화학공학소재연구정보센터
Materials Science Forum, Vol.396-4, 265-270, 2002
A new shear method for testing aluminum alloys in the mushy state
This paper is concerned with the experimental determination of the shear behavior of aluminum alloys during solidification with the objective of modeling hot tearing phenomena that can occur during DC casting. For this purpose, a new experimental set up for shear testing at small strains and high solid fractions has been designed. Preliminary experiments concerning a grain refined Al-8wt%Cu alloy show satisfactory thermal conditions as well as a fairly good reproducibility. In addition the results of these experiments are in agreement with former Couette viscometry data. Isothermal experiments carried out at low strain rates (typically 10(-4)s(-1)-10(-3)s(-1)) and high solid fractions (>0.8) on a grain refined Al-2wt%Cu model alloy show that the stress-strain curves exhibit a significant strain hardening at the beginning of shearing. Non isothermal tests have also been carried out in order to reproduce in a controlled manner the typical strains that are generated during solidification. They show that stresses developed during such experiments are smaller than those during isothermal experiments under identical conditions.