The susceptibility to Stress Corrosion Cracking (SCC) of Grade X80 linepipe steels was investigated in near neutral pH conditions in comparison with a conventional Grade X65 linepipe. SCC properties were evaluated by cyclic loading tests, constant load tests and Slow Strain Rate Tests (SSRT) in simulated underground solutions with and without cathodic charging. In constant load tests, both X80 and X65 showed no remarkable degradation. In cyclic loading tests, SCC susceptibility of both grades depended upon the levels of applied stress and cathodic potential. In SSRT, the most severe evaluation, both grades showed ductility loss in solutions compared to an inert environment. It was concluded that Grade X80 revealed an identical resistance to near neutral SCC as Grade X65. The SCC mechanism was discussed based on the levels of applied stress or strain, and hydrogen ingress into the steels. This study was carried out through the activity in High Strength Line Pipe (HLP) Research Committee in the Iron and Steel Institute of Japan (ISIJ).

Subject
Constant load, Test methods, Hydrogen permeation, Cathodic potential, Notches, Cyclic loading, Stress cracking, Open circuits, Stress, Solutions, Steel, Stress corrosion cracking, Hydrogen
Keywords:
stress corrosion cracking, SCC, linepipe, hydrogen
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2009
Association for Materials Protection and Performance (AMPP)
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