STRESS-CORROSION CRACKING OF HY-180 STEEL IN AQUEOUS 3.5 PCT NACL

Crack propagation rates were studied as a function of stress intensity under both freely corroding potentials and potentials produced by coupling to Zn. Crack fractography was studied by scanning electron microscopy and corrosion products were identified by electron diffraction analysis. The stress intensity below which SCC could not be detected was approximately 45 MPa m** one-half for both freely corroding and Zn-coupled conditions. Cracking was consistent with a hydrogen embrittlement mechanism, irrespective of potential. Comparison of the data with a similarly heat treated and related alloy (HY-180 M) containing 14 Co-0. 16 C showed no significant difference in SCC behavior.