What is Welding? (Its 22 Different Types You Should Know!)

what is welding

What is Welding?
Definition: Welding is defined as a joining process in which two or more parts are joined together by using a very high amount of heat which melts the parts and fuses them with each other which ultimately forms a strong joint on cooling.

Welding of workpiece leads to a permanent joint of that workpiece.

The strength of the welded joint can be as high as that of the base metal or parent material used for joining.

The perfect weld is a weld in which there is continuity between the joined parts. And also, every part of the welded joint is homogeneous.

Different Types of Welding Joints

different types of welding joints

5 Different Types of Welding Joints used for metal joining are mentioned below.

  1. Butt weld joint
  2. Lap weld joint
  3. Corner weld joint
  4. Tee weld joint
  5. Edge weld joint

For more detailed information on types of welding joints, I would recommend you to visit this separate article: 5 Different Types of Welding Joints & Weld Positions.

22 Different Types of Welding Process

You might have a question “How many welding types are there?”
Well, there are more than 20+ types of metal welding processes.

Here is a list of most common types of welding  process.

(Note: For detailed information on each of these welding processes, just click on the above links to visit the separate articles.
Or 
If you want to see all types of welding in this article only, then keep reading below. You will get to know about all these types of metal welding process with diagrams.)

So let’s dive right into it.

#1) Oxy-acetylene gas welding

Oxy acetylene gas welding

What is Oxy Acetylene Gas Welding?
Definition: Oxy Acetylene Gas Welding (also known as Oxy fuel Gas Welding or Gas Welding) is a type of welding process that uses the heat from the fuel gases such as acetylene in combination with oxygen, in order to melt and weld the metal parts.

The heat produced by the combustion of acetylene gas is enough to melt any metal. And hence the oxy acetylene welding process is universally accepted.

There are basically 3 types of flames obtained in the oxy acetylene gas welding process.

  • Neutral flame
  • Reduction flame or carburizing flame
  • Oxidizing flame (excess oxygen)

Oxy acetylene gas welding process is used for welding the ferrous as well as non ferrous metals.

#2) Oxy-hydrogen gas welding

The Oxy-hydrogen gas welding is exactly similar to the Oxy-acetylene gas welding, but the only difference is that the fuel used is hydrogen gas.

Gases like propane and butane are also used for gas welding process, but the most used process is Oxy-acetylene gas welding process.

#3) Carbon Arc Welding

carbon arc welding

What is Carbon Arc Welding?
Definition: Carbon Arc Welding (CAW) is an old welding process in which the arc is produced between the carbon electrode and workpiece or between the two carbon electrodes by using low voltage and high ampere current.

There are two types of Carbon Arc Welding

  • Single Carbon Arc Welding
  • Twin Carbon Arc Welding

What is single carbon arc welding process?
The single carbon arc welding process is a type of carbon arc welding process in which the arc is produced between the carbon electrode and the workpiece.

What is twin carbon arc welding process?
The twin carbon arc welding process is a type of carbon arc welding process in which the arc is produced between the two carbon electrodes.

#4) Stick Welding (or Shielded Metal Arc Welding (SMAW))

principle of stick welding

What is Stick Welding?
Definition: Stick Welding Process (or Shielded Metal Arc Welding Process or SMAW process) is a common and versatile method which is used for joining shapes that cannot be welded using automated processes.

In shielded metal arc welding process, the stick electrode (or welding electrode) is used as a filler material between the weld grooves.

The stick electrode consists of an inner core wire and the outer coating material which is also known as flux coating.

The arc formation takes place when the electrode is stuck with the workpiece surface.

When the arc is formed, the electrode is moved along the weld groove which deposits the filler material along the weld groove.

After solidification of the filler material, the final welded joint is obtained.

#5) MIG Welding (or Gas Metal Arc Welding (GMAW))

MIG welding gas metal arc welding GMAW process

What is MIG welding?
Definition: MIG welding is a type of arc welding process which uses a welding gun to continuously feed the heated solid wire electrode into the weld pool. The welding gun also supplies shielding gas along with the electrode for protecting the weld pool from air contamination.

The shielding gases like argon, helium, or its mixture is used in the MIG welding process.

During MIG welding process, the metal transfer from electrode to workpiece can be achieved by following methods.

#6) TIG Welding (or Gas Tungsten Arc Welding (GTAW))

tig welding diagram

What is TIG welding?
Definition: TIG welding is a type of welding process that uses non-consumable tungsten electrode to produce the weld. The heat is generated by an electric arc between the tungsten electrode and the workpiece.

During the TIG welding process, the tungsten electrode and the workpiece are shielded from the surrounding atmosphere using inert gas (like helium or argon).

Gas Tungsten Arc Welding process (GTAW or TIG process) is generally used for welding of stainless steel, nickel alloys, titanium, aluminum, brass, bronze, magnesium as well as gold.

GTAW process is also used for welding of dissimilar metals like copper with brass, stainless steel with mild steel.

#7) Submerged Arc Welding

submerged arc welding

What is Submerged Arc Welding?
Definition: Submerged Arc Welding process is a type of arc welding process in which the consumable electrode is fed continuously to the weld zone which is completely submerged under the large amount of granulated flux.

The Submerged Arc Welding process (SAW welding process) is generally used for doing faster welding jobs.

By using Sub Arc Welding process, a large deposition rate of metal can be achieved by using larger diameter electrodes and high current flow (around 4000 A).

By using Sub Arc Welding process, the metal deposition rate of upto 20 kg/hour can be achieved.

Submerged Arc Welding machine has a capacity to weld the metal having thickness upto 100 mm.

#8) Plasma Arc Welding

plasma welding

What is Plasma Arc Welding?
Definition: Plasma Arc Welding is a type of welding process in which the arc is produced between the tungsten electrode and workpiece.

Plasma welding is similar to TIG welding but the only difference is that in plasma welding, the position of electrode is inside the body of the torch, while in TIG welding, the position of electrode is outside the body of torch. (Visit TIG welding diagram to see its electrode position.)

The high temperature plasma is then forced through the fine-bored copper nozzle and this plasma exits the nozzle which is then used to weld the metal.

#9) Electroslag Welding

electroslag welding

What is Electroslag Welding?
Definition: Electroslag Welding is a welding process which is generally used for joining thick metals (25 mm to 300 mm thick) by using a molten slag that melts the filler metal and the surface of workpieces.

In Electroslag Welding Process, the heat is generated by electric current which passes from electrode to the workpiece through the molten slag present between the workpieces.

#10) Spot welding

What is Spot Welding?
Definition: Spot Welding (also known as resistance spot welding) is a fusion welding process in which the two metals sheets (or metal plates) are joined by applying heat and pressure that forms small nuggets at the interface of two metal plates.

The heat required for joining the metals is obtained by the heating effect of electrical resistance across the joint.

During the spot welding procedure, the pressure is applied either mechanically, hydraulically or pneumatically.

#11) Seam welding

seam welding

As shown in above diagram, the resistance seam welding process uses roller type electrodes.

As the workpiece moves further, the rollers are pressed and rotated over the workpiece.

The pressure applied in the resistance seam welding process ranges from 3 MPa to 8.5 MPa.

#12) Projection welding

projection welding

Projection welding is similar to the spot welding process, but the only difference is that the welding is carried out at the places where the projections are made.

The electric current is passed through the metal plates and the heat is generated at the point of contact between the metal plates.

This heat is generated due to the electrical resistance between the joints of metal plates.

This causes the metal to melt and during this time, the pressure is applied to the metal plates which on cooling forms a strong welded joint.

#13) Upset butt welding

upset butt welding

Upset butt welding (or resistance butt welding) is a type of resistance welding process in which the two metal pieces are welded by bringing their end to end contact under pressure and allowing the current to flow from one metal piece to the other.

For upset butt welding process, it is necessary to have a smooth contact surface.

#14) Flash butt welding

flash butt welding

Flash butt welding is a type of resistance welding process in which two metal pieces are welded with each other by pressing against each other in such a way that the contact will be at points due to surface roughness and then the electric current is passed to melt and weld the metal.

When the electric current is passed through the metal pieces, the metal heats up to its molten conditions and one of the metal pieces is then slowly pushed towards the other. 

Because of this, the welding of two metal pieces takes place.

#15) Friction welding

friction welding

What is Friction Welding?
Definition: Friction Welding is defined as a type of welding process in which the joining of metals takes place due to heat produced by the mechanical friction.

As shown in the image, the parts which are to be welded are aligned in a friction welding machine.

One part is stationary while the other part is rotating which is mounted in the chuck spindle.

The metal part which is mounted in the chuck is rotated at high speed, and at the same time the stationary part is pushed towards the rotating part.

Because of this, frictional heat is produced which is so high that it can deform the metal to its plastic conditions.

The rotation of the workpiece is stopped and the external pressure is increased which completes the weld.

#16) Ultrasonic welding

ultrasonic welding of metals

What is Ultrasonic Welding?
Definition: Ultrasonic Welding is defined as a solid state welding process in which the joining of metals occurs due to heat and pressure energy produced by the application of a high frequency vibrator (frequency >20000 Hz).

In ultrasonic welding process, the sonotrode which is connected to the transducer, oscillates at a very high ultrasonic frequency (more than 20000 Hz or 20000 cycles/sec.)

At this time, the pressure is applied to the sonotrode from the top (see diagram).

Due to this pressure and high frequency vibrations of the sonotrode, the metal molecules heat up and they start to deform. 

Because of the pressure acting on the deformed workpiece, the workpiece starts to fuse with each other and finally solid weld is obtained.

#17) Explosion welding

explosion welding

What is Explosive Welding? 
Definition: Explosive Welding (also known as explosion welding or explosive bonding or explosive cladding) is a type of solid state welding process in which a controlled explosive detonation is used to force two metals together at high pressure.

In Explosive welding, when the detonator is activated, the explosion takes place and it lasts for only a fraction of a second.

This high explosive force forces the top metal plate on the base metal plate with a very high velocity.

This creates a collision between the upper metal sheet and the base metal (which is at the bottom).

This pressure created by the explosion is higher than the yield strength of the materials, and because of this the welding of metals takes place easily.

#18) Forge welding

forge welding

What is Forge Welding?
Definition: Forge welding process is a solid state welding process in which two metals are heated at a high temperature and then they are hammered together to form a single strong joint.

In forge welding, the parts which are to be welded are heated to a plastic condition.

The heating of these metal parts is done in any furnace suitable for heating the metal.

After the metal parts are heated to their plastic condition, they are hammered together. In this way, the welding of metals takes place.

#19) Thermite welding

thermite welding of rails

What is Thermite Welding?
Definition: Thermite welding is a fusion welding process in which the joining of metals takes place with the help of superheated molten metal and slag resulting from chemical reaction between aluminum and metal oxide.

The heat produced in thermite welding process is just because of the exothermic reaction between aluminum and the metal oxide. No external heat or current is applied during the process.

Thermite Welding process is generally used for welding of rails. Hence the process is also referred as Thermite Rail Welding.

#20) Atomic hydrogen welding

atomic hydrogen welding torch

What is Atomic Hydrogen Welding? 
Definition: Atomic hydrogen welding is a welding process in which the joining of metals takes place by heating them with an electric arc maintained between two tungsten electrodes in the atmosphere of hydrogen which acts as a shielding gas.

Atomic hydrogen welding process does not require any kind of flux.

Also the welding rod (or filler material) may or may not be used during the atomic hydrogen arc welding process.

#21) Electron Beam Welding

electron beam welding

What is Electron Beam Welding?
Definition: Electron beam welding is a fusion welding process in which the metals are joined due to heat produced by the collision of high-velocity electron beam with the metal.

The electron beam welding operation is performed under the vacuum chamber so that the dissipation of electron beam can be prevented.

#22) Laser Welding

laser welding

What is Laser Beam Welding?
Definition: Laser welding (or laser beam welding) is a fusion welding process in which the joining of metals takes place due to heat produced by a laser beam.

In Laser beam welding, the laser acts as a concentrated heat source and it is focused on the weld region which melts the metal and welding takes place.

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