Avaliação da estabilidade do processo de revestimento por soldagem com arame tubular pulsado através da análise dos sinais de corrente e tensão

Abstract

This study analyzes overlay welds using flux-cored welding and pulsed direct current. The objective is to evaluate the effectiveness of stability verification methods through current, voltage, and power oscillograms. SAE 1020 steel specimens were used with a 410 NiMo martensitic stainless metal cored tubular wire strand. The main variables were average current, pulsation frequency, welding speed, and contact-tip-to-work distance. Taguchi’s method was applied to reduce combinations, totaling nine trials. Stability was evaluated quantitatively based on oscillograms, using indices for the pulsed process, and analyzing histograms and cyclograms. Transfer regularity indices were adapted to the context of pulsed current. Analysis of variance validated the results, establishing relationships between parameters and indices. Regression modeling and weld bead morphology analysis complemented the evaluation. The effectiveness of the regression and variance analysis tools for the interrelationships in the pulsed flux cored wire process was confirmed. Effective regressions used voltage, current, and average power, with the R2 index adjusted above 85%. The number of spikes per second was in line with the pulse rate, providing clarity in the assessment, but it was not related to the quality of the cords. The transfer index IVcc correlated significantly with data variations, showing indices between 0.154 and 2.797, lower values with a current of 170 A, and convexity index between 36.75% and 52.42 %. The cyclogram area had a tenuous correlation with reinforcement results, suggesting adjustments in the methodology for obtaining this data, either through better image processing or another method.