Effect of weld composition and microstructure on hydrogen assisted fracture of austenitic stainless steels

The effect of severe hydrogen environments on the tensile fracture behavior of a variety of austenitic stainless steel welds was investigated. In all cases, second phases or particulates common only to the weld microstructure were the origin of fracture initiation in hydrogen. These second phases formed as a result of microsegregation during solidification and/or solid state transformations during cooling or aging. In addition to second phases the weld microstructure matrix phase also influences fracture behavior. The fracture behavior is discussed in terms of localized chemical variations and the presence of second phases, and th interaction of dislocations with internal boundaries.