Dynamic recrystallization behavior of 35CrMo structural steel

Abstract

The dynamic recrystallization behavior of 35CrMo steel was studied with compression test in the temperature range of 1 223–1 423 K and the strain rate range of 0.01–10.00 s⁻¹. The initiation and evolution of dynamic recrystallization were investigated with microstructure analysis and then the critical strain ɛ_c for dynamic recrystallization initiation, the strain for maximum softening rate ɛ* and the steady strain ɛ_s were obtained to be 2.92×10⁻³Z^0.1381, 1.60 × 10⁻³Z^0.1780 and 3.26 × 10⁻² × Z^0.0972 respectively by analysis of work-hardening rate-strain θ-ɛ curves, where Z is the Zener-Hollomon parameter. The dynamic recrystallization fraction was determined using recrystallization theory, and the effects of initial grain size, strain rate and deformated temperature on the dynamic recrystallization kinetics were investigated. The results show:

\documentclass[12pt]{minimal}\usepackage{amsmath}\usepackage{wasysym}\usepackage{amsfonts}\usepackage{amssymb}\usepackage{amsbsy}\usepackage{mathrsfs}\usepackage{upgreek}\setlength{\oddsidemargin}{-69pt}\begin{document}$$X_{DRX} = 1 - \exp (\frac{{\varepsilon - \varepsilon _c }}{{\varepsilon _s - \varepsilon _c }})^{2.28} )$$\end{document}

, the dynamic recrystallization fraction is slightly delayed due to the somewhat larger initial grain size and markedly delayed with the decrease of temperature. On the other hand, it is significantly accelerated with the increase of the strain rate. Finally, the relationships between the initiation time, ending time of dynamic recrystallization and the deformed temperature were analyzed in detail.

Keywords

dynamic recrystallization / θ-ɛ curve / recrystallization kinetics / initial grain size