预置镍基合金片对异种钢UNGW接头组织及性能的影响  

Influence of presetting nickel base alloy sheet on microstructures and mechanical properties of dissimilar steels joints by UNGW

作　　者：郑韶先[1] 徐龙强 赵锡龙 史伟 Zheng Shaoxian;Xu Longqiang;Zhao Xilong;Shi Wei(Lanzhou Jiaotong University,Lanzhou 730070,China;Lanzhou LS Test Technology Co.,Ltd.,Lanzhou 730314,China)

机构地区：[1]兰州交通大学,兰州730070 [2]兰州兰石检测技术有限公司,兰州730314

出　　处：《焊接》2021年第1期1-7,61,共8页Welding & Joining

基　　金：国家自然科学基金资助项目(51765030);甘肃省自然科学基金资助项目(20JR5RA416)。

摘　　要：研究了预置镍基合金片对15CrMo/1Cr18Ni9Ti异种钢超窄间隙焊接接头组织及性能的影响。结果表明,预置镍基合金片厚度小于0.6 mm时,15CrMo熔合线附近焊缝区部分区域以A模式凝固并形成奥氏体胞状晶,而其它区域仍以FA模式凝固,其组织为等轴晶奥氏体+枝晶状铁素体,并且焊缝中心无凝固裂纹形成。预置0.9~1.2 mm厚的镍基合金片时,焊缝中心因镍偏聚而以A模式凝固,形成粗大的奥氏体柱状枝晶,并有凝固裂纹形成。预置镍基合金片厚度在0.6~0.9 mm时,可使15CrMo熔合线附近焊缝区的Ni质量分数比填充金属(ER347L)的提高约2%,明显比未预置镍基合金片的接头具有更好的抑制碳扩散效果,但当镍基合金片厚度在0.3~1.2 mm范围内变化时接头抑制碳扩散的效果并无明显变化。焊态的异种钢接头不均匀混合区内存在马氏体层,而热时效后在熔合线附近会形成一定宽度的富碳硬化区及贫碳软化区。Influence of presetting nickel base alloy sheet on microstructures and mechanical properties of 15CrMo/1Cr18Ni9Ti dissimilar steels joint by ultra-narrow gap welding(UNGW)was studied.The results showed that when the thickness of nickel base alloy sheet was less than 0.6 mm,part of weld zone near the fusion line solidified with A mode and formed austenitic cellular crystals,while the other zone still solidified with FA mode and was made of austenite equiaxed grains and dendrite ferrite.No solidified cracks appeared in the center of weld.When the thickness of nickel base alloy sheet was 0.9-1.2 mm,the center of weld zone solidified with A mode due to Ni macrosegregation,where coarse austenitic columnar crystal and solidification crack formed.When the thickness of presetting nickel base alloy sheet was 0.6-0.9 mm,Ni mass fraction of weld zone near the fusion line was 2%higher than that of filler metal(ER347L),which brought better effect of inhibiting carbon diffusion than that of the joint without presetting nickel base alloy sheet.However,when the thickness of presetting nickel base alloy sheet changed in the range of 0.3-1.2 mm,the effect of joint on inhibiting carbon diffusion had no significant change.Dissimilar steel welded joints had martensite layer in the uneven mixed zone,while a certain width of carbon-rich hardening zone and carbon-poor softening zone formed near the fusion lin after heat aging treatment.

关 键 词：异种钢焊接 碳扩散 镍基合金 凝固裂纹 微观组织 

分 类 号：TG457[金属学及工艺—焊接]