Efeito da variação da corrente elétrica de soldagem na microestrutura e na microdureza de ligas Fe-Cr-Mo com diferentes teores de Molibdênio

Abstract

This study aims at evaluating the effect of variation of the current during the welding of three different steel alloys Fe-Cr-Mo, using the TIG process without adding material, and identifying what changes may occur in the microstructure of these alloys when subjected to two different welding parameters studied here. Samples of the alloys were used in the annealed condition to perform the welding in the flat position, with thorium electrode, direct current negative electrode in two different energy levels, varying the current values. After welding, the alloys were subjected to microstructural characterization by optical microsopy and Vickers hardness to determine which was harder in accordance to the stablished parameters. The analysis of variance of the microhardness profile of the alloys heat affected zone was also made, in order to verify possible changes which might take place due to the variation of the welding parameters. The microstructure analysis revealed that one of the alloys showed the formation of martensite. The welding power with less current generated a melted zone with smaller area for the three alloys. However, the welds performed showed no harmful changes in the microstructure and hardness of the alloys studied.