高温运行后12Cr1MoV钢焊接接头的显微组织和力学性能

Microstructure and Mechanical Properties of 12Cr1MoV Steel Welded Joint after High Temperature Service

利用光学显微镜、拉伸和冲击试验机、显微硬度计等对高温运行前后12Cr1MoV钢焊接接头的组织及力学性能进行了研究。结果表明:高温运行后,焊接接头组织中除了原始组织中的铁素体和珠光体外,还出现颗粒状析出物,热影响区和焊缝处组织中出现了贝氏体;焊接接头的屈服强度和抗拉强度分别由高温运行前的455,625MPa下降为430和583MPa,平均冲击功从160J下降为124J;冲击断口上有许多裂纹,裂纹上有明显的台阶,断裂方式为塑性断裂;高温运行后母材和焊缝区的硬度分别为190,265HV,焊缝的硬度符合供货方技术要求,而母材硬度超标。

The microstructures and mechanical properties of lZGrttvto v steel wc,u^u a high temperature service were studied by optical microscopy, impact and tension test and micro-hardness test. The results show that after high temperature service, the microstructure of the welded joint consisted of not only ferrite and pearlite existed in the original structure but also granular precipitates. And the bainite was also found in the mierostructures of heat affected zone and weld seam. The yield strength and tensile strength of the welded joint decreased from 455,625 MPa before high temperature service to 430 MPa and 583 MPa respectively and the average impact energy decreased from 160 J to 124 J. Many cracks were observed at the impact fracture surface and obvious steps existed on them. The facture mode was plastic fracture. The hardness of base metal and weld seam after high temperature service were 190 HV and 265 HV respectively, and the hardness of weld seam met the technical requirement of the supplier while that of base metal exceeded badly.