直接焼入プロセスにおけるボロンの粒界偏析挙動と焼入性

概要

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The effect of boron (B) on hardenability is explained by the decrease of boundary energy due to the segregation of B atoms to austenite grain boundaries. In this paper, the effect of niobium (Nb) on hardenability of B treated direct quenching steel is studied with varing the condition of B segregation to austenite boundaries. And it is clarified that the effect of B on hardenability is fully obtained even at unrecrystallized state of austenite, and that the maximum hardenability in direct quenching process can be attained at about 10 ppm soluble B which is about three times as the optimum ones of conventional reheat quenching process. It is concluded that the addition of 0.015% Nb rather give rise to the hardenability of B even in unrecrystallized state of austenite in direct quenching process because Nb hinders boundary migration of austenite and enables soluble B to segregate to the grain boundaries and deformation bands.
社団法人日本鉄鋼協会の論文
1988-11-01