Copyright Goodheart-Willcox Co., Inc. Chapter 17 Welding Procedures, Defects, and Corrective Actions 155 Craters. A depression formed when weld metal shrinks below the full cross section of the weld. How to correct: • Do not stop welding at the end of the joint (use run-off tabs). • Using the same gun travel angle, move the gun backward a quarter inch, over the completed weld, to backfi the crater before stopping the weld. fill Cracks. Fractures in the weld. They occur in fi llet welds just as they do in groove welds. fi How to correct: • Use the suggestions given for groove weld cracks. Burn-through. A hole created when the molten pool melts through the base material. How to correct: • Decrease the amperage. • Increase the travel speed. • Change the gun angle. Porosity. Small internal voids in the weld caused by gas bubbles that did not have enough time to rise to thee surface of the molten weld pool before it froze. How to correct: • Use the suggestions provided for groove weld porosity. Goodheart-Willcox Publisher Goodheart-Willcox Publisher Goodheart-Willcox Publisher Goodheart-Willcox Publisher