(1. 南昌航空大學 輕合金加工科學與技術(shù)國防重點學科實驗室，南昌 330063；
2. 九江學院 機械與材料工程學院，九江 332005)
摘 要: 采用真空電子束焊接方法對3 mm厚TiNi合金與TC4異種金屬進行對接焊，添加Nb為填充金屬控制焊接裂紋的形成；分析了裂紋形成機理，Ti2Ni脆性相的形成條件，接頭元素分布特點及接頭力學性能。結(jié)果表明：TiNi合金與TC4直接焊接易使焊接接頭產(chǎn)生裂紋，大量Ti2Ni脆性相的形成導致焊縫中裂紋和孔洞的產(chǎn)生，添加Nb為填充金屬有效降低接頭裂紋敏感性。填充金屬厚度為0.55 mm時獲得無裂紋缺陷的焊接接頭，Ti2Ni生成焓較小，使TC4側(cè)熔合線附近形成Ti2Ni脆性金屬間化合物層，焊縫中心組織Nb含量較高，接頭力學性能良好，抗拉強度達到391 MPa，伸長率為2.7%。
關(guān)鍵字: TiNi/Nb/TC4；異種金屬；Nb填充金屬；真空電子束焊；焊接裂紋
（1. National Defense Key Disciplines Laboratory of Light Alloy Processing Science and Technology, Nanchang Hangkong University, Nanchang 330063, China)
2. School of Mechanical and Material Engineering, Jiujiang University, Jiujiang 332005, China）
Abstract:The TiNi alloys and TC4 alloys with thickness of 3 mm were welded by vacuum electron beam welding method, the formation of welding cracks was controlled by adding Nb for the filler metal. The formation mechanism of crack, the formation conditions of Ti2Ni brittle phase, the distribution characteristics of joint elements and the mechanical properties of joint were analyzed. The results show that it is easy to generate cracks in the joint when welding of TiNi alloy to TC4 directly; adding Nb as the filler metal can reduce the crack sensitivity of joint when welding TiNi alloy and TC4 alloy, the Ti2Ni brittle phase can contribute to the formation of cracks and holes in weld. The crack defect can eliminate when the thickness of the filler metal is 0.55 mm; the Ti2Ni brittle intermetallic compound layer formed near the fusion line of TC4 side due to the Ti2Ni enthalpy of formation is smaller; the Nb content in the center of weld is higher, the mechanical performance of joint is excellent. The tensile strength of joint reaches 391 MPa, and elongation is 2.7%.
Key words: TiNi/Nb/TC4; dissimilar metal; filler metal; electron beam; welding crack
