高碳钢连铸冷却工艺技术研究
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- 英文论文题名：Investigation of Mold Cooling Process in a Continuous Casting Slab of High-carbon Steel
- 论文作者：郭亮亮 ; 徐正其 ; 周灿栋
- 英文论文作者：Guo Liangliang ; Xu Zhengqi ; Zhou Candong ; Baoshan Iron & Steel Co. ; Ltd.
- 年：2016
- 作者机构：宝山钢铁股份有限公司;
- 论文关键词：结晶器冷却 ; 高碳钢 ; 连铸
- 英文论文关键词：Mold Cooling ; High-carbon Steel ; Continuous Casting
- 会议召开时间：2016-05-19
- 会议录名称：第十九届（2016年）全国炼钢学术会议大会报告及论文摘要集
- 语种：中文
- 分类号：TF777
- 学会代码：ZGJS
- 会议名称：第十九届（2016年）全国炼钢学术会议
- 会议地点：中国湖南长沙
- 主办单位：中国金属学会炼钢分会
- 学会名称：中国金属学会
- 页数：1
- 文件大小：67k
- 原文格式：O
- 会议级别：全国
摘要
连铸结晶器传热对结晶器寿命、铸坯表面质量、连铸漏钢和连铸其它缺陷至关重要。本文基于高碳钢(w_C>1.0%)一系列实验研究,对高碳钢连铸冷却工艺进行了详尽研究。研究方法包括:ThermoCalc软件、热力模拟试验机、金相与扫描电镜、激光共聚焦高温显微镜(CSLM)等,同时基于反问题的数学模型计算研究结晶器内坯壳的热流密度与凝固厚度。计算结果表明,结晶器周向热流密度和坯壳厚度不均匀,尤其是靠近铸坯宽度中心的坯壳厚度相对较薄。热力学计算与CSLM原位观察结果,发现MC型碳化物加剧了凝固坯壳厚度的不均匀性。相比于低碳钢,高碳钢具有较低的液相线温度(低100℃)和更宽脆性温度区间,连铸开浇初期弯月面附近难以尽快形成稳定的液渣层,铸坯/结晶器间摩擦力较大,引发或加剧凹陷与纵裂。高碳钢初始凝固坯壳的均匀性可通过连铸结晶器弱冷工艺进行改善。
Mold heat transfer is important to mold life,surface quality,breakouts and many other aspects of the steel continuous-casting process.Based on a series of related investigation,the mold cooling process on continuous casting slab of high-carbon steel(w_C>1.0%) was investigated.Thermodynamic calculation has been carried out on a high-carbon steel by means of Thermo-Calc program.High-temperature tensile tests performed on slab samples,as well as heat flux and shell thickness in continuous casting predicted on the basis of an inverse mathematic model were conducted.The slab samples were observed in situ using confocal laser scanning microscopy in order to simulate various mold cooling process.The calculated results of inverse mathematic model showed that heat flux and and shell thickness were uneven along the mold width and that the shell was thinner and close to the centra line of the slab surface.The shell growth was slower than in other regions,which led to a thinner shell and depressed shrinkage observed by this study.The precipitated MC type of carbides that aggravated heterogeneity of solidified shell,were predicted and detected by the calculated equilibrium phase diagram and confocal laser scanning microscopy under 1270℃,respectively.The results showed that the liquidus and corresponding pouring temperature of high-carbon steel were ~100℃ lower than low-carbon steel,and the high-carbon steel exhibited a wider brittle temperature range immediately after solidification compared with those of low-carbon steel.Thus,the formation of a stable liquid flux near the meniscus within a short time at the beginning of casting is difficult.The amounts of liquid slag film and crystalline slag film were inefficient to provide adequate lubrication between the shell and the mold under intensive cooling process,which resulted in greater friction force that induced or aggravated depression and crack.Therefore,homogeneity of initial solidification under the condition of mild cooling process in the mold should be improved to reduce the concentration of high-carbon slab surface defects.
Mold heat transfer is important to mold life,surface quality,breakouts and many other aspects of the steel continuous-casting process.Based on a series of related investigation,the mold cooling process on continuous casting slab of high-carbon steel(w_C>1.0%) was investigated.Thermodynamic calculation has been carried out on a high-carbon steel by means of Thermo-Calc program.High-temperature tensile tests performed on slab samples,as well as heat flux and shell thickness in continuous casting predicted on the basis of an inverse mathematic model were conducted.The slab samples were observed in situ using confocal laser scanning microscopy in order to simulate various mold cooling process.The calculated results of inverse mathematic model showed that heat flux and and shell thickness were uneven along the mold width and that the shell was thinner and close to the centra line of the slab surface.The shell growth was slower than in other regions,which led to a thinner shell and depressed shrinkage observed by this study.The precipitated MC type of carbides that aggravated heterogeneity of solidified shell,were predicted and detected by the calculated equilibrium phase diagram and confocal laser scanning microscopy under 1270℃,respectively.The results showed that the liquidus and corresponding pouring temperature of high-carbon steel were ~100℃ lower than low-carbon steel,and the high-carbon steel exhibited a wider brittle temperature range immediately after solidification compared with those of low-carbon steel.Thus,the formation of a stable liquid flux near the meniscus within a short time at the beginning of casting is difficult.The amounts of liquid slag film and crystalline slag film were inefficient to provide adequate lubrication between the shell and the mold under intensive cooling process,which resulted in greater friction force that induced or aggravated depression and crack.Therefore,homogeneity of initial solidification under the condition of mild cooling process in the mold should be improved to reduce the concentration of high-carbon slab surface defects.
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