(1. 江蘇大學(xué) 機(jī)械工程學(xué)院，鎮(zhèn)江 212013；
2. 江蘇理工學(xué)院 材料工程學(xué)院，常州 213001；
3. 東南大學(xué) 機(jī)械工程學(xué)院，南京 210096)
摘 要: 研究激光沖擊處理(LSP)和固溶-時(shí)效兩種焊后處理工藝對(duì)7075鋁合金等離子弧焊接頭微觀組織和力學(xué)性能的影響規(guī)律。通過固溶-時(shí)效處理工藝優(yōu)化設(shè)計(jì)，確定焊接頭的最佳熱處理工藝為固溶(575 ℃，2 h)、時(shí)效(140 ℃，2 h)，并與激光沖擊處理工藝進(jìn)行了對(duì)比。結(jié)果表明：焊接頭經(jīng)2次激光沖擊后，表層焊縫區(qū)的顯微硬度提高23.3%，殘余應(yīng)力由拉應(yīng)力9 MPa變?yōu)閴簯?yīng)力23 MPa；在熱影響區(qū)，顯微硬度提高44.4%，殘余應(yīng)力提高42.8%，抗拉強(qiáng)度達(dá)到607.89 MPa，與未處理樣品相比提高61.96%；固溶-時(shí)效在硬度的影響層深度、斷面收縮率方面優(yōu)于激光沖擊，而激光沖擊導(dǎo)致裂紋源萌生于次表層，提高了焊接頭的抗拉性能。
關(guān)鍵字: 等離子弧焊接頭；激光沖擊；固溶-時(shí)效；力學(xué)性能；拉伸斷口
（1. School of Mechanical Engineering, Jiangsu University, Zhenjiang 212013, China;
2. School of Materials Engineering, Jiangsu University of Technology, Changzhou, 213001, China;
3. School of Mechanical Engineering, Southeast University, Nanjing 210096, China）
Abstract:The effects of laser shock peening(LSP) and solution and aging treatment on the microstructure and mechanical properties of plasma arc welded joints of 7075 aluminum alloy were studied. The process of the solution and aging treatment was optimized and the optimum process was selected as solid solution treated at (575 ℃, 2 h) and aged at (140 ℃, 2 h)．Then the effect of solution and aging treatment was compared with that of LSP. The results show that, in the weld zone of crown surface, the microhardness of welded joint with LSP 2 times is increased by 23.3%, and the residual stress is changed from tensile stress of 9 MPa to compressive stress of 23 MPa; in the heat affected zone, the microhardness is increased by 44.4%, the residual compressive stress is improved by 42.8%, the tensile strength is enhanced to 607.89 MPa, increased by 61.96% compared with untreated; the solution and aging treatment process is better than LSP on the depth of influence and the contraction ratio of section. While LSP makes the cracks mainly initiate at the subsurface thus improves the tensile strength of 7075 aluminum alloy resultant joint.
Key words: plasma arc welded joint; laser shock peening; solution and aging treatment; mechanical property; tensile fracture
