Control of penetration zone GMAW

Abstract

Thermal properties of the base metal, shielding medium and the nature of the electrode metal transfer to a great extent determine the penetration area formation in gas-arc welding. It is not always possible to take into account the influence of these factors on penetration front forming within the existing models. The aim of the work was to research the penetration area forming in gas-arc welding. The research of the penetration area forming in gas-arc welding of CrNi austenitic steels was made. The parameters of the regime as well as the kind of the gaseous medium influence on the formation of the penetration zone were studied. The article shows a linear proportional relationship between the electrode feed rate and the size of the base metal plate. The penetration area formation mode for welding in argon and carbon dioxide have been worked out. Diameter, feed rate and the speed of the electrode movement have been chosen as the main input parameters. Multiple regression analysis method was used to make up the modes. The relations of the third order that make it possible to take into account the electrode metal transfer and thermal properties change of the materials to be welded were used. These relationships show quite good agreement with the experimental measurements in the calculation of the fusion zone shape with consumable electrode in argon and carbon dioxide. It was determined that the shape of the melting front curve can be shown as a generalized function in which the front motion parameters depend on feed rate and the diameter of the electrode. Penetration zone growth time is determined by the welding speed and is calculated as a discrete function of the distance from the electrode with the spacing along the movement coordinate. The influence of the mode parameters on the formation of the fusion zone has been investigated and the ways to manage and stabilize the weld pool formation have been identified. The modes can be used to develop effective ways to manage and control the welding process. Making up of the control systems as well as surfacing control involve the selection of the parameters that directly influence the formation of the melting zone as well as the use of these parameters as control signals in real time regime. The influence of the mode parameters on the formation of the fusion zone has been investigated and the ways to manage and stabilize the weld pool formation have been identified. The penetration zone modes formation for the fixed and moving electrodes have been worked out. The relations were calculated through statistical processing of macrosections penetration zones parameters measurement results, the macrosections being obtained by means of arc welding in shielding gases for various diameters of the electrode and various feed rate ranges (current), according to the arc time and its speed of movement