HYDROGEN AND TEMPERATURE EFFECTS ON THE SLOW BEND BEHAVIOR OF 21-6-9 STAINLESS-STEEL

Three-point bend test studies on 21-6-9 austenitic stainless steel at 293 K and 77 K demonstrated that hydrogen charging promoted the format ion of facets at 293 K, increased the size of facets at 77 K and reduc ed the energy absorbed by the material at both temperatures. These obs ervations suggest that some stainless steels can exhibit changes in th eir ductile to brittle transition behavior in the presence of hydrogen . Further, the observation that embrittlement exists even at liquid ni trogen temperatures indicates that little or no localized rearrangemen t of hydrogen during the test is required or that relatively high stra in rate effects on hydrogen embrittlement need not be necessarily attr ibuted to enhanced transport of hydrogen atmospheres by mobile disloca tions. The data presented in this paper are consistent with a model th at predicts the lowering of interfacial strengths in the presence of a n environment.