What is the major cause of cold lap when using GMAW short-circuit metal transfer?

What is the major cause of cold lap when using GMAW short-circuit metal transfer?

• A. Fast Travel With A Small Bead
• B. Slow Travel With A Large Bead
• C. Slope Control Set To A Flat Volt-Amp Curve
• D. Wire Stickout Too Short

Answer: (B)

Cold lap shows up when the molten weld metal does not fuse properly with the base metal at the advancing edge, so the joint isn’t wetted and a ridge of unmelted base metal remains under the bead. In short-circuit GMAW, how you travel and how much bead you deposit control heat distribution. If you move slowly and deposit a large bead, a lot of heat ends up in the bead itself and the pool grows ahead of the joint rather than at the toe. That can leave the edge of the joint underheated and not fully fused to the weld metal, creating a cold lap underneath the bead. The slower travel and bigger bead emphasize this wetting problem, making it the most likely cause in this scenario. The other factors change arc behavior or heat a different way, but they don’t promote this specific lack of fusion at the joint edge as directly.

Cold lap shows up when the molten weld metal does not fuse properly with the base metal at the advancing edge, so the joint isn’t wetted and a ridge of unmelted base metal remains under the bead. In short-circuit GMAW, how you travel and how much bead you deposit control heat distribution. If you move slowly and deposit a large bead, a lot of heat ends up in the bead itself and the pool grows ahead of the joint rather than at the toe. That can leave the edge of the joint underheated and not fully fused to the weld metal, creating a cold lap underneath the bead. The slower travel and bigger bead emphasize this wetting problem, making it the most likely cause in this scenario. The other factors change arc behavior or heat a different way, but they don’t promote this specific lack of fusion at the joint edge as directly.