【作者】 龙木军； 董志华； 陈登福； 张星； 盛俊豪； 陈春梅；

【Author】 Long Mu-jun,Dong Zhi-hua,Chen Deng-fu,Zhang Xing,Sheng Jun-hao,Chen Chun-mei School of Materials Science and Engineering,Chongqing University,Chongqing 400030,China

【机构】 重庆大学材料科学与工程学院；

【摘要】 采用热膨胀仪测试研究了Q450NQR1钢连铸坯5℃·min^-1及20℃·min^-1冷却速率下的线性热膨胀和瞬时热膨胀系数随温度的变化规律。在此基础上,发展了一种基于平均原子体积的相体积计算模型,量化研究了奥氏体溶解过程中各相体积分数的变化规律,并在将计算结果与显微组织观察结果对比分析基础上,讨论了连铸冷却速率对铸坯奥氏体溶解过程的影响。结果表明,该计算模型可以较为准确地描述铸坯的奥氏体溶解过程,适用于多相连续析出相变;随着冷却速率的增大,铸坯瞬时热膨胀曲线中对应于铁素体和珠光体析出的两个变化峰向低温区移动,峰值明显增大;冷却速率由5℃·min^-1上升至20℃·min^-1时,铁素体及珠光体起始析出温度分别降低约32℃和37℃,体积分数分别由0.894和0.106上升/下降至0.945和0.055。更多还原

【Abstract】 To understand the knowledge of liner thermal expansion and thermal expansion coefficient of Q450NQR1 casting steel, the dilatometry experiments were performed at two different cooling rates with values of 5℃·min^-1 and 20℃·min^-1,respectively. Then,a method to quantitatively extract the kinetic information of austenite dissolution based on the concept of average atomic volume was suggested in present paper,and the calculated results were compared with that from microstructure examination. Moreover,the influence of cooling rate on the austenite dissolusion was discussed finally.The results show that this method is indeed reasonable to accurately describe the behavior of austenite dissolution and could be applied to the multi-phase transformation.With increased the cooling rate,two peaks associated to the precipitation of ferrite and pearlite on the thermal coefficient curve shift to lower temperature with higher values.When the cooling rate varies from 5℃·min^-1 and 20℃·min^-1,the initial temperature of ferrite and pearlite precipitation decrease by 32℃and 37℃,and the final volume fraction of ferrite and pearlite gradulaly rises/drops from 0.894 and 0.106 to 0.945and 0.055,respectively.更多还原