Fatigue crack growth rate studies of medium sulfur low alloy steels tested in high temperature water.

摘要

Fatigue crack propagation tests of medium sulfur (0.007 to 0.011 wt %) ASTM A508-Class 2 forgings were performed in deaerated high purity, high temperature water. In general, these forgings did not exhibit environmentally assisted cracking (EAC) in tests at 149C (300F) or at 260C (500F). Lowering the pH did not raise the crack growth rates significantly. However, adding a small amount of oxygenated water to the feedwater increased the fatigue crack growth rates (FCGR) by a factor of about 4. Automated analyses of the sulfide inclusions in polished sections of the forgings supported a previously proposed relationship for susceptibility to EAC.