Effect of δ-ferrite on the stress corrosion cracking behavior of 321 stainless steel

摘要

The stress corrosion cracking behavior of 321 stainless steel has been studied In high temperature water. Analytical electron microscopy was utilized to characterize the cracking process to better understand the delta-ferrite effect. Results showed that delta-ferrite inhibited the crack growth by changing the cracking direction along the gamma/delta boundary and creating a highly branched crack path. delta-ferrite was also a source of Cr to facilitate the formation of protective Cr-rich oxides at the gamma/delta boundaries. Ti(CN) particles in the gamma/delta boundary tended to blunt the crack tip and inhibit further oxidation, and thus impeded the total crack growth.