Effects of Strain Rate and Clad Ratio on Dynamic Tensile Behavior of Stainless-Clad Bimetallic Steel

Stainless-clad (SC) bimetallic steel, consisting of SUS304 stainless steel as the cladding layer and Q235 carbon steel as the substrate layer, is deemed as a good while economic candidate to be applied in marine structures due to the fact that the stainless steel layer can protect it from corrosion. This study experimentally and theoretically investigated the dynamic mechanical properties of SC bimetallic steel. To examine the influences of strain rate and clad ratio, quasi-static and high-speed uniaxial tensile tests were conducted at strain rates of 0.001 s−1, 0.1 s−1, 1 s−1, 10 s−1, and 200 s−1, with clad ratios of 0.168, 0.345, and 0.46, respectively. A combined experimental-numerical method was adopted to determine the true stress–strain curves of SC bimetallic steel, and the dynamic increase factors (DIFs) were determined. The plastic fracture strain was also determined based on the experimental and numerical results. Finally, a modified Cowper–Symonds (C–S) model was proposed to capture the coupling dependency of yield strength, strain rate, and clad ratio, enabling the accurate prediction of DIFs of SC bimetallic steel. A modified Johnson–Cook (J–C) model was also developed by considering the effect of clad ratio to predict the true stress–strain behavior of SC bimetallic steel under quasi-static and medium strain rates. The proposed models were verified through comparison with experimental results, facilitating the application of SC bimetallic steel in ocean engineering practices under impact and other extreme dynamic loading conditions.