(哈爾濱工業(yè)大學(xué) 先進(jìn)焊接與連接國(guó)家重點(diǎn)實(shí)驗(yàn)室，哈爾濱 150001)
摘 要: 為了改善2A14鋁合金TIG焊接頭的顯微組織與力學(xué)性能，在TIG焊過(guò)程中，利用超聲變幅桿對(duì)焊縫進(jìn)行超聲沖擊，超聲通過(guò)固體母材和焊縫傳入熔池內(nèi)，影響熔池的流動(dòng)及凝固，從而達(dá)到細(xì)化焊接接頭晶粒和提高接頭力學(xué)性能的目的，利用激光測(cè)振儀對(duì)熔池表面的振動(dòng)進(jìn)行測(cè)量。結(jié)果表明：超聲沖擊使焊接接頭的顯微組織發(fā)生明顯的變化，焊縫中心和熔合區(qū)的晶粒由柱狀晶變?yōu)榱说容S晶，晶粒尺寸減小，第二相尺寸變小且分布更加分散。超聲沖擊使接頭抗拉強(qiáng)度提高，抗拉強(qiáng)度由246.18 MPa 提高到265.50 MPa，斷后伸長(zhǎng)率由5.33%增加到6.47%。超聲沖擊使熔池的流動(dòng)性增強(qiáng)，導(dǎo)致熔池內(nèi)溫度更加均勻；溫度梯度減小，有利于等軸晶的形成及晶粒的細(xì)化。
關(guān)鍵字: 鋁合金；超聲沖擊；TIG焊接；熔池；顯微組織；力學(xué)性能
（State Key Laboratory of Advanced Welding and Joining, Harbin Institute of Technology, Harbin 150001, China）
Abstract:In order to improve the microstructures and mechanical properties of tungsten inert gas(TIG) welded joint of 2A14 aluminum alloy, ultrasonic horn periodically impacts the seam during TIG welding. The ultrasound propagates into the weld pool through the weld and base material, so that the ultrasonic energy can effectively influence the fluidity and crystallization of weld pool. Finally, the grain was refined and the mechanical properties were improved for welded joints. The results show that the microstructures are significantly improved after applying the ultrasonic impact. The grain is changed from the column grain to the equiaxed grain in the weld center and the fusion zone, and the grain size decreases in the weld center. Moreover, the distribution of the second phase becomes more uniform and the size becomes smaller after applying the ultrasonic impact. The ultrasonic impact during TIG welding can improve the tensile strength of welded joint and it is improved from 246.18 MPa to 265.50 MPa. The elongation is improved from 5.33% to 6.47%. The ultrasonic impact can improve the fluidity of weld pool, which results in an uniform temperature, so that the form of equiaxed grain and the grain refinement can be promoted.
Key words: aluminum alloy; ultrasonic impact; TIG welding; weld pool; microstructure; mechanical property
