Physically-Based Modeling and Characterization of Hot Flow Behavior in an Interphase-Precipitated Ti-Mo Microalloyed Steel

Abstract

Abstract:In this contribution, a series of hot compression tests was conducted on a typical interphase-precipitated Ti-Mo steel at relatively higher strain rates of 0.1~10 s −1 and temperatures of 900~1150 • C using a Gleeble-2000 thermo-mechanical simulator. A combination of Bergstrom and Kolmogorov-Johnson-Mehl-Avrami models was first used to accurately predict the whole flow behaviors of Ti-Mo steel involving dynamic recrystallization, under various hot deformation conditions. By comparing the characteristic stresses and material parameters, especially at the higher strain rates studied, the dependence of hot flow behavior on strain rate and deformation temperature was further clarified. The hardening parameter U and peak density ρ p exhibited an approximately positive linear relationship with the Zener-Hollomon (Z) parameter, while the softening parameter Ω dropped with increasing Z value. The Avrami exponent n A varied between 1.2 and 2.1 with lnZ, implying two diverse nucleation mechanisms of dynamic recrystallization. The experimental verification was performed as well based on the microstructural evolution and mechanism analysis upon straining. The proposed constitutive models may provide a powerful tool for optimizing the hot working processes of high performance Ti-Mo microalloyed steels with interphase precipitation.

High-Temperature Deformability of a Fe-Cr-Mn-Ni Austenite Stainless Steel with High Nitrogen and High Carbon Contents

“…It is interesting to note that the fracture elongation started to increase appreciably as the work softening became dominant in the stress-strain curves above 950 • C, suggesting the increase of ductility above 950 • C was associated with dynamic recovery and/or dynamic recrystallization. The critical strain at which the softening set in, decreased with an increase of temperature, which was consistent with the easier dynamic recrystallization with an increase of temperature [23,24].…”

Advances in Microalloyed Steels

“…The present Special Issue on Advances in Microalloyed Steels includes two review papers [1,2] and nine research papers [3][4][5][6][7][8][9][10][11]. In all of them, different combinations of microalloying elements are analyzed in terms of process, microstructure, and mechanical property modification.…”

“…Nb is present in many of them [1,2,5,7,8,10,11], alone or in combination with Mo [2,5,10], Ti [8], and V [10]. Two papers deal with Ti-Mo combinations [6,9], and the last two articles analyze the addition of V [4] and Al [3] as microalloying elements. Microalloyed grades are currently used in different sectors such as energy and structural and automotive sectors.…”

“…Even if some papers cover specific performance problems and optimization alternatives for industrial processing conditions [1,2,7,11], most of the papers deal with more fundamental analyses of the relationship between microstructure and mechanical properties [4][5][6]8,10]. Some papers also analyze the effect of microalloying on hot and cold working behaviors [3,9].…”