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A Unique Bimodal Microstructure Induced by Ultrafine Inclusions to Improve Mechanical Properties of Low‐Carbon Steels Produced by Twin‐Roll Casting
Author(s) -
Song ZiHao,
Song HongYu,
Liu HaiTao
Publication year - 2020
Publication title -
steel research international
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.603
H-Index - 49
eISSN - 1869-344X
pISSN - 1611-3683
DOI - 10.1002/srin.201900471
Subject(s) - materials science , microstructure , acicular ferrite , nucleation , metallurgy , ferrite (magnet) , acicular , casting , carbon fibers , thermomechanical processing , composite material , bainite , martensite , chemistry , organic chemistry , composite number
A unique bimodal microstructure is proposed to improve the mechanical properties of low‐carbon steels produced by twin‐roll casting. The ultrafine inclusions (0.2–2.0 μm) are produced in the as‐cast matrix. A high proportion of ultrafine acicular ferrite (UFAF) is induced due to these inclusions by controlling the critical processing factor, i.e., the cooling rate during γ → α transformation process. Therefore, heterogeneous microstructure is characterized by UFAF cluster, and network‐like coarse polygonal ferrite (PF) with a bimodal grain size distribution is engineered, significantly increasing the strength while not obviously damaging the plasticity. In addition, a new acicular ferrite (AF) heterogeneous nucleation mechanism is reported.