Effect of Laser Power on Hybrid Laser-Gas Metal Arc Welding (GMAW) of a 6061 Aluminum Alloy
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Effect of Laser Power on Hybrid Laser-Gas Metal Arc Welding (GMAW) of a 6061 Aluminum Alloy Huiling Zhou and Fanglian Fu School of Materials Science and Engineering, Jiangsu University of Science and Technology, Zhenjiang 212003, China
Zhixin Dai Institute of Metal Research, Chinese Academy of Sciences, Shenyang 110016, China
Yanxin Qiao,∗ Jian Chen,† Lanlan Yang and Wen Liu School of Materials Science and Engineering, Jiangsu University of Science and Technology, Zhenjiang 212003, China (Received 6 April 2020; revised 14 August 2020; accepted 17 August 2020) The effect of laser power on the geometrical characteristics, microstructure and micro-hardness of the welding joints for 6061 aluminum alloy after hybrid laser-gas metal arc welding (GMAW) was investigated. The results showed that the welding joints from “Bottom” to “Top” were mainly composed of planar crystals, columnar crystals, and equiaxed dendrites. With increasing laser power, the weld depth and width and the grain size increased. When the laser power reached 5 kW, pores could be found in the weld pool region. Micro-hardness measurements showed that the application of higher laser power hardly changed the hardness of the welding joint. Keywords: Hybrid welding, Laser power, Microstructure, Micro-hardness DOI: 10.3938/jkps.77.991
I. INTRODUCTION The 6061 aluminum alloy has been widely used in various fields due to its excellent properties such as resistance to corrosion and to stress corrosion cracking [1–3], excellent wear properties [4], good weldability [5], and superior plasticity [6,7]. Laser beam welding (LBW) is widely employed in welding of aluminum alloys due to its concentrated heat source and great flexibility [8], but the high cost limits its application [9]. Because the high welding speed of this method leads to a high solidification rate, the LB welding joints usually contains a series of defects that cause collapse and porosity, leading to rapid decrease in the hardness and strength of the welding material [9,10]. Although gas metal arc welding (GMAW) allows easy filler metal addition and automation and has low cost and high welding efficiency [11,12], it still has some disadvantages, e.g., its limited welding speed (traditional GMAW < 0.6 m/min). The welding speed is crucial to improving welding efficiency and decreasing the cost for the aluminum alloy [13]. Thus, the use of a laser as a second energy source has attracted tremendous attention during the past decades [2,5,7]. Hybrid laserGMAW is such a process that combines the advantages ∗ E-mail: † E-mail:
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pISSN:0374-4884/eISSN:1976-8524
of laser beam welding and gas metal arc welding via the keyhole laser beam. Compared to laser welding or traditional arc welding, this technique has an easier ignition of the arc, a higher stability of the arc and energy penetration into the molten pool. Combining the use of these two heat sources improves energy utilization, producing a greater welding stability, a higher melting efficiency and a lower power input. Furthermore
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