奥氏体化温度对P20B钢淬透性的影响行为

Behavior of Austenizing Temperature on Hardenability of P20B Steel

采用DIL805A型相变仪,测定含硼P20B钢在850-1 000℃的奥氏体化条件下的过冷奥氏体在640-720℃等温时的C曲线;结合850-1 000℃奥氏体化条件下晶粒度的测定和第二相分析,研究硼对P20B钢淬透性的影响行为.结果表明：在850-920℃的温度范围内,随着奥氏体化温度的升高,晶粒略有长大,固溶硼含量显著增加,使高温C曲线明显右移,即淬透性明显提高;而在920-1 000℃的温度范围内,随着奥氏体化温度的升高,晶粒显著长大,固溶硼含量不再明显增加,此时淬透性不再明显提高.

The C curve of supercooled austenite of plastic mould steel P20B was investigated with the DIL805A dilatometric instrument.The austenitizing temperature was between 850 ℃ and 1 000 ℃ and the isothermal temperature between 640 ℃ and 720 ℃.We compared austenite grain size at different austenitizing temperatures and analyzed the second phase which obtained from the electrolytic extraction procedure.The results show that at 850~920 ℃ in the temperature range when the austenitizing temperature is increased,the grains grow slightly,the content of B increased significantly to make the C curve strongly shift right.At 920~1 000 ℃ in the temperature range when the austenitizing temperature is increased,the grains grow significantly,and the content of B no longer increases so hardenability of P20B steel does not increased.