Formation of Ferrite-Cementite Ultrafine Grained Microstructure by Warm Compression for SM490 Martensite Steel
The low carbon steel, SM490 was austenized at different temperatures followed by quenching into water to obtain martensite microstructures with different grain sizes. Then specimens were heated up to 600°C followed by warm-compression at έ=1.7x10-3 s-1 (strain rate) to investigate the dynamic recrystallization behavior. The influence of pre-tempering before compression was also investigated. The microstructure observations were performed with FE-SEM and orientation imaging analysis with EBSD. It is confirmed that the dynamic recrystallization occurred in the tempered martensite as well as the as-quenched marteniste, resulting in fine grained ferrite microstructure with about 2μm. The dynamic recrystallization grain size is hardly dependent on the block size of initial martensite.
S.-J.L. Kang, M.Y. Huh, N.M. Hwang, H. Homma, K. Ushioda and Y. Ikuhara
J.H. Li et al., "Formation of Ferrite-Cementite Ultrafine Grained Microstructure by Warm Compression for SM490 Martensite Steel", Materials Science Forum, Vols. 558-559, pp. 539-544, 2007