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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 weld was taken as the main research object. Rolling deformation heat treatment process was applied to the pure nickel weld by rolling compaction heat treatment process. With optical microscope (OM), scanning electron microscope (SEM), microhardness tester and static strain measurement System analysis of pure nickel weld organization, performance. The results show that the temperature of rolling deformation increases from 300 ℃ to 500 ℃, the tensile strength of weld increases from 329.62 MPa to 335.12 MPa, increasing by 1.7%. The elongation at break increases first and then decreases At 400 ℃, the elongation at break of the weld is 48.44%, which is 5.2% higher than that at 300 ℃. Elongation at break increases faster than that at tensile strength, indicating that superalloy deformation is very effective in improving the ductility of pure nickel weld. Rolling deformation heat treatment can refine the weld grains, grain size without rolling deformation heat treatment from 5.5 to an average of 6.1; at the same time effectively reducing the pure nickel weld welding residual stress, weld longitudinal residual The stress σx decreases by up to 66.86%, and the horizontal residual stress σy decreases by up to 65.87%. The comprehensive analysis shows that the rolling deformation heat treatment can make the microstructure of the weld uniform, refine the grains and reduce the residual stress of the weld, which has a positive effect on improving the weld microstructure and improving the weld properties, and can obtain the high strength and high weld strength of the pure nickel weld Plastic good match.