疲劳载荷对P92钢高温拉伸性能的影响

摘要

在650℃、应变控制条件下对P92钢进行了不同循环周次的疲劳试验,随后在650℃进行了拉伸性能试验,研究了疲劳载荷对该钢高温拉伸性能的影响.结果表明:经不同周次疲劳试验后,P92钢的高温拉伸性能下降,当循环周次达到20%Nf(Nf为疲劳寿命)时,抗拉强度和屈服强度分别下降了19.1%和38.6%,当循环周次高于20%Nf时,抗拉强度和屈服强度趋向稳定;疲劳试验试样的拉伸断口均呈韧性断裂特征,当循环周次由0增至20%Nf时,拉伸断口上的韧窝由小而深变为大而浅,当循环周次达到20%Nf以上时,韧窝尺寸变化不大.%The strain controlled fatigue tests at 650 ℃ for different cycles,followed by the tensile property tests at 650 ℃,were conducted on P92 steel.The effects of fatigue load on the high-temperature tensile properties of the steel were investigated.The results show that after fatigue testing for different cycles,the high-temperature tensile properties of P92 steel decreased.When the number of cycles reached 20%Nf(Nf refers to fatigue life),the tensile strength and yield strength decreased by 19.1% and 38.6%,respectively.When the number of cycles was higher than 20%Nf,the tensile strength and yield strength tended to be stable.The tensile fractures of the fatigue tested specimens illustrated ductile fracture characteristics.The dimples on the tensile fracture changed from small and deep to big and shallow when the number of cycles increased from 0 to 20%Nf,while changed little when the number of cycles reached higher than 20%Nf.