Strain performance and life prediction for P91 steel under creep-fatigue interaction

Stress controlled creep-fatigue interaction test for P91 steel was investigated at 546℃.Hysteretic loops,total strain range,mean strain and inelastic strain range for the P91 steel were discussed and analyzed.Based on the characteristics of creep-fatigue interaction test controlled by stress,considering the effect of top and bottom tensile hold time on life,the frequency amendment method was used to predict the life of P91 steel.The research results show that the failure model of P91 steel is cyclic creep and static creep under the stress controlled interaction test.With cyclic times increasing,hysteretic loops are moving rightward.Inelastic strain has great contributions for the life of P91 steel,whose rising rate is increasing with the P91 life reducing.Results of life prediction and test are inosculated better,and the 95% of the data point were in the two times error band scope.The research results can provide the theoretical and experimental base for life prediction of P91 steel.