Efeito da soldagem na resistência à corrosão intergranular do aço inoxidável ferrítico Aisi 410s avaliada pelo método de reativação eletroquímica

Abstract

The ferritic stainless steel are susceptible to intergranular corrosion after cooling from 950 ° C. The theory of impoverishment in chromium content in neighborhoods of precipitates is the accepted most mechanism to describe this phenomenon. The welding process is responsible for promoting cyclic heating and cooling and inhomogeneous in regions close to the weld. Thus, both the fusion zone as the heat affected zone may present significant microstructural differences after welding. In principle, these differences are related the chemical composition, the microsegregation of alloying elements, the grain size, the phase transformation and the emergence of new precipitates. This work aimed to evaluate the effect of welding on the resistance to intergranular corrosion and strength of a ferritic stainless steel, using the method of electrochemical potentiodynamic reactivation in double loop version (DL-EPR) and Microhardness testing. The material was welded through the process of welding GTAW in three different conditions measured by the DLEPR, microhardness, optical microscopy and scanning. Moreover, samples with higher degree of sensitization suffered heat treatments followed by rapid cooling. The metallurgical changes occurring in the fusion zone and thermally affected by heat did not increase the degree of sensitization of the material, heat treatments were effective in reducing the sensitization.