论文部分内容阅读
Stress corrosion cracking (SCC) susceptibility of aged CF8A cast austenitic stainless steels (CASS)with different ferrite contents were evaluated by slow strain rate tests (SSRT).The CF8A was thermally-aged at either 385 or 450℃ from 2400 to 6000 hours, and SSRT tests were conducted in air and simulated BWR coolant water environment.Elongation loss was used as an index of SCC degradation based on the SSRT results in air and water condition.The microstructure of CF8A composed primary ofγ matrix and δ-ferrite.Regardless of the aging temperature, the hardness ofδ-ferrite slightly raised with the aging time, but not of that ofγ matrix.The elongation loss of high ferrite specimens was greater than that of the low ferrite specimens, especially in 450℃-aged condition.In water environment, the fractograph of all 380℃-aged specimens presents dimple fracture, while the counterpart specimens aged at 450℃ show brittle fracture at high ferrite condition, which could be the results of the greater age-hardening behavior of δ-ferrite in 450℃-aged specimens.Overall, the SCC susceptibility of CF8A in simulated BWR coolant water environment was eliminated when the aging temperature drop down from 385℃ to 450℃.