Influência do modo de transferência controlada na penetração e velocidade de soldagem aplicados em aços de alta resistência e baixa liga

Abstract

The purpose of this work was to compare two GMAW welding processes with controlled transfer, controlled short-circuit by pulsed current HD-Pulse and the controlled short-circuit S-AWP, evaluating the productive and metallurgical characteristics of the beads produced. The modernization of GMAW welding modes transfer processes has been increasingly explored, due to the growing production demands and the metallurgical and mechanical requirements arising from the development of new materials. Furthermore, the study of transfer modes is essential to qualify the characteristics of the process, such as arc stability, incidence of spatter, geometric aspects of the weld bead, and the melting efficiency of the base metal. For this purpose, the processes were applied to two high-strength and low-alloy steels (HSLA), in two thickness variations. For all conditions, the horizontal position was assumed with a gas mixture of 82% Argon and 18% Carbon Dioxide, solid wire 1.2 mm in diameter and identical torch angles. The techniques were evaluated through measurements of welding energy (heat input), deposition rate, metallic yield, macrography, hardness profile, in addition to collecting the electrical curve at the output of the power source. Correlations were also made between deposition rate and wire feed speed and welding energy with the average hardness in the HAZ. The results revealed that the controlled short circuit has lower welding energy to perform the same size of weld, however, it had a lower metallic yield and deposition rate compared to the pulse curve. It was also noted that for the same average current, in both processes, the wire feed rate was different, indicating that each synergistic curve has its own characteristics, in addition to reinforcing the deposition rate results. Due to the lower energy input of the short circuit, the process proved to be an advantage in most of the HAZ hardness analyses, presenting lower values, even so, the energy variations between the processes had no significant impact when analyzed with the average of the hardness in the heat-affected zone. Macrographs showed that both processes reached acceptable penetrations. The HD-Pulse was more efficient by having deeper fusion at the joint root and presenting a smaller weld fillet concavity, even at 23% higher welding speeds. The relevance of this study resulted in the aid of decision making regarding the choice of the controlled transfer mode that best resembles productivity and some engineering characteristics already mentioned. [resumo fornecido pelo autor]