Stress Corrosion Cracking and Corrosion Fatigue in Cr-Mo Low Alloy Steel

Abstract

Abstract Corrosion fatigue crack propagation tests were performed below and above KISCC in AISI 4145 steel heat treated to 1230 MN/m2 and 0.1 N H2SO4 system with particular reference to effects of frequency and stress intensity parameters. The crack growth results above KISCC could not be described by simple linear summation hypothesis, and this fact suggested the importance of the synergestic effect term in crack growth rate. This synergestic effect denoted hereafter as the dynamic SCC rate was strongly influenced by frequency and showed the maximum at a particular frequency. This frequency effect on the dynamic SCC rate suggested that crack growth enhancement under cyclic loading would be induced by dissolution mechanism in spite of the fact that the material had high sensitivity to hydrogen stress cracking under constant load.