Dynamic recrystallization behaviour of H13-mod steel
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ORIGINAL PAPER
Dynamic recrystallization behaviour of H13‑mod steel Chang‑min Li1 · Yuan‑biao Tan1 · Fei Zhao1 Received: 18 July 2019 / Revised: 22 December 2019 / Accepted: 27 December 2019 © China Iron and Steel Research Institute Group 2020
Abstract H13-mod steel developed after optimizing the composition and heat treatment process exhibits good hardness and impact toughness and can be used as a shield machine hob. Based on the Avrami equation, the dynamic recrystallization (DRX) behaviour of H13-mod steel during hot compression was studied in the temperature of 900–1150 °C and strain rate ranges of 0.01–10 s−1. A DRX model and finite element software were used to study DRX behaviour of H13-mod steel. Significant DRX was found at both low and high strain rates. Electron backscatter diffraction and optical microscopy analyses found different DRX nucleation mechanisms at low and high strain rates under different deformations. At a low strain rate, the nucleation was dominated by the strain-induced grain boundary migration, whereas the subgrain coalescence mechanism was dominant at a high strain rate. Moreover, dynamic recovery occurred in both processes. In addition, it was easier to obtain small and uniform equiaxed grains at high strain rates than at low strain rates. Keywords H13-mod steel · Dynamic recrystallization · Dynamic recrystallization volume fraction model · Finite element simulation · Nucleation mechanism
1 Introduction The properties of metallic materials are often improved by controlling the microstructure via thermal processing, and the microstructural evolution is often accomplished through dynamic recrystallization (DRX). Through DRX process, the deformation resistance of a material can be reduced, and the deformation defects of cast materials can be eliminated. In addition, the coarse dendrites and columnar crystals can be broken up to eliminate partial segregation. Moreover, the grains in the material will be refined, and the compactness and mechanical properties of the material will be improved. Therefore, it is important to predict or understand the microstructural evolution during material deformation [1]. During thermal deformation, the essence of work hardening (WH) and dynamic softening is the process of accumulation and disappearance of dislocations. DRX is the main softening mechanism in the hot deformation process of H13-mod steel; hence, DRX is the main method for improving the processing performance and optimizing the microstructure * Fei Zhao [email protected] 1
College of Materials and Metallurgy, Guizhou University, Guiyang 550025, Guizhou, China
of the material. H13-mod steel developed after optimizing the composition and heat treatment process exhibits good hardness and impact toughness and can be used as a shield machine hob [2]. The hob is a key component of a shield machine, and a uniform microstructure will help to improve the service life of a component under various complicated conditions. Therefore, thermal processing optimization is particularly important. Beca
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