【作者】 付福旗；

【导师】 马幼平； 黄彰荣；

【作者基本信息】 西安建筑科技大学 ， 冶金工程， 2007， 硕士

【摘要】 课题以企业工程实际为基础,根据龙钢生产实际,在对龙钢目前连铸坯存在质量缺陷和影响因素进行分析的基础上,利用系统分析技术、生产比对方法,铸坯低倍检验等手段,调整转炉冶炼和中间包冶金工艺、结晶器参数、浇注温度、二冷配水、铸坯拉速,强化钢坯对弧和喷水的精确度,旨在改善连铸坯质量。获得以下成果:通过注流偏斜、结晶器工艺参数、二冷配水系统、拉速与浇注温度、钢坯成分等进行对比试验、低倍检验和统计分析,提出龙钢铸坯脱方的主要因素首先是结晶器铜管磨损及其装配精度,其次是二次冷却系统的正常运行,而浇注温度与铸坯速度、注流偏斜对龙钢方坯脱方的影响不是主要因素。通过对龙钢铸坯化学成分、矫直温度与压力、钢水过热度、拉坯速度等进行统计分析,得出影响龙钢铸坯内裂纹的主要因素是浇注温度与铸坯拉速。在龙钢的现有工艺条件下,拉坯速度为2.6～3.2m/min,中间包过热度控制在40℃以下,可以降低铸坯内裂的级别,且不影响下道工序产生。通过对铜管锥度和材质、润滑油、振动系统等进行对比分析,得出影响龙钢铸坯横裂的主要因素是铜管锥度与材质,而振动参数、铸坯矫直温度、钢水成分等因素对龙钢铸坯表面横裂纹的形成影响不明显。龙钢铸坯夹杂物控制应主要在冶炼工艺环节,同时中间包液面高度和冲击区钢流的形式对夹杂形成具有显著影响。通过把中间包加高150mm,钢水液面提高150mm;冲击区_使用稳流器后,钢坯夹杂级别下降一个级别。通过以上工艺控制措施的实施,使龙钢铸坯脱方率小于0.03%,铸坯夹杂级别下降一个级别,消除了铸坯表面横裂纹的发生,整体铸坯合格率达到99.93%。更多还原

【Abstract】 According to Longsteel practical production, this research is based on the analysis of quality defects and influencing factors of continuous casting billets. By using system analysis technique, producing alignment-free method and macroscopic test, the converter smelting and tundish metallurgy process, mold parameters, casting temperature, secondary cooling water, casting speed and the adjusting of the arc and water-jet’s accuracy in the billet are studied. The results showed that:The major factors of the breaking-off in Longsteel are the mould copper pipe wearing and assembling accuracy. The following factor is the safety of secondary water cooling system. The casting temperatures, casting speeds and injection flow deflection have a little effect on the breaking off.The major factors of the inner crack are the billet casting temperature and the casting speed. The reduction of casting speed is favor of preventions of inner crack. The casting speed should be 2.6～3.2m/min in the test. The reduction of overheating temperature in the tundish could eliminate the inner crack. The overheating temperature in the tundish is below 45℃.。The main factors of transverse crack are taper and material of the copper pipe for mould. But, the vibration parameters, temperature straightening of casting billet, molten steel composition have almost no effect on transverse crack.The main influential factor of billet inclusions is the link of smelting, and the liquid heightin tundish and the form of liquid in ladle lashed area also have significantly effects on inclusions. The billet inclusions could descend significantly after heightening 150mm to the tundish height and raising 150mm to the steel liquid level and using the current regulator in ladle lashed area.Through the research of the above items and the implement of the control measures, the billet breaking-off rate is less than 0.03%, the inclusions level reduced one grade, the transverse cracks are basically eliminated in the surface, and the qualified rate of the continuous casting billet in Longsteel reached to 99.93%.更多还原