Effect of Temperature and Strain Amplitude on Low-cycle Fatigue Behavior of Sub-stable Austenitic Stainless Steel S321
Low-cycle fatigue tests were conducted on S321 and S321H stainless steels at 0.5%,0.7%,and 0.9%strain amplitude at room temperature and 650 ℃.Fatigue loading history tests were performed on S321 and S321H at room temperature for several life points,and the amount of deformation-induced martensite was measured by quantitative XRD analysis.The results show that deformation-induced martensite generation leads to continuous cyclic hardening in austenitic steels,and the alloys continue to secondary harden after the primary hardening at room temperature,whereas there is no deformation-induced martensite generation at 650 ℃,and the alloys enter into cyclic stabilization phase after the primary hardening.The lower the carbon content during cycling,the more deformation-induced martensite there is,and the higher the degree of cyclic hardening of the alloy.At two temperatures,the fatigue life of the two materials in the low strain amplitude are not much different,the greater the strain amplitude,the greater the difference between the fatigue life of the two materials.Therefore,it can be considered to use S321 stainless steel instead of S321H stainless steel.Therefore,it can be considered to use S321 stainless steel instead of S321H stainless steel for service conditions of low strain amplitude.
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