DICTRAsimulation of holding time dependence of NbC size and experimental study of NbCon autenite grain growth
DICTRAsimulation of holding time dependence of NbC size and experimental study of NbCon autenite grain growth
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NbC尺寸保持时间依赖性的DICTRA模拟及NbCon奥氏体晶粒长大的实验研究
DOI：
10.1007/s11661-015-2922-4
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发表时间：
2015
期刊：
影响因子：
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通讯作者：
王福明
中科院分区：
文献类型：
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作者：
王福明
在由海洋结构钢 EQ70 制成的样品的横向和纵向上检查了奥氏体化温度和保温时间对原奥氏体晶粒尺寸的影响。原奥氏体晶粒尺寸采用线截距法测定。平衡相图用于解释异常晶粒长大。利用Thermo-Calc软件包计算了EQ70钢的平衡析出量，并基于DICTRA模拟了NbC尺寸与保温时间的关系。实验结果表明，原奥氏体晶粒尺寸最初对奥氏体化温度从1123K（850℃）升高、保温时间从1小时到6小时不敏感，并在大约1373K（1100℃）时呈现突然增长。当均热温度低于1223K（950℃）或高于1373K（1100℃）时，奥氏体晶粒尺寸的增长对保温时间的增加也不敏感，并且当保温时间从4小时延长到1323K（1000℃和1000℃）之间时，晶粒突然长大。 1050°C）。 DICTRA模拟和TEM观察的结果证实，1373 K（1100 °C）时的异常晶粒长大行为是由半径大于平均的NbC粗化和AlN的完全溶解以及半径等于或小于平均的NbC几乎完全溶解的影响，而1223 K和1273 K（950 °C和1000 °C）之间的相同行为是由半径大于平均的NbC粗化和AlN的完全溶解造成的。半径大于平均值的NbC和半径等于或小于平均值的AlN完全溶解但NbC部分溶解。本实验和模拟结果可为EQ70钢奥氏体化参数的确定提供有益的参考。
The effect of austenitizing temperature and holding time on the prior austenite grain size was examined in both the transverse and the longitudinal directions of the samples that were made of the offshore structure steel EQ70. The grain size of the prior austenite was measured by using the linear intercept method. The equilibrium phase diagram was used to explain the abnormal grain growth. The equilibrium precipitation of steel EQ70 was calculated by Thermo-Calc software package, and the relationship between NbC size and the holding time was simulated based on DICTRA. The experimental results show that the prior austenite grain size is initially insensitive to increasing the austenitizing temperature from 1123 K (850 °C) with holding times from 1 to 6 hours, and presents a sudden growth at approximately 1373 K (1100 °C). The growth of the austenite grain size is also insensitive to increasing the holding time while the soaking temperature is lower than 1223 K (950 °C) or higher than 1373 K (1100 °C), and a sudden growth of grains takes place as the holding time is prolonged from 4 to 5 hours at the temperatures between 1273 K and 1323 K (1000 °C and 1050 °C). The results of DICTRA simulation and TEM observation confirm that the abnormal grain growth behavior at 1373 K (1100 °C) was influenced by coarsening of NbC with radius larger than the average and full dissolution of AlN and almost full dissolution of NbC with radius equal to or less than the average, while the same behavior between 1223 K and 1273 K (950 °C and 1000 °C) was caused by coarsening of NbC with radius larger than the average and the full dissolution of AlN but partial dissolution of NbC with radius equal to or less than the average. The present experimental and simulation results can provide a useful reference for determining the austenitizing parameters of steel EQ70.