超大厚度钛合金电子束焊接熔合区精细组织表征

发布时间：2018-05-11 19:27

本文选题：Ti + 电子束焊接　；参考：《中国科学:技术科学》2017年09期

【摘要】：对大厚度船用钛合金电子束焊接接头熔合区组织进行了研究,采用金相显微镜观察熔合区在不同厚度的微观组织特点,并通过透射电子显微镜对相形貌进行了分析.结果表明:熔合区晶粒从两端面向90mm处逐渐增大.显微组织从两端面交错生长的细长马氏体,向厚度中部逐步转变成相互平行具有一定方向性的马氏体束域.相形貌在两端面主要是由含有大量位错的初生α'相和相互平行且细小的针状马氏体组成,交界面上有少量β相析出.90 mm处在细长的针状马氏体之间形成短棒状的马氏体.熔合区显微硬度在60 mm处最低,90 mm处最高,上下表面处相当,这与组织有密切关系.由于电子束焊接温度分布和温度梯度的特点,造成熔合区在厚度上晶粒和相形貌尺寸的不均匀,使得界面成为焊缝的薄弱部位.
[Abstract]:The microstructure of the fusion zone of large thickness marine titanium alloy welded joints by electron beam welding was studied. The microstructure of the fusion zone in different thickness was observed by metallographic microscope and the phase morphology was analyzed by transmission electron microscope (TEM). The results show that the grain size in the fusion region increases gradually from both ends facing 90mm. The microstructure changes from the thin martensite with intersecting two ends to the middle of the thickness into a martensite beam region which is parallel to each other and has a certain directionality. The morphology of the phase is mainly composed of the primary 伪 'phase containing a large number of dislocations and the parallel and fine acicular martensite. A small amount of 尾 -phase precipitates at the interface between the slender acicular martensite and the short bar martensite. The microhardness of the fusion zone is the lowest at 60 mm and the highest at 90 mm, and the upper and lower surface is the same, which is closely related to the microstructure. Due to the characteristics of electron beam welding temperature distribution and temperature gradient, the thickness of the fusion zone and the size of the phase morphology are not uniform, which makes the interface become the weak part of the weld.
【作者单位】：中国船舶重工集团公司第七二五研究所;
【基金】：国家重点研发计划项目(编号:2016YFC0304203)资助
【分类号】：TG456.3

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