多层多道TIG焊对高强钢焊缝组织和韧性的影响

发布时间：2018-02-11 16:32

本文关键词： TIG多层多道焊组织残余奥氏体韧性　出处：《机械工程学报》2017年18期 　论文类型：期刊论文

【摘要】：对890 MPa级以上的高强焊接接头采用钨极氩弧焊(Tungsten inert gas,TIG)多层多道焊接工艺。应用光学显微镜、扫描电镜和透射电镜等手段对高强焊接接头焊缝的末道组织、焊缝的再热组织以及不同焊道下的冲击断口的形貌进行观察,分析钨极氩弧焊工艺下不同的焊道组织对焊缝韧性的影响。结果表明,焊缝末道组织由板条马氏体和联合贝氏体组成。联合贝氏体对冲击韧性是不利的。多层多道焊的再热作用有利于改善和细化组织,使柱状晶消失,同时使原来方向一致的板条马氏体组织变为回火马氏体组织,粗大的联合贝氏体组织消失,这也是焊缝韧性提高的主要原因。此外,多层多道焊接工艺还会使焊缝中残余奥氏体形态发生改变,由薄膜态转变为块状残余奥氏体,但由于块状残余奥氏体尺寸较小且含量较少,所以其对韧性影响较小。
[Abstract]:The multilayer and multipass welding technology of Tungsten inert gas gas arc welding (Tungsten inert TIG) for high strength welded joints of 890 MPa grade was used. The final microstructure of high strength welded joints was studied by means of optical microscope, scanning electron microscope and transmission electron microscope. The reheat microstructure of weld and the morphology of impact fracture under different welding pass were observed, and the effect of different weld structure on weld toughness under TIG welding process was analyzed. The final microstructure of the weld is composed of lath martensite and combined bainite. The combined bainite is unfavorable to the impact toughness. The reheat effect of multilayer and multi-pass welding can improve and refine the microstructure and make the columnar crystal disappear. At the same time, the same direction lath martensite structure is changed into tempering martensite structure, and the coarse joint bainite microstructure disappears, which is also the main reason for the improvement of weld toughness. The morphology of residual austenite in the weld will be changed from thin film state to block retained austenite by multi-layer and multi-pass welding process. However, due to the smaller size and less content of bulk retained austenite, it has little effect on toughness.
【作者单位】：南瑞集团公司(国网电力科学研究院);北京国电富通科技发展有限责任公司;钢铁研究总院焊接研究所;
【分类号】：TG457.11

【相似文献】