超大厚度钛合金电子束焊接熔合区精细组织表征  

Fine microstructure of electron beam welding joint in fusion zone of large thickness titanium alloy

作　　者：高福洋[1] 高奇[1] 蒋鹏[1] 刘志颖[1] 廖志谦[1] 

机构地区：[1]中国船舶重工集团公司第七二五研究所,洛阳471000

出　　处：《中国科学：技术科学》2017年第9期941-945,共5页Scientia Sinica(Technologica)

基　　金：国家重点研发计划项目(编号:2016YFC0304203)资助

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.The microstructure of fusion zone in the welded joints welded by electron beam in titanium alloys with large thickness for ships was studied by optical microscopy observation and transmission electron microscopy in different thickness. The results show that the grain size of the fusion zone increased from the two ends to 90 mm deep. The microstructure is transformed from the elongated martensite in the two ends to martensitic beam with a certain direction in the middle of the thickness gradually. The morphology at the two ends is mainly composed of primary α＇ phase with large numbers of dislocations, fine acicular martensite that is parallel to each other,and interfaces with a small amount of β phase. The morphology at 90 mm deep mainly consists of needle martensite and short rod martensite. The electron beam welding temperature distribution and temperature gradient characteristics result in uneven distribution of the grain size and phase morphology along the different thickness of the fusion zones, forming the weak parts at the interface.

关 键 词：Ti6321 电子束焊接 熔合区 精细组织 

分 类 号：TG456.3[金属学及工艺—焊接]