QUANTIFYING THE EFFECTS OF STRAINING-HARDENING AND WATER CHEMISTRY ON CRACK GROWTH RATES OF 316L SS WELDS IN HIGH TEMPERATURE WATER

摘要

A series of stress corrosion crack (SCC) growth rate tests with in-situ crack length monitoring for 316L stainless steel weld heat-affected zones with different Vickers hardness and 316 weld metals with different delta-ferrite contents in 288°C pure water with different concentrations of dissolved oxygen were performed. Typical intergranular stress corrosion cracking (IGSCC) and branching of the crack front were observed for two 316L HAZ specimens. Crack growth rate increases with Vickers Hardness in the 316L HAZ specimens. CGRs for 316L HAZ specimens in 2ppm and 7ppm DO are moderately higher than that in 0.2ppm DO water. After a single overloading, CGR tends to be lower for a period of time. Crack growth near the fusion line is monitored and the crack front of a 316L HAZ specimen is near the fusion line, while ACPD still shows an increase before stopping the test.