Abstract
A previous constitutive modeling for single-phase steels is extended using the mixing law to predict the behavior of hot deformation in the dual phase ferritic-austenitic intercritical zone of Fe-C-Mn-Si alloys. Mixing law considers two phases instead one, so one phase formula was modified. The constant’s values used represents average values to the same conditions in austenitic and ferritic model. The amount of each phase is determined as function of temperature and chemical composition. The developed constitutive modeling is validated by comparing the theoretical stress-strain curves with experimental isothermal uniaxial compression tests of 1008 and 1035 carbon steels at different temperatures and strain rates. The compression tests were carried out in a dilatometer with the compression load at strain rate of 10-3, 10-2 and 10-1 s-1. A good agreement was obtained between the calculated and experimental results over different stages of deformation and hardening. Microstructural analysis was also carried out to relate the deformation results to the microstructure of the steels. Finally, a general constitutive equation has been proposed for hot deformation of steels in the intercritical zone.
Highlights
Steel is one of the most researched materials, even though today certain aspects of its behavior under given conditions continue to be ambiguous, such as the hot deformation of steels[1,2,3,4]
There is considerable agreement regarding the impact of the elements C, Si and Mn on the mechanical properties of carbon steels, especially when analyzing their behavior when subjected to cold work; there exist uncertainties with respect to the behavior of the aforementioned elements during deformation operations at high temperatures[5]
Given the multiplicity of variables involved in this type of operations[6], it is expected that the analysis will become complex and that greater efforts will be required to distinguish or attribute the effect of the chemical composition[4]
Summary
Steel is one of the most researched materials, even though today certain aspects of its behavior under given conditions continue to be ambiguous, such as the hot deformation of steels[1,2,3,4]. The phenomena involved in the processes of deformation at high temperatures are controlled by diffusion, movement of dislocations and atomic interaction with the environment. Examples of this include strain hardening and dynamic restoration phenomena[7,8]. Carbon affects the hot behavior of steels depending on their possibilities of diffusion through the network and their interaction with other atoms and dislocations. This behavior is not entirely clear[9,10,11]. It is believed that the addition of C causes distortions in the crystal lattice, resulting in an increase in the kinetics of the self-diffusion mechanisms of
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