• CN:11-2187/TH
  • ISSN:0577-6686

机械工程学报 ›› 2018, Vol. 54 ›› Issue (14): 58-65.doi: 10.3901/JME.2018.14.058

• 材料科学与工程 • 上一篇    下一篇

添加Si粉激光深熔焊钢/铝接头的显微组织与性能

周惦武, 刘金水, 卢源志, 周来沁, 潘井春   

  1. 湖南大学汽车车身先进设计制造国家重点实验室 长沙 410082
  • 收稿日期:2017-10-29 修回日期:2018-03-19 出版日期:2018-07-20 发布日期:2018-07-20
  • 通讯作者: 周惦武(通信作者),男,1971年出生,博士,教授,博士研究生导师。主要研究方向为汽车轻量化材料计算与设计理论、异种材料连接技术及机理。E-mail:zdwe_mail@126.com
  • 基金资助:
    国家自然科学基金资助项目(51674112,51774125)。

Microstructure and Mechanical Properties of Deep Penetration Laser Welding Joints in Steel/Aluminum with Si Powder Addition

ZHOU Dianwu, LIU Jinshui, LU Yuanzhi, ZHOU Laiqin, PAN Jingchun   

  1. State Key Laboratory of Advanced Design and Manufacturing for Vehicle Body, Hunan University, Changsha 410082
  • Received:2017-10-29 Revised:2018-03-19 Online:2018-07-20 Published:2018-07-20

摘要: 钢/铝结构件在现代交通领域具有广泛应用前景,易生成脆性Fe-Al化合物是钢/铝异种金属焊接亟待解决的难题。采用光纤激光器对1.4 mm厚DP590双相钢和1.2 mm厚6016铝合金进行添加Si粉激光深熔焊接实验,利用卧式金相显微镜、扫描电镜、X射线衍射和微机控制电子万能试验机等研究添加Si粉前后焊接试样金相组织、断口形貌、界面元素分布、主要物相与接头力学性能,采用高速摄像机同步拍摄焊接过程中金属蒸汽/等离子体形貌,采用光谱仪采集金属蒸气/等离子体的发射光谱。结果表明,激光功率2 000 W,焊接速度50 mm/s,离焦量+2 mm,Ar气为保护气体且流量为15 L/min条件下,添加Si粉焊接试样焊缝表面成形性良好,没有气孔、裂纹等缺陷,焊接接头平均线载荷108 N/mm,与没有添加Si粉相比,线载荷提高8%。由于添加Si粉增大焊接试件对激光能量吸收,增加焊接熔深,熔宽两侧Al含量变化不大,焊缝区晶粒未粗化,钢、铝熔池流动性得到改善,钢/铝界面层厚度降低,Si与Fe、Al发生冶金反应形成延性Al0.5Fe3Si0.5新相,抑制或减少脆性Fe-Al化合物生成,因此添加Si粉能改善焊接接头力学性能。

关键词: 钢/铝异种金属, 激光深熔焊, 添加Si粉, 冶金反应

Abstract: The interest in steel/aluminum structure parts is continuously increasing in modern transportation tools, however, such the technical problems as the generation of Fe-Al brittle intermetallic compounds need to be solved urgently for steel and aluminum dissimilar metal welding quality. Deep penetration laser welding test with Si powder is carried out on the DP590 dual phase steel with thickness 1.4 mm and the 6016 aluminum alloy with thickness 1.2 mm. By using optical microscopy, scanning electron microscopy, X-ray diffraction and tensile test, the microstructure, fracture morphology, interface element distribution, main phase and mechanical properties of joints are studied. Metal vapor/plasma shape of welding process is simultaneously shooted by using high-speed cameras, and emission spectrum of metal vapor/plasma is also collected by using spectrometer. The results indicate that the morphology of welding surface is well, and some defects such as pore and crack is not seen when the welding power is 2 000 W, welding speed is 50 mm/s and the defocus distance is + 2 mm, and Ar gas as the protection gas and the flow rate is 15 L/min. The average linear load of the welding sample with Si powder reaches 108 N/mm. Compared to that without Si powder, the average linear load of joint increases by 8%. The laser energy is more easily absorbed by the sample, which leads to the weld penetration increasing, while there is no obvious change for the Al content on both sides of weld width, the grain in the weld zone is not coarsened, the fluidity of steel and aluminum molten pool is improved, the thickness of the intermetallic layer is decreased, in addition, Al0.5 Fe3Si0.5 phase with better ductility is obtained by the metallurgical reaction among the Si, Fe and Al elements, which retard and reduce the generation of Fe-Al brittle intermetallic compounds. Hence, the mechanical properties of joint can be improved with Si powder.

Key words: deep penetration laser welding, metallurgical reaction, Si powder addition, steel/Al dissimilar metal

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