P92钢高温拉伸断口形貌的研究

High-temperature Tensile Fracture Morphology of P92 Steel

采用热模拟法进行600～1300℃温度区间P92钢的高温拉伸实验。利用SEM,LSCM对不同拉伸温度下的断口形貌及近断口组织进行分析,并对P92钢的力学性能进行研究。结果表明：P92钢拉伸时,抗拉强度由467.32MPa下降到24.32MPa,屈服强度由56.88MPa下降到1.07MPa;不同拉伸温度下,断口表现以韧性断裂为主,韧性与脆性特征共存的现象。在600～900℃时,P92钢发生了动态回复过程,断口形貌表现为韧窝特征。冷却至室温,P92钢近断口处组织均为马氏体＋残余奥氏体组织＋M7C3＋MC＋M23C6＋M6C＋M3C型碳化物。随着温度升高,P92钢发生了动态再结晶,断口形貌以塑孔为主。P92钢近断口处组织为马氏体＋残余奥氏体组织＋MC＋M6C型碳化物。

High temperature tensile tests of P92 steel were carried out at 600-1300℃ by means of thermal simulation method.The fracture morphology and microstructure near fracture at different tensile temperatures were analyzed by SEM and LSCM,and the mechanical properties of P92 steel were investigated.The results indicate that tensile strength decreases from 467.32 MPa to 24.32 MPa,and yield strength decreases from 56.88 MPa to 1.07 MPa.The rupture is mainly ductile rupture with ductile and brittle characteristics co-existing.Dynamic recovery occurs with P92 steel at 600-900℃,and the fracture is mainly dimple.The microstructure near fracture of P92 steel is martensite＋residual austenite＋M7C3＋MC ＋M23C6＋M6C＋M3C after cooling down to the room temperature.With the increasing of the temperature,dynamic recrystallization occurs with P92 steel,and the fracture is mainly plastic hole.The microstructure is martensite＋residual austenite＋ MC＋M6C carbides.