What is the primary difference between welding and brazing in terms of the base metal?  

Explanation:

Welding:

• Welding is a fabrication process that joins materials, usually metals or thermoplastics, by causing coalescence. This is typically done by melting the base material and adding a filler material to form a pool of molten material (the weld pool) that cools to form a strong joint. The key aspect of welding is that the base metal is melted during the process. This means that the pieces to be joined are heated to a high enough temperature that they melt and fuse together.

Brazing:

• Brazing, on the other hand, is a metal-joining process that uses a filler metal with a melting point above 450°C (about 840°F) but lower than the melting point of the base metals. The filler metal is drawn into the joint between the two close-fitting parts by capillary action. The critical difference is that in brazing, the base metal is not melted. Instead, the filler metal is melted and flows over the surfaces of the base metals, bonding them together as it cools and solidifies.

In welding, the base metal is melted to create the joint, while in brazing, the base metal remains solid and only the filler metal melts and bonds the base metals together