Effect of Combinative Addition of Sr and La on Hydrogen Content of SAl 4047 Welding Wire and Mechanical Properties of Welded Joints
FEI Wenpan1, XUE Songbai1, CHEN Yuhao1, WU Jie1, WANG Bo1, LIN Zhongqiang2
1 College of Materials Science and Technology, Nanjing University of Aeronautics and Astronautics, Nanjing 210016, China 2 Zhejiang Yuguang Aluminum Material Co., Ltd, Wuyi 321200, China
Abstract: The effect of alone or combinative addition of Sr and La on hydrogen content of SAl 4047 welding wire and mechanical properties of 6082 welded joints were investigated. The results show that the secondary dendrite arm spacing of α-Al dendrites in the as-cast microstructure of SAl 4047 welding wire with 0.015% Sr is reduced, and the primary silicon phase is suppressed and disappears, the average size of the eutectic silicon phase is decreased by 84% compared with the wire alloy without Sr or La,it is only 0.56 μm; the hydrogen content of the SAl 4047 welding wire with 0.015% Sr is 0.53 mL/100 g Al in the solid hydrogen test results, the porosity of the 6082 weld joint obtained by using the wire is 1.81%, and the hydrogen content of the welding wire and the porosity of the weld are higher than the limit value. Adding 0.08% La alone can reduce the hydrogen content of SAl 4047 wire to 0.18 mL/100 g Al. The size of primary silicon is reduced in the as-cast microstructure, and the corners are passivated; some α-Al dendrites are transformed into equiaxed crystals. The average size of eutectic silicon particles is 1.24 μm, and the effect of La metamorphism is significantly weaker than that of Sr. When the addition amount of La exceeds 0.08%, it will lead to the formation of needle-like La-rich phase and reduce the mechanical properties of the wire and weld. The as-cast silicon and eutectic silicon phases are dete-riorated completely in the as-cast microstructure of the composite Al-12Si-0.015Sr-0.08La wire. The average size of the eutectic silicon particles is 0.6 μm, and the α-Al phase coexists as columnar and equiaxed crystals; the hydrogen content of the composite wire is 0.31 mL/100 g Al. The porosity of the 6082 weld obtained by welding the wire is 0.38%. The hydrogen content of the wire and the porosity of the weld meet the stan-dard. The test results of the mechanical properties of the joint indicate that the tensile strength, elongation after fracture, and bending fracture angle of the joint obtained by welding the composite wire are 186.7 MPa, 8.4% and 45° to 52°, which are 6.7%, 29.2% and 76% higher than the joint without Sr or La, respectively.
费文潘, 薛松柏, 陈宇豪, 吴杰, 王博, 林中强. Sr、La复合添加对SAl 4047焊丝氢含量及焊接接头力学性能的影响[J]. 材料导报, 2020, 34(10): 10150-10156.
FEI Wenpan, XUE Songbai, CHEN Yuhao, WU Jie, WANG Bo, LIN Zhongqiang. Effect of Combinative Addition of Sr and La on Hydrogen Content of SAl 4047 Welding Wire and Mechanical Properties of Welded Joints. Materials Reports, 2020, 34(10): 10150-10156.
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2020, Vol. 34 
