低炭素低合金鋼の逆変態
1974 年 60 巻 2 号 p. 226-238
詳細
1974 年 60 巻 2 号 p. 226-238
The process of formation of austenite has been studied in low-carbon low alloy steels. The specimens with acicular structures such as martensite, bainite or tempered martensite are heated at temperatures between Ac1 and Ac3. The structual changes in these specimens during heating are observed in detail.
The main results are as follows.
1) Austenitizing processes are divided into two stages. In the first stage globular austenites are formed accompanying the dissolution of cementite. Acicular austenites are as well formed at an early stage.
2) In the second stage a globular austenite is formed by the coalescence of the acicular austenite grains and those formed in the both stages grow to form extended austenite grains.
3)γ′ transformation prevails in a boron containing steel.
Based on these results, it is proposed that the reverse transformation are mainly controlled by the rate of recrystallization of austenite.
