Toughness of 2·5%Ni and 1Ni–0·5 Mo alloyed weldments

Abstract

The two alloyed weldments E8018–G and E8018–C1 are studied with respect to the relation between fracture resistance, microstructure, and welding conditions. The COD/J fracture-toughness results show that the Ni-alloyed deposit gives reasonable toughness even at −60°C, where no significant difference was observed for the two welding conditions studied, while the Ni–Mo alloyed weldment may be regarded as tough down to temperatures of −40° and −20°C, for heat inputs of 2 and 1kJ mm⁻¹ respectively. However, the corresponding Charpy V-notch values indicate that the heat input should be limited to 1kJ mm⁻¹. Finally, the microstructural part of the study clearly showed that the local microstructure in the vicinity of the crack tip had a major influence on the fracture toughness, and optimum toughness was recorded when the crack tip was located in the overlap region of the weld beads where maximum recrystallization takes place.