Caracterização do aço inoxidável ferrítico AISI 410S soldado pelo processo friction stir welding.

• Autor(a) principal: Sousa, Ana Beatriz Ferreira
• Data de Publicação: 2021
• Tipo de documento: Trabalho de conclusão de curso
• Idioma: por
• Título da fonte: Repositório Institucional da Universidade Federal do Ceará (UFC)
• Texto Completo: http://www.repositorio.ufc.br/handle/riufc/62742
• topic: Soldagem por fricção e mistura mecânica; Aço inoxidável ferrítico AISI 410S; Caracterização Microestrutural

Nowadays, the search for economic stainless structural steel influences replacing austenitic stainless steels, which contains a high nickel content, with ferritic stainless steels. However, when submitted to conventional fusion welding processes, these steels suffer a significant increase in the grains of the microstructure in the Stir Zone and in the Thermally Affected Zone, which harms the mechanical properties of these steels. Recent researches focus on the welding of ferritic stainless steels by Friction Stir Welding (FSW) process. Because of this, this work aimed to characterise an AISI 410S ferritic stainless steel FSW welded joint. The focus was to perform a detailed microstructural evaluation of the different zones originated by the FSW process, considering the advanced and retreat sides separately. The analysis was carried out using optical microscopy, grain size measurement and phase quantification. The zones were correlated in their cross-section, grain refining and, ferrite and martensite phase content. Through the analyses performed, it was found that the microstructure of the sample, along with its transverse extent, there was a grain refining in the welded joint, which presented itself differently in the heat-affected zone, in the thermally affected zone and the stir zone, which were correlated with the effects of the temperature and strain rate reached in each zone during welding. In addition, it was noticed that a refining gradient along with the sample thickness occurs, being more accentuated at the lower region. A significant effect of the tool’s geometry on the microstructural changes that occurred in the SZ was also found. The martensite content was higher as it approached the lower part of the joint and the centre of the stir zone. It also was found that the most intense grain refining occurred in the stir zone and that ferrite and martensite grains in this zone were distributed uniformly.