Mixed gas for welding

Gas shielded welding is a new welding process developed on the basis of the wide application of manual arc welding and submerged arc automatic welding. In the practice of gas shielded arc welding for many years, it has been found that replacing a single pure gas with a mixed gas as a shielding gas can effectively refine droplets, reduce spatter, improve forming, control penetration, prevent defects and reduce porosity. , Can significantly improve the welding quality of weldments.

　　 At present, the welding shielding gas mixture commonly used in industry can be roughly divided into three types: binary gas mixture, ternary gas mixture and quaternary gas mixture. Commonly used binary gas mixtures are Ax-He, Ar-N2, Ar-H2, Ar-O2, Ax-CO2, CO2·O2, N2·H2, etc.; commonly used ternary gas mixtures are Ar-He-CO2, Ar -He-N2, Ar-He-O2, Ax-O2·CO: etc.; the quaternary gas mixture is less used, and is mainly made of Ax, He, H2, O2, N2, CO2, etc. The ratio of each component of various mixtures can be changed in a wide range, mainly determined by a combination of factors such as welding process, welding material, welding wire type and so on.

　　 Generally speaking, the higher the requirements for the quality of the weld, the higher the purity requirements for each unit of the mixed gas. In European and American countries, the purity of Ax, H2, N2 and other gases used in the preparation of mixed gas is 99.999%, He is 99.996%, and CO2 is 99.99%. Generally, moisture is regarded as a harmful impurity, requiring H20<10mg/m3.