When only one part of a joined assembly is hot enough during brazing, what will happen to the filler metal?

During the brazing process, it is crucial for the filler metal to reach a specific temperature to flow and bond effectively with the base metals being joined. When only one part of the assembly is hot enough, the filler metal will primarily respond to the temperature of the hot piece.

This means that the filler metal will tend to flow towards the area where the temperature is sufficient to melt it, which is the hot part. As the filler metal reaches its melting point, it will adopt a liquid state and start to flow in that direction. However, if the cooler piece has not reached the necessary temperature for the filler metal to properly bond, the flow will not be able to bridge the gap effectively between the two pieces.

Thus, the outcome is that the filler metal will remain concentrated around the hotter area, and it may not be able to establish a good bond or flow to the cooler piece, leading to poor joint integrity. This understanding is crucial for proper brazing techniques and achieving strong, reliable joints in metalworking.