オーステナイト結晶粒の成長性におよぼす高温加工の影響について

抄録

For medium-carbon steels and a medium carbon Cr-Mo steel having different grain size, the effect of hot working on growth characteristics of austenite grains was studied by changing the forging ratio from 2 to 10.
From this work, it was concluded that hot working lowered the coarsening temperature of austenite and that annealing after forging much lowered it. These were more clearly observed in a duplex-grained steel than in a fine-grained steel. It was also found that the effect of hot working and annealing on coarsening temperature was much smaller than that of the difference of ingot size. It was veritied, therefore, difference of grain size and grain growth characteristics between a ladle sample and a finished product was mainly due to the difference of teeming conditions.
Moreover, taking account of the behavior of AlN in steels, it was deduced that the effect of hot-working and annealing was the function of the state of aggregation of AlN and the occurrence of duplex grain structure, detected in this work, in as-forged state was also related to the behavior of AlN in austenite.