Influencia de la torsión plástica sobre la resistencia a esfuerzo axial del acero AISI/SAE 1018 laminado en frío.

Abstract

The study of the influence of plastic twist on resistance to axial stress of AISI / SAE 1018 cold rolled steel, it aims to determine the microstructural and mechanical property damages that occur in the steel due to torsional deformation. The study began with the characterization of steel by metallographic analysis and implementation of the tensile test. Through trial torsional yield strength was obtained, which was the starting point for six case studies at different angles of deformation, corresponding to the plastic zone. Each case required a metallographic analysis to quantify the change in shape, orientation and grain size; Likewise experimentation Vickers microhardness testing was supplemented. Through tensile tests were determined from the mechanical properties of cases. The tests are governed ASTM standards. Finally the fracture surfaces were analyzed to determine whether the behavior of ductile or brittle material has different degrees of deformation character. The torsional deformation occurs microstructural changes of shape, orientation and decreasing grain size, they evolve from the center to the periphery of the shaft. A deformation angle greater width of the peripheral area affected and deformation smaller angle increases the width of the zone is reduced. This is because the maximum shear stress is generated in the periphery of the shaft, while at its center the stress is zero. There by producing greater surface hardening. It was not possible to evaluate the variation of mechanical along the radius of the shaft resistance, the tensile test results showed that the resistance increases as axial force increases the torsional deformation. However this increase in mechanical strength produces a significant reduction of the ductility of the steel.