Numerous mechanisms of crack advance have been proposed for iron- and nickel-base alloys in high temperature water, with most focusing on a slip / film rupture / oxidation or a direct hydrogen mechanism of crack advance. Numerous roles for hydrogen have been proposed, including etits on dislocation mobility, on the cohesive strength of metal bonds, on void / bubble / blister formation, etc.; some of these roles could influence other mechanisms of crack advance. The objective of this paper is to review the evidence of hydrogen effects in environmental cracking in hot water. While additional critical tests are needed to more precisely define its role, present evidence provides only weak support that hydrogen plays a predominant role in environmental cracking in hot water.
Keywords: stress corrosion cracking, high temperature water, hydrogen effects, stainless steel, nickel alloys.