Thermal deformation behavior and constitutive model of 45 steel
Under the conditions of deformation temperature of 600-700℃,strain rate of 0.001-1 s-1 and deformation amount of 60%,isothermal compression tests were conducted on 45 steel using Gleeble-3500 thermal simulation testing machine to study its thermal deformation behavior.On the basis of friction correction and adiabatic correction on the true stress-true strain curves of the 45 steel,the constitutive equation based on Arrhenius equation,the Arrhenius constitutive model based on strain compensation and the BP(Back propagation)neural network constitutive model were established for the 45 steel.The results show that the flow stress of the 45 steel is highly sensitive to deformation temperature and strain rate,decreasing with increasing deformation temperature and increasing with increasing strain rate.By calculating the correlation coefficient and the average relative error between the predicted values of the constitutive equation and experimental values,it is found that the correlation coefficient of the constitutive equation based on Arrhenius equation is 0.98537,and the average relative error is 3.1197%;the Arrhenius constitutive equation based on strain compensation has a correlation coefficient of 0.97923 and an average relative error of 4.42948%;the constitutive equation based on BP neural network has a correlation coefficient of 0.99682 and an average relative error of 2.28368%,indicating that the overall predictive performance of the constitutive equation based on BP neural network is good,with lower errors and better predictive performance.
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