Comportamento mecânico dos corpos de prova de cobre com geometria especial preparados por meio de compressão no estado plano de deformação em matriz Ford

Abstract

The tensile test is highly important in analyzing the mechanical properties of materials for thermomechanical processing and application projects. The preparation of the specimen for this test requires several complex processing steps due to the size and geometry defined by specifications, which must be produced with precision in shape, dimensions, and surface finish. Furthermore, with advances in research in the field of severe plastic deformation (SPD), which can produce new materials in limited quantities, there has been a growing demand for non- standard samples that can reach submicrometric dimensions. In this context, this study investigated the mechanical behavior of specimens prepared through a new processing route using plane strain compression. For this purpose, high-purity copper was used. This material plastically deforms with relative ease due to its good ductility. Thus, the objective of the research was to develop a new method for preparing samples for tensile testing in cold-rolled thin sheets. Cold rolling, Ford test, and full annealing were carried out on copper samples. Subsequently, tensile tests were performed, and flow curves were developed for comparison and validation of the samples prepared using the Ford die. Finite element simulations of both the tensile and Ford tests were also conducted to select the best stress and strain path for designing the physical and virtual experiments used to validate the new proposed method. The dimensions of the useful parts of the sheets were: thickness of 0.5 mm, widths of 2, 5, and 20 mm, and lengths of 2 and 4 mm. The results of the flow curves obtained from the physical and virtual tests were consistent. The sheets with widths of 2 mm, as well as the sheet with a width of 5 mm and a length of 4 mm, deformed under a uniaxial stress state, as indicated by the numerical simulation. The sheet with a width of 20 mm showed a state close to plane strain under tension. The sheet with a width of 5 mm and a useful length of 2 mm was stretched under an intermediate condition between uniaxial stress and plane strain. In this case, new mathematical models were used to calculate the flow curve. The new method proved to be a viable practical alternative for the physical testing route involving rolling followed by tensile testing