A gamma prime precipitate hardenable alloy (22%Cr-48%Ni-3%Mo-2.7%Ti- 0.6%Al-0.5%Nb-Fe) was tested for the resistance to SCC(stress corrosion cracking) and HEC (hydrogen embrittlement cracking) in H2S and Cl- environments. In this alloy, the susceptibility to both SCC and HEC was enhanced by the increace of the yield strength rather than by aging conditions. In addition to gamma prime precipitation in matrix, M23C6 carbide and sigma phase precipitated at grain boundaries during high temperature aging with time. This sigma phase was not only deletorius for ductility, but also enhanced the intergranular SCC. The grain size also affected the susceptibility to the cracking. Further, it was considered that the evaluation of SCC resistance by the SSRT method was more severe than that by the constant strain method for this type of precipitate hardenable alloys.

Subject
Sigma phase, Environmental cracking, Grain size, Precipitation (solids), Precipitates, Nickel based alloys, Intergranular cracking, Constants, Grain boundary, Alloys, Yield strength, Aging, Samples
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1989
Association for Materials Protection and Performance (AMPP)
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