Caracterização da junta soldada de aço SAE 1020 com tratamento térmico pós soldagem

Abstract

Welding is a process of joining materials widely used for the manufacture of metal parts, in the assembly of structures and in the maintenance of these. However, the localized heating leading to coalescence of the surfaces promotes changes in the microstructure and material properties, resulting in distinct regions in the weld joint, which are referred to as base metal (MB), thermally affected zone (ZTA), and zone fused (ZF). This project is based on the characterization of a SAE 1020 welded steel joint obtained through the welded electrode process (SMAW), where two subcritical annealing thermal treatments were applied at different temperatures in order to compare its effects on the microstructure, mechanical properties and corrosion resistance of the gasket. Each region of the welded joint was evaluated for its microstructural characteristics, impact energy absorbed on the impact, Vickers microhardness measurements, in order to construct a microhardness profile along the joint and measurements of the corrosion rate through an immersion test in chloride solution. All assays were performed under the three conditions (as received, treated at 600 ° C and treated at 700 ° C). From the results, an increase in grain size was observed in the ZTA region closest to the melting line; a reduction in the residual stresses of the ZTA region with the increase of energy absorbed by impact; decrease in the hardness of the joint after the accomplishment of the thermal treatments and decrease of the resistance to the corrosion of the samples treated thermally.