中炭素鋼の球状化挙動に及ぼす制御圧延, 制御冷却の効果

概要

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The medium carbon steels have been used for structural parts. In process to make these parts, sphe-roidization treatment has been applied to obtain good cold forgeability. In this study, the effect of controlled rolling and cooling process on the spheroidization behavior of medium carbon steel has investigated using hot deformation simulater and actual rolling process. Following results were obtained. (1) By controlling the cooling rate immediately after controlled rolling to be 10℃/s, the dynamicaly recrystallized fine austenite grains did not show further grain growth and transformed to fine ferrite-pearlite microstructure. This microstructure revealed high volume fraction of ferrite compared with coarse austenite grains. (2) During the spheroidization treatment, fine ferrite-pearlite microstructure showed rapid spheroidization. (3) The bars controlled rolled and cooled by actual rolling process showed good upsetting limit. It has been discussed that rapid sheroidization is caused by enhanced reaustenitization occurred at ferrite-pearlite interphase boundary and increased carbon content in pearlite phase due to the increasing of ferrite volume fraction.
社団法人日本鉄鋼協会の論文
1989-07-01