材料期刊网

采用金相法测定了在不同温度(950~1270℃)下固溶不同时间(30~150 min)后高铌低碳贝氏体钢的奥氏体晶粒尺寸,研究了其奥氏体晶粒的长大行为；计算了试验钢中铌的固溶含量,建立了奥氏体晶粒长大数学模型并进行了试验验证.结果表明：在1220~1270℃温度区间内试验钢奥氏体晶粒尺寸增加值最大,其次为1100~1150℃区间的；由于1000℃时试验钢中合金渗碳体的快速溶解,使得950~1000℃区间内的晶粒尺寸增加值大于1000~1050℃区间的；计算得到1150℃时的固溶铌质量分数达到0．088％,此时绝大部分 NbC 已经溶解,导致1100~1150℃温度区间内奥氏体晶粒的快速长大；在950~1270℃范围内,试验钢的奥氏体晶粒长大激活能为154．4 kJ?mol－1,由晶粒长大模型计算得到的奥氏体晶粒尺寸与实测值较吻合.

The austenite grain sizes of low carbon bainite steel with high Nb content after solid solution at different temperatures from 950 ℃ to 1 270 ℃ for different time from 30 min to 150 min were determined by metallographic method and the growth behavior of the austenite grains was studied.The solid solution Nb content in the tested steel was calculated,and then the mathematical model for the austenite grain growth was established and verified by the experiments.The results show that the austenite size increase value in the temperature range 1 220-1 270 ℃ was maximum and followed by that in the range 1 100-1 150 ℃;The grain size increase value in the temperature range 950-1 000 ℃ was larger than that in the range 1 000-1 050 ℃ due to the rapid dissolution of the alloying cementite in the experimental steel at the temperature of 1 000 ℃.The solid solution Nb content calculated at 1 150 ℃ reached 0.088wt%,and by this time the most NbC particles were dissolved,resulting in the rapid growth of the austenite grains in the temperature range of 1 100-1 150 ℃.In the range 950-1 270 ℃,the activation energy for austenite grain growth was 154.4 kJ?mol-1 .The austenite grain sizes calculated by the as-established grain growth model of the tested steels were in accordance with the measured values.