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Hot-Deformation Behavior of High-Nitrogen Austenitic Stainless Steel under Continuous Cooling: Physical Simulation of Surface Microstructure Evolution of Superheavy Forgings during Hot Forging

by 1,2,* and 1
1
School of Mechanical Engineering, Yanshan University, Qinhuangdao 066004, China
2
State Key Laboratory of Metastable Materials Science and Technology, Yanshan University, Qinhuangdao 066004, China
*
Author to whom correspondence should be addressed.
Materials 2019, 12(7), 1175; https://doi.org/10.3390/ma12071175
Received: 26 March 2019 / Revised: 6 April 2019 / Accepted: 9 April 2019 / Published: 10 April 2019
Superheavy forgings are increasingly used in the nuclear industry. The strain rate is extremely low during hot forging due to the huge size of the superheavy forging; in fact, the surface temperature of the forging decreases obviously during each deformation step. Hot-deformation behavior differs from that of isothermal deformation. In this study, 18Mn18Cr0.6N steel was selected as a model material. Hot-compression tests were conducted using a Gleeble 3800 simulator at a strain rate of 10−4 s−1 and continuous cooling rates of 0.0125 Ks−1 and 0.025 Ks−1. The microstructure was observed using electron backscatter diffraction analysis and transmission electron microscopy. The flow stress increased with increasing strain: the higher the cooling rate, the higher was the hardening rate. Continuous cooling inhibited dynamic recrystallization by delaying its nucleation. The subgrain/cell size increased linearly with increasing final temperature of deformation in the temperature range 1273 to 1448 K. An intense <001> texture formed in 0.8-strained specimens and the matrix exhibited a low Taylor factor orientation. Most dislocations were separately distributed in subgrains and did not entangle with each other or with the subgrain boundary. Dislocation arrays transferred easily through boundaries and dislocation accumulation at boundaries was weak. This study contributes to understanding the hot-forging process of superheavy forgings. View Full-Text
Keywords: high-nitrogen austenitic stainless steel; superheavy forging; continuous cooling; microstructure evolution; dislocation high-nitrogen austenitic stainless steel; superheavy forging; continuous cooling; microstructure evolution; dislocation
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MDPI and ACS Style

Wang, Z.; Wang, Y. Hot-Deformation Behavior of High-Nitrogen Austenitic Stainless Steel under Continuous Cooling: Physical Simulation of Surface Microstructure Evolution of Superheavy Forgings during Hot Forging. Materials 2019, 12, 1175. https://doi.org/10.3390/ma12071175

AMA Style

Wang Z, Wang Y. Hot-Deformation Behavior of High-Nitrogen Austenitic Stainless Steel under Continuous Cooling: Physical Simulation of Surface Microstructure Evolution of Superheavy Forgings during Hot Forging. Materials. 2019; 12(7):1175. https://doi.org/10.3390/ma12071175

Chicago/Turabian Style

Wang, Zhenhua, and Yong Wang. 2019. "Hot-Deformation Behavior of High-Nitrogen Austenitic Stainless Steel under Continuous Cooling: Physical Simulation of Surface Microstructure Evolution of Superheavy Forgings during Hot Forging" Materials 12, no. 7: 1175. https://doi.org/10.3390/ma12071175

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