Thermomechanical response of Q355B steel under varying strain rates and temperatures: experiments and modeling

In this study, uniaxial compression experiments were performed on Q355B steel to investigate its mechanical response under coupled loading of varying strain rates (0.0008–5000 s −1 ) and temperatures (25–900 °C). The plastic behaviors of the Q355B steel showed strong dependencies on temperature and strain rate. Abnormal mechanical responses of Q355B steel, marked by elevated flow stress at higher temperatures and lower strain rates, were also observed at certain loading scenarios due to dynamic strain aging (DSA). Additionally, the temperature associated with DSA shifted to higher value as the strain rate increases. A novel phenomenological constitutive model was proposed to characterize the thermomechanical responses of Q355B steel. Moreover, a three-hidden-layer artificial neural network (ANN) was first developed to predict the DSA-affected material behaviors over a wide range of strain rates. The prediction accuracy of the phenomenological and ANN models was quantitatively assessed using four statistical indicators: correlation coefficient, root mean square error, average absolute relative error, and relative error. The results demonstrated that both models achieved acceptable accuracy, and the ANN exhibited significantly superior predictive performance compared to the phenomenological constitutive model. • Compressive loading tests on Q355B steel were conducted at varied temperatures and strain rates. • Anomalous material behaviors induced by dynamic strain aging (DSA) were discussed. • A phenomenological model incorporating the DSA effect was proposed and calibrated. • An artificial neural network (ANN) was developed to improve the prediction accuracy of material behavior. • Two model performances were quantitatively compared using statistical indicators.