论连铸高碳铬轴承钢的质量

提出了小方坯连铸高碳铬轴承钢中心偏析的形成机理。改善连铸高碳铬轴承钢的中心偏析的方法和途径有：提高连铸坯的宽厚比;减少钢中残余元素和有害元素及钢中夹杂物含量;降低和稳定过热度;合理选择拉速;二冷强度和电磁搅拌参数;采用软压下技术。小方坯连铸高碳铬轴承碳与模铸轴承钢的接触疲劳寿命比较试验表明：连铸材的质量优于模铸材。     

轴承钢GCr15连铸坯中心碳偏析控制

根据高碳轴承钢在凝固末端固液两相区碳含量选分结晶特点,在理论计算和射钉试验的基础上,将末端电磁搅拌线圈准确定位.结合连铸机弧半径较大、拉速较低的工艺特点,通过对比不同搅拌方式试验,对轴承钢中心碳偏析进行分析,最终确定合理的搅拌参数,将中心碳偏析控制在0.95～1.05.     

连铸工艺参数对45#、70#钢铸坯冶金效果影响的探讨

通过对45#、70#钢铸坯低倍组织情况的分析以及连铸工艺参数的总结，探讨出钢水过热度、拉速、塞棒自动控制、二冷配水及电磁搅拌等连铸工艺参数对铸坯低倍组织的影响。通过对45#、70#钢中心碳偏析分析，表明随着钢中碳含量升高，连铸拉速、钢水过热度的增加，铸坯中心碳偏析有增大趋势。     

电磁搅拌对连铸小方坯的质量影响

本文着重对上海五钢有限公司转炉炼钢厂４＃连铸机第１流电磁搅拌器国产化试运行过程中，采用Ｍ－ＥＭＳ，Ｓ－ＥＭＳ，（Ｍ＋Ｓ）－ＥＭＳ三种形式的电磁搅拌与对应的不搅拌的第４流铸坯低倍试样的检验结果作对比，分析了电磁搅拌对连铸小方坯在扩大中心等轴晶区、消除非金属夹杂物方面的作用，同时较详细地分析了电磁搅拌对铸坯低倍检验中的缩孔、中心疏松、中心偏析及裂纹产生的影响，并提出了“从适应铸坯质量要求的目的出发，选     

轴承钢连铸坯碳偏析的形成机理及影响因素

对高碳铬轴承钢连铸坯白亮带和中心碳偏析的形成机理及其影响因素进行了系统的分析研究，提出了改善偏析的措施，同时进行了连铸钢与模铸钢内在质量和疲劳性能对比试验。结果表明，连铸轴承钢坯存在轻微的碳偏析（C／C0＝0．92－1．10），其材质的疲劳寿命达到了模铸钢的水平。     

电磁搅拌技术在连铸机上的应用及其对铸坯质量的影响

就电磁搅拌在连铸机上的应用和对铸坯质量的影响，作基本介绍和分析，就如何选择电磁搅拌工艺有一定参考意义。     

GCr15轴承钢大方坯连铸生产中动态轻压下工艺的应用

介绍了动态轻压下技术(轻压下区域铸坯固相率40%～96%,总压下量8.3～12.5mm)在邢台钢铁公司285 mm×325 mm连铸机生产GCr15轴承钢连铸坯的应用。结果表明,当钢水过热度20～30℃,拉速0.65～0.75m/min,实施动态轻压下后,中心疏松评级≤1.5级和中心缩孔0～1.5级的比例分别由未压下的49.45%和63.74%增加到了85.0%和87.5%;碳偏析值范围由未压下的0.875～1.390变为0.872～1.086;中心偏析和V型偏析明显改善。     

控制高碳钢中心碳偏析的工艺实践

针对方坯连铸过程中产生的连铸坯中心偏析问题,日钢第一炼钢厂采取了一系列控制措施,如减少钢液成分波动、降低中间包内钢液过热度、制定合适的拉速和温度匹配制度并保持恒拉速、优化结晶器电磁搅拌参数、控制合适的二冷强度、使用凝固末端电磁搅拌等,使高碳钢铸坯中心偏析明显改善,w[C]≥0.60%的高碳钢中心碳偏析(≤1.5级)合格率100%。     

Study on Mitigating Center Macro‐Segregation During Steel Continuous Casting Process

In the current paper, Methods of enlarging the area for the distribution of segregation solutes were introduced to mitigate center macro‐segregation in steel billets and steel slabs during continuous casting process, which cost less and have significant effect. The location of center macro‐segregation is relative to the shape of liquid‐core at the solidification end during steel continuous casting. A method of dissymmetrical cooling on different surfaces, by which the area for the precipitation of segregation solutes was enlarged, was introduced to mitigate the center macro‐segregation in billets during continuous casting process. Method of optimizing the uniformity of solidified shell in the transverse direction was introduced to mitigate the center macro‐segregation in steel slabs. The uniform cooling intensity along the transverse direction guaranteed a regular solidification end in the continuous casting slab, which aided in the effective application of dynamic soft reduction technology. A relevant 2‐D heat transfer model was developed for the optimization of uniform solidification. The current method was applied to the industrial slab continuous casting using the heat transfer model. The results indicated a better industrial slab quality with much less center macro‐segregation after the use of the method.     

轻压下技术在高碳钢方坯连铸应用中的参数选取

轻压下技术作为改善铸坯偏析的有效措施之一,被广泛应用于高碳钢方坯连铸中,其压下参数的选取对于轻压下技术至关重要.通过理论分析并结合其他厂的生产经验,认为压下位置在中心固相率为0.2～0.8、总压下量为4～8 mm时,轻压下效果最佳.合理地应用轻压下技术,可以有效地减轻铸坯的V型偏析、降低中心碳偏析并改善铸坯的宏观组织.     

Control of Macrosegregation Behavior by Applying Final Electromagnetic Stirring for Continuously Cast High Carbon Steel Billet

Solidification behavior of continuously cast high carbon steel billets was investigated with an objective of producing high quality billets by determining the optimum final electromagnetic stirring (F-EMS) parameters. Characteristics of centerline segregation were analyzed for lots of billet samples collected from the plant through obtaining the carbon concentrations of drill chips, which were correlated with the operating parameters of the caster and stirrers, but a problem occurred that segregation control results of trial billets with the same casting and stirring parameters often have drastic fluctuations. An attempt was made to find out the induced reasons of this problem by measuring the electromagnetic torque, analyzing the secondary dendrite arm spacing (SDAS) and the corresponding cooling rate of the typical specimens, and observing the longitudinal profile of etched billet samples. Then a simple dynamic secondary cooling model was developed based on the solidified shell thickness control mode, by which the maximum carbon segregation index was reduced effectively, and thus the segregation fluctuation problem was basically solved. Finally, the most favourable stirring parameters were determined as the casting speed of 1.65 m/min, the liquid core thickness of 40 mm, stirring current of 360 A and frequency of 12 Hz.     

优质碳素结构钢板坯工艺研究

分析45钢、50钢板坯的生产实践，探讨该钢种的碳、磷、硫、氮的控制以及铸坯质量，夹杂物和钢板性能的关系，并提出相应的工艺改进措施。     

Study on Intermediate Crack in Continuous Casting Slab of Medium Carbon Steel

According to the analysis of the macro and micro characteristics of the center of continuous casting blooms by acid wash, SEM, metallographic and scanning-type electron microscope, there was a serious segregation and some shrinkage cavities in the slab; Cracks occurred at the end of the columnar crystal and spread along the boundary of the primary dendrite. At the crack enriched a large number of impurity elements, carbon, phosphorus, sulfur, whose crystal boundary segregation is the internal factor of the intermediate cracks. Determining the originated location of intermediate cracks and calculating the total strain in this area during solidification process of slab, it is found that the load is the ex- ternal factor of cracks’ generation and expansion.     

结晶器电磁搅拌对轴承钢大方坯碳偏析的影响

针对南钢大方坯连铸机轴承钢连铸电磁搅拌冶金效果不明显的问题,开展了优化轴承钢连铸结晶器电磁搅拌工艺参数的试验,对不同电磁搅拌参数及搅拌方式下铸坯和轧材碳偏析进行了研究。结果表明:大方坯心部和边部均为负偏析,1/4处为正偏析,320 mm×480 mm大方坯碳偏析指数基本在0.87～1.05,轧材碳偏析指数基本在0.94～1.03;正反交替的电磁搅拌有利于降低碳偏析,电磁搅拌的电流参数较大时,心部的负偏析较严重,随着搅拌电流的增大,产生的白亮带向铸坯中心移动并且白亮带宽度增大;轴承钢铸坯中的碳偏析会遗传到轧材上。     

高碳铬不锈轴承钢孪晶碳化物研究

研究了高碳铬不锈轴承钢“孪晶碳化物”（直线状和链状碳化物）的影响因素及形成原因,结果表明：加热温度达到1140℃,退火后开始出现沿晶界分布的链状碳化物;加热温度≥1160℃,退火后出现大量直线状和链状两种形态的碳化物。材料从高温直接冷却时,温度≥1080℃并且冷却速度≤80℃／h可能析出链状碳化物,并且温度越高冷却速度越慢析出的可能性就越大。直线状碳化物形成原因为：材料加热温度过高．晶粒长大的过程中晶界迁移时偶然发生堆垛错误形成了生长孪晶,在随后的退火过程中碳化物向奥氏体挛晶界面沉淀而形成,是真正意义上的孪晶碳化物。链状碳化物是由于材料过热或者局部过热,在随后冷却过程中碳化物沿奥氏体晶界析出而形成的,本质上是一种网状碳化物。     

SWRH72A连铸坯中心碳、硫偏析试验研究

为了解决150mm×150mm规格的SWRH72A连铸坯内部严重的碳、硫偏析问题,试验采用了结晶器电磁搅拌(M-EMS)技术。对比发现,采用M-EMS技术后,能有效减轻连铸坯内部严重的碳、硫偏析,中心碳偏析系数由1.234降为1.101,中心硫偏析系数由1.555降为1.335,提高了连铸坯内部质量。     

工艺模拟软件在连铸机二冷优化方面的应用

以鞍钢一炼钢厂厚板坯连铸机为对象，基于凝固-传热学基本理论，建立板坯连铸三维凝固传热计算软件，根据二冷区铸坯表面实际水流密度分布和辊子接触传热建立边界条件，计算整个铸坯温度及固相分数分布。以模拟软件为基础，对铸坯冬夏季冷却水温差异造成的铸坯温度波动进行计算，并根据计算结果，对冬季冷却水量进行了调整，保障了铸坯质量的稳定。