Final answer:
The process described, involving joining metal at 400 degrees Celsius with low joint strength, is likely soldering. Welding and brazing generally require higher temperatures and result in stronger joints.
Step-by-step explanation:
The process described in the question is most likely soldering. Soldering is a technique used to join small pieces of metal together at relatively low temperatures (around 200 - 450 degrees Celsius). This is consistent with the mentioned temperature of 400 degrees Celsius. It also typically results in lower joint strength when compared to other high-temperature metal-joining techniques like welding or brazing. Welding usually involves melting the work pieces to fuse them together, which often requires much higher temperatures than soldering, and it can lead to distortion of the parts due to the high heat input. Brazing involves a similar process to soldering but is typically carried out at temperatures above 450 degrees Celsius.