Multistage serrated flow behavior of a medium-manganese high-carbon steel
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ORIGINAL PAPER
Multistage serrated flow behavior of a medium‑manganese high‑carbon steel J. Chen1 · Y. Zhang2 · J.J. Wang1,3 · C.M. Liu1,4 · S.X. Zhao5 Received: 17 July 2019 / Revised: 9 September 2019 / Accepted: 17 September 2019 © China Iron and Steel Research Institute Group 2019
Abstract The deformation mechanisms and the flow stress behavior of a medium-manganese high-carbon steel during cold deformation at a strain rate of 10−5 s−1 were explored using a universal testing machine, an X-ray diffractometer, a field emission scanning electron microscope and a high-resolution transmission electron microscope. The results show that continuous step-up serrated flow behavior appears after the yielding point, and the true stress–strain curve is roughly divided into five stages based on distinctive densities and amplitudes of serration. The strengthening mechanisms of the experimental steel involve Cottrell atmosphere, twinning-induced plasticity (TWIP) effect and transformation-induced plasticity (TRIP) effect. TWIP effect is the dominant deformation mechanism, and deformation twins formed by TWIP effect comprise primary, secondary and nanotwins. Furthermore, TRIP effect arises in the local high-strain region. Carbon element plays a key role in the transformation of the deformation mechanism. A small amount of carbide precipitates around twin boundaries lead to the formation of local carbon-poor regions, and Md temperature and stacking fault energy of medium-manganese high-carbon steel are propitious to the occurrence of TRIP effect. In addition, the contributions of various deformation mechanisms to plasticity are calculated, and that of TWIP effect is the greatest. Keywords Serrated flow · Deformation mechanism · Deformation twin · Twinning-induced plasticity · Transformationinduced plasticity
1 Introduction High-manganese (Mn) steel (circa 13 wt.%, Hadfield steel) is regarded as the most crucial wear-resistant steel because of its excellent mechanical properties and work hardening ability [1–4]. Extensive research has revealed that a twinning-induced plasticity (TWIP) effect dominates the main * J.J. Wang [email protected] 1
Key Laboratory for Anisotropy and Texture of Materials, Ministry of Education, Northeastern University, Shenyang 110819, Liaoning, China
2
Shenyang Industrial Transformation Upgrading Promotion Center, Shenyang 110083, Liaoning, China
3
The State Key Laboratory of Rolling and Automation, Northeastern University, Shenyang 110819, Liaoning, China
4
School of Materials Science and Engineering, Northeastern University, Shenyang 110819, Liaoning, China
5
Central Research Institute, Baoshan Iron & Steel Co., Ltd., Shanghai 201999, China
deformation mechanism of high-Mn steels [5, 6], which can effectively improve the wear resistance and work hardening ability of high-Mn steels. With the enhancement of TWIP effect, the fraction of deformation twins in high-Mn steels increases, which results in obvious refinement of the grains and effectively impedes the movement of disl
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