Constitutive Modeling of Hot Deformation of Carbon Steels in The Intercritical Zone

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.

Effect Mechanism of α-Ferrite Sustained Precipitation on High-Temperature Properties in Continuous Casting for Peritectic Steel

“…Overall, these studies primarily focus on the effect of the formation and distribution of film-like ferrite on hot ductility in the pre-austenite phase transition stage, with fewer quantitative descriptions of the properties evolution during the whole α-ferrite precipitation advancement process. Actually, as the austenite phase transition process advances, the microstructure of the as-cast slab undergoes complex changes such as the generation of new phases, the depletion of the original phases, and the change in the crystal structure of the matrix phases [30,31], which has a substantial impact on the properties [32,33]. Furthermore, avoiding cracks is only a basic requirement for high-quality steel products, and further improvements in strength and toughness should be considered as a new aim.…”