保载时间对P92钢蠕变-疲劳交互行为的影响

为研究保载时间对蠕变-疲劳寿命和应力-应变响应的影响规律,对P92钢在650℃下进行了应变幅为±0.5％,保载时间为36,600,3600 s的蠕变-疲劳试验,采用Chaboche塑性本构模型和应变强化蠕变模型进行有限元模拟,并对P92钢断裂试样进行透射电镜检测.试验结果表明:保载时间增长导致拉压屈服极限降低,最大拉应...

Experimental investigation on effect of holding time on creep-fatigue behaviors of P92 steel

In order to study the effect of holding time on creep fatigue life and stress-strain response,creep-fatigue tests with strain amplitude of±0.5%and holding times of 36,600,3600 s were carried out on P92 steel at 650℃,the Chaboche plastic constitutive model and the strain hardening creep model were used for finite element simulation,and the fracture specimens of P92 steel were tested by transmission electron microscopy.The test results show that the increase of holding time leads to the decrease of tensile and compressive yield limit,the decrease of maximum tensile stress,the decrease of inelastic strain range and the decrease of creep-fatigue life.The simulation results show that the maximum tensile stress of the simulated results and the stress relaxation amount during the holding period are basically the same as the experimental results.The test results show that in the creep-fatigue test,as the holding time increases,the creep cavity slowly forms and grows.The creep damage induced by increase of holding time will accelerate fatigue crack expansion,and the creep-fatigue mechanism gradually changes from dominant fatigue damage to dominant creep damage.Finally,a fitting formula for the variation of the maximum tensile stress with the number of cycles under different holding times was proposed.In combination with the cycle-by-cycle concept introduced by the WANG et al′s model,an improved creep-fatigue life model was obtained,and by using this model,it is convenient to realize the creep-fatigue life prediction of P92 steel under different holding times.