S.No. 

Welding

Soldering

Brazing

1.

Welding is a process in which two or more similar metals are permanently united by bringing them to fusion temperature.

The soldering is a metal joining process by means of a fusible alloy or metal and is applied in molten state spreads between properly fitted surfaces of joint by capillary action.

Brazing can join any two dissimilar metals. In brazing the base metals are heated to a temperature that is below the fusion temperature. The joint is formed by capillary action of filler material.

2.

In welding the filler material (flux) is added at the joint and solidified at same place.

Filler material used in soldering has low melting point will below 427ºC.

Brazing filler material has melting point above 427ºC.

3.

In welding, the welding arc penetrates deep into base metals.

In soldering there is no such penetration.

In brazing, there is no such penetration.

4.

Strength of welded joint is similar to base metals.

Soldered joint is weaker in mechanical strength.

Brazing operation gives a joint with moderate strength.