Classification of Industrial Welding Processes

Classification of Welding Processes

Industrial  welding  processes  are  set  out  here  according  to  the  criteria  defined

above, namely: 

• Processes utilizing the fusion without mechanical action
• Processes utilizing the fusion combined with mechanical action
• Processes utilizing heating without fusion but with a mechanical action
• Processes utilizing a mechanical action without heating

Details of each are covered below.

It is also a common practice to classify welding processes according to

• Modes of action :  flame,  electric  arc,  plasma,  Joule  effect,  spark, induction, friction, explosion, etc.
• Means of protection against atmosphere: shielding gas or slag

Processes utilizing the fusion without mechanical action

For welding processes operating without voluntary mechanical action, welding can be described by distinguishing the modes of heating used and protecting the molten metal against the chemical action of surroundings. Following are the types

• Flame or gas welding
• Plasma welding
• Arc welding
• Vertical electroslag welding
• Aluminothermic welding
  

In all the above listed processes the molten metal is contained in a containment formed by molten area of parts to be assembled. This results in an increase in temperature of solid metal in vicinity of molten pool. The structure and properties of this heated area might change and thus this area is called the Heat Affected Zone (HAZ).

Processes using local fusion with mechanical action

The contribution of heat used to form the molten weld pool is assured here by the Joule effect of a high intensity alternating current which crosses the mating plane. 

• Resistance welding with containment of the molten metal
• Resistance welding with expulsion of the molten metal

Processes using heating without fusion, with mechanical action

For such processes heating can be achieved from an external source (resistance or induction) or by
mechanical action (friction).

• Diffusion Welding
• Friction Welding
• Forge Welding

Processes using mechanical action without heating 

Following are the types that utilize mechanical action but do not involve heat.

• Ultrasonic Welding
• Explosive Welding