Fracture Toughness of Underwater Wet Welds

Abstract

The wet and wet-backed shielded metal-arc welding (SMAW) process can produce welds suitable for structural applications provided fracture control is considered in the design. Welding procedure qualification tests and fracture toughness tests [the ASTM Test for JIc, a Measure of Fracture Toughness (E 813-87)] were performed on the heat-affected zone (HAZ) and weld metal of wet, wet-backed, and dry fillet and groove welds made with (1) A36 steel and E6013 electrodes, and (2) A516 steel and nickel alloy electrodes. Despite Vickers hardness (HV) measurements exceeding 300 HV [xl.O kgf (HV 1.0)] in the HAZ of the ferritic welds and 400 HV in the HAZ of the austenitic welds, no hydrogen cracking or brittle fracture behavior was observed. Generally, the Charpy tests indicated upper-shelf fracture behavior at -2°C (28°F), and the HAZ was found to be tougher than the weld metal. Crack-tip opening displacement (CTOD) estimates were made using British Standard (BS) 5762, and the CTOD was found to be proportional to J even after large crack extension. The maximum load point values of CTOD and J are compared with the initiation values determined by the procedure of ASTM Test E 813. The fracture toughness of the welds is sufficient to be tolerant of flaws much larger than those allowed under American Welding Society (AWS) specifications.