Combined effect of elevated temperature and high strain rates on S690QL high strength steel

Abstract

The effects of elevated temperature and high strain rate on S690QL high strength steel material properties are described. These data are meaningful for the design and structural safety assessment of critical artefacts (bridges, cranes, offshore structures) under combined extreme loadings (impact and explosion) and temperature conditions (fire). Tests were carried out in 20–900 °C temperature range and under three different high strain rates (250, 450 and 950s−1) by means of a Split Hopkinson Tensile Bar equipped with a water-cooled induction heating system. An insight into the influence of the material sampling position on the mechanical properties, i.e. core or peripheral samples is shown. The evolution of the main mechanical properties as a function of both temperature and strain-rate, spanning from quasi-static to dynamic conditions, is assessed. Prediction formulas, valid for 40 mm thick sections, for the yield strength of the core and peripheral materials are proposed. The constitutive parameters of Johnson–Cook’s strength model have been calibrated based on test results.