研究目的
To investigate the influence of different shielding gases (100% argon, 25% argon + 75% helium, and 50% argon + 50% helium) on weld appearance, interfacial microstructure evolutions, and mechanical properties of laser-MIG welding-brazing of Al/steel butt joints.
研究成果
The addition of helium significantly promotes the wettability of the molten filler metal on stainless steel, improves the stability of the droplet transfer process, and results in a thinner, more uniform interfacial intermetallics layer. The highest tensile strength and best ductility were obtained with 50% helium + 50% argon shielding gas.
研究不足
The study focuses on the effect of shielding gas composition on the welding process and joint properties, but does not explore the optimization of other welding parameters such as laser power, welding speed, or filler wire composition.
1：Experimental Design and Method Selection
Laser-MIG hybrid welding was applied to dissimilar butt joining of 304 stainless steel and 6063 aluminum alloy using three different shielding gases. The influence of helium–argon shielding gas on the weld appearance and interfacial intermetallics layer was discussed.
2：Sample Selection and Data Sources
AA 6063-T6 Al alloy sheet and S30403 stainless steel sheet were chosen as the base metals. Al-5Si (ER4043) with a diameter of 1.2 mm was chosen as the filler wire. Noncorrosive Nocolok flux was employed to promote the spreading of the metal filler on the stainless steel.
3：List of Experimental Equipment and Materials
A Trudisk10000 disk laser and an MIG welding machine (Fronius TPS5000) were employed as the heat source. A high-speed camera (Photron Fastcam SA4) was used to obtain the pictures of plasma and droplet transfer.
4：Experimental Procedures and Operational Workflow
The laser beam was focused by a lens with a focal length of 350 mm, and a laser spot with a diameter of 0.3 mm was directly irradiated to the workpiece. The laser and arc combination method used was the paraxial compound model. Three kinds of shielding gas were used: 100% argon, 25% argon + 75% helium, and 50% argon + 50% helium.
5：Data Analysis Methods
Weld microstructure was obtained using an optical metallographic microscope and a scanning electron microscope (SEM), and elemental contents were investigated by energy-dispersive x-ray spectroscopy (EDS). Tensile test samples were tested under room temperature by a testing machine at a tensile speed of 1 mm/min.
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