Yonemura Mitsuharu, Nishibata Hitomi, Nishiura Tomohiro, Ooura Natsumi, Yoshimoto Yuki, Fujiwara Kazuki, Kawano Kaori, Terai Tomoyuki, Inubushi Yuichi, Inoue Ichiro, Tono Kensuke, Yabashi Makina
Advanced Technology Research Laboratories, Nippon Steel Corporation, 1-8 Fuso-cho, Amagasaki, Hyogo, 660-0891, Japan.
Department of Materials Science and Engineering, Graduate School of Engineering, Osaka University, 2-1 Yamadaoka, Suita, Osaka, 565-0871, Japan.
Sci Rep. 2019 Aug 2;9(1):11241. doi: 10.1038/s41598-019-47668-6.
In this study, phase transformation kinetics was directly evaluated using a femtosecond X-ray diffraction technique for operand measurements of the dislocation densities and carbon concentrations in Fe-0.1mass%C martensitic steel. To identify the reverse transformation mechanism from α' to γ, we used an X-ray free-electron laser and ultrafast heating. A maximum heating rate of 10 °C/s, which is sufficient to avoid diffusive reversion, was achieved, and the reverse transformation during ultrafast heating was successfully observed. Our results demonstrated that a fine microstructure formed because of a phase transformation in which the dislocation density and carbon concentrations remained high owing to ultrafast heating. Fe-C martensitic steels were also found to undergo a massive reverse transformation during ultrafast heating. The formation of a fine microstructure by a simple manufacturing process, without rare elements such as Ti, Nb, or Mo, can be expected. This study will help further the development of functional steels.
在本研究中，使用飞秒X射线衍射技术直接评估了相变动力学，用于对Fe-0.1质量%C马氏体钢中的位错密度和碳浓度进行原位测量。为了确定从α'到γ的逆转变机制，我们使用了X射线自由电子激光和超快加热。实现了足以避免扩散逆转的10 °C/s的最大加热速率，并成功观察到超快加热过程中的逆转变。我们的结果表明，由于超快加热导致位错密度和碳浓度保持较高的相变，形成了精细的微观结构。还发现Fe-C马氏体钢在超快加热过程中会发生大量的逆转变。预计可以通过简单的制造工艺形成精细的微观结构，而无需使用Ti、Nb或Mo等稀有元素。本研究将有助于进一步推动功能钢的发展。
