Dynamic Process And Mechanical Behavior In The Thermal Deformation Of AISI1215 Steel And Ti6Al4V Alloy

Thermal deformation of metallic materials is a complex dynamic physical process, involving changes in strain, strain rate, mechanical properties, microstructure and temperature range in certain situation, such as work hardening, dynamic recovery and recrystallization of the material. These changes have significant influence on the rolling force, the phase transformation in the cooling process, and the product’s final properties. At present, as the extensive application of thermal simulating equipments and software simulations, the study of the thermal deformation of metallic materials is going deeper and deeper with the help of many flow stress models and dynamic recrystallization models. And together with the software simulation researchers will make a better understanding of the metal’s thermal deformation so as to see problems beforehand which helps to designing a better hot working process as well as improving the quality and reducing costs of the product.Through uniaxial compressing experiments on Gleeble in different strain rates and temperatures and drawing of material’s true stress-strain curve, the influence of deformation rate and temperature on the curve becomes clear, thus giving relations between hot deformation activation energy of the material and parameters such as thermal flow stress during deformation. According to Jonas’ method, the hardening rate- true stress curve is introduced to analyze the the critical strain of dynamic recrystallization and its relation with the maximum strain, also to build up its functional relationship with critical strain, deformation temperature and rate as a criterion for the dynamic recrystallization in thermal deformation. At last, the models tally with the experimental results well.