焊后热处理温度对G115/T92异种钢接头组织及力学性能的影响

Effect of PWHT temperature on microstructure and mechanical properties of G115/T92 dissimilar steel welded joint

利用钨极氩弧焊(GTAW)和手工电弧焊(SMAW),采用767、774、790℃3种焊后热处理温度对G115/T92异种钢进行焊接试验,并利用光学显微镜、显微硬度仪、拉伸试验机、冲击试验机等对焊接接头的显微组织及力学性能进行研究。结果表明:接头焊缝、热影响区均为典型的回火马氏体组织,T92钢侧熔合线附近δ-铁素体的体积分数分别为0. 3%、0. 1%、0. 1%。随着焊后热处理温度升高,显微硬度、室温强度降低,焊缝冲击吸收能量增大,室温强度和冲击吸收能量均符合母材标准要求。室温拉伸断裂均发生在T92钢侧母材,650℃高温断口位于T92钢侧不完全相变区。推荐焊后热处理温度为(770±5)℃,偏上限控制。

The experimental study on the welding process of G115/T92 dissimilar steels was conducted using gas tungsten arc welding( GTAW) and shielded metal arc welding( SMAW) with post-weld heat treatment( PWHT) temperature of 767 ℃,774 ℃ and 790 ℃,respectively,then the microstructure and mechanical properties of the welded joints were investigated by means of optical microscope,hardness,tensile and impact tests. The results show that the welding seam and heat-affected zone( HAZ) of the joints have a typical tempered martensite structure. The volume fraction of polygonal δ-ferrite near the fusion line is 0. 3%,0. 1% and 0. 1%,respectively. With the increase of PWHT temperature,Vickers hardness and strength at room temperature decrease while impact absorbed energy increases.Both of room temperature strength and impact absorbed energy meet the requirement of base metal standards. All the tensile fracture occurs in base metal of T92 steel at room temperature while in the ICHAZ of T92 steel side at 650 ℃. The PWHT temperature should be controlled in the range of( 770 ± 5)℃,and the upper limit is recommended.