Copyright Goodheart-Willcox Co., Inc. Chapter 17 Welding Procedures, Defects, and Corrective Actions 157 Overlap. Excessive weld metal that mushrooms out onto the top plate. Caused by too much metal being deposited. How to correct: • Shorten the welding time so less metal is deposited into the plug weld hole. Craters. Depressions that occur in the center of the plug weld when not enough metal is placed in the hole during the weld cycle. How to correct: • Lengthen the weld cycle. Spot Weld Defects Lack of penetration. Failure of the weld metal to reach the proper depth in the bottom plate. How to correct: • Increase the amperage. • Increase the weld time. • Decrease the voltage. • Decrease the electrode stickout. Excessive penetration. Weld metal that penetrates through the bottom plate. How to correct: • Decrease the amperage. • Decrease the weld time. • Increase the voltage. • Increase the stickout. Porosity. Small internal voids in the weld caused by gas bubbles that did not have enough time to rise to the surface of the molten weld pool before it froze. How to correct: • Increase the arc time. • Increase the amperage. • Decrease the voltage. • Decrease the stickout. • Make sure the metal is clean before mating the assembly. Cracks. Fractures that occur for the same reasons they do in plug welds. How to correct: • Use the suggestions provided for plug weld cracks. Goodheart-Willcox Publisher Goodheart-Willcox Publisher