Effect of process parameters on joint properties of brass CuZn37 welded with a pulsed TIG welding power source

Abstract

The aim of these experimental studies was to find appropriate process parameters for the pulsed TIG welding of common brass to solve relevant problems of the fusion welding of common brass. That was done by optimising welding parameters for the application of TIG welding to the selected brass materials. The main problem with brass welding is the evaporation of zinc during the fusion welding process which leads to a colour change in the weld seam from a desired golden surface colour to the usually unwanted dark red colour of copper. The parameters to be varied are: all the electric values of the power source, the gap, the torch angle, the electrode tip angle and the rate of shielding gas flow. It was found out that it was the main point to determine the appropriate fusion welding operation parameters. An acceptable surface colour which looks likes the colour of brass can be produced in this way. It is evident that a brass workpiece with a weld seam which looks like copper will not be accepted by most of the applicants. Additionally, some technological values had to be investigated. These values are of importance for the industrial engineering process after welding. As a consequence, some important material properties found before and after welding the brass parts were of interest. The main mechanical values in this case are: tensile strength and the values of Erichsen deep drawing tests on the welded parts compared with the unwelded material. The experimental studies showed that the gap and the torch angle have a small or sometimes no effect on the mechanical properties of a welded joint. But it was also found that the electrode tip angle and the rate of shielding gas flow have an influence on the mechanical properties of a joint but that these two parameters do not have such an important effect on the quality of the weld seams as the electric parameters.