Different types of welding processes used in all over the world. More than 50 different types of welding operation have categorized by the American Welding Society (AWS). We can divide all those welding processes into two major groups’ fusion and solid state welding.
1. Fusion Welding
Fusion welding further classified as:
Arc Welding (AW)
- Shielded Metal Arc Welding (SMAW)
- Gas Metal Arc Welding (GMAW)
- Pulsed Arc (GMAW-P)
- Short Circuit Arc (GMAW-S)
- Electrogas (GMAW-EG)
- Spray Transfer (GMAW-ST)
- Gas Tungsten Arc Welding (GTAW)
- Flux Cored Arc Welding (FCAW)
- Submerged Arc Welding (SAW)
- Plasma Arc Welding (PAW)
- Stud Welding (SW)
Oxyfuel Gas Welding (OFW)
- Oxyacetylene Welding (OAW)
- Pressure Gas Welding (PGW)
Resistance Welding (RW)
- Resistance Spot Welding (RSW)
- Resistance Seam Welding (RSW)
- Resistance Projection Welding (RPW)
2. Solid State Welding
- Diffusion Welding (DFW)
- Friction Welding (FRW)
- Ultrasonic Welding (USW)
- Forge Welding (FOW)
- Cold Welding (CW)
- Explosion Welding (EXW)
- Roll Welding (ROW)
Some other unique classification of welding/ welding types is the following:
- Thermit Welding (TW)
- Laser Beam Welding (LBW)
- Electroslag Welding (ESW)
- Flash Welding (FW)
- Induction Welding (IW)
- Electron Beam Welding (EBW)
Fusion welding processes use heat to melt the base metals. In some fusion welding operations, filler metal added to the molten pool. This filler metal facilitates the welding process and provides strength to the welded joints. A fusion welding process that uses no filler metal referred to as an autogenous weld. According to the American Welding Society (AWS), the fusion welding category includes the most widely used types of welding processes (Arc Welding, Resistance Welding, Oxyfuel Gas Welding).
Arc Welding (AW):
Heating of metals in arc welding performed with the help of electric arc. However, some arc welding processes also apply pressure during welding. It utilizes the filler metal most. Metal arc welding, TIG welding, and MIG welding is the most popular arc welding.
Shielded Metal Arc Welding (SMAW):
In metal arc welding, arc produced between the metal electrode and workpiece. The metal electrode also called filler metal. During the welding process, the metal electrode melted with the help of arc heat and fused with a workpiece. The temperature produced in the metal arc is 24000C to 27000C.
Gas Metal Arc Welding (GMAW):
It is also known as metal inert gas welding (MIG). In this welding, the electrode is consumable. The filler metal is deposited by the arc which is completed surrounded by the inert gas. Shielding provided through the flow of gas and the fluxing and slag forming agents is no longer required.
Gas Tungsten Arc Welding (GTAW):
In TIG welding, the heat produced between the non-consumable electrode and the workpiece. The welding zone shielded from an atmosphere with the help of inert gas. Argon or helium used as the inert gas. The electrode current with straight polarity is used for welding stainless steel and copper alloys. Reverse polarity used in magnesium. The alternating current is more versatile in welding for cast iron, magnesium, and aluminum.
Oxyfuel Gas Welding (OFW):
These joining processes use Oxyfuel gas. This Oxyfuel gas is the mixture of oxygen and acetylene. The mixture of oxygen and acetylene produces a hot flame for melting the base metal and filler metal. The approximate flame temperature produced in OFW is 32000C.
Pressure Gas Welding (PGW):
PGW uses similar equipment as the OFW to produce butt joints between the ends of objects such as pipe and railroads rail. Object ends heated with the help of gas flame to a temperature below the melting point and the soft metal is then forced together under pressure.
Resistance Welding (RW):
RW using heat from electric resistance to the flow of current passing between the faying surfaces of the two parts held together under pressure. It is used for joining of sheet metals or wires.
Spot Welding (RSW):
This type of welding used for lap joints. Joining of components performed from plate materials 0.025mm to 1.25mm thickness. Welded sheets placed between the two electrode tips of copper or copper alloy. The electrode diameter should be equal to the square root of the sheet thickness.
Solid State Welding:
In this type of welding processes, the joining of two parts accomplished with the application of pressure alone or a combination of pressure and heat. If heat used, the temperature in the process is below the melting point of the metals being welded. In simple words, no melting of base metals in solid state welding. No filler metal utilizes in solid state welding. Following welding processes are included in this group.
Diffusion Welding (DFW):
Two surfaces held together under pressure at an elevated temperature and the parts combine/ coalesce through solid state diffusion.
Friction Welding (FRW):
Coalescence achieved with the help of the heat of friction between two surfaces.
Ultrasonic Welding (USW):
In Ultrasonic Welding, moderate pressure applied between the two parts. An oscillating motion at the ultrasonic frequency used in a direction parallel to the contacting surfaces. The combination of normal and vibratory forces results in shear stresses that remove surface films and achieve atomic bonding of the surface.
Thermit Welding (TW):
TW used Mixture of iron oxide and aluminum (Thermit). This mixture ignites only at a temperature of 15000C. A major advantage of Thermit welding is that all parts of the weld section molt at the same time and weld cools uniformly. This results in a minimum problem with internal residual stresses.