Effect of heating-rate on the thermomechanical behavior of aluminum alloy LY12 and a phenomenological description

The effect of heating-rate and its history on the thermomechanical behavior of aluminum alloy LY12 is investigated with a Gleeble 1500 thermal–mechanical material testing system. It was found that the material experiencing higher heating- rate histories possesses lower rupture strength, and the pre-stressed material fails at a lower temperature when it is heated at a higher heating-rate. The SEM observation shows that, in general, there are more defects in the material subjected to higher heating-rates or higher heating-rate histories. The concept of local thermal inconsistency is introduced to account for the effect of heating-rate on mechanical properties, such as hardening and damage. A constitutive model is proposed for the description of the behavior of the materials subjected to thermomechanical loading incorporating fast heating, which can take into account the effect of plastic deformation, temperature and its rate, and recrystallization on the mechanical property, hardening and damage of the material. The constitutive behavior of LY12 subjected to uniaxial thermomechanical loading incorporating fast heating is described, and the comparison with the experimental results demonstrates the validity of the proposed model.