Fracture toughness analysis of laser‐beam‐welded superalloys Inconel 718 and 625

Abstract

ABSTRACT In this study, two 3.2‐mm thick Ni‐base superalloys, Inconel 718 and 625, have been laser‐beam‐welded by a 6‐kW CO 2 laser and their room temperature fracture toughness properties have been investigated. Fracture toughness behaviour of the base metal (BM), fusion zone (FZ) and heat affected zone (HAZ) regions was determined in terms of crack tip opening displacement (CTOD) using compact tension‐type (C(T)) specimens. Laser‐beam‐weld regions showed no significant strength overmatching in both alloys. Ductile crack growth analysis (R‐curve) also showed that both materials exhibited similar behaviour. Compared to the BM there is a slight decrease in fracture toughness of the fusion and the HAZ.