Materials Science Forum, Vol.475-479, 3863-3866, 2005
Effect of grain boundary character distribution on stress corrosion cracking behavior in austenitic stainless steels
The effect of grain boundary character distribution (GBCD) on intergranular stress corrosion cracking (IGSCC) in austenitic stainless steels in high temperature water was verified experimentally. GBCD control using the strain annealing method increased the fraction of low-Sigma coincidence site lattice (CSL) boundaries and the segmentalized network of random grain boundaries in austenitic stainless steels. The fractions of low-Sigma CSL boundaries of GBCD controlled steels were 75-85%, while those of uncontrolled steels were 60-70%. Creviced bent beam tests were conducted at 561 K in pure water containing 8 ppm dissolved oxygen for stress corrosion cracking (SCC) evaluation. The tests revealed that GBCD control suppressed IGSCC initiation or propagation and that cracks were predominantly propagated along random grain boundaries. It is considered that induced lower-Sigma CSL boundaries result in high resistance to IGSCC.
Keywords:grain boundary character distribution;sensitization;stress corrosion cracking;thermo-mechanical treatment;stainless steel;creviced bent beam test