低炭素鋼のオーステナイト粒界に生成する初析フェライトの形態

抄録

This paper describes morphologic features of proeutectoid ferrite (α) formed at austenite (γ) grain boundaries in three kinds of steel ; a HSLA steel with 0.04%Nb and 0.04%V, a commercial 0.2%C steel and an Fe-0.1%C alloy. Shape of the proeutectoid α at γ grain boundaries strongly depended on the austenitizing temperature. At the higher temperature, the proeutectoid (α) grains precipitated in the shape of film along planar γ grain boundaries, and a coalescence of several α grains with the same orientation made the film-shaped α in which many subgrain boundaries were observed. At the lower austenitizing temperature, on the other hand, they precipitated in the shape pf globe (allotriomorph) form along curved γ grain boundaries. Each a grain had a different orientation and led to allotriomorph. This trend was commonly observed in all the steels investigated.