Strain-shock-induced early stage high pH stress corrosion crack initiation and growth of pipeline steels

Abstract

This investigation demonstrated the occurrence of strain-shock associated with steels having discontinuous yielding and its effect on high pH stress corrosion cracking (SCC) under load-control (e.g., internally pressurized pipeline), instead of displacement-control, for the first time. Results showed that microcrack initiation in the plastic zone and microcrack coalescence to the main crack tip were the main growth mechanism in the early stage of crack growth, distinct from the generally believed stochastic initiation and coalescence mechanisms. Discontinuous yielding associated with strain-aging would create a strain-shock effect under load-control and substantially enhance the early stage crack initiation and growth.