Influence of the formulation of a flux-cored wire on the microstructure and hardness of welded metal

For this paper, the microstructure and hardness of the weld metal were investigated by conducting experiments with the flux cored arc welding process in underwater and air conditions. A rutile/oxidizing tubular wire was used, manufactured by the Robotics, Welding and Simulation Laboratory at Minas Gerais Federal University, especially for underwater wet welding. Underwater welds had a lower volumetric fraction of acicular ferrite in the weld metal compared to air welds. In the thermally affected zone, for both welds, there was a predominant formation of martensite. However, the grain size and width of the thermally affected zone of underwater welds are smaller. The hardness values shown correspond to the microstructure formed in the weld metal. On the other hand, in the region of the thermally affected zone, the hardness values were higher underwater welds, due to the smaller martensite grains presented.

A Fuzzy Model for Establishing Two Main Parameters of GTAW Process

In the last period, the quality and productivity of arc welding operations increased more than ever, especially in the areas that require high technology, represented mainly by the aerospace and nuclear industry, which led naturally to automation and robotics welding operations. The paper proposes a fuzzy system for the establishing of the main control parameters (welding current and welding speed) function of two important input parameters (plate thickness and diameter of the non consumable tungsten electrode). In this way, one of the actual modeling techniques (fuzzy logic) can be extended in welding technologies as an alternative tool, being particularly attractive for automated and robotized welding processes.