含不同循环变形历史P92钢的高温拉伸性能

High Temperature Tensile Properties of P92 Steel with Different Cyclic Deformation Histories

在650℃下对P92钢进行不同周次循环加载试验,再在650℃下进行拉伸试验,研究了循环变形对其显微组织和高温拉伸性能的影响。结果表明:未循环变形P92钢的显微组织由细小板条马氏体组成,马氏体内存在亚晶粒和位错,晶界析出M23C6碳化物,循环变形后钢中板条马氏体发生明显回复,亚晶粒长大、位错向胞状结构转变;与未循环变形相比,循环变形后P92钢的高温拉伸性能明显降低,且抗拉强度和屈服强度随循环周次的增加而降低;循环变形对P92钢的拉伸断裂机制没有产生明显影响,拉伸断口均存在明显韧窝,拉伸断裂机制均为韧性断裂。

Cyclic loading tests at 650℃for different number of cycles were conducted on P92 steel,and then tensile tests at 650℃were carried out on the steel.The effects of cyclic deformation on microstructure and high temperature tensile property were studied.The results show that the microstructure of P92 steel without cyclic deformation consisted of fine lath martensite;subgrains and dislocations existed inside the martensite and M23 C6 carbide precipitated on the boundaries.After cyclic deformation,the recovery of the lath martensite in the steel occurred obviously,the subgrains grew and the dislocations changed to the cellular-like structure.Compared with those without cyclic deformation,the high temperature tensile properties of the P92 steel after cyclic deformation decreased significantly,and the tensile strength and yield strength decreased with the increase of the number of cycles.The cyclic deformation did not greatly influence the tensile fracture mechanism of the P92 steel;dimples appeared on the tensile fracture surface,indicating that the tensile fracture mechanism was ductile fracture.