Upset welding is defined as fusion produced simultaneously over which area?

• A. The entire area of abutting surfaces
• B. A small localized point
• C. Only the edges
• D. The outer circumference

Answer: (A)

Upset welding relies on resistance heating across the full contact area of the two abutting surfaces. When the parts are pressed together and current passes through, heat is generated throughout the entire interface, so the surfaces fuse over the entire contact area at once. This is what gives a continuous weld along the entire abutting surface.

If fusion occurred only at a small localized point, or only along the edges or outer circumference, that would reflect different heating patterns or welding modes rather than upset welding, which uses the entire interface for fusion.