CAJ | 학술논문

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(△L/L0)和热膨胀系数随温度的变化规律.在此基础上,建立了一种基于平均原子体积的相体积计算模型,量化研究了奥氏体相变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相变过程的影响.结果表明：该计算模型可以较为准确地描述铸坯的奥氏体相变过程,适用于多相连续析出相变；随着冷却速率的增大,铸坯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℃,最终体积分数分别由0.894和0.106变为0.945和0.055.
채용열팽창의측시연구료Q450NQR1강련주배5℃·min-1급20℃·min-1냉각속솔하적선성열팽창(△L/L0)화열팽창계수수온도적변화규률.재차기출상,건립료일충기우평균원자체적적상체적계산모형,양화연구료오씨체상변과정중각상체적분수적변화규률,병재장계산결과여현미조직관찰결과대비분석기출상,토론료련주냉각속솔대주배오씨체상변과정적영향.결과표명：해계산모형가이교위준학지묘술주배적오씨체상변과정,괄용우다상련속석출상변；수착냉각속솔적증대,주배열팽창곡선중대응우철소체화주광체석출적량개변화봉향저온구이동,봉치명현증대；냉각속솔유5℃·min-1상승지20℃·min-1시,철소체급주광체기시석출온도분별강저약32℃화37℃,최종체적분수분별유0.894화0.106변위0.945화0.055.
To understand the knowledge of liner thermal expansion and thermal expansion coefficient of Q450NQR1 casting steel, dilatometry experiments were performed at two different cooling rates of 5℃·min-1 and 20℃·min-1 . A mathematical model was de-veloped to quantitatively extract the kinetic information of austenite transformation based on the concept of average atomic volume. The model was verified by microstructure examinations, indicating that the model was appropriate to describe the behavior of austenite transformation and could be applied to multi-phase transformations during steel continuous casting. The influence of cooling rate on the austenite transformation was discussed with the model. it is found that, with increasing cooling rate, two peaks associated to the pre-cipitation of ferrite and pearlite on the thermal expansion coefficient curve shifted towards a lower temperature region with higher val-ues. As the cooling rate increases from 5℃·min-1 to 20℃·min-1 , the initial temperatures of ferrite and pearlite precipitation de-crease by 32℃ and 37℃, and the final volume fractions of ferrite and pearlite gradually change from 0. 894 and 0. 106 to 0. 945 and 0. 055, respectively.