Strain rate effect and dynamic constitutive model of 7A04-T6 high-strength aluminium alloy

In recent decades, various aluminium alloys have been developed and employed in construction engineering. They are light, corrosion-resisting and recyclable, making them attractive to engineers and researchers. Among these aluminium alloys, 7A04 high-strength aluminium alloy, which is an Al-Zn-Mg-Cu alloy, has now gained focus for its excellent strength-to-weight ratio, hardness, formability, etc. To date, the investigations into its dynamic mechanical properties are still limited. In this context, the mechanical behaviour of 7A04-T6 aluminium alloy at high strain rates was studied in this work. A split Hopkinson pressure bar test system was employed to conduct the dynamic experiments. 6061-T6 aluminium alloy was also included in the tests for reference. Then, comparisons were made between the tested 7A04-T6 and 6061-T6 aluminium alloys and among the studied 7A04-T6 aluminium alloy and steels with approximate yield strengths (Q420 and Q550 structural steels) and similar strength-density ratios (4340 M and Aermet 100 steels), to assess the strain rate sensitivity of 7A04-T6 aluminium alloy. Based on the Johnson-Cook model and the Cowper-Symonds model, which are widely used models that describe the dynamic constitutive behaviour of metallic materials, a modified dynamic constitutive model was developed for 7A04-T6 aluminium alloy, in which the influence of deformation-induced temperature rise on the dynamic mechanical properties is well considered.