急冷凝固した工具鋼の鋳片の特性

概要

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The rapid solidification of high speed steel was investigated by using water-cooled chill block apparatus, which was simulated to function similarly to a caterpillar-type caster or roll caster. The secondary dendrite arm spacing near the surface was 4 μm in every cast ingot. By increasing the thickness of the ingot, the dendrite arm spacing at the center also increased. By analyzing the relationship between the dendrite arm spacing and cooling rate, the cooling rate near the surface was estimated at 10^3℃/s and that at the center of 40 mm-thick cast ingot was 10^0℃/s. The size of eutectic carbide decreased with the thickness of the cast ingot. The cast ingots were heat treated at 1150℃ for 2 h. Lamellar eutectic carbide changed to the spheroidal one by heat treatment. Furthermore, plates of carbon tool steel were made by the twin roll test caster. Casting speed was 5∿10 m/min. The size of cast plate was 1∿2.5 mm in thickness and 260 mm in width. The carbon tool steel plate was heat-treated at 690℃ for 1∿50 h. The spheroidal cementite structure was obtained by the heat treatment. The plates of high speed steel were also made by the twin roll test caster. Fine eutectic carbide was observed in the cast plate by the heat treatment.
社団法人日本鉄鋼協会の論文
1988-03-01