Usinabilidade do aço fundido alto carbono e alto silício na operação de torneamento

• Ano de defesa: 2023
• Autor(a) principal: Natália Fernanda Santos Pereira
• Tipo de documento: Tese
• Tipo de acesso: Acesso aberto
• Idioma: por
• Instituição de defesa: Universidade Federal de Minas Gerais
• Palavras-chave em Português: Engenharia de produção; Aço fundido; Torneamento; Usinagem; Aspereza de superfície; Metais - Corte; Forças de usinagem; Rugosidade; Temperatura do cavaco; Desgaste de ferramentas de corte
• Link de acesso: https://hdl.handle.net/1843/61392

During the last decades, studies involving the bainitic structure have attracted the attention of researchers, due to the combination of high strength and high ductility. However, the material with these properties tends to impair machinability in manufacturing processes, as it is a material that is difficult to machine. The present work consisted of studying the influence of turning conditions when machining a steel containing high carbon and high silicon (HC-HSi) manufactured by the casting process, whose chemical composition was designed to obtain the final bainitic microstructure after austempering heat treatment. However, the study of HC-HSi steel was carried out before obtaining the bainitic microstructure. After manufacturing HC-HSi steel through the casting process, homogenization heat treatment was carried out to minimize segregation. In this way, the influence of turning conditions for HC-HSi steel using carbide and cermet tools was evaluated on cutting efforts, surface roughness, chip temperature and wear assessment of cutting tools. To characterize the HC-HSi steel, the chemical composition, microstructural analysis, mechanical properties and fractographic analysis of the specimens were evaluated after mechanical testing. A fully pearlitic microstructure was obtained for the HC-HSi steel manufactured by the casting process. Regarding mechanical properties, the hardness values presented close values when analyzing the microhardness in the cross section of the test specimen manufactured for the turning operation. Little plastic deformation was observed after tensile testing and brittle fractures were observed for HC-HSi steel. Regarding the machinability results of HC-HSi steel, it was observed that when the cutting speed increased, the cutting force reduced, which was attributed to the dry cutting conditions and the effect of temperature in the primary and secondary shear zones. . Carbide and cermet tools did not influence the average feed force values for the cutting speed parameter. For a feed of 0.35 mm.rev-1, the carbide tool provided lower feed force values. For passive force, the use of carbide and cermet tools did not significantly influence the evaluated feed values. Regarding roughness, feed was the most significant parameter regarding Ra, Rz and Rt and did not depend on the type of tool used. The cutting speed and cutting tool parameters were significant on chip temperature. The carbide tool presented lower chip temperatures for the evaluated cutting speeds. Regarding wear, the carbide tool proved to be the most suitable for machining HC-Si steel. The contribution of this thesis was to characterize HC-Si steel and indicate the parameters and cutting tools most suitable for machining HC-Si steel, which minimized cutting efforts, surface roughness, chip temperature and wear on the cutting tools used in this process study.