Confecção de canais subsuperficiais de resfriamento/aquecimento em peças metálicas pela ação de um arco de soldagem

Abstract

The manufacturing of subsurface channels can be a solution for heating or cooling of parts that need to be heated or cooled. The welding process, although known and used for many years, has never been used for this purpose. Therefore the aim of this work was to study the factors (type of arc - TIG, Plasma, A-TIG, type of current - continuous or pulsed, current pulse shape, pulse parameters, current and voltage values, electrode sharpening angle, working angles, the torch travel speed, physical characteristics of the base metal, etc.) that would provide improved process efficiency (greater depth and cross section of the channels and increased productivity), aiming to improve the robustness of the formation of subsurface cooling/heating channels in metal parts by the action of the arc. Simple deposition tests were done on carbon steel sheets and stainless steel, using TIG and Plasma welding processes and varying all the factors mentioned above. The idea was to enhance the defects called in the literature as "tunneling" (elongated cavities) and "convert" them in subsurface cooling/heating channels. The most appropriate welding techniques and the most favorable welding conditions were looked for to achieve this aim. The influence of the factors mentioned above on the bead geometry and on the channel formation was studied as well. It was concluded that the most promising process for the channel manufacturing is the Pulsed TIG welding with high amplitude current pulses. It was shown that continuous current is not appropriate for the channel formation. It was also shown that the channel formation phenomenon using an arc welding process is a rather complex process, sensitive to any small changes of the used welding process parameters.