Study on determination of true stress and strain of low carbon steel based on tensile test

In order to obtain the true stress-strain relationship of material necking section, based on the principle of invariable plastic deformation volume, the formulas for calculating the minimum section diameter and radius of the necking section were derived based on the assumption that the profile of the specimen after necking was an arc. According to the calculated minimum diameter and contour radius, the real stress-strain calculation model of the material is obtained. Because the necking part of the specimen is in the state of three-dimensional stress, based on the research of this model, the calculated real stress value is corrected according to Bridgeman’s stress formula. The real stress-strain curve of low carbon steel was obtained by processing the uniaxial tensile test data of low carbon steel by using the real stress-strain calculation method. Based on the real stress-strain curve of carbon steel and the data and conditions of tensile tests, the finite element model of unidirectional tensile test was established. By comparing the force and displacement curves obtained from simulation and test, the rationality and feasibility of this method for calculating the real stress-strain were demonstrated, and it has certain engineering practicability.