Differences between Welding, Soldering and Brazing

Welding, soldering and brazing are metal joining processes. Each type of joining process has its own significance. The type of joining process to be applied for joining two parts depends on many factors. The tabular comparison tells us the differences between the joining processes welding, soldering and brazing in aspects like strength comparison, temperature requirement, change in properties after joining, cost involved, heat treatment, preheating, etc.

S.No	Welding	Soldering	Brazing
1	Welding joints are the strongest joints used to bear the load. Strength of the welded portion of the joint is usually more than the strength of the base metal.	Soldering joints are the weakest of the three. Not meant to bear the load. Used to make electrical contacts generally.	Brazing joints are weaker than welding joints but stronger than soldering joints. This can be used to bear the load up to some extent.
2	The temperature required is 3800°C in welding joints.	The temperature requirement is up to 450°C in soldering joints.	Temperature may go up to 600°C in brazing joints.
3	To join work pieces need to be heated to their melting point.	Heating of the workpieces is not required.	Workpieces are heated but below their melting point.
4	Mechanical properties of base metal may change at the joint due to heating and cooling.	No change in mechanical properties after joining.	>May change in mechanical properties of joint, but it is almost negligible.
5	Heat cost is involved and a high skill level is required.	Cost involved and skill requirements are very low.	Cost involved and skill required are in between the other two.
6	Heat treatment is generally required to eliminate undesirable effects of welding.	No heat treatment is required.	No heat treatment is required after brazing.
7	No preheating of the workpiece is required before welding, as it is carried out at high temperature.	Preheating of workpieces before soldering is good for making a good-quality joint.	Preheating is desirable to make a strong joint as brazing is carried out at relatively low temperature.