Development of Two-Wrinkled Tubes Using an Electrostatic Structural Analysis Samara C. R. Soares, Gilmar C. Silva, Elza M. M. Fonseca Applied Sciences Switzerland, 2025 The primary aim of this study is to develop an axisymmetric numerical model, employing the finite element approach, to simulate a two-wrinkling tube in T6 aluminum. The method uses an electric potential applied to the tube mesh, which passes through a solid die to induce the wrinkling process, facilitated by contact elements between the tube and the die. A lateral incremental voltage electric potential (0–50 kV), due to an electric coil, and applied axial and compressive displacement (0–12 mm) was considered. The materials’ properties were established as nonlinear, with elastoplastic behavior. The results were analyzed, which allowed the tube deformation with two wrinkles, comparable with previous results.
Hardness profile of AISI 444 steel after a stamping operation João Marcos do Carmo Antunes, Gilmar Cordeiro Silva, Victor Souza Esteves Lima, Elaine Carballo Siqueira Corrêa, Wellington Lopes Revista Materia, 2025 RESUMO A caracterização mecânica e microestrutural de produtos estampados é essencial para a identificação de defeitos e orientar a melhoria das propriedades, ampliando a gama de aplicações para diferentes tipos de materiais. Nesse contexto, o estudo da relação entre as propriedades mecânicas e o respectivo arranjo microestrutural assumidos por um material após uma operação de estampagem é um método útil para o controle de qualidade, assim como para avaliar a ocorrência de falhas como o desenvolvimento de uma orientação cristalográfica inadequada e a identificação de regiões que sofreram um estado de tensões e deformação plástica que podem ocasionar problemas como o afinamento da espessura da chapa. Este trabalho executa a caracterização mecânica de um copo estampado com uso do aço inoxidável ferrítico AISI 444 por meio da operação de embutimento com a descrição do perfil de dureza Vickers em diferentes posições, combinada com a apresentação do respectivo aspecto microestrutural nessas mesmas posições da caracterização mecânica. Considerando que a operação de estampagem foi realizada a frio, a análise microestrutural indicou reduzida orientação dos grãos, mesmo nas regiões que sofreram maior quantidade de deformação plástica e encruamento, e consequentemente, maior dureza Vickers. Observou-se ainda que a variabilidade da dureza em função doo posição do copo estampado foi maior que a detectada para o aspecto microestrutural.
Computational Methodology for the Development of Wrinkled Tubes by Plastic Deformation Samara C. R. Soares, Gilmar C. Silva, Elza M. M. Fonseca Applied Sciences Switzerland, 2024 Traditional methods for wrinkled tubes involve welding processes and additional elements, such as plates, screws, rivets, and guides. Considering all the limitations of these processes, this work aims to propose a methodology that allows for maximising the manufacturing process of carbon steel tube joints with seaming using cold forming and minimising the cost of the final product. Therefore, the present work aims to develop a computational model, based on the finite element method, to optimise the deformation process of T6 Aluminium tubes (ø 45 × ø 38.6 mm) with a length of 120 mm. The method uses a steel die with cavities to achieve wrinkled tubes by a forming process. This numerical study was carried out using the Ansys® 2022 R2 software. A nonlinear material and an incremental structural analysis were used. The applied methodology allowed the optimisation of process parameters, the application of forces during tube deformation, the geometry of the die cavity, boundary conditions, and mesh discretisation. Numerical modelling was carried out using the axial symmetry of the assembly (tube–die), enabling a simplified and efficient execution of the final tube geometry. The results were analysed based on the maximum pressure applied to the tube, and the vertical and horizontal displacements of the deformed component, thus obtaining the tube flow with complete filling inside the die cavity at the end of deformation. The die geometry that produced the best results presented a cavity with a radius of curvature of 3 mm, 6 mm in height, and with a depth of 4 mm. The optimised result of the die geometry generated satisfactory results, with the displacement on the x-axis of the tube of approximately 2.85 mm, ensuring the filling of the cavity at the end of the process. For this, the maximum pressure exerted on the tube was approximately 374 MPa.
Characterization of Iron Aluminide Diffusion Coatings Obtained after Friction Surfacing Norberto Martins, Ana Paula Silva, Gilmar Cordeiro da Silva, Ítalo Bruno dos Santos, Carlos Eduardo dos Santos, Fernanda Troysi, Pedro Brito Metals, 2023 Iron aluminides are considered as candidate materials for high temperature applications for their excellent high temperature corrosion and oxidation resistance. In the present work, iron-aluminide coatings were developed by friction surfacing (6351 aluminum alloy deposited on a low-carbon steel substrate) followed by a diffusion heat treatment. The initial coatings were found to be geometrically homogenous and adhered well to the steel substrate. The heat treatment process was carried out at 550 °C for 48, 72 and 96 h and the resulting coatings were characterized in terms of microstructure, chemical composition, hardness distribution and phase composition. After heat treatment, the coating/substrate interface morphology was modified and presented patterns typical of Fe-Al intermetallic formation, as well as a substantial increase in hardness (>900 HV) relative to the initial as-deposited condition. With the diffusion treatment, initially Fe2Al5 was found to develop in the coatings, which was converted into FeAl2 after longer exposures.