Caracterização das morfologias encontradas no metal de solda variando a energia de soldagem

Abstract

The study of the importance of the welding parameters on the microstructure of the metallic materials is of great importance since the evaluation of the microconstituents has a direct relation with the final mechanical properties obtained in the welded joint, as well as the grain morphology that plays an important role in the toughness of the welding metal. Some variables in the welding process may influence the solidification of the weld metal, such as welding energy, material thickness, material thermal conductivity and preheating, that the two parties contain cooling rates which, in turn, directly influences the processes of nucleation and growth in solidification. The present work has the objective of identifying different grain morphologies that can be found in a weld metal as a depending on the variation of the welding energy. Thus, experiments with autogenous TIG welding were performed, varying the welding current, whereby the welding energy varied in two levels, 157.51 J / cm and 272.02 J / cm (welding at 100A and 150A), maintaining the temperature environment and other constant parameters. The weld metals were analyzed by metallography, characterizing the grain morphologies present in the cross sections of the weld beads. Combinations of different morphologies were found for each welding energy. In the sample in which the current of 100 A was used, a columnar zone followed by a central equiaxial was observed, besides the absence of a quenched zone and in the sample of 150 A presented along with the morphologies found in the 100A sample a little epitaxial growth , revealing the influence of welding energy. In addition, it was possible to verify that the width and depth of the weld bead increase as the parameter is increased.