| About this Abstract |
| Meeting |
MS&T24: Materials Science & Technology
|
| Symposium
|
Austenite Formation and Decomposition V: A Symposium in Memory of Prof. Mats Hillert
|
| Presentation Title |
Effects of Mn Heterogeneity on Bainite and MA Microstructure in Low Carbon Steel |
| Author(s) |
Goro Miyamoto, Kaito Matsumoto, Shunichi Nakayama, Masao Yuga, Tadashi Furuhara |
| On-Site Speaker (Planned) |
Goro Miyamoto |
| Abstract Scope |
Control of steel microstructure using Mn heterogeneity has been applied to retain austenite in sheet steels; however, its application to thick plate steels remains limited. In this study, we report the significant influence of Mn heterogeneity on the distribution of MA (martensite and austenite constituent), which affects the toughness and strength of low-carbon bainitic steels. Mn heterogeneity is introduced in an Fe-0.1C-2Mn alloy through intercritical annealing from an initial martensite structure and subsequent short annealing in γ single-phase regions, followed by austempering for bainite transformation. Needle-like γ formed during intercritical annealing is enriched with Mn, persisting even after complete γ reversion. Mn heterogeneity accelerates bainite transformation kinetics in the early stages of transformation, while it retards the transformation in the final stages, resulting in a higher volume fraction of less-elongated MA. This peculiar MA distribution in Mn heterogeneous specimens achieves a better balance of strength and ductility. |