The fracture toughness of nickel based alloys can be degraded when exposed to low temperature
deaerated water. This paper uses elastic-plastic fracture mechanics testing to explore some
fundamental environmental and metallurgical factors that influence this form of environmentally
assisted cracking. Elastic-plastic fracture toughness tests were performed on 0.6T compact tension
samples of EN82H weld metal as a function of temperature, hydrogen content in the water, and
hydrogen content in the weld metal. Tests were also performed on EN52 and three candidate
replacement alloys for EN52 in order to compare their low temperature crack propagation resistance to
EN82H. These results are used in conjunction with literature data and fundamental understanding to
outline the environmental and material conditions that promote susceptibility to this form of hydrogen
embrittlement.
Keywords: nickel based alloys, low temperature crack propagation, fracture toughness