Estudo do efeito de fluxos em aspectos operacionais da soldagem MIG/MAG

Abstract

MIG/MAG welding is widely used for joining steel components and various non-ferrous alloys, but this process often has stability and control problems. Nowadays, many aspects of this shortcoming have been controlled by developments in electronic power sources and special welding systems that, however, tend to be expensive. A possible alternative to minimize instability and control problems in this process is the application of active fluxes. Inspired by A-TIG, A-MIG/MAG welding is still little known. In it, a powder flux is applied on the surface of the joint before welding. This study evaluates the effect of application of simple fluxes of a single component on operational aspects of MIG/MAG welding of carbon steel (SAE 1020). It is with this aim that this study was divided into two phases. Initially, exploratory tests were performed to evaluate the effect of nine simple component fluxes on welding electrical signals and weld bead shape with short-circuit metal transfer operation. Then, based on the results of the first step, two simple fluxes were selected to evaluate their effects on operational characteristics and shape of weld bead, when the welding voltage was changed. These tests were performed with a mechanized torch displacement device, the welding current and voltage were monitored and their signals analyzed together with geometric parameters of weld bead. The results indicated changes in voltage and current oscillograms by several simple fluxes tested when compared with non-flux welding. However the observed effects were less intense than those generally reported in active flux TIG welding (A-TIG), especially in relation to the weld bead penetration. It is suggested asan important agent in the A-MIG/MAG welding effect the ability of the component to forma uniform film on the base metal surface, the flux properties as an electrical and thermal insulation and the characteristics of the slag film formed on welding.