ESCO Brazing and Soldering Practice Test 2026 - Free Soldering and Brazing Practice Questions and Study Guide

In brazing, you heat the joint until the filler metal melts and flows into the gap, while the base tubing remains solid. To make this work, the filler metal must melt at a lower temperature than the base metals. That way you can reach the filler’s liquidus without risking the tubing itself melting or distorting. The flux helps remove oxides and improve wetting, and the shielding gas protects the molten filler from oxidation, but neither dictates the melting behavior of the joint. The base metal’s high melting point is what you want to avoid exceeding, so the filler metal is the only material whose melting point needs to be lower.