Effect of Low Temperature Aging on Hall-Petch Coefficient in Ferritic Steels Containing a Small Amount of Carbon and Nitrogen

Satoshi Araki; Kohei Fujii; Daichi Akama; Toshihiro Tsuchiyama; Setsuo Takaki; Takahito Ohmura; Jun Takahashi

doi:10.2355/isijinternational.ISIJINT-2018-130

Mechanical Properties

Effect of Low Temperature Aging on Hall-Petch Coefficient in Ferritic Steels Containing a Small Amount of Carbon and Nitrogen

Satoshi Araki , Kohei Fujii, Daichi Akama, Toshihiro Tsuchiyama, Setsuo Takaki, Takahito Ohmura, Jun Takahashi

Author information

Satoshi Araki Corresponding author
Graduate Student, Kyushu University
Kohei Fujii
Graduate Student, Kyushu University
Daichi Akama
Department of Materials Science and Engineering, Graduate School of Engineering, Kyushu University
International Institute for Carbon-Neutral Energy Research (WPI-I²CNER), Kyushu University
Toshihiro Tsuchiyama
Department of Materials Science and Engineering, Graduate School of Engineering, Kyushu University
International Institute for Carbon-Neutral Energy Research (WPI-I²CNER), Kyushu University
Setsuo Takaki
Department of Materials Science and Engineering, Graduate School of Engineering, Kyushu University
International Institute for Carbon-Neutral Energy Research (WPI-I²CNER), Kyushu University
Takahito Ohmura
National Institute for Materials Science
Jun Takahashi
Advanced Technology Research Labs., Nippon Steel & Sumitomo Metal Corporation

Keywords: grain boundary segregation, age hardening, grain refinement strengthening, ferritic steel, Hall–Petch relationship

JOURNAL OPEN ACCESS FULL-TEXT HTML

2018 Volume 58 Issue 10 Pages 1920-1926

DOI https://doi.org/10.2355/isijinternational.ISIJINT-2018-130

Details

Abstract

In this study, the effect of aging treatment at 373 K on Hall–Petch coefficient (k_y) was investigated by considering the change in friction stress associated with carbide/nitride precipitation in ferritic steels containing 60 mass ppm carbon or nitrogen (C60 and N60). Tensile tests revealed that the k_y monotonously increased with increasing aging time in both steels. Additionally, C60 exhibited a k_y value exceeding that of N60 with respect to the same aging time. The results of the 3DAP analysis and theoretical calculation for the grain boundary segregation of carbon and nitrogen indicated that the k_y corresponded to the amount of carbon and nitrogen existing at the grain boundary. No difference in the effect on increments in k_y between the two elements was observed. The increase in k_y in C60 under the same aging condition was due to the higher amount of segregated carbon when compared with that of nitrogen.

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