No melted double layer gas of CO

2

+Ar shielded arc welding

a small amount of Ar inside and CO

2

outside

was realized by self designed double layer welding torch. In this paper

influence of CO

2

on arc shape and appearance of weld were discussed by welding test of no melted double-layer gas CO

2

+Ar shielded arc welding and conventional TIG welding under the same welding parameters and obtaining information of arc temperature

distribution of gas mass fraction and heat flux information on the workpiece surface with the help of numerical simulation. The results showed that the introduction of the outer layer of CO

2

had a compressive effect on the arc compared to the conventional pure argon arc

the arc voltage increased by about 4.5 V

the maximum heat flux on the workpiece surface increased by 26%

and the penetration reached 3.6 times that of the traditional TIG welding.