Análise dos efeitos da composição do eletrólito e parâmetros de soldagem GTAW na sensitização do aço inoxidável ferrítico 11%cr

Abstract

This work studies the effect of the electrolyte composition, heat treatment after fabrication and frequency variation of pulsedGTAW process (Gas Tungsten Arc Welding) in the sensitization of ferriticstainless steel with 11% Cr. Experimentswere performed by the method DL-EPR (Double-Loop Electrochemical Potentiodynamic Reactivation), which showed that the compounds H2SO4 and KSCN interfere directly in the activation and reactivationcurves, respectively. Moreover, microstructural analysis indicates that, despite the low values of the degree of sensitization measured in some solutions, samples weremoreattacked when compared to results ofsolutions that had higher values. The heat treatment in Box furnace,of the steel study,produced more equiaxed grains, hardnessand susceptibility to corrosion slightly larger than the heat treatmentincontinuous furnace. Through the experiments and survey the area attacked, it was revealed that the ratio of the areas of the curves (Ar / Aa) is the best way of representing the sensitization forthe material studied. The samples were welded at different pulse frequencies,to obtain results referring toonly this parameter,was keptconstant theenergy imposed on thesystem. The microhardness analysis reveals that there is a significant increase for this property as compared to the material as received. With the choice of the appropriate solutions, DL-EPR results indicate that,the frequency variation did not influence the sensitization, however, when comparing with the material as received, the welded samples have less susceptibility to intergranular corrosion