Constitutive Model Over Wide Temperature Range and Considering Negative-to-Positive Strain Rate Sensitivity for As-Quenched AA2219 Sheet
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An accurate constitutive model over a wide temperature range is very important for research on the quenching process. In this study, uniaxial tension tests of an as-quenched AA2219 aluminum alloy sheet were first conducted at different strain rates (10−3-10−1 s−1) over a wide temperature range (298-773 K). The tension results showed an increase in the strain rate sensitivity (SRS) from negative to positive with temperature. Different increasing trends were observed in the low-temperature range (298-473 K), high-temperature range (573-773 K), and transitive-temperature range (473-573 K). In order to more accurately capture these variations in the SRS, the existing function that considers the negative-to-positive SRS was modified by adding a coupling effect term for the temperature and strain rate. The temperature sensitivity increased linearly and exponentially with the strain and temperature, respectively, and also had obviously different tendencies in the low- and high-temperature ranges. The new coupling effect term for the temperature and strain was constructed to consider these effects. Finally, a phenomenological constitutive model was proposed, in which the negative-to-positive SRS and the coupling effects of the strain and temperature were considered. This constitutive model could predict the flow stress of the as-quenched AA2219 with very good correlation over a wide temperature range.
Keywordsas-quenched AA2219 sheet constitutive model negative-to-positive strain rate sensitivity temperature sensitivity
The authors would like to acknowledge the support from the National Science Fund for Distinguished Young Scholars of China (Project 51625505), Key Program Project of the Joint Fund of Astronomy and National Natural Science Foundation of China (Project U1537203), and the Research Fund of the State Key Laboratory of Solidification Processing (Projects 118-TZ-2015, 97-QZ-2014, and 90-QP-2013).
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