What effect does overheating have on a brazed joint?

• A. Improves joint strength by annealing the joint.
• B. Excessive oxidation, dissolution of filler into base metal, and degradation of joint strength or distortion.
• C. Decreases oxidation and improves flow.
• D. No effect on joint integrity.

Answer: (B)

Overheating a brazed joint pushes the process beyond the proper temperature range, which damages the joint in several ways. Excess heat promotes oxidation on the metal surfaces, and even with flux, oxide films can form and hinder wetting and capillary flow, so the filler doesn’t bond cleanly. It also drives diffusion between the filler metal and base metal, dissolving filler into the base metal and altering the joint’s composition, which weakens the bond. Additionally, the extra heat can cause distortion and thermal stresses, further degrading strength. So the joint becomes weaker or warped, not stronger, making overheating clearly detrimental.