Toughness and fatigue properties of martensitic stainless steels for nuclear applications

Abstract

The use of high-strength stainless steels in pressurized water reactors may allow reductions in weight and cost of some components. As a preliminary requirement to the use of these materials, a good knowledge of their mechanical properties and corrosion resistance is needed. In this study, the toughness and fatigue properties of five low-carbon martensitic stainless steel grades were determined. The test materials were forged bars in the as-quenched and tempered condition, with or without a thermal aging treatment of 5000 hours at 400/sup 0/C. Charpy V-notch transition curves were determined in the aged or unaged condition. J tests were performed at room temperature using the multiple specimen interrupted loading method. Low-cycle fatigue properties at 20/sup 0/ and 320/sup 0/C and the fatigue limit in air and NaCl aqueous solution environments were determined in the aged and unaged conditions. The fatigue life is not sensitive to test temperature and to thermal aging. All materials exhibit cyclic softening during testing. The fatigue limit is considerably lowered in the aqueous chloride solution as compared to air. A small improvement of the fatigue limit in air is brought up by thermal aging (which increases the tensile strength), but not definite effect of thermal agingmore » on corrosion-fatigue in NaCl aqueous solution could be detected.« less