V-C-N 鋼の初析粒界フェライト成長速度に及ぼすオーステナイト域等温保定処理の効果

概要

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The mechanism of retarded growth rate of intergranular proeutectoid ferrite in a V-C-N steel has been investigated by examining the effect of holding in austenite region during cooling from the solutioning prior to the isothermal transformation at 600℃. The growth rate increases and the transformation start time decreases by increasing the holding temperature, while a C-curve behaviors appears. The growth rate can be ascribed to the supersaturation of C at the transformation interface. THERMO-CALC calculation indicates that substantial precipitation of V(C, N) takes place in the V-C-N steel and the fraction of C in the precipitate decreases with the increasing holding temperature. Analysis of the transformation kinetics in terms of the Johnson-Mehl-Avrami equation shows a two-step process, suggesting decrease in the ferrite nucleation rate by the holding. It is concluded that absorption of C into the precipitate during the incubation period decreases the supersaturation of C at the transformation interface.
社団法人日本鉄鋼協会の論文
1998-08-01