What is a common defect associated with poor fit-up in brazing?

• A. Excessively smooth surface finish.
• B. No impact on joint integrity.
• C. Excessively rapid cooling with better joints.
• D. Voids or incomplete bonding due to inadequate contact.

Answer: (D)

In brazing, joint quality hinges on proper fit-up so the molten filler metal can be drawn into the joint by capillary action. If the parts don’t fit tightly, gaps form at the joint interface. Those gaps prevent the filler metal from wetting and bridging the joint completely, so voids and areas that aren’t bonded remain. The result is an incomplete joint with reduced strength and possible porosity from trapped flux or impurities. This is the most common defect when fit-up is poor.

Other options don’t reflect this fundamental issue. An excessively smooth surface finish isn’t the primary problem with poor fit-up, and saying there’s no impact on joint integrity is incorrect because poor fit-up directly compromises the bond. Rapid cooling isn’t a defect caused by bad fit-up and would more likely introduce other issues rather than indicate a better joint.