کد مقاله | کد نشریه | سال انتشار | مقاله انگلیسی | نسخه تمام متن |
---|---|---|---|---|
831223 | 1470365 | 2011 | 6 صفحه PDF | دانلود رایگان |
In the field of deformation process modeling, the constitutive equations may properly represent the flow behavior of the materials. In fact, these valuable relationships are used as a calculation basis to simulate the materials flow responses. Accordingly, in the present study a hot working constitutive base analysis has been conducted on a 7075 aluminum alloy. This has been performed using the stress–strain data obtained from isothermal hot compression tests at constant strain rates of 0.004, 0.04 and 0.4 s−1 and deformation temperatures of 450, 500, 520, 550 and 580 °C up to a 40% height reduction of the specimen. A set of constitutive equations for 7075 Al alloy have been proposed employing an exponent-type equation. The related material constants (i.e., A, n and α) as well as the activation energy Q for each temperature regime have been determined. The correlation of flow stress to strain rate and temperature can be deduced from the proposed equations. Furthermore, a change in deformation mechanism has been realized in the semi-solid temperature range. This has been related to the onset of lubricated flow mechanism during processing.
► Two constitutive models has been proposed for the hot working of 7075 Al alloy.
► Constitutive models show the temperature and strain rate dependence of flow stress.
► Deformation mechanism changes to lubricated flow at 550 °C during hot deformation.
► Lubricated flow mechanism becomes more pronounced with increasing strain rate.
Journal: Materials & Design - Volume 32, Issue 10, December 2011, Pages 4955–4960