多维应力状态下高温低周疲劳寿命评价

EVALUATION ON HIGH TEMPERATURE LOW-CYCLE FATIGUE LIFE UNDER MULTIPLE-DIMENSION STRESS CONDITION

现代工业正在向着高速、高温、高压的方向发展 ,疲劳问题严重威胁着现代工业设备的安全。该文采用 2 2 5Cr 1Mo带预裂纹环状缺口圆柱形试样的实验数据及有限元分析结果 ,研究了采用当量塑性应变范围Δεp 、当量蠕变应变范围Δεc 和当量应变范围Δε,来评价材料在 4 0 0℃、应变速率为每秒 0 2 %、不同缺口形式下的高温低周疲劳总寿命和裂纹扩展寿命的可行性、缺口形式对疲劳寿命 (疲劳总寿命和裂纹扩展寿命 )的影响以及蠕变 疲劳交互作用对高温低周疲劳总寿命和裂纹扩展寿命的影响 ,最后利用最小二乘回归方法 ,得到了该材料高温低周疲劳总寿命和裂纹扩展寿命评价方程〔1～ 7〕 。

With the modern industry development into high speed,high temperature and high pressure,the fatigue problem is threatening the safety of its equipment.By the use of experience data of 2.25Cr 1Mo cylindrical specimen with precrack ring type nothes,the finite element analysis,and by means of equipment plastic strain rang Δ ε p,equivalent creep strain range Δ ε c and equivalent strain rang Δ ε ,the material was evaluated under 400℃,strain rate 0.2% per second,with different nothes shape.The results included that:The feasibility of high temperature low cycle fatigue total life and the crack propagation life;The influence of notch shape on fatigue life (fatigue total life and crack propagation life);The influence of creep fatigue interaction on high temperature low cycle fatigue total life and crack propagation life.Finally the evaluation equition of high temperature low cycle fatigue total life and crack propagation life for that material were obtained by the use of the least square regression method.