相位角对定向合金DZ125热/机械疲劳行为与寿命影响的试验研究

The Effects of Phase Angle on Thermomechanical Fatigue Behavior and Life in DS Superalloy DZ125

对DZ125定向凝固铸造镍基高温合金进行了同相位、反相位和-135°相位的550℃～1000℃热/机械疲劳试验研究。试验结果表明:同相位寿命曲线与反相位寿命曲线有一交点,-135°相位的热/机械疲劳寿命比同相位热/机械疲劳寿命与反相位热/机械疲劳寿命长。试样的微观断口分析显示了在热/机械疲劳试验中同时存在疲劳、蠕变和氧化损伤。对同相位、反相位和-135°相位热/机械疲劳循环应力响应行为进行了研究。用Manson-Coffin方程、微裂纹扩展模型和拉伸迟滞能(Ostergren)寿命预测模型对DZ125合金的热/机械疲劳寿命进行了预测(分散带为2倍左右)。

Three types of test (in-phase,out-of-phase and-135 ° phase angle) were performed in directional solidification superalloy DZ125,with temperature cycling from 550'C to 1000 C. The results of experiment showed that DS superalloy DZ125 exhibited a crossover point of the in-phase and out-of-phase mechanical strain-life curves, - 135° phase angle lives were longer than that of in-phase and out-of-phase thermomechanical fatigue. Besides fatigue damage, creep damage and oxidation damage exist in thermal-mechanical fatigue. The effect of phase angle on TMF cyclic stress-strain response in DS superalloy DZ125 was investigated. Manson-Coffin e-quation, Ostergren method and microcrack propagation model were chosen to predict TMF life. The results of TMF life prediction showed that all of methods chosen were able to give a reasonable life prediction for DS superalloy DZ125.