This document discusses welding and its various types. Welding is defined as a process of joining similar or dissimilar metals by applying heat, with or without pressure and filler material. The document outlines the history and development of welding, including important early processes like forge welding and more modern techniques such as laser beam and robot welding. Welding is classified into fusion welding, which joins metals in a molten state without pressure, and pressure or solid state welding, which uses pressure in addition to heat. Specific fusion welding processes discussed include gas welding, arc welding, and others using energy sources like plasma arcs, electron beams, and lasers.

1. 1131 March 2020 Dr.Abhishek Sharma
By
Dr. Abhishek Sharma
Metal Joining (Welding)
KME-403
Unit - IV
GL BAJAJ INSTITUTE OF TECHONOLOGY & MANAGEMENT

2. 2
Welding
Welding can be
defined as a
process of joining
similar or
dissimilar metals
by application of
heat with or
without application
of pressure and
filler material.
31 March 2020 Dr.Abhishek Sharma

3. 31 March 2020 Dr.Abhishek Sharma 3
•Until the end of the 19th century, the only welding process was forge welding.
•Arc welding and oxyfuel welding were among the first processes to develop
during the 1800s, and resistance welding followed soon after.
•Welding technology advanced quickly during the early 20th century as World War
I and World War II drove the demand for reliable and inexpensive joining methods.
•Following the wars, several modern welding techniques were developed, including
manual methods like shielded metal arc welding, now one of the most popular
welding methods, as well as semi-automatic and automatic processes such as gas
metal arc welding, submerged arc welding and flux-cored arc welding.
•Developments continued with the invention of laser beam welding and electron
beam welding in the latter half of the century.
•Robot welding is becoming more commonplace in industrial settings today.

4. welding
Solid state welding Soldering and brazingFusion welding
Electrical energy Chemical energy
Other processesNon consumable
electrode
Consumable electrode
Resistance welding
Cold welding
Friction welding
Diffusion welding
Flash welding
Ultrasonic welding
Explosion welding
Gas metal arc welding
Shielded metal arc
welding
Submerged arc welding
Flux cored arc welding
Electrogas welding
Electroslag welding
Gas tungsten arc
welding
Atomic hydrogen
welding
Plasma arc welding
Oxyacetylene welding
Oxyfuel gas welding
Laser beam welding
Thermit welding
Electron beam welding
Soldering
Brazing
WELDING CLASSIFICATION

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Advantages of Welding over other joints:
• Lighter structures with higher joint strength can be easily and rapidly made.
• Thus are cheaper.
• welded joints have higher corrosion resistance.
• Are fluid tight for tanks and vessels.
• Can be easily and economically altered.
• Variety of joints are possible.
Disadvantages:
• Produces waves of longer wavelength than X and γ rays.
• These are made up of visible light rays, infra red rays and ultraviolet rays.
•Ultraviolet rays can cause burns to corners and eye retina.
• Infrared rays have longer wavelength and produce heat when they strike and are
absorbed into surface.
• For protection, welders should wear welding jackets made of leather, denim, boot.
31 March 2020 Dr.Abhishek Sharma

6. 6
Solid Phase or plastic or pressure welding:
• Clean faces of component are brought into intimate contact to produce a metallic
bond with or without application of heat.
• Here application of pressure is essential to produce the plastic flow.
• Now a days means to weld dissimilar metals have been found out.
• Welding gives 100% strength of the joint and is very easy process.
Weldability:
• Is capacity of being welded into inseparable joints having specific
properties like definite weld strength, proper structure etc.
• Weldability is based on criterion like ease of welding and weld quality.
Thus welding can be defined as a process of joining
similar or dissimilar metals by application of heat
with or without application of pressure and addition
of filler material.
Welding can be categorized in following two wide groups:
1. Fusion or Non Pressure Welding
2. Plastic or Pressure Welding
31 March 2020 Dr.Abhishek Sharma

7. 7
Fusion welding
• Process of joining two metal pieces by application of heat.
• Parts to be joined are placed together, heated (often with addition of filler
metal), until they melt and solidify on cooling.
• Following methods could be used to develop heat:
 Combustion of fuel gas with oxygen.
 Electric arc.
Plasma arc, electron beam, laser beam.
• Sometimes pressure is also applied with heat to have better joining section.
• Fillers are used to attain additional strength of the joint.
• Ways of applying pressure can be hammering, rolling or using dies.
• In fusion welding metals to be joined are brought to fluid state without
application of pressure and joined by filler material.
31 March 2020 Dr.Abhishek Sharma

8. 8
Fusion welding
Gas Welding
• Air Acetylene
• Oxy Acetylene
• Oxy Hydrogen
Arc Welding
• Shielded Carbon Arc
• Unshielded Carbon Arc
• Metal Arc Welding
• Gas Metal Arc (MIG)
• Gas Tungsten Arc (TIG)
• Atomic Hydrogen Arc
• Plasma Arc
• Submerged Arc
• Flux Cored Arc
• Electro Slag
Others
• Electron Beam
• Thermit welding
• Laser Welding
31 March 2020 Dr.Abhishek Sharma