Effects of He-Ar shielding gas compositions on arc plasma physical properties in rotating laser + GMAW hybrid fillet welding: Numerical simulation.

• A numerical model is established for rotating laser hybrid fillet welding with He-Ar shielding gas compositions. • Effects of rotating laser and He-Ar shielding gas compositions on arc physical properties are investigated. • With the He content increases, the arc temperature and distribution are more concentrated, the arc flow velocity and pressure decrease. • He-Ar shielding gas mixtures increase the arc heat flux density, suppress the shielding effect of laser-induced plume, and improve the weld penetration. To understand the influence mechanism of He-Ar shielding gas composition on arc physical properties in laser + GMAW hybrid welding, this study establishes an arc numerical analysis model in rotating laser + GMAW hybrid fillet welding by considering the geometric feature of joint configuration and the physical parameters of He-Ar shielding gas. The effects of He-Ar shielding gas mixtures in different ratios on arc plasma temperature, velocity, and pressure are investigated, respectively. The results show that with the increasing He content in the shielding gas, the overall shape of arc is compressed, the peak temperature decreases, the arc temperature distribution range is more concentrated, which is beneficial to increasing the weld penetration depth. The arc plasma flow velocity increases with the He content increases, but the plasma flow pattern becomes disordered when the He content reaches 50 %, which is not conducive to the stability of arc. The arc pressure value and the high-pressure distribution region near the workpiece surface increase significantly with an increasing He content ratio, due to the contraction effect of high He content mixed shielding gas on the arc. [ABSTRACT FROM AUTHOR]