Ref.: MmeCa09-032
Apresentador: Helen Rodrigues Araújo
Autores (Instituição): Araújo, H.R.(Universidade Federal de Pernambuco); Pessoa, K.P.(Centro Universitário Estácio do Recife); de Souza, J.R.(Centro Universitário Unifbv Wyden); da Silva Junior, M.E.(Universidade Federal de Pernambuco); dos Santos, M.L.(Universidade Federal de Pernambuco);
Resumo:
Materials known as tools steels are defined as alloys used to manufacture tools, dies and, molds, with the ability to cut other materials, including ferrous metals, non-ferrous metals and, plastics. The control of the chemical composition is preponderant in checking specific characteristics of the steels that belong to this group of materials, which generally have high hardenability, which is associated with the carbon content in this alloy. They can be applied in a wide variety of applications, which, in general, require high hardness, wear resistance, mechanical resistance, as well as adequate toughness. The high carbon content related to tool steels contributes to cracks susceptibility to the occurrence of or surface imperfections caused by mechanical stress. Normally, repairs to components manufactured with this type of material occur with the application of a welding process, an operation whose resulting heat input is responsible for modifying the microstructure of the welded joints. D series cold working tool steels, including AISI D6 steels, have a high chromium and carbon content in their composition, giving this alloy high resistance to wear and low distortion in heat treatments. In this context, the present study proposed to analyze the microstructure of the material AISI D6 (VC131) manufactured by the Gas Tungsten Arc Welding (GTAW) welding process, varying the current values and the type of polarity adopted, also analyzing the influence of the welding thermal cycle on Vickers microhardness in different regions of the welded joint. The welded joint presented microstructures with different morphologies, with the formation of ferrite and pearlite being observed in the base metal region and the formation of dendritic columnar grains in the fusion zone region, due to the characteristic of dissimilarity between the compositions of the filler metal and the base metal. Significant changes were observed in the microhardness values associated with different regions of the welded joint, as a result of the different microstructures observed.