Hot compressive deformation behavior of the as-quenched A357 aluminum alloy

The objective of the present work was to establish an accurate thermal-stress mathematical model of the quenching operation for A357 (Al-7Si-0.6Mg) alloy and to investigate the deformation behavior of this alloy. Isothermal compression tests of as-quenched A357 alloy were performed in the temperature range of 350-500°C and at the strain rate range of 0.001-1 s^-1. Experimental results show that the flow stress of as-quenched A357 alloy decreases with the increase of temperature and the decrease of strain rate. Based on the hyperbolic sine equation, a constitutive equation is a relation between 0.2 pct yield stress and deformation conditions (strain rate and deformation temperature) was established. The corresponding hot deformation activation energy (Q) for as-quenched A357 alloy is 252.095 kJ/mol. Under the different small strains (≤0.01), the constitutive equation parameters of as-quenched A357 alloy were calculated. Values of flow stress calculated by constitutive equation were in a very good agreement with experimental results. Therefore, it can be used as an accurate thermal-stress model to solve the problems of quench distortion of parts.