes, then stick welding can be chosen. Because stick welding uses fewer resources and equipment.

However, this is only a suggestion as many factors are important in the choice of welding process for a beginner welder such as:-

Available Training Schools in the Area

What welding processes are in vogue in which industry do you aspire to work in. etc.

Following articles can help beginners to choose the right kind of welding process.

⇒Stick welding process

⇒Smaw (Shielded metal arc welding)

⇒TIG or GTAW (Gas tungsten arc welding)

फोर्ज वेल्डिंग प्रक्रिया

2022-04-23T09:51:00.006+05:30

फोर्ज वेल्डिंग का इतिहास

फोर्ज वेल्डिंग अब तक का सबसे प्राचीन वेल्डिंग पद्यत है जो कांस्य युग में धातु ( ताम्बे और कांस्य आदि)की खोज के साथ आरम्भ हुआ था। यह प्रक्रिया धातुओं को मिलाने के सबसे सरल तरीकों में से एक है और प्राचीन काल से इसका इस्तेमाल पारंपरिक रूप से होता चला आरहा है ।

फोर्ज वेल्डिंग का परिचय

फोर्ज वेल्डिंग अब तक की सबसे पुरानी वेल्डिंग विधि है जो कांस्य युग में धातुओं (तांबा और कांस्य आदि) की खोज के साथ शुरू हुई थी।

उस समय धातुओं को मिलाने की एक ही विधि ज्ञात थी, जिसमें भट्टियों में धातुओं को उच्च तापमान पर गर्म कर के हथौड़े की सहायता से पीट कर जोड़ा जाता था ।

फोर्ज वेल्डिंग प्रक्रिया

फोर्ज वेल्डिंग ,ठोस अवस्था वेल्डिंग प्रक्रिया( solid state welding process) के तहत आता है, जिसमे धातु के दो टुकड़ों को उच्च तापमान पर गर्म करके और फिर उन्हें एक साथ दबाव बना कर जोड़ा जाता है ।

फोर्ज वेल्डिंग क्या है

फोर्ज वेल्डिंग में, धातु के हिस्सों को कोयले, कोक या चारकोल जैसे ईंधन के साथ फोर्ज फर्नेस में गरम किया जाता है। जुड़ने वाले भागों को तब तक गर्म किया जाता है जब तक कि धातु की जुड़ने वाली सतह नर्म न हो जाए। जब यह स्थिति पहुँच जाती है, तो दोनों भागों को जल्दी से एक दुसरे के साथ आरोपित कर दिया जाता है और वेल्ड को दबाव या हथौड़े से बनाया जाता है।

फोर्ज वेल्डिंग में इंधन (तापमान का प्रयोग )

इस विधि में धातु के हिस्सों को फोर्ज फर्नेस(भट्टियों ) में गरम किया जाता है जिसमे कोयले, कोक या चारकोल जैसे ईंधन का प्रयोग होता है । अधिक बड़े उपकरणों को जोड़ने के लिए बड़ी भट्टियों की व्यवस्था की जाती है ।

फोर्ज वेल्डिंग में दबाव का प्रयोग

फोर्ज वेल्डिंग में हथौड़े या दबाव का बल शामिल होने वाले भागों के आकार और द्रव्यमान पर निर्भर करता है।

फोर्ज वेल्डिंग में फ्लक्स का उपयोग

इस प्रक्रिया में, जुड़ने वाली सतहों को बाहरी पदार्थों जैसे ऑक्साइड और गंदगी आदि को हटाने के लिए धातु के वेल्डिंग तापमान तक पहुंचने से ठीक पहले एक फ्लक्स का उपयोग किया जाता है (आमतौर पर रेत या बोरेक्स को जोड़ने के लिए सतहों पर छिड़का जाता है)। फ्लक्स धातु पर फैलता है, हवा को बाहर रखकर ऑक्सीकरण को रोकता है, पैमाने के गलनांक को कम करता है, और इसे तरल बनाता है ताकि धातु को हथौड़े से दबाने पर इसे वेल्ड से बाहर निकाला जा सके।

फोर्ज वेल्डिंग का आधुनिकीकरण

औद्योगिक क्रांति के दौरान विद्युत वेल्डिंग और गैस वेल्डिंग विधियों के आविष्कार के साथ, मैनुअल फोर्ज-वेल्डिंग को काफी हद तक बदल दिया गया है, हालांकि स्वचालित फोर्ज-वेल्डिंग एक सामान्य निर्माण प्रक्रिया है।

फोर्ज वेल्डिंग का उपयोग

फोर्ज वेल्डिंग का उपयोग धातु के अलग-अलग टुकड़ों को जोड़कर अधिक महत्वपूर्ण धातु बनाने के लिए किया जाता है जैसे इसका उपयोग जंजीर, तलवारें, रेल की छड़ें और फाटक बनाने का पारंपरिक तरीका है। इसका उपयोग कुकवेयर और कृषि उपकरण बनाने में भी किया जाता है।
इसका उपयोग प्लेट को घुमाकर प्लेटों से पाइप बनाने के लिए भी किया जाता है
इसके अतिरिक्त फोर्ज वेल्डिंग द्वारा बेलनाकार रूप और फोर्ज द्वारा अनुदैर्ध्य जंक्शन बनाना आदि

कार्य विधि

फोर्ज वेल्डिंग प्रक्रिया को मूल रूप से चार चरणों में पूरा किया जाता है ।

सबसे पहले जोड़ने वाले सिरों को फोर्ज फर्नेस (भट्टियों)में गर्म करने के लिए डाला जाता है तथा इस पूर्ण रूप से प्लास्टिक स्तिथि तक तपित किया जाता है ।
पूर्ण रूप से गरम होने के पश्चात इसे निकाल कर इसपर फ्लक्स का छिडकाव किया जाता है ,सामान्यत: फ्लक्स के रूप में बोरेक्स का उपयोग किया जाता है जो एक निम्न-तापमान, कांच की ढाल के रूप में कार्य करता है जो धातु के ऑक्सीकरण को रोकता है।
फ्लक्स के उपयोग के पश्चात धातु को वापस फोर्ज में रखते हैं । इसे वापस एक चमकदार पीली रंगत कीई दशा तक गर्म किया जाता है।
जब यह चमकीले पीले रंग का हो तो धातु के टुकड़े को फोर्ज से हटा कर जुड़ने के लिए पावर हैमर या हाइड्रोलिक प्रेस की सहायता से दबाव बनाया जाता है और इस प्रकार वेल्डिंग की प्रक्रिया पूर्ण की जाती है ।

फोर्ज वेल्डिंग के द्वारा जुड़ने वाले मेटल और उनकी मोटाई

गढ़ा लोहा और कम कार्बनव की मात्रा वाले स्टील ।
फोर्ज वेल्डिंग के द्वारा लगभग 30 मिमी की मोटाई वाले धातुओं को आपस में जोड़ा जा सकता है ।

फोर्ज वेल्डिंग के उपयोग

प्राचीन काल से ही फोर्ज वेल्डिंग का उपयोग घरेलु बर्तनों को बनाने में किया जाता रहा है ।

वर्त्तमान समय में भी कृषि कार्य हेतु इस विधि का उपयोग व्यापक रूप से किया जाता है, जैसे हंसिया ,फावड़ा, खुरपी ,कुदाल कुल्हाड़ी एवं हल आदि के साथ साथ सामान ढोने वाली पारंपरिक धक्का गाड़ियों का निर्माण ।

इसकी सहायता से आज भी पारम्परिक डिजाइन वाले कलश के कंगूरे एवं खिडकियों के फूल पत्तों के डिजाइन बनाये जाते हैं

फोर्ज वेल्डिंग के लाभ

इस विधि में अधिक लागत नही आती है।छोटे औजारों को आसानी से भट्टी में वेल्ड किया जा सकता है। कम स्थान एवं कम पूंजी में इस व्यापार को किया जा सकता है ।

फोर्ज वेल्डिंग की सीमाएं

फोर्ज वेल्डिंग के द्वारा निश्चित आकार की वस्तुओं एक सीमा तक ही का जोड़ा जा सकता है। बड़े उपकरणों को जोड़ने के लिए अधिक ताप की आवश्यकता होती है जो बड़े फर्नेस से ही संभव है। फोर्ज एल्डिंग की सहायता से सीमित धातुओं को ही आपस में जोड़ा जा सकता है ।

निष्कर्ष वाक्य

फोर्ज वेल्डिंग प्राचीन पद्यत होने के बाद भी आज अपने पारंपरिक और आधुनिक दोनों रूपों में प्रयोग में लाई जाती है जो बहुत जगहों पर अन्य वेल्डिंग प्रक्रियाओं से कम खर्चीली यो सरल प्रक्रिया भी सिद्ध हुई है ,इसी लिए फोर्ज वेल्डिंग आज भी लोकप्रिय है ।

Weld bead and its properties

2021-08-18T23:48:00.005+05:30

Weld bead and its properties

Weld beads have a greater impact on the quality of a sound weld joint. In this article, we discussed the basic structure of a weld bead.

Weld bead geometry

In terms of the properties of a weld joint, weld bead geometry has considerable parameters that can alter the mechanical properties of a welded joint. These properties are affected by certain welding parameters like

Arc current,
Arc voltage, and
Arc travel speed, etc.

Specification of a weld bead

Bead geometry can be defined on the basis of the following points ...

Weld bead width,
Reinforcement height,
Reinforcement area,
Penetration height,
Penetration area, and
Contact angle of the weld bead.

Many other factors like nugget area, percent dilution, pool shape factor, bead shape factor, and ripple shape factor may also be included in the bead geometry.
Aspects of weld bead geometry

Width of the weld bead

The maximum width of the deposited metal is considered the width of the weld bead. It increases with arc current, arc voltage, and electrode weaving and decreases as arc travel speed increases.

Penetration

The efficiency of load-carrying capacity is determined by the penetration of a welded structure.

Penetration height

The height of penetration is actually the distance from the plate top surface to the maximum extent of the weld nugget.

Penetration area

The Penetration area is covered by the fusion line below the base metal level. It is responsible for the affection of the weld strength.

Reinforcement height

The maximum distance between the base metal level and the top point of the deposited metal is called reinforcement height.

Reinforcement Area

Reinforcement area is one included between the contour line of the deposited metal above the base metal level

Contact angle

The contact angle is included between the tangent to the weld metal at the point weld metal and base metal meet and the base metal line. It influences bead shape undercuts and overlapping.

Penetration height, penetration area reinforcement height, and reinforcement area, all increase the arc current increase and as arc travel speed decreases.

Conclusion

Thus thinner workpieces require lesser currents, small diameter electrodes, and faster arc travel speed as compared to thicker jobs,
Penetration can also be increased or decreased by deflecting the welding arcs in the backward or forward direction, using DC magnetic fields.
forward direction, using DC magnetic fields.

Acetylene gas generator

2021-08-11T18:26:00.003+05:30

About Acetylene

Who could have believed that an accidental event of 1836 would prove to be a boon for the coming age?

That 1836 event was the identification of a new element "the new carbonate of hydrogen" when potassium metal was heated to high temperatures by Edmund Davy producing a residue now known as potassium carbide,

Today we’ll discuss the potassium carbide which plays a major role in the formation of acetylene gas today.

Potassium carbide

Potassium carbide reacts with water and forms a new gas (acetylene). Which is flammable and is mainly used in the gas welding process due to the extreme temperature given by burning in combination with oxygen/air.

In the modern era, large quantities of acetylene gas are being consumed.

Although it is more economical to produce the gas at the site for use with the help of acetylene gas generators, it needs to be produced on a large scale in other plants.

Acetylene gas generation

Acetylene gas is produced by "carbide-to-water" methods such as a generator unit feeding controlled amounts of calcium carbide into the water.

When these ingredients are mixed, acetylene gas is produced.

Acetylene gas generator

Generally, two types of acetylene gas generators are being used such as:

Low pressure Genetator

The low-pressure generator can also be called a portable generator, its output capacity is low.

it can produce acetylene about

above 30ft³/hr(15 ltr/min.).

Medium pressure Generator

A medium pressure gas generator is more commonly used because this type of generator is considered stationary, it can deliver gas up to 0,6 bar (from 1-15 psi) of pressure. The acetylene production rate by a medium pressure gas generator is approximately 6000ft³/hr(3000 Ltr/min.

Operational concept

In general, acetylene gas generators are automatic ie it automatically controls the amount of calcium carbide falling into the water. As shown in the figure, the control valve opens and closes automatically when acetylene increases or decreases in the chamber.

Safety manners

Various components are additionally incorporated in this to make the operation of the acetylene generator safe.

Disadvantages

Although the acetylene gas generation process is cheap and beneficial, it also has some disadvantages such as:

Gas generation by the process of carbide-to-water methods requires additional safety precautions.
If a low-pressure type generator is used, there is a tendency for the pressure to fluctuate with the resulting unstable flame.

वेल्डिंग

2021-07-13T20:58:00.014+05:30

वेल्डिंग

वेल्डिंग शब्द का प्रयोग वास्तव में धातु के पुर्जों को आपस में जोड़ने के लिए किया जाता है। यह एक प्राचीन तकनीक है जिसका उपयोग आधुनिक युग में एक लोकप्रिय व्यवसाय के रूप में भी किया जाने लगा है।

वेल्डिंग किया है

यह एक विनिर्माण गतिविधि है, जिसमें दो भागों को एक साथ जोड़ने के लिए गर्मी और दबाव, या दोनों का उपयोग किया जाता है।

धातु, लकड़ी और थर्मोप्लास्टिक आदि को वेल्डिंग विधि द्वारा आपस में जोड़ा जाता है, जिसके लिए मुख्य रूप से ऊष्मा और दबाव या दोनों का उपयोग किया जाता है।

वेल्डिंग की उत्पत्ति

वेल्डिंग एक प्राचीन तकनीक है जो शुरू में एक कला के रूप में लोकप्रिय हुई, लेकिन मानव विकास के साथ-साथ इसका विकास भी हुआ और इसने आधुनिक समय में विज्ञान का रूप ले लिया है।

वेल्डिंग का इतिहास बहुत ही प्राचीन है इसका उपयोग आज से लगभग 4000 ईसा पूर्व में ही मानव समाज ने ,विश्व के विभिन्न भागों में करना प्रारंभ कर दिया था ।यह तांबे से शुरू हुआ और फिर कांस्य, चांदी, सोना और लोहे में विस्तारित हुआ। चूँकि उस समय तांबा एक अयस्क के रूप में पाया जाता था, इसलिए इसका उपयोग केवल घरेलू उपयोग की वस्तुओं और शिकार के हथियारों तक ही सीमित था।

वेल्डिंग की परिभाषा

वेल्डिंग , धातुओं या थर्मोप्लास्टिक्स, को आपस जोड़ने की प्रक्रिया है सिसमे ताप/दाब या दोने के प्रयोग से दो सामान या भिन्न धातुओं को आपस में जोड़ा जाता है तथा आवश्यकता पड़ने पर अलग से भराव धातु का प्रयोग किया जाता है । या

उच्च तापमान पर बेस मेटल को पिघलाकर भराव धातु की सहायता से वेल्डिंग दो धातुओं को आपस में मिलाने की प्रक्रिया वेल्डिंग कहलाती है ।

सामान्यत: वेल्डिंग प्रक्रिया का उपयोग विभिन्न प्रकार के धातुओं ,थर्मोप्लास्तिक या लकड़ी को जोड़ने में किया जाता है किन्तु प्रत्येक को जोड़ने के लिए अलग अलग प्रक्रियाओं का उपयोग किया जाता है ,जिस पर नीचे विस्तार से चर्चा करेंगे ।

वेल्डिंग प्रक्रिया में भराव सामग्री का उपयोग

भराव सामग्री आधार धातुओं के बीच एक मजबूत संबंध स्थापित करने में मदद करती है। भराव सामाग्री ,प्राय : उन धातुओं में प्रयोग किया जाता है जनकी मोटाई होती है ,अत्यधिक पतले गटकों को जोड़ने के लिए भराव सामग्री आवश्यक नहीं होता है ।

भराव सामग्री का चयन धातु के आतंरिक तत्वों के मिश्रण के आधार पर किया जाता है ।

परिरक्षण प्रक्रिया

आधार और भराव घटकों को ऑक्सीकृत होने से बचाने के लिए वेल्डिंग के बाद परिरक्षण प्रक्रिया का उपयोग किया जाता है। इस प्रक्रिया के अन्तर्गत सामान्यत : अक्रिय गैसों , फ्लक्स ,आदि का उपयोग किया जाता है ।

वेल्डिंग के बारे में

यद्यपि प्राचीन काल में वेल्डिंग का उपयोग मात्र एक कला के रूप में आरम्भ हुआ किन्तु समय बीतने के साथ साथ इसका विस्तार होता चला गया , आज यह एक पूर्ण रूप से विकसित विज्ञान का रूप ले चूका है । आज विश्व व्यापी स्तर पर कंपनिया एवं संस्थान इस तकनीक पर दिन रात काम कर रहे हैं । जिसके परिणाम स्वरुप आधुनिक समाज का निर्माण संभव हो सका है । इसके बारे में पिछले आर्टिकल(वेल्डिंग का इतिहास ) में विस्तार से चर्चा की जा चुकी है ।

वेल्डिंग के अनुप्रयोग

वर्त्तमान युग में वेल्डिंग का प्रयोग जीवन के हर क्षेत्र में हो रहा है , चाहे वह घरेलु उपकरण हों या व्यावसायिक संस्थानों में लगने वाले उपक्रम हों ,कुछ सामान्य अनुप्रयोग निम्न हैं :-

निर्माण कार्यों में

वेल्डेड इंजन माउंट आदि
जेट इंजन के लिए टर्बाइन फ्रेमआदि
रॉकेट मोटर ईंधन और ऑक्सीडाइज़र टैंक आदि
डक्ट्स, फिटिंग्स, काउलिंग, कंपोनेंट्स आदि

ऑटोमोबाइल निर्माण कार्य में

आर्क वेल्डेड कार के पहिये इत्यादि
स्टील रियर एक्सल हाउसिंग आदि
फ्रेम साइड रेल आदि
ऑटोमोबाइल फ्रेम ब्रैकेट आदि।

पुलों एवं घाटो निर्माण में

सेक्शन की लंबाई।
सेक्शनकी दुकान और फील्ड वेल्ड असेंबली, आदि।

इमारतें की संरचना के निर्माण में

कॉलम और बेस प्लेट्स इत्यादि
संरचना का निर्माण, आदि।

दबाव वाहिकाओं और टैंक निर्माण में

क्लैड और लाइनेड स्टील प्लेट्स।
शैल निर्माण
नोजल को खोल से जोड़ना, आदि।

भंडारण टंकियों के निर्माण में

तेल गैस और पानी भंडारण टैंक।

रेल सड़क उपकरण निर्माण में

लोकोमोटिवअंडरफ्रेम
हवा रिसीवर यन्त्र।
फ्रंट और रियर हुड, आदि।

पाइपिंग और पाइपलाइन बिछाने में :

रोल्ड प्लेट पाइपिंग
खुले पाइप जोड़
तेल, गैस, और गैसोलीन पाइपलाइन इत्यादि।

जहाजों के निर्माण में :

शैल फ्रेम
डेक बीम और बल्कहेड स्टिफ़नर।
गोले के लिए गर्डर्स।
चढ़ाना, आदि के लिए बल्कहेड जाले।

इसके अतिरिक्त अन्य क्षेत्र भी हैं जिनमे वेल्डिंग प्रक्रिया का उपयोग अधिक होता है जैसे,

ट्रक और ट्रेलर के निर्माण में ।
मशीन टूल फ्रेम, कटिंग टूल्स, आदि।
घरेलू और कार्यालय फर्नीचर।
अर्थमूविंग मशीनरी और क्रेन।

इस प्रकार हम देखते हैं कि लगभग हर क्षेत्र में वेल्डिंग प्रक्रिया का उपयोग व्यापक रूप से हो रहा है और मानव समाज को प्रगितिशील बनाये रखने में इसका भरपूर योगदान है।

वेल्डिंग के प्रकार

वर्त्तमान में बहुत मेटल्स को जोड़ने के लिए , कई विधियों का उपयोग किया जाता है जिनमे सोल्डरिंग ,रिविटिंग ,ब्रेजिंग के साथ साथ कई वेल्डिंग प्रक्रियाओं का उपयोग किया जाता है जिनको उनके द्वारा उपयोग किये गए स्रोतों एवं कार्य शैली के आधार पर निम्न प्रकार वर्गीकृत किया जा सकता है जैसे :-

आर्क वेल्डिंग ,गैस वेल्डिंग ,रेजिस्टेंस वेल्डिंग ,सॉलिड स्टेट वेल्डिंग ,थर्मो केमिकल वेल्डिंग ,रेडिएंट एनर्जी वेल्डिंग इत्यादि इन वेल्डिंग प्रक्रियाओं के अंतर्गत बहुत सारी आधुनिक वेल्डिंग प्रक्रियाएं आती हैं जिनपर नीचे विस्तार से चर्चा करेंगे ।

आर्क वेल्डिंग ARC WELDING

आर्क वेल्डिंग प्रक्रिया (Arc welding process ) को चाप वेल्डिंग प्रक्रिया भी कहा जाता है । आर्क वेल्डिंग ,वेल्डिंग प्रक्रियाओं का एक समूह होता है जिसमे बहुत सारी वेल्डिंग प्रक्रियाएं सम्मिलित हैं जैसे :-

SMAW (परिरक्षित धातु आर्क वेल्डिंग)
GTAW (गैस टंगस्टन आर्क वेल्डिंग)
CAW (कार्बन आर्क वेल्डिंग)
SAW (जलमग्न आर्क वेल्डिंग)
GMAW (गैस मेटल आर्क वेल्डिंग)/MIG
PAW (प्लाज्मा आर्क वेल्डिंग)
ASW (आर्क स्पॉट वेल्डिंग)
FCAW (फ्लक्स कोर्ड आर्क वेल्डिंग )
इलेक्ट्रोस्लैग वेल्डिंग तथा इलेक्ट्रोगैस वेल्डिंग (Electro slag and Electrogas welding)
SW (स्टड आर्क वेल्डिंग)

वेल्डिंग के फायदे और नुकसान

लाभ

वेल्डिंग मजबूत, टिकाऊ और स्थायी संयुक्त लिंक स्थापित करता है।

वेल्डिंग की प्रक्रिया एक उत्कृष्ट फिनिश में परिणाम देती है।
भराव सामग्री के साथ उपयोग किए जाने पर यह तकनीक आधार सामग्री की तुलना में अधिक मजबूत वेल्ड का उत्पादन करती है।
वेल्डिंग किसी भी स्थान पर की जा सकती है।
वेल्डिंग एक किफायती और किफायती प्रक्रिया है।
निर्माण, लोहा और इस्पात, ऑटोमोबाइल और कई अन्य उद्योगों जैसे क्षेत्रों में वेल्डिंग की भारी मांग है।
वेल्डिंग के माध्यम से जोड़ी गई सामग्री , सामान्य सामग्री संरचना के अनुरूप हो जाती है तथा इसको आसानी से टुकड़ों में नहीं काटा जा सकता है।

हानि

वेल्डिंग एक कठिन प्रक्रिया है; इसलिए, इसे सुरक्षा और सुरक्षा मार्गदर्शक सिद्धांतों के तहत किया जाना आवश्यक है ।
वेल्डिंग के लिए कुशल श्रम और एक अच्छी बिजली की आपूर्ति की आवश्यकता होती है,
वेल्डिंग के लिए प्रयुक्त मिश्र धातु हानिकारक धुंए का उत्सर्जन करते हैं जो स्वास्थ के लिए हानिकारक होता है ,

Welding as compared to riveting

2021-06-21T23:40:00.003+05:30

Welding as compared to riveting

Riveting is an old and important technique used to join metals together. But nowadays its area is decreasing due to the developed welding technology.

Preface

Several new methods of welding and soldering have been adopted in today's modern era. The main reason for using different sources of welding is to reduce the cost/time involved in manufacturing the equipment or in the plant.

In today's time, the welding process is being used more than the riveting process, used earlier in bridges, ships, boilers., etc. Similarly, in many fields, the welding process has gradually replaced the riveting process due to time and cost savings.

Welding as compared to riveting and casting

If welding is compared with riveting then it is a more economical and faster method.
The use of mild steel has increased in place of cast iron as compared to earlier because it is lighter than cast iron and welding can also be done easily, by this way, it is cheaper and the work gets done faster.
In terms of tensile strength, mild steel structures are stronger than cast iron.
With the development of advanced welding techniques, it became possible to join metals of two different properties (dissimilar metals) together.
It also became possible to manufacture complex structures such as structures with high tension and other desired properties.
The most important fact is that Structural shapes that are not easily obtained with riveting or casting can be produced by welding without much difficulty.

Apart from this, many other factors are influential in reducing the popularity of rewriting such as:-

Welding as compared to riveting and casting

There is less noise in the welding process as compared to riveting, this becomes more important when a modification, repair, or extension work has to be done in a sensitive area, such as in a hospital area.
Less manpower is used in doing fabrication work through welding as compared to riveting work.
Welding fabrication against riveted construction involves a lower cost of handling.
The welding design involves low cost and is very flexible as well as saves the machining cost involved in the manufacturing of cast parts.
In this context, the most important fact is that the ratio between the weight of the weld metal and the overall weight of the structure is much less than the ratio between the weight of the rivets and the overall weight of the structure.
The cover plate connecting angle gusset plates etc. is not required in riveted construction when welding structures.
Such shaped members that present difficulty for riveting can be easily welded.
Welding can be done at any point on a structure, but riveting always requires adequate clearance.
The layout does not require punching or drilling of holes in welding.
Drilling holes in plates to accommodate rivets break the continuity of the material and weakens a riveted structure.
Old structures can be easily strengthened by welding.
A welded structure processes a better finish and appearance than the related riveted structure.
The cost of a standard rolled section is much lower than casting, resulting in lower material costs involved in welded structures.
Making changes to an already inserted or riveted structure is extremely difficult, if not impossible. On the other hand, a welded structure can be modified or repaired without any difficulty.
Welding can produce a 100% efficient joint that is difficult to make by riveting.

Riveting high strength steels increase the problem of obtaining high-strength steel rivets.

Conclude

While welding claims its supremacy, casting, although it has its good points. such as A product is obtained as one piece, very heavy and bulk parts like those of power plants and mill housings, which are otherwise difficult to fabricate can be cast.

Absorption of gases in weld

2021-06-03T01:10:00.005+05:30

Absorption of gases in welds

Absorption of gases can cause a significant metallurgical change in the formation of molten weld pools.

The gases may react with the molten welds and with each other. Gases such as hydrogen, nitrogen, and oxygen are the most frequently absorbed in the weld pool.

Typical faults include

Defects such as Porosity, Cracking, and Oxide inclusions are produced as a result of the gases absorbed in the weld metal.

Source of gas

There are three major sources that cause Absorption in almost all metal arc welds.

Electrodes
Atmosphere and
Parent metal

Electrodes

Electrode core wire is a source that can contain significant amounts of dissolved oxygen as well as some hydrogen and nitrogen.

Electrode coatings release gases such as hydrogen, CO, and CO2 during welding. Coatings cause more problems if they are moist.

Atmosphere

In the absence of adequate shielding, the molten weld metal comes in contact with atmospheric oxygen, nitrogen, and water vapor. The gas content of the base material frequently depends on the method of manufacture of the metal.

Parent Metal

The gas content of the parent metal will depend to a very great extent on the method of manufacture of the plate. Usually, the hydrogen content of plate materials is much lower, which is of the order of 1ml H2 per 100 grams. The oxygen content may range from 0.001%to 0.004% or higher if a Bessemer-quality plate is considered.

Hydrogen and its effects

As discussed above, the main source of hydrogen is electrode coating or the atmosphere. Hydrogen may often be present in the coating, as cellulose or moisture, and as moisture in the atmosphere.

Immediately after the welding process, the hydrogen weld starts to come out of the metal and continues to do so for a long time.

Defects arising due to the presence of hydrogen

The presence of hydrogen may cause of reduction in the tensile strength of the weld, make the arc erratic, and contributes to the formation of colling cracks or fisheyes in welds. Underbead cracking is often attributed to the effect of hydrogen dissolved in retained austenite in combination with other factors.

Nitrogen and its effects

The source of nitrogen is also the base metal, electrode core wire, and atmosphere.

Compared to the acetylene welding process, the absorption of nitrogen is much higher in arc welding.

Nitrogen is found in weld metal trapped in a blowhole (although nitrogen itself does not form a blowhole)and in the form of crystals or iron nitride (Fe4N).

Defects arising due to the presence of Nitrogen

Nitrogen tends to

Lower the corrosion resistance of weld metal
Increase hardness, yield, and tensile strength
Decrease ductility and impact resistance.

Oxygen and its effects

Oxygen is a major factor in gas contamination of the weld metal as it is present in significant quantities in the electrode core wire and may also be present in large amounts in the parent metal and on the parent metal as oxide or scale.

Oxygen may be absorbed into the weld, forming iron oxide(Fe3O4)and other oxides such as silicon. The iron oxide may react with carbon in the steel to form CO resulting in blowholes.

C + O ⇾ CO ( gas bubbles)

If the iron oxide is present, oxidation of the weld will occur and this will produce a great increase in the grain size.

Absorption of oxygen by weld:

Reduces its tensile strength and ductility and

Decrease its resistance to corrosion.

Deoxidizers such as Mn, Si, Al, Ti, etc. may be added to electrodes to prevent the formation of iron oxide

Prevention of Gaseous Contamination

In metal arc welding, the method employed to prevent contamination of the weld metal by gases is to coat the electrode wire with non-metallic materials. This coating serves two purposes

By decomposition in the heat of the arc, it provides a protective atmosphere of the gas, which resists contamination of the weld metal by the air.

It forms a low melting point slag which protects the molten weld metal from contamination during solidification.

Conclusion

Finally, in some coatings, additions of deoxidants are made, which reduces the available oxygen in the weld metal.

Oxygen Arc Cutting

2021-05-17T12:03:00.003+05:30

Oxygen Arc Cutting

Oxygen arc cutting is a process of severing metals. It is processed at high temperatures through the chemical reaction of oxygen with the base metal.

This cutting method is quite similar to the oxy-acetylene cutting process, except that the heat is supplied by the electric arc

The required temperature is maintained through an arc between a consumable tubular electrode and the base metal. The tubular electrode is a covered electrode with a small diameter hole down through the center through which oxygen is blown.

Principle of Operation

In this method, a specially designed electrode holder is used to hold the tubular electrode and pass oxygen flow through the electrode.

Here, an arc is generated between the metal and the electrode to be cut, then the oxygen valve and electrode holder are opened, the oxygen passes through the electrode hole and impinges over the area of the metal to be cut and heated by the arc action than the cutting begins as in the oxy-acetylene cutting process.

The point to note here is that, in the oxy arc cutting process, the current value is up to a maximum of 30–45 volts, and during cutting, the electrode is slowly consumed at the cutting site due to intense heat.

Equipment used in oxygen-arc cutting

Power source
Electrode holder
Tubular electrode
Oxygen cylinder, Pressure regulator, Hose pipe,
Safety equipment

Applications of oxygen-arc cutting

The oxygen arc cutting process is primarily used in underwater cutting applications,

Advantages of oxygen-arc cutting

it can cut, pierce and gouge the metals,

The disadvantage of oxygen-arc cutting

It is not suitable for cutting non-ferrous metals.

Chemical Flux Cutting

2020-12-10T01:56:00.001+05:30

Chemical Flux Cutting

Chemical Flux Cutting is an oxygen cutting process wherein the severing or removal of metals is obtained by the use of a chemical flux to obtain cutting.

Since chemical flux is mixed with oxygen in this process, it is also called the flux injection cutting process.

Use of Chemical Flux cutting

Chemical Flux Cutting is used to prevent the interference of refractory oxides formed during the cutting of stainless and other oxidation-resistant alloys. It is achieved through the use of a chemical flux. Flux cutting is mainly used for cutting stainless steel materials.

Principle of operation

While passing through the flux feed unit, the cutting oxygen carries the flux to the torch as a mixture of oxygen and flux flows through the oxygen hole of the torch tip.

Fluxes are prepared to react with oxides of chromium and nickel, to build combinations with melting points near iron oxides. In order terms, the flux increases the fluidity of the refractory oxides so that they fly out of the iron to the kerf, and can be more easily oxidized.

Equipment

The equipment required for cutting flux is similar to that used for cutting powder.

Benefit

Stainless steel can be cut without torch oscillation and at approximately the speed at which carbon steel of the same thickness is cut by cutting oxy-acetylene.

Metal powder cuttng process

2020-12-03T22:51:00.001+05:30

Metal power cutting

Metal powder cutting process is a type of oxygen cutting process wherein the severing or removal of metal is affected by the use of metal powder such as iron powder to facilitate cutting.

Introduction

Metal powder cutting was introduced in 1943 for cutting stainless steel.

Materials such as stainless steel, cast iron, and other oxidation-resistant metals/alloys are not readily cut by the ordinary oxidation process, primarily because high melting point (refractory) oxides are formed. These oxides such as chromium, oxide are not oxidized or melted at the usual temperatures produced in oxy-acetylene cutting, and they also prevent the cutting oxygen from coming in contact with the iron in the material being cut.

Therefore in order to cut the above-mentioned materials, two processes were developed namely

Metal power cutting and Chemical flux cutting

Principle of operation

Finely divided iron powder is injected into the cutting flame through a special opening in the tip of the torch. These iron particles are rapidly oxidized, causing a sudden increase in heat at the surface of the metal. As a result of intense filler heat, refractory oxidation occurs as the metal is melted from the surface and consequently flows through the cutting area. This allows the flame of the torch to come into contact with the metal iron and thus proceeds without any disruption.

Iron powder, when introduced into the cutting area, accelerates and promotes the oxidation reaction and also melts and swallows hard to cut material.

Some powders react chemically with refractory oxides produced in the kerf and increase their fluidity.

The resulting molten slag is washed from the reaction zone by a jet of oxygen.

Fresh metal surfaces are in constant contact with the oxygen jet.

Mixtures of iron powder and metal powder, such as iron and aluminum, are used.

Equipment

Cutting torch
Hopper and a supply of powder
Powder dispensing unit

One type of dispenser is a vibratory device in which the quantity of powder dispensed from the hopper is governed by a vibrator i.e., by adjusting the amplitude of vibration. This system gives a uniform and accurate powder flow and is used for precision cutting of materials.

The second dispensing unit is a completely pneumatic device. In this, an enclosed iron powder hopper(vessel)is used. The hopper is filled with iron powder and then pressurized. The powder is then fed under constant pressure to the powder cutting torch whenever the powder control valve on the torch is opened. Air or Nitrogen may be used to supply the pressure on the powder dispenser. Never use oxygen in place of air or nitrogen as it may form an explosive mixture.

The iron powder hopper is designed to provide an automatically uniform flow of powder and may operate in conjunction with the cutting oxygen valve on the torch.

The gas conveyed powder is introduced into the cutting oxygen prior to its discharge from the tip.

Cylinder, supplies, and regulators of oxygen, acetylene, and nitrogen.

Oxygen and acetylene hoses.
Powder control regulator
Powder control valve and ejector device.

Metals cut by powder cutting

Stainless steel
Cast iron
Nickel chrome, nickel, and chrome alloys (Oxydation resistant steels)
Aluminum
Steels containing more than 5% alloy
Copper

Advantages of powder cutting

Powder cutting method can cut oxidation resistant steel at approximately the same speed as oxy-acetylene cutting of carbon steel at equivalent thickness.

By this method (mechanized) can cut metals up to 150 cm thicker sections.

Disadvantages

Powder cutting raises quite a bit of smoke that may interfere with other operations in the area.

Extra work is required to grind off powder contamination of the cut surface.

Oxygen Lance cutting process

2020-12-01T23:52:00.001+05:30

Oxygen Lance cutting process

Oxygen lance cutting is a metal severing /removal process wherein metal is effected by oxygen supplied through a consumable lance and the pre-heat is obtained by means.

Oxygen Lance

Oxygen lance is actually a steel pipe having an internal diameter of 3 to 6 mm..Oxygen lance cutting process is used to cut heavy thick sections which are not possible to be cut by an oxy-acetylene flame cutting process.

By the oxygen lance cutting process, up to 240 cm, thicker sections can be cut properly, whereas an oxy-acetylene process can cut up to 60 cm.

Equipment

Oxy-acetylene Welding or cutting torch
Cylinder(oxygen+acetylene)
Pressure regulators and hose pipe
PPE

Operating principle

The metal edge is first heated through a heavy-duty welding or cutting torch until it turns red. Then bring the oxygen lens against this preheated section and release oxygen (about 40 to 50 psi pressure) through the pipe. Oxygen in combination with preheated steel results in rapid oxidation of the surface. The oxygen jet cuts the metal section and blows the reaction products there.

When cutting relatively light sections, the torch is removed, once the oxygen for the lance is on. When cutting extremely thick sections, constant temperature is maintained using a special, long torch during cutting. The cut is usually initiated at an angle and brought to a vertical position by manipulating the lens and of course torch if used continuously.

During cutting, as the lance reaches the bottom of the metal in the direction of depth, it is brought back( up) and lowered again by cutting.

Advantages of oxygen lance cutting

BY this process heavy thick steel sections can be cut.

Suitable for cutting economically large steel and cast iron sections.

An excellent tool for piercing holes in steel plates and castings.

See More- Flame cutting process Oxygen cutting process

Thermal cutting of metals

Next Issue- Metal Power Cutting

Flame cutting ,types and process

2020-11-26T20:18:00.010+05:30

As we have discussed earlier, Flame cutting is a process of Oxygen cutting and. . It is affected by, the chemical reaction of oxygen with the base metal at elevated temperatures.

Flame cutting

The flame cutting process is also called the oxy-fuel gas cutting process and is mainly used in two ways:

By manual flame cutting process,
By machine flame cutting process.

Manual or Hand Flame Cutting

Manual flame cutting is fully operated upon the skill of the operator, in this process, the torch is held and guided by the operator, it gives less accuracy and smoothness as compared to machine flam cutting. However, manual cutting can be used with serviceable accurateness on thicknesses up to 200 to 300mm.

The consumption of oxygen is usually much greater in manual cutting than in machine cutting, it is widely employed on production jobs and in scrapping operations

Machine flame cutting.

Machine cutting machines are designed to hold the torch(or torches)in specific predetermined positions, it provides greater speed, accuracy, and economy. These types of machines are preferred when materials to be cut in large amounts. The flame cutting machine may be categorized as follows:

Portable (transportable) machine

Generally, a portable system includes a variable speed driven motor carriage with an adjustable mounting for the torch. the device generally travels on a track, which guides to the torch.

To function ignites the torch positions it at the beginning point, adjust torch height above the work floor to be cut, initiates cutting oxygen flow and carriage travel. At the end of the cutting, shut off the carriage and cutting torch. Maximum transportable machines are made to work both on a line or in a circular track. numerous sized circles can be cut through the putting made on a radius-rod attachment.

Cutting machine

Stationary Machines

Static machines are much heavier and larger than portable machines. These machines mainly cut plates into straight-line cuttings or strips, plate edge preparations for welding purposes, bevel cuts from these machines can easily be made by tilting the torch at the desired angle.

Stationary machines remain in a fixed location, a machine in the workshop, a system to supply oxygen and acetylene, and a material handling system. The torch support train runs on the track. The cutting machine structure either expands the work with a gland. Type bridge across tracks or it can be cantilevered from one side of the tracks.

Shape cutting

Shape cutting refers to any regular or irregular contour cutting of metal. Shape cutting of metal. Shape cutting machines are of two types, a pantograph and a cross-carriage mechanism type.In both these machines the basic element is a floating bar with one or more torches located on one end and a tracing or driving device on the other.

In the cross carriage type, the carriage rides on the rails. The bar holding the torches can be easily moved at right angles to the carriage on which it rides. In the pantograph machine, the bar is held by two arms that fold open and shut. The complete pantograph assembly is mounted on a carriage riding on rails.

A shape cutting machine has to make use of tracing devices, as listed below, to guide it to cut different shapes:

Magnetic tracer

The amagnetic tracer adheres to and follows the outline of a steel template. The workpiece gets cut to the same shape as that of the template. Big gears may be cut from the plates by using a magnetic tracer.

Photoelectric tracer

A photoelectric tracer, which in essence, is an electric eye, follows the outline of a pencil or ink sketch of an intricate shape and guides the driving wheel. Traction for driving the machine comes solely from the driving wheel.

Metals cut by Flame Cutting

· Carbon steel and low alloy steels, Cast iron, Wrought iron, High alloy, and stainless steel

· Advantages of Flame cutting

This process is faster than mechanical cutting methods and costs less than machine cutting machines such as mechanical cutting machines.
Shapes and sizes machined by mechanical means can be cut easily by cutting flame.
Flame cutting equipment, being portable, can be easily used for fieldwork
Multi-torch machines can cut multiple pieces at once.

Disadvantages of Flame cutting

· Flame cutting is limited to the cutting of steel and cast iron.
As compared to mechanical cutting, the dimensional tolerances are poor.
The area of cutting needs adequate ventilation and proper fume control.
The expelled red hot slag and other particles produced fire and burning risk to plants and workers.

· Uses and applications

To prepare edges for bevel and groves of the weld joint.

To cut small-sized workpieces from bigger plates for further processing, cut rivets, gates, and risers from castings. cutting many layers of thin sheets at the same time(stack cutting)to reduce both time and cost for production works. pierce holes and slots in steel plates, for salvage works.

Oxygen cutting: Types and processes

2020-11-25T22:31:00.007+05:30

Oxygen cutting

The oxygen cutting process is the most common (metal severing ) process used by industries in daily practice.

Definition

Oxygen cutting is a group of metal cutting processes in which the decomposition or removal of metals is carried out through a chemical reaction of oxygen with the base metal at elevated temperatures.

Generally in this process, the required temperature is being maintained through a gas flame obtained from the combustion of acetylene, hydrogen, propane, etc.

The chemical reaction of oxygen with the base metal

Fe +O ➝FeO + Heat (276 KJ)

3Fe+2O₂ ➝Fe₃O₄ +Heat (1120 KJ)

Types of oxygen cutting processes

There are many methods used in oxygen cutting process, such as

Oxy-fuel Gas cutting

Oxy-Fuel Gas Cutting Process is also called Flame Cutting Process. It is a process of gas cutting metal, which effected by the chemical reaction of oxygen with the base metal at elevated temperatures. The required temperature is being maintained through a gas flame derived from the combustion of fuel gas.

Equipment used in Oxy-Acetylene Metal Cutting Process

Cutting torch
Oxygen and acetylene gas cylinders
Oxygen and acetylene hose and fittings
Regulators
Flame striker
Flame

Cutting torch

Cutting a torch made of a yellow brass body. It combines acetylene and oxygen and carries the gas mixture into the holes where it is ignited to produce flames. The cutting torch differs in some ways from the Oxy-fuel gas welding torch because it has an extra pass for the flow of high-pressure cutting oxygen and it has a tip with a centrally located hole and several others located around the central one in a circular pattern. Small orifices.

The act of cutting off the oxygen takes place in the central pore from which it emerges, it oxidizes the metal and blows away from an open slot (kerf).

Types of cutting torches

There are two types of cutting torches

Injector type,

In these types of torches, acetylene is transported to the torch at pressures below 1 PSIG. Acetylene is drawn into the torch with the help of an injector. For preheating flames, acetylene and oxygen are added to the tip of the cutting torch.

Equal pressure type

In these types of torches, oxygen and acetylene are distributed at pressures above 1 PSIG.

The mixture of gases is inside the torch (and not in the tip)

Torch Tip

The tip of the torch is usually made of copper alloy material and is available in many designs and sizes, it is tightened through the tip nut inside the torch. It has a hole in the middle and around it There are small holes which are circular in shape.

The design of the tips (ie, the size and number of preheating flame ports and the size of the central orifice) varies for different metal thickness cuts and also depends on the material and its surface condition.

Next issue: Types of Flame cutting

Thermal cutting of metals: definition, types and processes

2020-11-24T00:51:00.003+05:30

Thermal cutting of metals

Cutting is the process of separating metals. Through this, the metal is obtained with a specific size or desired length. Today metal cutting is a daily practice in the industry.

Introduction

Countless kilometers of pipes are being laid today for various purposes in the industry world, where the cutting of metals is an everyday practice.

Cutting desired length and shapes of (rolled)metal pieces for assembly and other processing work performed on various machine tools and presses require either the gear blonde to be cut from the plate or the subsequent formation requires an empty cut from the plate.

The main reasons for cutting metals can be as follows:

To prepare the edges of plates for simultaneous welding
For cutting gate and riser from casting
For dispose

Types of cutting Process

The cutting process is employed by several methods, the following being the mainly used procedures.

By mechanical process

Under this process, metal is cut through machines. Nowadays a lot of new updated machines have come up, using which it has become very easy to cut the metal, which also reduces the cost over time.

By chemical reaction

In this process, flammable gases along with oxygen are used to cut the metal. Which are as follows:

Oxygen cutting

The oxygen cutting process is the most common cutting method used by industries in today's era.

Oxygen cutting is a set of cutting processes, in which the separation or removal of metals is effected through the chemical reaction of oxygen with the base metal at elevated temperatures.

In the case of oxidation-resistant metals, this reaction is facilitated by a chemical flux or the use of a metal powder.

Oxygen cutting may be categories as follows:

The oxy-fuel gas(Flame)cutting process
Oxygen Lance cutting process
Metal powder cutting process
Oxygen Arc cutting process

Next issue: Oxygen cutting

Brazing process

2020-11-22T01:03:00.002+05:30

Brazing process

Brazing process is a group of joining processes wherein coalescence is produced by heating to an appropriate temperature and by using a filler metal having a liquidus above 800°F(470°C) and below the solidus of the base metals.

Introduction

Although brazing is a process of joining metals together by using an appropriate heating method, it differs from the welding process.

Brazing associated with melting of a relatively low melting point filler material. Typically, brazing involves comparatively melting point filler content (450℃ ) or below the melting point of the base metal,

Steps involved in Brazing process

The brazing process involves the following steps:

1-Cleaning and surface preparation

2- Application of flux on both surfaces of base metal and filler metal.

3-Heating the joint

4-Application of filler metal on to the joint

5- Cooling of the braze joint and removing the flux residue from the compleated joint.

Difference between Brazing and welding

The main difference between a welded joint and a brazed joint is the penetration. A brazed joint has no penetration into the base metal whereas welded joint achieves penetration into the base metal.

Surfaces to be brazed are not raised to the melting point, rather the joint is produced by the solidification and adhesion of a thin layer of molten filler metal to closely-adjacent mating surfaces; whereas, in welding, the two surfaces to be joined are actually melted.

Weld bead shows ripples whereas a brazed joint does not because the molten brazing filler alloy spreads along the joint whereas molten filler metal in welding solidifies almost at the same place where it melts.

Joint design for Brazing

The controlled closed fit between the surfaces to be joined is essential in the brazing process.

It is kept in mind that the joint should meet service requirements such as

Mechanical performance, Electrical and Thermal conductivity, Pressure tightness, corrosion resistance, service temperature and good appearance.

Gravity welding process

2020-11-14T04:06:00.003+05:30

Gravity welding process

Gravity welding is a type of Arc welding process wherein heat is obtained by an electric arc, between a long electrode and a job..

Preface

Gravity welding could not expand much due to its complexity. The reduced length of the electrode and the difficulties of controlling the arc length have hindered the development and exploitation of suitable systems.

Working process of Gravity welding.

Gravity welding is an arc welding process in which electrodes of maximum size are fastened to an electrode holder, which can slide up and down a bar or rod held at a predetermined angle. The top of the electrode is located at the root of the joint. After the arc starts, the end of the electrode melts.

As the electrode shrinks, the holder bar slides down. Keeping the tip of the electrode with the joint. This weld is deposited until the electrode is lowered to about 50 mm, at which point the motion of the holder stops, and the arc is extinguished.

Again the fresh electrode is placed in the holder. The slider strip is moved along the joint, and the weld is restarted at the point at which the previous electrode was closed.

The successful operation of gravity welding depends on two factors. First, the electrode must have a flux that melts as a cone at the tip. While resting the outer edge of the flux cone on the plate in the joint, the arc length is controlled by the melting of the flow.

The second point is that the angle between the slider bar and the joint must match the melting rate of the electrode if the system is to be stable.

Definition of the Gravity welding process

The gravity welding process is an arc welding process wherein
heat is obtained by an electric arc, between a long electrode and a job.

Advantages of Gravity welding

Electrodes used in gravity welding are made over a larger length, leading to fewer electrode changes for a given run length than manual welding.
The gravity welding process reduces the time it takes to convert electrodes, which is why it is slightly faster than the manual welding process.

Diffusion welding (Bonding) Process

2020-11-01T01:19:00.005+05:30

Diffusion welding

Preface

The recent development of solid-state welding technology has further enabled the production of welds in various metals. Diffusion welding is also a type of solid state welding.

Definition of diffusion welding

Diffusion welding / bonding is a solid-state welding process, in which welding is performed with applications of pressure and elevated temperature for coalescence of faying surfaces. This is done to cleaned carefully and mated metal surfaces so that they actually grow together by atomic diffusion.

.Theory of Diffusion welding

The diffusion welding process develops in two stages.

First stage

The first step is to bring the intimate metal into contact with the metal. This is done by the application of pressure which distorts the roughness of the substrate and disrupts and expands the above mentioned surface layers and contaminants.

Second stage

The second stage consists of diffusion and grain growth to complete the weld and finally to eliminate the interface formed in the previous phase. The second phase induces complete metal bonding in the area of contact.

Method of diffusion welding (bonding)

Diffusion welding includes the following types of methods.

Gas-pressure bonding

The joining parts are held together in intimate contact and then heated to around 815 degrees centigrade. During heating, an inert gas pressure is created on all surfaces of the parts to be welded. Non-ferrous metals are joined with the help of the gas pressure bonding method.

Vacuum fusion bonding

The parts joining it are pressed together mechanically or hydraulically. A welding press which is used for diffusion welding, is employed in forging and is equipped to make pressures from three directions.

The heating is done in the same way as in gas pressure bonding. These processes are performed in a vacuum chamber. Nevertheless, more pressure than can be applied to gas pressure bonding can be applied in this process, steel and for that vacuum fusion bonding is used.

The temperature and pressure required for the propagation relationship of steel is about 1150 degrees centigrade and 700 kg / Cm²

Eutectic fusion bonding

It is a low temperature diffusion welding process in which a thin plate of some other material, such as nickel, is added. As the pieces are heated to an elevated temperature, the filler material expands and forms an Eutectic compound with the base metals.

Parameters of Diffusion Welding

The parameters of diffusion welding are as follows:

Pressure
Temperature
Time Surface

Uniform pressure assures stability of bond formation and The elevated temperature performs the important function of increasing the surface energy (mobility of the atom).Time is a dependent process parameter such as an increase in temperature, reducing the time required to complete the confounding process.

Other parameters

Metallurgical Factors
Surface Preparation.

Advantages of Diffusion welding

The main advantage of diffusion welding is that the weld metal having essentially the same properties as the base metal.
Dissimilar metal can be welded by this process also.

Application of Diffusion welding

This process is mostly applied in the nuclear power industries to fabricate components, manufacture composites materials, and use in the aerospace missile and rocket industries

Cold welding process Ultrasonic welding process

Importance of gases in the welding operations

2020-10-08T23:51:00.007+05:30

Introduction

Welding processes include various gases used for different purposes. Some of them are combustible and some are inert, some gases are also rich in oxygen. These gases are described here based on their usage.

Use of flammable gases by weld

Flammable gases are commonly used in a gas welding process in which oxygen is added to obtain the desired heat. The most commonly used gases in gas welding are as follows :

Acetylene +oxygen = 3100 °C to 3300 °C (Oxyacetylene)
Hydrogen + oxygen = 2500 °C (Oxyhydrogen)
Propane +Oxygen = 2500 °C ( Oxypropen)

See detail - Gas welding

Use of Shielding gases by weld

Shielding gases are used to protect the weld pool from harmful atmospheric gases, among these the gases mainly used in the welding process are as follows :

Argon, Helium, Carbon dioxide, Nitrogen, Hydrogen, and propane, etc.

See detail- Shielding gases

Absorption of gases by weld

A very important metallurgical change resulting from the creation of molten weld pools is the absorption of gases by it. These gases are absorbed into the molten metal and react with each other, resulting in welding defects such as porosity, cracks, oxide inclusions. etc.

This category contains gases such as hydrogen, oxygen, and nitrogen, which often cause problems.

There are three major sources of gases such as an electrode, the atmosphere, and the patent metal.

Electrodes

The electrode wire may contain considerable amounts of dissolved oxygen as well as some hydrogen and nitrogen. Which can develop carbon monoxide (CO), carbon dioxide (CO2), etc. gases at the time of welding.

See Detail -Welding electrodes,

The atmosphere

Shielding gases are used to protect the molten metal from atmospheric contamination. If there is no adequate shielding protection, these gases such as oxygen, nitrogen, and water vapor can come into contact.

The patent metal.

The amount of hydrogen, oxygen and nitrogen in the plate material is also in a limited proportion, and the hydrogen content of the plate material is, in general, fairly low, being of the order of 1 ml/100grms. If this amount becomes too much, then a problem can occur. The oxygen content may range from 0.001% to0.03 %. The Nitrogen content may vary from 0.001% to0.004% or higher if the Bessemer quality plate is considered
See Detail- The Material

See More:-

Protective tools for gas welding operation

2020-09-12T20:05:00.466+05:30

Protective tools for gas welding operation

OBJECTIVE

Flammable gas fires become more effective when combined with oxygen, which may invite any potential danger. To avoid this, some necessary steps should be taken before starting the welding as well as suitable safety tools should also be used.

GAS WELDING

Gas welding is a fusion welding process wherein the desired heat is obtained by mixing oxygen with flammable gas for welding work.

PRECAUTIONS

Keeping these precautions in mind, the risk associated with welding can be reduced to a great extent.

Gas cylinders...

The cylinder should be kept away from physical damage, heat, and tampering and Chain tools should be used safely to prevent falls, it is very important to keep them away from flammable and combustible materials.
Gas cylinders should not be exposed to welding flame, direct sunlight, water, etc.
Gas cylinders should be stored in a well-protected, well ventilated, and dry location.
Gas cylinders should not be stored near the welding work area or near the electrical circuit area and it should be Store in an upright position.
The gas cylinder shall be closed when it is empty.
Gas cylinders should be moved by tilting and rolling them off their bottom edges. Dragging or sliding of cylinders should be avoided. and valves of gas cylinders shall be closed before moving it.

Hosepipe...

A hosepipe connects the gas cylinder to the welding torch and through it, the gas reaches the torch. Typically, blue or green pipes are used for oxygen, while red-colored pipes are used for acetylene.

Since flammable gas with oxygen is used to ignite fires in gas welding, there is a risk of fire in this process, which requires some necessary steps to reduce.

Pressure regulators...

It is a type of valve that regulates the pressure of the gas and only allows the required value of the gas to flow from within.

Different types of regulators are used for oxygen and flammable gas. There are basically two types of regulators.

Single-stage regulator and
Double stage regulator See Detail👉 Pressure regulators...

Flashback arresters

Flashback arrester is also known as a flame trap. It is fitted to both oxygen and acetylene gas lines. The purpose of installing a flashback arrestor is to prevent a flashback flame from reaching the regulators. Flashback arrestors, usually detect/stop reverse
gas flow. Flashback arrester is actually allowed gas to move through it but prevents a flame to avoid a fire or explosion
.

Welding/cutting torch

A basic torch has the following parts

The torch body or handle - through which the torch is captured.

The Two separate gas tubes - through a handle attached to the hoses) that carry oxygen and combustible gases and further transport to the mixer chamber.

Apart from this, there are separate control valves, mixer chamber, flame tube, and welding tip, etc.

Welding Arc stability

2020-07-26T19:07:00.002+05:30

Welding Arc stability

Arc stability is an essential issue in the welding operation. in the sense of a stable arc, it must be uniform and steady

It produces a good weld bead and a defect-free weld nugget if it is stable.

An unstable arc can introduce many welding imperfections such as porosity, blowhole, slag entrapment, and lack of fusion, etc.
Several factors are responsible for the stability of the welding arc. Some common factors are discussed below.

Power source:

Appropriate matching of the welding arc and power source characteristics can control the welding arc variation.such as this can prevent the arc from extinguishing when the arc voltage is slightly variable.

For this purpose, a number of power sources are used to meet the requirements of various arc welding processes. A power source AC., DC. or both can give. It may also have the characteristic of providing constant current or voltage. In relation to the input.

Movement of electrode:

Mixing thorium or zirconium metal in welding electrodes to control electrode movement can maintain arc stability to some extent. By this, the electrode (cathode) and thermal ionization in the arc column produce a continuous and reasonable emission of electrons.

Other factors:

Electrodeposition
Arc current
Arc length
Presence of dirt, oil, grease on the surface of the base metal.

Possible welding imperfection due to unstable welding arc:

porosity:

Porosity is the group of cavities in the weld metal that results due to freezing of gas from the weld pool as it freezes. There can be many reasons for this defect such as:

Absorption of atmospheric gases like (oxygen, nitrogen, and hydrogen) in the molten weld pool.
The improper coating on the electrode.
Long arc length
Improper Current
Lack of welding technique.

Blowhole:

When entrapped gas pocket formed a single large cavity called Blowholes.

slag entrapment:

Slag inclusion is a type of slag entrapment between weld layers or between the base metal and weld metal, especially in the multilayer welding process, but sometimes it can come in single pass welding also. Slag inclusion occurs in which the slag material is used like SMAW, SAW.

Lack of fusion:

Lack of fusion occurs, when the weld metal fails to fuse boundaries of the base metal or sidewall of the base metal,

Lack of fusion can come in the sidewall of the base metal or between inter pass and root area respectively called Lack of sidewall fusion, Lack of inter run fusion, and Lack of root fusion. The root cause of this defect is an unstable arc due to improper cleaning, Low welding current, fast arc travel speed, short arc length, and lack of preheating in thicker metals.

Welding of carbon steels: Standard codes and classifications

2020-05-16T12:14:00.002+05:30

Welding of carbon steels

Carbon steel is a type of steel that is most widely used for welding in industries today, due to its flexibility, strength, and workability under the fabricating method and relatively low price.

Carbon steels are classified as follows:

Low carbon steel

Medium carbon steel

High carbon steel

Although carbon steel is a metal that is welded over a wide range, it has some grades that are not easily welded. Carbon steel is grouped with different percentages of "carbon". This percentage of carbon also affects weldability.
Carbon steels are classified with different ASTM codes and grades for different types of products :
ASTM code for carbon steels pipes:
ASTM A53 Gr. A/B, ASTM A106 Gr. A/B/C, ASTM A333 Gr.1/Gr.6
ASTM code for carbon steels tubes:
ASTM A178/179/192, ASTM A334 Gr.1/6.
ASTM code for carbon steels plates: -
ASTM A285, ASTM A515, ASTM A516.

Welding of carbon steels

Low carbon steel

Low carbon steel can be easily welded due to the low percentage of carbon content in the metal. The melting point of low carbon steel is about 1539-1515 ͦC. Low carbon steel may be welded by any of the commonly used welding processes, the choice depending upon the section the thickness, and quality requirements.

Welding of Low carbon steels

The most commonly used welding processes for low carbon material are as follows:
1- Oxy-acetylene welding 2- Flux shielded metal arc welding 3- Submerged arc welding 4- Gas tungsten arc welding 5- Gas metal arc welding 6- Plasma arc welding 7- Thermit welding 8- Resistance welding 9- Electroslag welding 10- Brazing etc.
Low carbon steel is easy to weld and machine. Basically, it is applied to make rivets, screws, press sheets, pipes, nails, and chains when the carbon content is between (0.05-0.015%)and plate, structural shapes, and bars with the carbon content between (0.15-0.30%)

Medium carbon steel

Medium carbon steels are not so easily weldable as low carbon steels due to the higher carbon content (0.30-0. 50%). the higher carbon content may lead to brittleness. The melting point of medium carbon steel is about 1492 to1515 ͦC.

Welding of Medium carbon steels

Medium carbon steels may be welded with some special care and precautions, for that need to care some facts, such as:

Martensite is formed in the heat-affected zone due to rapid cooling and may lead to cracking due to its hardness and brittleness. Moreover, its hardened zone is not easily Machinable.

Weld cracking may be avoided by using low hydrogen-type electrodes.

Pre-heating is recommended to eliminate and reduce the hard and brittle areas.

For thicker sections, post-heat (595-675 ͦC) for one hour/25 mm of section thickness should be performed after welding to improve the metallurgical structure and increase the ductility, also reducing residual welding stresses.

Medium carbon steel may be welded by the following welding processes:
Flux shielded metal arc welding, Oxy-acetylene welding, Resistance welding, Thermit welding, Submerged arc welding.
Medium carbon steels are harder and stronger than low carbon steels. Medium carbon steels are usually applied for Shafts, axles, connecting rods, etc.

High carbon steels

High carbon steels are high carbon content metal where the percentage of carbon is (0.50-1.5%), that percent of carbon creates limit weld quality. The melting point of high carbon, steels is about 1405-1492 ͦC. This metal is seldom welded except for repair purposes.

Welding of High Carbon steels

High carbon steel may be welded by the following welding processes:
Oxyacetylene welding, Flux shielded metal arc welding, Thermit welding, Resistance welding.

High carbon steels are basically used for making crankshaft, scraper blades, automobile springs, anvils, band saws, etc. Oxy-acetylene welding with carbon steel

When welding Medium carbon steel with Oxyacetylene welding, An excess of acetylene is used in the gas flame to obtain sufficient heat,

No flux is needed when employing oxy-acetylene welding.

A Carburizing flame should be used when welding of high carbon steel, to obtain welds strong and free from defects.

Welding symbols

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Welding symbols

In today's era, welding technology is expanding in a big way and welding has acquired an important position in the manufacturing sector. Welding symbols are naturally an appropriate tool by designers to inform welding operators about welding.

Several symbols are used to represent the welding symbol, indicating the weld type, size, and location. The following elements need to be used to demonstrate these on the drawing:

The basic symbol is required to specify all types of welds.
Symbols used to indicate weld location, weld length, weld termination, etc.

A reference line and arrow on welding symbols

The reference line is actually a horizontal line along which all the necessary information is shown by means of arrows and some other symbols along or around it.

The arrow is known as the other important part of the welding symbol.

Basic welding symbols

Weld Location

In welding symbols, to indicate the weld position, size, and types of the weld is displayed on the drawing with the help of a reference line, arrows, and some words and circles.

most commonly used weld symbols

If no welding symbols are displayed, the welding joint must be fully welded.
Here are some welding symbols displayed as per symbol and there drawing representation:

Supplementary welding symbols

supplementary welding symbols to mark weld all-round, the finish of welds, etc.

In the case of intermittent welding, when the joint commences with a weld, dimensions shall be marked a follows:
a- the length of each weld shall be indicated on the right-hand side of the symbol and
2- The unwelded length of the joint between each weld shall be indicated in brackets following the length dimension.

Example of welding symbols

Conclusion:

Thus, through welding symbols all the information such as weld position, type of weld, weld location, size can be shown on the drawing.

Stainless steel, types and properties

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Stainless steel, types, and properties

Stainless steel made up of adding chromium and other elements in the iron.

More than 11.5% chromium is added to the iron, a fine film (Chromium oxide) is formed on the surfaces exposed to air, which acts as a fence to further oxidation, corrosion, or retardation. These types of steels cannot be stained easily, that is why these kinds of steels called stainless steel.

Stainless steel, types, and properties

Stainless steels can be classified into three metallurgical classes:

Austenitic ·
Ferritic
Martensite·

Based on their microstructures. Each of the classes has different welding requirements, that will be discussed later.

MATERIALS

Austenitic stainless steel

This steel has a strong structure at room temperature, the highest corrosion resistance compared to all stainless steel, and the greatest strength and scale resistance at high temperatures.

Composition of the Austenitic stainless steel

The composition of the Austenitic stainless steels are as follows:

Carbon	0.03-0.025%
Manganese	2-10%
Silicon	1-2%
Chromium	16-26%
molybdenum and Titanium	In some cases
Nickel	3.2-22%
Sulfur and phosphorus	normal

Applications of the Austenitic stainless steel

Austenitic stainless steel is widely used, Some of the main uses are as follows:

Dairy industries,
Transportation industry,
Household items,
Food processing,
Chemical processing,
Aircraft industry, etc

Ferritic stainless steel

With a low amount of carbon to chromium ratio ferritic steels possess a microstructure that is primarily ferritic. These kind of steels are magnetic and have good ductility and do not work harden to any appreciable degree. Also, this kind of steels have the capacity to resist corrosion more than martensitic steels.

Composition of the Ferritic stainless steel

The composition of the Ferritic stainless steels are as follows:

Carbon

0.08-0.20%

Manganese

1-1.5%

Silicon

1%

Chromium

11-27%

Applications of the Ferritic stainless steel

The uses of the Ferritic stainless steels are as follows:

The parts of oil burner
Interior decorative
Screws and fittings
Petroleum industries

Martensitic stainless steels

Due to the higher carbon to chromium ratio, Martensitic stainless steels are the only types hardenable by heat treatment. These steels are having good thermal conductivity, hardness, and ductility. This kind of steel is also magnetic in all conditions and can be rectified easily due to magnetic ability.

Composition of the Martensitic stainless steel

The composition of the Martensitic stainless steel is as follows:

Carbon	0.15-1.2%
Manganese	1%
Silicon	1%
Chromium	11.5-18%

Applications of the Martensitic stainless steel

Some typical uses of the Martensitic stainless stees are as follows:

The parts of Pumps and valves
Turbine buckets
Surgical instruments
Rules and tapes, etc

ROLE OF VALVES IN PIPING

Next story

¥Welding of Austenitic sta'inless steels

Aluminum and its Alloys

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Aluminum

Aluminum is a light, silver-colored metal with approximately one-third the density of steel or brass. It is a good conductor of electricity. Compared to other metals in steels, aluminum has a higher resistance to corrosion, protecting the oxide provided by the thin but tenacious film that forms on its surface.

Aluminum is also a good conductor of heat, more ductile and no magnetic metal with the melting point of 659°C in the pure form. The melting point of Aluminum alloys varies between about 520°C to 650°C.
Aluminum forms high strength alloys in conjunction with other metals such as Cu, Cr, Ni, Fe, Zn, Mn, Si, and Mg, because it is not particularly strong in its pure form.
The Aluminum and its alloys can be: Cast iron, Forged, Welded, Extruded, Rolled, etc.

Application of Aluminum and its alloys

The intense demand for aluminum and its alloys is very high today, mainly due to its attractive physical, mechanical and chemical properties. Aluminum and its alloys are often used in many ways such as:

Transportation and Architectural field

Structural frameworks, Engine parts, Trim and decorative features, hardware, doors, window frames, tanks, furnishings, and fittings. Overhead conductors and heat exchanger parts,

Food preparation equipment

Refrigeration, storage containers, bakery equipment, shipping containers, Mangles, waffle molds, Roofing, coping sills railings, fasteners, lighting fixtures, solar shading, grills, gratings, and Cryogenic applications, etc.
In heavy-duty such as: dragline booms, traveling cranes, hoists, conveyor supports, bridges, etc.
In the process industry, Aluminum and its alloys are used as handle organic chemicals, petrochemicals and drugs. Tanks, drums, pipes, heat exchangers, gratings, smokestacks, drilling towers, precipitators, centrifuges, valves, fittings, etc.

Welding of Aluminium And its alloys

Compared to other metals, aluminum, and alloys have certain welding characteristics, which require some special attention during welding.

Oxide film or Moisture

The important consideration is the effect of a thin film of oxide that always exists on the surface of the aluminum.
This film has moisture that can react during fusion welding with the liquid metal in the molten weld pool, forming another oxide and liquefying hydrogen that can cause perforation.

Removing of Oxide film

The oxide film on the base metal surface is chemically or mechanically removed by brush or scrubbing prior to the welding operation.
the problem can also occur during welding. To avoid this problem the following measures can be taken:-
Gas welding and Brazing
In the gas welding and brazing process, the oxide film can be removed using a suitable welding flux. Metallic arc weldings
It can be removed by using an electrode with a suitable coating in metallic arc weldings.

GMAW welding process
In the GMAW welding process, the oxide layer is removed by the arc cleaning action when the aluminum base metal forms the negative pole.

Gas Tungsten Arc Welding

If DCRP is used in the Gas Tungsten arc welding process, the tungsten electrode will be overheated and the base metal may not melt adequately. Therefore AC is preferred for tig welding.
In AC tig welding, the cleaning of oxide is carried out in the positive half cycle and in the negative half, the electrode gets cooled down while the base metal gets heated up aiding adequate fusion in the joint interface.

Welding Processes Used in Aluminium and its Alloys

The methods employed for welding aluminum and its alloy components can be discussed under the following heads:
GTAW Welding:-
GTAW welding is the most commonly used welding process today. With this process, a thin section of aluminum can be welded very well without adding any filler metal.
Tig welding resembles gas welding because both employ a heat source independent of the filler (metal)electrode. In the Gas welding process, Flux is used whereas shielding gas is used in the tig welding process.
Joint preparation
By the tig welding process, there is a range from 1 to 10 mm for manual welding and 0.25 mm to 25 mm for automatic welding.
Shielding Gas
Usually, Argon gas is used for GTAW Welding process aluminum welding, because, in DCRP, it establishes an arc more easily and provides better arc control, but sometime Helium is used for the thicker section of aluminum when DCSP is used.A Mixture of Helium and Argon is used with DCSP to providing the deep, narrow penetration essential for the best properties and a minimum heat-affected zone.
Electrodes
Unalloyed tungsten and tungsten-zirconium electrodes are preferred for Ac welding. zirconiated electrodes are likely to be contaminated by aluminum and have a slightly higher current rating. The pure tungsten is minimized inclusions in the weld bead and current unbalance. When welding with AC the tip of the electrode should be hemispherical.
For DC welding of Aluminum, Thoriated tungsten is used, the tip of the tungsten should be ground to a blunt conical point, having an included angle between 60 to 120 degrees to attain maximum penetration.

Resistance Welding.

Aluminum and aluminum alloys whether they are cast or wrought, heat-treatable or non-heat treatable can be resistance welded some more readily than others. Resistance welding processes are particularly useful in joining high strength heat-treatable alloys.

Resistance Spot Welding

All types of commercial aluminum alloys in the form of sheet, extrusions or castings can be spot welded. Resistance welding processes are particularly useful in joining high strength heat-treatable alloys. While resistance spot welding is best suited for non-heat treatable aluminum alloys. The thickness range for Aluminum welding, using normal Resistance Spot Welding process is 12mm to18 mm.

Other welding processes, used in Aluminium and its alloys

Oxy Gas welding process

Metallic Arc Welding process

GMAW Welding process

Solid-State Welding process

Carbon arc welding process

Atomic hydrogen welding process

Brazing process