热连轧Ti-Al-Nb-Zr-Mo系钛合金无缝管电子束焊组织和力学性能

Microstructure and Mechanical Properties of Hot Continuous Rolling Ti-Al-Nb-Zr-Mo Titanium Alloy Seamless Tube Welded by EBW

摘要:

采用真空电子束焊接工艺对热连轧成型的8 mm厚新型Ti-Al-Nb-Zr-Mo系钛合金无缝管进行了环缝焊接试验，并对焊接接头的微观组织和力学性能进行了测试分析。结果表明，该无缝管母材基体主要由初生α相、β转变组织和魏氏组织组成；焊接接头的熔合区由针状马氏体α′相、块状α相和魏氏组织组成，针状马氏体α′的尺寸从上至下逐渐减小；热影响区由初生α相和针状马氏体α′相组成。焊接接头显微硬度平均值大小依次为：熔合区>热影响区>母材，热影响区的显微硬度从近熔合区侧到近母材侧逐渐降低。焊接接头抗拉强度约为893 MPa， 断裂均发生在母材基体上，拉伸试样断后伸长率可达10%。熔合区的冲击功约可以达到母材的80%，弯曲试样弯曲角度可以达到180°并且无裂纹产生。

Abstract:

Electron beam welding (EBW) was applied to an 8-mm-thick new type Ti-Al-Nb-Zr-Mo titanium alloy seamless tube produced by hot continuous rolling. The microstructure and mechanical properties of welded joint were investigated. Results show that the base metal (BM) consists of primary α, transformed β and Widmanstatten structure. For the EBW joint, the fusion zone (FZ) consists of acicular α′, block α and Widmanstatten structure, and the size of acicular α′ decreases gradually from top to bottom of the FZ. Moreover, only primary α and acicular α′ form in the heat affected zone (HAZ). The average microhardness in welded joint is ranked as follows: FZ＞HAZ＞BM, and the microhardness of the HAZ decreases gradually from the FZ to the BM side. The joint's tensile strength is 893 MPa and the fracture occurs at the base metal. The elongation of tensile specimens can reach 10%. The impact energy of FZ reaches ~80% of that of BM and the bending specimens are bended to 180° without cracks.