Hot Deformation Characteristics-Constitutive Equation and Processing Maps-of 21-4N Heat-Resistant Steel

Yiming Li; Hongchao Ji; Wangda Li; Yaogang Li; Weichi Pei; Jinping Liu

doi:10.3390/ma12010089

Hot Deformation Characteristics-Constitutive Equation and Processing Maps-of 21-4N Heat-Resistant Steel

Materials (Basel). 2018 Dec 27;12(1):89. doi: 10.3390/ma12010089.

Authors

Yiming Li¹, Hongchao Ji^{2

3

4}, Wangda Li⁵, Yaogang Li⁶, Weichi Pei^{7

8}, Jinping Liu⁹

Affiliations

¹ College of Mechanical Engineering, North China University of Science and Technology, Tangshan 063210, China. jxlym666@163.com.
² College of Mechanical Engineering, North China University of Science and Technology, Tangshan 063210, China. jihongchao@ncst.edu.cn.
³ National Center for Materials Service Safety, University of Science and Technology Beijing, Beijing 100083, China. jihongchao@ncst.edu.cn.
⁴ School of Mechanical Engineering, University of Science and Technology Beijing, Beijing 100083, China. jihongchao@ncst.edu.cn.
⁵ College of Mechanical Engineering, North China University of Science and Technology, Tangshan 063210, China. lwd13731542189@163.com.
⁶ College of Mechanical Engineering, North China University of Science and Technology, Tangshan 063210, China. jxlyg@ncst.edu.cn.
⁷ College of Mechanical Engineering, North China University of Science and Technology, Tangshan 063210, China. pwc@ncst.edu.cn.
⁸ School of Mechanical Engineering, University of Science and Technology Beijing, Beijing 100083, China. pwc@ncst.edu.cn.
⁹ School of Mechanical Engineering, University of Science and Technology Beijing, Beijing 100083, China. liujp@ustb.edu.cn.

Abstract

The hot deformation behavior of 21-4N heat-resistant steel was studied by hot compression test in a deformation temperature range of 1000⁻1180 °C, a strain rate range of 0.01⁻10 s^-1 and a deformation degree of 60%, and the stress-strain curves were obtained. The functional relationship between flow stress and process parameters (deformation degree, deformation temperature, strain rate, etc.) of 21-4N heat-resistant steel during hot deformation was explored, the constitutive equation of peak stress was established, and its accuracy was verified. Based on the dynamic material model, the energy dissipation maps and destabilization maps of 21-4N heat-resistant steel were established at strains of 0.2, 0.4 and 0.6, and processing maps were obtained by their superposition. Within the deformation temperature range of 1060~1120°C and a strain rate range of 0.01⁻0.1 s^-1, there is a stable domain with the peak efficiency of about 0.5. The best hot working parameters (strain rate and deformation temperature) of 21-4N heat-resistant steel are determined by the stable and instable domain in the processing maps, which are in the deformation temperature range of 1120⁻1180 °C and the strain rate range of 0.01⁻10 s^-1.

Keywords: 21-4N heat-resistant steel; constitutive equation; hot deformation; microstructure; processing map.

Grants and funding

2018M641186/China Postdoctoral Science Foundation