Environmentally Assisted Cracking Initiation in High-Temperature Water
Anna Hojná
Abstract
Environmentally assisted cracking (EAC) is a very complex process that develops in materials that involve combining actions of environment and tensile loading. Crack initiation is the least explored stage and is not clearly defined. For this paper, current knowledge of crack initiation mechanisms was reviewed for three types of commercial structure materials exposed to high-temperature (HT) water coolants of power plants, namely ferritic low-alloy (LAS) and carbon (CS) steels, austenitic stainless (AS) steels, and nickel-based alloys. Physicochemical microprocesses engaged in the two earliest phases of the mechanism, the precursor and the incubation phases, are rather specific for each of these materials. In the latter, the slow growth phase, the crack development process passes into a sequence of repeating steps where the specific key microprocesses persist.