DISLOCATION TRANSPORT AND HYDROGEN EMBRITTLEMENT

Tensile tests of several austenitic stainless steels show that when smooth bar samples are exposed to very high pressure hydrogen significant degradation in mechanical properties is observed. This degradation is accompanied by fracture along interfaces such as grain and twin boundaries although microvoid coalescence remains a prominent fracture feature. The interface cracking and loss in ductility increases as the exposure pressure increases to 172.5 MPa and at the higher pressures the adverse effects of hydrogen are enhanced by warm working operations. Rationalization of these data show that dislocation transport of hydrogen is not required in the embrittlement process; constraint, local lattice dilation, hydrogen content of interfaces are the dominant variables influencing the hydrogen affected fracture processes. © 1979 American Society for Metals and the Metallurgical Society of AIME.