154 GMAW/FCAW Handbook Copyright Goodheart-Willcox Co., Inc. Lack of fusion. A failure of fi ller metal to join with the base metal or with previous passes in a multiple-pass weld. fi How to correct: • Remove oxides and scale from the previous weld passes. • Increase the amperage. • Decrease the voltage. • Decrease the travel speed. • Change the gun’s work or travel angle. • Decrease the electrode stickout. • Keep the arc on the leading edge of molten pool. Overlap. A weld face that is larger than, and protrudes over, the weld toe. How to correct: • Reduce the size of the weld pass. • Reduce the amperage. • Change the gun angle. • Increase the travel speed. Undercut. A groove formed at the top of the weld bead in horizontal fi llet welds due to the base metal melting fi and not being filled. fi How to correct: • Make a smaller weld. • Make a multiple-pass weld. • Change the gun angle. • Use a smaller diameter electrode. • Decrease the amperage. • Decrease the voltage. Convexity. A weld that has a high crown. How to correct: • Reduce the amperage. • Decrease the electrode stickout. • Decrease the voltage. • Decrease the gun angle. Goodheart-Willcox Publisher Goodheart-Willcox Publisher Goodheart-Willcox Publisher Goodheart-Willcox Publisher