Influence of intermittent loading on SCC behavior for an X70 pipeline steel in a near neutral pH solution

摘要

The influence of intermittent loading on stress corrosion cracking (SCC) behavior for an X70 pipeline steel was studied using slow strain rate tests (SSRT) in a near neutral pH soil solution at various applied potentials. The d.c. potential drop method was used to measure the crack initiation and propagation. The crack length at the cross section of the fractured sample was observed using scanning electron microscopy (SEM). The results showed that the crack initiation stress in solution was lower than the yield stress in air. SEM observation showed that the crack length was longer in intermittent loading than that in continuous loading. At anodic potential, the crack initiation stress was the lowest and the crack length was the longest. The crack kept growing during constant loading period.