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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.
The welding zone structure of large-thickness marine titanium electron beam welded joint was studied, and the microstructure of fused zone in different thickness was observed by optical microscope, and the phase morphology was analyzed by transmission electron microscope.The results show that the fusion zone The grains grow gradually from 90mm to 90mm.The microstructure changes from the elongated martensite which is interlaced at both ends to the martensite bundle with the direction parallel to the middle of the thickness.The morphology of Both ends are mainly composed of primary α ’phase containing a large number of dislocations and acicular martensite parallel to each other and small, with a small amount of β phase precipitated at the interface .90 mm is between the elongated acicular martensite The formation of a short rod-shaped martensite.The micro-hardness of the fusion zone at 60 mm minimum, the highest 90 mm, the upper and lower surface at the same, which is closely related with the organization due to electron beam welding temperature distribution and temperature gradient characteristics, resulting in fusion The non-uniform grain size and phase morphology in the region of the region make the interface a weaker part of the weld.