研究論文
高クロム鋳鉄の連続冷却変態挙動に及ぼすCr/C値の影響
2018 年 90 巻 5 号 p. 224-229
詳細
2018 年 90 巻 5 号 p. 224-229
Continuous cooling transformation of plain high chromium cast iron with Cr/C value from 2 to 15 was investigated using a transformation measuring apparatus with subzero function, and the transformation behavior was clarified. Both AC1 and nose temperature of pearlite transformation (TP-n) rose slightly and its nose time (tP-n) shifted to long time side with an increase in Cr/C value. When the austenitizing temperature was increased, TP-n did not change but tP-n moved to the long time side regardless of the Cr/C value. The relationship between tP-n and Cr/C value can be expressed by the following equations (1). Ms and Mf temperatures rise with increasing Cr/C value and the relations can be expressed by the equations below (2). As Cr/C value increased, the maximum hardness after finishing transformation increased to the highest at 6 of Cr/C value, and then decreased in spite of subzero treatment.
tP-n (s) (1273Kγ) ＝ 43exp (0.3 (Cr/C)) }
tP-n (s) (1323Kγ) ＝ 79exp (0.3 (Cr/C)) } ― (1)
Ms (K) (1273Kγ) ＝ 342 ＋ 8.5 (Cr/C) }
Mf (K) (1273Kγ) ＝ 150 ＋ 6.8 (Cr/C) }
Ms (K) (1323Kγ) ＝ 262 ＋ 8.0 (Cr/C) }
Mf (K) (1323Kγ) ＝ 143 ＋ 4.0 (Cr/C) } ― (2)
