Estudo comparativo entre as técnicas de curto circuito convencional e controlado a partir de soldagens exploratórias por simples deposição e passe de raiz em soldagem MIG/MAG

Abstract

Short-circuit transfer is regularly obtained from sources with constant voltage, adjusted with low values of voltage and electric current and short CTWD. This process has the advantage of welding in all positions and the use of low energies, which optimize its use in very thin plates and in root passes. However, the disadvantage is that the quality of the weld tends to be lower than the weld performed in the spray transfer mode, with low arc stability and the presence of many spatters. To alleviate this problem, the "Controlled Short Circuit" (CCC) method was developed by some manufacturers of welding sources, which controls the metal transfer through the imposition of a current waveform. The purpose of the present work is to compare the conventional and controlled short circuit forms of welding and make exploratory welding, using as methodology exploratory tests in the vertical and plane position. To reduce the number of preliminary tests, the Taguchi Method was used and the Villarinho Stability (IVcc) was used as stability criterion. The welding was carried out in the KUKA robot of the Laboratory of Research in Welding Technology (LTPS) in the Pici Campus. The welds were analyzed for IVcc, bead geometry, microhardness, ZAC extent, grain size and metallurgical properties. The analysis of variance of the exploratory tests showed that the DBCP was statistically influential in Im, Energy and penetration, while the welding angle was influent in the width and IVcc and the short circuit technique was influent in the Medium voltage, Energy and IVcc. After finishing the work, it was concluded that the CCC has more operating parameters, but once well defined it can perform a welding with less spatter and more stable than the conventional short circuit.