Microstructure and mechanical properties of laser welding joint with aluminum/steel surface preset filler powder addition

被引：0
作者：
Zhou D.-W. [1 ]
Jiang D.-F. [1 ]
Liu J.-S. [1 ]
Zhou L.-Q. [1 ]
Pan J.-C. [1 ]
机构：
[1] State Key Laboratory of Advanced Design and Manufacturing for Vehicle Body, Hunan University, Changsha
来源：
Zhongguo Youse Jinshu Xuebao/Chinese Journal of Nonferrous Metals | 2019年 / 29卷 / 05期
基金：
中国国家自然科学基金;
关键词：
Aluminum/steel; Fe-Al compounds; Laser welding; Preset filler powder;
D O I：
10.19476/j.ysxb.1004.0609.2019.05.07
中图分类号：
学科分类号：
摘要：
In view of the technical difficulties of aluminum/steel welding, the 1.2 mm-thick 6016 aluminum alloy and 1.4 mm-thick DP590 dual phase steel was laser welded by adding AlSi12Mg1.5 powder to aluminum surface and Sn powder to aluminum/steel interlayer layer with lap joint applied with aluminum sheet on the top and steel sheet at the bottom. The weld appearance, microstructure and mechanical properties of welding joint were studied. The temperature field distribution of aluminum/steel joints was calculated by establishing the transient finite element model of aluminum/steel laser welding based on ANSYS finite element software. The modulus and thermodynamic properties of compounds such as FeSn, Fe3Sn, FeAl3 and Fe2Al5, were calculated by using first-principles method based on density functional theory. The results indicate that 6016 aluminum alloy and DP590 double phase steel can be effectively connected with preset filler powder to aluminum/steel surface, no obvious porosity, cracks, and other defects are seen when the welding power is 2750 W, welding speed is 32 mm/s, the defocus distance is -2.0 mm, Ar gas acts as the protection gas with flow rate 20 L/min, and laser deflection is along welding direction 10°. The average linear load of the welding sample with aluminum/steel surface preset filler powder reaches 54.16 N/mm. Compared to that without aluminum/steel interlayer powder addition, the average shear strength of weld joint increases by 1.6 times. The relative intensity of spectra and electron density of plasma increases, which shows that the laser energy absorption rate increases by adding AlSi12Mg1.5 powder to the aluminum surface. Thus, the surface of the weld is improved. When Sn powder is added to aluminum/steel interlayer layer, the aluminum and steel are both melted, the fusion width of the upper aluminum and the lower steel increases, the combined area of aluminum/steel increases, and the welding rate is improved. In addition, grain size of weld zone is fine, Fe-Al compound layer thickness decreases. FeSn and Fe3Sn compounds has better ductility and is more stable than that of Fe-Al compounds at high temperature, which can improve the mechanical properties of weld joint. © 2019, Science Press. All right reserved.
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页码：942 / 953
页数：11
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