Q14Basic Mechanical Engineering
Question
4 marks
Q.4. Differentiate among the welding, brazing and soldering.
Answer
Welding, brazing, and soldering are distinct joining processes varying by temperature, filler material, and whether the base metal itself is melted.
While all three are crucial metal joining processes, they differ drastically in their thermal requirements and joint strength.
- 1. Welding: This is a high-temperature fusion process. The edges of the actual base metals being joined are heated to their melting point (usually well over for steel). A filler metal of similar composition may be added. Upon cooling, the metals fuse into a single, continuous, highly strong joint. It is used for heavy structural fabrication.
- 2. Brazing: This is a lower-temperature process where the base metal is NEVER melted. Instead, the joint area is heated, and a non-ferrous filler metal (like a copper-zinc alloy) is melted and drawn into the tight gap between the base metals via capillary action. The filler must have a melting point above but strictly below that of the base metals. It provides moderate strength and is excellent for joining dissimilar metals.
- 3. Soldering: Similar in principle to brazing (capillary action without melting the base metal), but performed at significantly lower temperatures. The filler metal (solder, typically a tin-lead alloy) has a melting point strictly below . It produces the weakest joint mechanically but provides excellent electrical conductivity, making it universally used in electronics and PCB assembly.