汽轮机转子用镍基合金/耐热钢异种焊接接头组织及性能研究  

Study on Microstructure and Mechanical Property of Dissimilar Welded Joints Between Ni-based Alloy and Heat Resistant Steel for Rotors of Steam Turbine

作　　者：聂甫恒 熊建坤[1,2] 杨林 徐健[1,2] 许德星 毛桂军[1] 吴海峰 余勇 向冲 NIE Fuheng;XIONG Jiankun;YANG Lin;XU Jian;XU Dexing;MAO Guijun;WU Haifeng;YU Yong;XIANG Chong(Dongfang Turbine Co.,Ltd.,Deyang Sichuan,618000;State Key Laboratory of Long-life High Temperature Materials,Deyang Sichuan,618000)

机构地区：[1]东方电气集团东方汽轮机有限公司,四川德阳618000 [2]长寿命高温材料国家重点实验室,四川德阳618000

出　　处：《东方汽轮机》2022年第1期33-38,共6页Dongfang Turbine

基　　金：四川省重点研发项目(2017GZ0112)。

摘　　要：采用GTAW焊接方法进行了4762镍基高温合金的对接焊接,并对4762镍基高温合金板材与1Cr10Mo1NiWVNbN耐热钢(12Cr钢)板材进行异种金属对接焊接,对接头的微观组织、力学性能及失效机理作了分析。拉伸试验结果表明,4762合金同种接头的室温抗拉强度达到1137 MPa,4762/12Cr异种焊接接头的室温抗拉强度达到827 MPa,室温接头拉伸试样的断裂位置都位于焊缝区。异种接头高温拉伸试样均断裂于12Cr母材,焊缝及热影响区强度大于12Cr母材。微观组织分析结果表明,焊缝组织为γ-Ni奥氏体基体和晶界及晶内分布的析出相颗粒,主要为碳化物。而4762侧热影响区微观组织为γ-Ni奥氏体基体+γ′强化相+尺寸较大的二次碳化物颗粒,可以看到大量退火孪晶的存在。采用较小的焊接电流进行堆焊及对接焊,严格控制层间温度,减小焊接热输入,降低了熔合区及部分熔融区形成液化裂纹的趋势,接头的4762合金侧未观察到液化裂纹现象。异种接头的显微硬度值范围为218~371 HV,其最小值出现在焊缝顶层位置,最大值出现在4762合金侧的热影响区。Butt welding of 4762 nickel based alloys plates and dissimilar metal welding between 4762 alloy and1Cr10Mo1NiWVNbN heat resistant steel(12Cr)were performed by GTAW welding respectively,and the microstructure,mechanical property and failure mechanism were analyzed.The results of tensile test showed that the tensile strength of 4762 alloy joints at room temperature reached up to 1137 MPa,the tensile strength of 4762/12Cr dissimilar joints at room temperature reached up to 827MPa,and the tensile specimens at room temperature of all joints were fractured in weld zone.High temperature tensile specimens of dissimilar joints were all fractured in 12Cr base metal,indicated that the tensile strength of weld zone and heat affected zone(HAZ)at 12Cr side was greater than that of 12Cr base metal at high temperature.The results of microstructure analysis showed that the microstructure in weld was mainly consisted ofγ-Ni austenite matrix and precipitated particles,mainly carbides,in the grain and grain boundary.Moreover,the microstructure in HAZ of 4762 alloy side wasγ-Ni austenite matrix+γ′strengthening phase+secondary carbide particles with large size,and a large number of annealing twins would be observed.In order to control the temperature between layers,reduce the heat input and reduce the tendency of forming of liquation cracks in the fusion zone and partial melted zone,a small welding current was used to surfacing and butt welding,and no liquation cracks were observed in the joints on the side of 4762 alloy.The microhardness of the dissimilar joint ranges from 218 to 371 HV,the minimum value appeared at the top of the weld,and the maximum value appeared in the HAZ of 4762 alloy.

关 键 词：高温合金 耐热钢 异种接头 微观组织 力学性能 

分 类 号：TG407[金属学及工艺—焊接]