Low Temperature Isothermal Strain in a Metastable Austenitic Stainless Steel Sheet

Low temperature stationary creep strain in a metastable austenitic stainless steel was studied at −162°C under various combinations of prestrain and stress ratio. It was found that the amount of transformed martensite during low temperature stressing increased with the number of thermal cycles as well as the degree of prestrain and stress ratio. When the applied stress exceeded 70 percent of the material yield strength at −162°C, the martensite volume increased significantly. At the same time, the stationary low temperature creep rate exceeded 1.8x10−10 (s−1), which would cause approximately 0.44 percent strain after continuous operation for a year.