PRODUÇÃO DE JUNTAS DE OVERLAY EM AÇO ESTRUTURAL PARA SISTEMAS HÍDRICOS MANUEL

• Autor(a) principal: Manuel António Ribeiro da Rocha
• Data de Publicação: 2021
• Tipo de documento: Dissertação
• Idioma: por
• Título da fonte: Repositório Científico de Acesso Aberto de Portugal (Repositórios Cientìficos)
• Texto Completo: https://hdl.handle.net/10216/137271
• topic: Engenharia dos materiais; Materials engineering

The present Master Dissertation was developed in partnership with the company Tüv Austria Iberia, to evaluate four stainless steel Overlay joints on a carbon steel substrate, produced by the company ONIRAM. The work started in ONIRAM with the follow-up of the production of the Overlay joints in stainless steel SAE 316LSi and SAE 309LSi on a steel substrate S355J2+N. Afterwards non-destructive tests were carried out to validate the integrity of the welded joints, which were all approved. A metallographic analysis of the different coatings was carried out to compare them with the prediction obtained by the Schaeffler diagram, and satisfactory values were obtained. Hardness profiles were performed, which allowed characterising the different zones of the HAZ, with values below 350HV. However, at the interface of all Overlays joints the formation of a martensite layer was witnessed with an average hardness of 446 ± 22HV and a thickness of 36 μm. Throughout the study through the chemical analysis, it was possible to verify that the percentage of sulphur present in the carbon steel was much higher than that specified in the material's certificate, and in the SEM and EDS analyses several manganese sulphide precipitates were identified along with the base metal.