加热工艺对低碳稀土高铌钢奥氏体化行为的影响

发布时间：2018-04-21 18:34

本文选题：稀土 + 低碳高铌钢　；参考：《内蒙古科技大学》2015年硕士论文

【摘要】：随着现代物理冶金技术的发展，低碳高铌钢成为目前钢铁材料中最广泛应用的钢种。铌、钛在钢材加热过程中是否能较为充分的固溶对随后的轧制过程中组织与性能的控制有重要影响。已有研究表明：低碳高铌钢中添加少量稀土，可以降低铌、钛的平衡固溶温度，促进铌、钛在钢中的固溶，这对节省能源和提高铌、钛的利用率有非常重要的意义。但是对不同稀土添加量对铌、钛固溶以及奥氏体晶粒大小的影响还少有报道。本文以含微量稀土的低碳高铌钢为研究对象，对比含稀土与不含稀土的情况下，稀土对低碳高铌钢奥氏体化行为的影响，，以及对比不同稀土添加量对低碳高铌钢奥氏体化行为的影响，为正确制定低碳稀土高铌钢的加热工艺提供实验依据。本实验利用电感耦合等离子体原子发射光谱仪（ICP）测定了低碳高铌钢不同加热条件下Nb、Ti的固溶量，采用光学显微镜获取低碳高铌钢的原始奥氏体组织，并通过扫描电子显微镜和透射电子显微镜来观察未固溶颗粒的大小及分布情况。以此来分析不同加热工艺、不同稀土含量对低碳高铌钢奥氏体晶粒大小及分布、Nb和Ti的固溶、未固溶的第二相颗粒的影响。实验结果表明：不含稀土的实验钢随着均热温度的升高、均热时间的延长，铌固溶百分量分别由13.9%升高到51.4%，钛的固溶百分量由10.5%升高到41.0%；添加稀土的实验钢在不同工艺下铌、钛固溶百分量变化不大，分别在70%和55%左右。在1250℃均热1h时，添加稀土量为64ppm的实验钢的平均晶粒尺寸比不添加稀土的实验钢的平均晶粒尺寸小13μm；在1250℃均热1h时，稀土含量为64ppm的实验钢与未添加稀土的实验钢相比，铌固溶的百分含量提高了54.1%，钛固溶的百分含量提高了44.9%。在1280℃均热1h时，添加稀土的实验钢的原始奥氏体晶粒大小与不添加稀土的基本相同，而铌、钛固溶的百分含量是添加稀土的比不添加稀土的分别高25.5%和13.7%。不同稀土含量的两种实验钢在相同的温度下铌、钛固溶的百分含量基本相同，并且在1250℃均热40min后基本达到平衡。两种含稀土的实验钢在均热温度不超过1250℃时晶粒都较小且相差不大，当加热到1280℃和1300℃时，高的稀土添加量更能细化低碳高铌钢的原始奥氏体晶粒，稀土含量为40ppm的实验钢的奥氏体平均晶粒尺寸要比稀土含量为6ppm的实验钢分别小8.4μm和28.1μm。
[Abstract]:With the development of modern physical and metallurgical technology, low carbon and high niobium steel has become the most widely used steel in steel materials. It has an important effect on the control of microstructure and properties in the subsequent rolling process. The results show that the addition of a small amount of rare earth in low carbon and high niobium steel can be achieved. To reduce the equilibrium solution temperature of niobium and titanium and to promote the solid solution of niobium and titanium in steel, it is very important to save energy and improve the utilization of niobium and titanium. However, there are few reports on the effect of different addition of rare earth on niobium, titanium and austenite grain size. The influence of rare earth on austenitizing behavior of low carbon and high niobium steel and the effect of different rare earth addition on austenitizing behavior of low carbon and high niobium steel are compared in the case of rare earth and rare earth, and the experimental basis is provided for the correct formulation of the heating process of low carbon rare earth high niobium steel.
An inductively coupled plasma atomic emission spectrometer (ICP) was used to determine the solid solution of Nb and Ti in low carbon and high niobium steel under different heating conditions. The original austenite structure of low carbon and high niobium steel was obtained by optical microscope, and the size and distribution of undissolved particles were observed by scanning electron microscope and transmission electron microscopy. The effects of different heating processes on the grain size and distribution of austenite grain in low carbon high Nb steel, the solid solution of Nb and Ti and the second phase particles of unsolid solution in different heating processes are analyzed.
The experimental results show that with the increase of heat average temperature and the prolongation of heat average temperature, the 100 components of niobium solid solution increase from 13.9% to 51.4%, and the solid solution of titanium increases from 10.5% to 41%, and the 100 components of niobium and titanium with the addition of rare earth in different processes have little change, respectively, 70% and 55%, respectively, and 1250. The average grain size of experimental steel added with rare earth content of 64ppm is 13 m smaller than that of experimental steel that does not add rare earth, while the average grain size of the experimental steel with a rare earth content of 64ppm is 13 u m smaller than that of the experimental steel that does not add the rare earth. The content of the niobium solid solution increase by 54.1% and the content of the titanium solid solution increase by 44. compared with the experimental steel without the rare earth's rare earth content at the temperature of 1H. When 9%. is 1H at 1280 C, the original austenite grain size of the experimental steel adding rare earth is basically the same as that of the addition of rare earth, while the content of niobium and titanium in the solid solution is 25.5% and 13.7%. higher than that of the addition of rare earth.
The content of niobium and titanium in the two kinds of experimental steels with different rare-earth content is basically the same at the same temperature, and the equilibrium is basically reached after the heat of 40min at 1250. Two kinds of experimental steel with rare earth are smaller and have little difference when the temperature is not more than 1250 C. When heated to 1280 and 1300 degrees, the high rare earth addition can be more effective. The original austenite grain of low carbon and high niobium steel is refined. The average austenite grain size of the experimental steel with a rare earth content of 40ppm is 8.4 micron m and 28.1 M. smaller than that of the experimental steel with a rare earth content of 6ppm.

【学位授予单位】：内蒙古科技大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：TG142.1

【参考文献】