碾压形变热处理对纯镍N6焊缝组织与性能的影响  

Microstructures and Properties of Welded Joint of Pure Nickel with Thermomechanical Treatment and Roller Compaction

作　　者：柴廷玺[1,2] 王希靖[1] 王博士[1] 张金银[1] 刘骁[1] 王江[3] Chai Tingxi Wang Xijing Wang Boshi Zhang Jinyin Liu Xiao Wang Jiang(State Key Laboratory of Advanced Processing and Recycling of Nonferrous Metals, Lanzhou University of Technology, Lanzhou 730050, China Peili School of Mechanical Engineering, Lanzhou City University, Lanzhou 730070, China Jinchuan Group Co. , Ltd., Jinehang 737100, China)

机构地区：[1]兰州理工大学省部共建有色金属先进加工与再利用国家重点实验室,甘肃兰州730050 [2]兰州城市学院培黎机械工程学院,甘肃兰州730070 [3]金川集团股份有限公司,甘肃金昌737100

出　　处：《稀有金属》2017年第7期768-774,共7页Chinese Journal of Rare Metals

基　　金：甘肃省科技支撑计划项目(1104GKCA051)资助

摘　　要：以纯镍N6焊缝为主要研究对象,采用碾压形变热处理装置对纯镍焊缝进行碾压形变热处理工艺研究,借助光学显微镜(OM)、扫描电镜(SEM)、显微硬度计以及静态应变测量系统等手段分析纯镍焊缝的组织、性能。结果表明:碾压形变热处理温度从300℃升高到500℃,焊缝抗拉强度从329.62 MPa升高到335.12 MPa,增长了1.7%,焊缝断后伸长率呈现出先增大后减小的趋势,400℃时焊缝断后伸长率最高48.44%,比300℃时焊缝断后伸长率增长了5.2%。断后伸长率的增长率高于抗拉强度的增长率,表明碾压形变热处理对提高纯镍焊缝塑性十分有效。碾压形变热处理可细化焊缝晶粒,晶粒度从未经碾压形变热处理时的5.5级升高到平均6.1级;同时有效降低了纯镍焊缝的焊接残余应力,焊缝纵向残余应力σx下降幅度最高达66.86%,横向残余应力σy下降幅度最高达65.87%。综合分析表明碾压形变热处理可以使焊缝组织均匀,细化晶粒、降低焊缝残余应力,对改善焊缝组织,提高焊缝性能有积极作用,能够得到纯镍焊缝的高强度、高塑性的良好匹配。Pure nickel N6 welds, as the main research objects, were studied for the process of thermomechanical treatment with roller compaction using the thermomechanical treatment with roller compaction device, and the microstructures and properties of welds were investigated with the help of analysis methods such as optical microscopy （OM）, scanning electronic microscopy （SEM） , micrnhard- ness tester and static strain measurement system. The results showed that with the roiling temperature increasing from 300 to 500 ℃ the tensile strength of welds increased from 329.62 to 335.12 MPa, increasing by 1.7%. And the fracture elongation of welds showed the trend of first increasing and then decreasing, which reached maxiumm 48.44% at 400 ℃, increasing by 5.2% than that at 300 ℃. The growth rate of the fracture elongation was higher than the tensile strength, which indicated that thermomechanical treatment with roller compaction could improve the plasticity of the welds effectively. The thermomechanical treatment with roller compaction could re- fine the weld grains with the grain size increasing from 5.5 grade to 6.1 grade under the effect of process, and simuhaneously reduce the residual stress of the welds with the descent range of the longitudinal residual stress （ σx ） and the transverse residual stress （ σy ） , reaching nmximum 66.86% and 65.87% , respectively. The comprehensive analysis showed that the thermomechanical treatment with roller compaction could make microstructure uniform, refine grain, reduce the residual stress with a positive effect on improving the weld organization and enhancing the weld performances and further obtained the welds with good matching connection between high strength and high plasticity.

关 键 词：碾压形变热处理 纯镍焊缝 显微组织 力学性能 

分 类 号：TG441.8[金属学及工艺—焊接]