Experimental study on the tensile behaviour of the high strength steel S690QL under combined high strain rates and elevated temperatures.
Strain-rate effects on the two constitutive layers (core and peripheral) with different microstructures and calibration of more used material models.
These results are useful for structural assessment in a multi-hazard approach involving high strength steel structures under a combined effect of fire and blast.
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 950 s−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.