Characteristic Analysis of Solidified Crust for Basic Tundish Flux With Al-Killed Steel Casting

The solidified crust was harmful to Al-killed steel casting using a basic tundish flux. After sampling from an actual tundish, XRD, SEM and EDX examinations were carried out to analyze the microstructure of solidified crusts. The conclusions were obtained as follows： main crystallization phases existing in tundish crust were Ca12 A14 O23, Ca2SiO4 and a little spinel; spinel and Ca2SiO4 distributed between the grain boundaries of Ca12 A14 Oa3, which increased the connection strength of crystallization phases by pinning grain boundary, density or hardness of solidified crust maybe also significantly increases; when initial composition of tundish flux was located in spinel region of CaO-SiO2-Al2 O3-10 % MgO phase diagram, it was easier to precipitate spinel from molten slag; three approaches of spinel formation in flux were summarized. When flux was saturated with magnesia on the metal/flux interface, MgO in flux was reduced by dissolved aluminum and then formed spinel. On the interface of steel/refractory, with feasible aluminum content, it was also easy to form spinel, and spinel inclusions will be floated and captured by tundish flux.

Investigation on Dissolution Behavior of Non-metallic Inclusions in Tundish Fluxes for Bearing Steel Continous Casting

With the development of steelmaking technology, tundish has become an important device that can clean steel and remove non-metallic inclusions. Tundish flux plays a more and more important role in tundish metallurgy, furthermore different types of steel and metallurgy technology of tundish must be cooperated with the suitable tundish flux. The tundish metallurgy properties of magnesia and calcium fluxes for bearing steel production were investigated and compared by high temperature simulation experiment and industrial experiment, respectively. Results show that the melting temperature of magnesia tundish flux is higher than that of calcium tundish flux. The calcium flux has the better kinetic condition of dissolution non-metallic inclusions than the magnesia flux. Main crystal phases of magnesia tundish flux change from 12CaO·7Al2O3, 2CaO·SiO2 and MgO to 12CaO·7Al2O3, MgO, 2CaO·SiO2, CaO·Al2O3·3SiO2 and 3CaO·MgO·2SiO2 after absorbing Al2O3 inclusions. The slab samples of bearing steel ware analyzed by the big sample electrolysis method. Results show that the content and size of Al2O3 system inclusions in slab samples using calcium tundish flux are lower than using the magnesia tundish flux. Therefore, the calcium flux should be used to tundish metallurgy in bearing steel production.

Lithofacies Phases Analysis of Cover Flux in Tundish for Rare Earth Treated Steel

Lithofacies structure of commercial cover flux and experimental slags were analyzed,and states of rare earth oxides in cover flux were studied. The results show that under the experiment conditions,the mineral structures of original slags are mainly the calcium feldspar,a lot of magnesium olivine and Fe-bearing silicate. Rare earth oxides in the cover flux exist mainly as rare earth silicates. When the content of rare earth oxides reaches a certain value,rare earth oxides precipitate in molten cover flux. It means that the solubility of rare earth oxides is limited. Rare earth oxides may be partly substituted for CaO to form rare earth-silicate which may increase with the basicity reducing.

Robotic system for adding tundish-covering flux based on machine vision

Tundish-covering flux bags can be depalletized and moved in the steel casting region using industrial robots and monocular vision simultaneously.An industrial robot mounted with a flexible vacuum sucker was used as the executor.For a structured bag model,a visual scheme based on the support vector machine and the histogram of oriented gradients was adopted.The computer was trained using a number of sample bag images that relied on the feature recognition algorithm.Finally,the automatic stacking and moving of the flux bags were realized.

超低碳IF钢冶炼过程炉渣对夹杂物控制研究进展

超低碳IF钢板主要应用于汽车面板等超深冲部件,其面临的主要质量问题是夹杂物、卷渣、气泡造成的炼钢缺陷,因此全生产流程中所采用的炉渣性质对控制炼钢缺陷具有重要作用。分别从炉渣的物化特性以及所在工序炉渣特性两个角度归纳总结了炉渣对夹杂物控制产生的影响,发现炉渣对夹杂物的吸附溶解与炉渣的物化性质和夹杂物的尺寸相关。RH精炼渣主要控制目标是低氧化性和合适的w(CaO)/w(Al_(2)O_(3)),TFe质量分数一般控制在2.0%~8.0%,w(CaO)/w(Al_(2)O_(3))控制在1.2~1.8,此外精炼渣碱度一般控制较高为4.0~10.0。中间包覆盖剂和结晶器保护渣首先要防止钢液增碳,其次是防止渣中SiO_(2)造成钢液的二次氧化,同时它们还应拥有良好的吸附夹杂物的能力。超低碳IF钢中间包高碱度覆盖剂一般碱度为2.9~11.5,w(CaO)/w(Al_(2)O_(3))控制在1.0~2.5,(FeO+MnO)质量分数控制在1.9%~4.0%。而超低碳IF钢结晶器保护渣的碱度一般控制较低在0.85~1.0,w(CaO)/w(Al_(2)O_(3))控制在5.0~8.5,(FeO+MnO)质量分数小于1%。

ER70S-6焊丝钢连铸全保护浇注工艺优化实践

唐钢公司长材事业部在拉拔生产ER70S-6焊丝钢时因氮质量分数高出现脆断情况,对此从焊丝钢连铸全过程保护浇注工艺改进以及连铸长水口、中间包密封、覆盖剂、浸入式水口和保护渣设计优化等方面采取措施,提高焊丝钢连铸保护浇注效果,降低焊丝钢氮质量分数(氮质量分数整体下降0.0012%),增强塑性和变形能力,避免焊丝钢因氮质量分数高导致其在拉拔和加工过程中金属流动性差造成的脆断现象。

连铸过程中钢液增氮影响因素的试验研究

研究了中包覆盖剂及连铸结晶器保护渣对82B及35K钢液吸氮的影响,结果表明:只要连铸钢液与大气接触就会增氮;熔点高于连铸钢液温度的中包覆盖剂不利于防止钢液吸氮;在同样的条件下,35K钢液吸氮量比82B大.

低碳碱性中间包覆盖剂成分的优化

通过测定中间包覆盖剂各配方的熔化温度、熔化时间、保温性能及其吸收Al2O3夹杂物能力等性能指标,利用正交分析理论中的综合评分法,优选出了覆盖剂最佳配方.

超低碳钢中间包覆盖剂的冶金效果试验

通过对所设计的新型中间包覆盖剂的工业应用试验结果的分析, 得出此覆盖剂保温性能良好, 钢水增碳量减少, 包壁挂渣情况明显改善, 同时对环境没有危害.

碱性中间包覆盖剂吸附夹杂能力的研究

根据CaO-SiO2-Al2O3三元相图研制开发了一种碱性中间包覆盖剂,研究了其与酸性和中性覆盖剂吸附Al2O3夹杂的能力,指出碱性覆盖剂具有优于酸性和中性覆盖剂吸附Al2O3夹杂的能力,并通过工业试验验证了所研制的碱性覆盖剂具有优良的冶金效果。

蛭石对中间包覆盖剂保温性能的影响

以高炉渣为原料配制中间包碱性覆盖剂,分别向覆盖剂中添加蛭石0、10%、15%、20%、25%,测定其保温性能,并通过扫描电子显微镜分析了蛭石对覆盖剂微观结构的影响。结果表明:蛭石可显著提高覆盖剂的保温性能,最佳添加量为20%,优选出配方为:高炉渣37%、石灰石35%、萤石12%、蛭石16%。工业试验结果表明,此覆盖剂具有良好的铺展性能和保温性能。

温度及组成变化对中间包覆盖剂黏度的影响

对由高炉渣演化而成的CaO-Al2O3-SiO2-MgO-CaF2五元系中间包覆盖剂的黏度进行了测试研究,得到覆盖剂中各主要组成和温度对黏度的影响规律及程度,并经回归分析,得到了回归方程。研究结果表明:高炉渣的利用率可达74.32%,随着渣中CaF2、CaO和MgO含量的增大,覆盖剂的黏度显著降低;随着Al2O3、SiO2含量的增大,覆盖剂的黏度不断升高,而且覆盖剂中各组成对熔渣黏度影响的程度为:CaF2>CaO>SiO2>Al2O3>MgO。

中间包镁钙质喷涂料及高钙覆盖剂对钢水洁净度的影响

通过对比中间包镁质喷涂料和低碱度覆盖剂与镁钙质喷涂料和高钙覆盖剂对钢水洁净度的影响 ,结果表明 ,使用镁钙质喷涂料和高钙覆盖剂可降低钢水全氧含量 8%～ 14 % ,降低钢水全氮含量 8%～16% 。

对以高炉渣为主料的中间包覆盖剂的熔化温度研究

为了研究以高炉渣为主料的中间包覆盖剂熔化温度的变化规律,本文采用二次正交设计方法,测定覆盖剂的熔化温度,建立二次回归模型,分析Ca_2添加量及碱度对覆盖剂熔化温度的影响,并利用TG-DSC热分析方法和XRD图谱分析,探究覆盖剂在熔融过程中的质量、物相变化,进一步说明覆盖剂熔化温度的变化规律。最终以覆盖剂熔化温度为指标,当覆盖剂中CaF_22添加量为10%～15%,碱度为1.75～2.0时,得到最优配方为:高炉渣76%、石灰粉8.77%、萤石15.23%。

无碳碱性中间包覆盖剂保温性能的研究

采用测量单向炉补偿功率的方法对影响无碳碱性中间包覆盖剂保温性能的各种原料进行分析,通过调整覆盖剂的化学成分、提高其熔化温度、降低体积密度,以达到更好的保温效果,满足实际生产需求。

减少中间包渣在涂料中渗透的途径

中间包渣在涂料中的渗透是影响涂料用后解体性能的关键因素。通过减小涂料气孔直径 ,增加中间包渣粘度及提高涂料基质的耐高温性能可以改善涂料的抗渗透性能。

稀土氧化物对中间包覆盖剂粘性特征的影响

稀土氧化物对中间包覆盖剂和实验室合成渣粘度的影响的试验表明 ,当稀土氧化物含量不大于 10 %时 ,具有降低覆盖剂高温粘度的功能 ,当稀土氧化物含量接近 2 0 %时 。

碱性中间包覆盖剂结壳机理分析

通过工业取样,研究了碱性中间包结壳物的成分和微观结构.研究发现,结壳物主要成分为钙铝酸盐、黄长石和少量硅酸二钙,且镁铝尖晶石、硅酸二钙先于铝酸钙析出.当覆盖剂成分位于CaO-S iO2-A l2O3-10%MgO相图尖晶石区域内,冷却过程析出尖晶石趋势增大.应适当引入其他保温材料以提高碱性中间包覆盖剂形成封闭气孔数量,防止凝固结壳的发生.

45#钢螺栓表面线状缺陷分析

针对45#钢螺栓表面线状缺陷进行了低倍、金相、电子探针等检测分析,结果表明,线状缺陷由大型夹渣造成,其主要成分为SiO2、CaO、Al2O3、Na2O,系连铸过程中酸性钢水中包覆盖剂卷入所致。

稀土处理钢用中间包覆盖剂岩相分析

分析了现场覆盖剂和实验室自配覆盖剂岩相结构,探讨了稀土氧化物在覆盖剂中的赋存状态。结果表明:在本实验条件下的覆盖剂,原渣矿物组成主要是黄长石,另有少量镁橄榄石和含铁的硅酸盐;稀土氧化物在覆盖剂中主要以稀土硅酸盐形式存在;当稀土氧化物含量增加到一定数量时,覆盖剂开始出现固态未溶的稀土氧化物,说明其在覆盖剂中有一定的溶解度;稀土氧化物在覆盖剂中可以部分代替CaO,形成稀土硅酸盐,其形成物种类随覆盖剂碱度降低有增加的趋势。