摘要
Ti-6Al-4V钛合金蒙皮和骨架叠焊在航空航天器制造领域有着广泛应用。采用4 k W ROFIN光纤激光器对其进行激光叠焊,利用数码显微镜、光学显微镜、扫描电镜和万能试验机研究激光焊接工艺参数对叠焊焊缝几何尺寸、气孔数量、显微组织和力学性能的影响。结果表明,三管侧吹保护气嘴优于单管侧吹保护气嘴,气流量≥5 L/min时可获得无氧化的焊缝;间隙控制在0.1 mm范围内能有效抑制气孔生成,重熔能有效地减少焊缝中已有的气孔;当激光焊接功率、焊接速度和离焦量分别为1700 W、1.5 m/min和+8 mm时可制得气孔最少、剪切强度最高的叠焊接头。
Stitch welding of plate covered skeleton structure of Ti-6Al-4V titanium alloys has a variety of applications in aerospace vehicle manufacture. The laser stitch welding of Ti-6Al-4V titanium alloys was carried out by a 4 k W ROFIN fiber laser. Influences of laser welding parameters on the macroscopic geometry, porosity, microstructure and mechanical properties of the stitch welded seams were investigated by digital microscope, optical microscope, scanning electron microscope and universal tensile testing machine. The results showed that the three-pipe nozzle with gas flow rate larger than 5 L/min could avoid oxidization, presenting better shielding effect in comparison with the single-pipe nozzle. Porosity formation could be suppressed with the gap between plate and skeleton less than 0.1 mm, while the existing porosity can be reduced with remelting. The maximum shear strength of stitch welding joint with minimal porosity was obtained by employing laser power of 1700 W, welding speed of 1.5 m/min and defocusing distance of +8 mm.
引文
[1]SCHUBERT E,KLASSEN M,ZERNER I,WALZ C,SEPOLD G.Light-weight structures produced by laser beam joining for future applications in automobile and aerospace industry[J].Journal of Materials Processing Technology,2001,115(1):2-8.
[2]ZHANG Bing-gang,SHI Ming-xiao,CHEN Guo-qing,FENG Ji-cai.Microstructure and defect of titanium alloy electron beam deep penetration welded joint[J].Transactions of Nonferrous Metals Society of China,2012,22(11):2633-2637.
[3]XU Pei-quan.Microstructure characterization of Ti-6Al-4V titanium laser weld and its deformation[J].Transactions of Nonferrous Metals Society of China,2012,22(9):2118-2123.
[4]GAO Xiao-long,ZHANG Lin-jie,LIU Jing,ZHANG Jian-xun.A comparative study of pulsed Nd:YAG laser welding and TIG welding of thin Ti6Al4V titanium alloy plate[J].Materials Science and Engineering A,2013,559(3):14-21.
[5]LI Z,GOBBI S L,NORRIS I,ZOLOTOVSKY S,RICHTER K H.Laser welding techniques for titanium alloy sheet[J].Journal of Materials Processing Technology,1997,65(1-3):203-208.
[6]BALASUBRAMANIAN T S,BALAKRISHNAN M,BALASUBRAMANIAN V,MANICKAM M A M.Influence of welding processes on microstructure,tensile and impact properties of Ti-6Al-4V alloy joints[J].Transactions of Nonferrous Metals Society of China,2011,21(6):1253-1262.
[7]AKMAN E,DEMIR A,CANEL T,SINMAZ?ELIK T.Laser welding of Ti6Al4V titanium alloys[J].Journal of Materials Processing Technology,2009,209(8):3705-3713.
[8]LIU J,WATANABE I,YOSHIDA K,ATSUTA M.Joint strength of laser-welded titanium[J].Dental Materials,2002,18(2):143-148.
[9]CAO X,JAHAZI M.Effect of welding speed on butt joint quality of Ti-6Al-4V alloy welded using a high-power Nd:YAG laser[J].Optics and Lasers in Engineering,2009,47(11):1231-1241.
[10]WANG S H,WEI M D,TSAY L W.Tensile properties of LBW welds in Ti-6Al-4V alloy at evaluated temperatures below450°C[J].Materials Letters,2003,57(12):1815-1823.
[11]WANG Hong,SHI Yao-wu,GONG Shui-li,DUAN Ai-qin.Effect of assist gas flow on the gas shielding during laser deep penetration welding[J].Journal of Materials Processing Technology,2007,184(1-3):379-385.
[12]COSTA A,MIRANDA R,QUINTINO L,YAPP D.Analysis of beam material interaction in welding of titanium with fiber lasers[J].Materials and Manufacturing Processes,2007,22(7):798-803.
[13]SCHNEIDER A,GUMENYUK A,LAMMERS M,MALLETSCHEK A,RETHMEIER M.Laser beam welding of thick titanium sheets in the field of marine technology[J].Physics Procedia,2014,56:582-590.
[14]GAO Xiao-long,ZHANG Lin-jie,LIU Jing,ZHANG Jian-xun.Porosity and microstructure in pulsed Nd:YAG laser welded Ti6Al4V sheet[J].Journal of Materials Processing Technology,2014,214(7):1316-1325.
[15]YU Yang-chun,WANG Chun-ming,HU Xi-yuan,WANG Jun,YU Sheng-fu.Porosity in fiber laser formation of 5A06 aluminum alloy[J].Journal of Mechanical Science and Technology,2010,24(5):1077-1082.
[16]MATSUNAWA A,MIZUTANI M,KATAYAMA S,STEO N.Porosity formation mechanism and its prevention in laser welding[J].Welding International,2003,17(2):431-437.
[17]WU Bing,LI Jin-wei,TANG Zhen-yun.Study on the electron beam welding process of ZTC4 titanium alloy[J].Rare Metal Materials and Engineering,2014,43(4):786-790.
[18]MENG W,LI Z G,LU F G,WU Y X,CHRN J H,KATAYAMA S.Porosity formation mechanism and its prevention in laser lap welding for T-joints[J].Journal of Materials Processing Technology,2014,214(8):1658-1664.