Strain-rate effect and constitutive models for S31803 duplex stainless steel

Engineering structures often experience dynamic loads, such as vehicle impacts, earthquakes, explosions, which exert high strain-rates. To address this issue, a S31803 duplex stainless steel (DSS) was investigated, due to its excellent structural performance, characterized by high strength, good ductility, and superior resistance to stress corrosion cracking. In this study, experiments were conducted on the quasi-static tensile and dynamic behavior of S31803 at strain-rates ranging from 0.00048 s⁻¹ to 2256.9 s⁻¹. Generally, the results indicate that as the strain-rate of DSS is increased, the yield stress increased by a large margin. To analyse the complete stress-strain behavior of S31803 DSS, the Johnson-Cook (J-C) and Cowper-Symonds (C-S) models were used, as both models are widely recognized and commonly used to characterize the strain-rate dependence of metallic materials, including structural stainless steel. A comparison with the test results revealed that, although the modified J-C model was able to capture the plastic strain-rate of the material accurately, the accuracy was not much different from the standard J-C model. However, the C-S model produced more accurate results than the Standard J-C model. The findings provide valuable insights into the behavior of DSS under dynamic loading conditions, which can contribute to the development of more accurate structural designs in engineering fields where this material is used.