Austenite Grain Refining of As-cast Bloom Surface by Reduction of Oscillation Mark Depth

抄録

Austenite grain refining in the surface layer of as-cast bloom is effective for the reduction of surface cracks in steel production. This study was carried out to clarify the influence of cooling rate on the as-cast austenite grain size and its growth mechanism. Depth and interval of oscillation marks were reduced and the austenite grains at the bloom surface were refined under the oscillation conditions of shorter stroke and higher frequency. The average cooling rates were estimated to be from 6 to 16 K/s in austenite phase temperature and the rates were related to characteristics of oscillation mark. It was found that the austenite grain growth direction did not vary even when characteristics of oscillation mark changed. The austenite grain size below the surface layer was also determined by austenite grain size at the bloom surface.