Torsional vibration measurement of the viscosity of a metallic melt

The liquid Co₉₁B₉ alloy is used as an example to study the influence of boundary conditions at the upper melt boundary on the results of viscosity measurements using torsional vibrations. Specific features related to film effects and wetting phenomena are shown to appear in the temperature dependence of logarithmic decrement. To exclude the influence of these effects and phenomena, viscosity measurements should be performed under the experimental conditions where the melt to be studied is in closed volume and the internal crucible walls are fully wetted. The temperature dependence of the kinematic viscosity of the Co₉₁B₉ melt that is obtained under such experimental conditions has a monotonic character.     

Effect of a lining on the degree of oxidation of a metallic melt

The interaction of periclase and alundum refractories with iron-based melts of various degrees of oxidation is studied under laboratory conditions. It is shown that a lining can accumulate iron oxide inclusions as a result of its interaction with an oxide metal, significantly increasing its oxidizing potential. The contact of such a lining with a metal with a low degree of oxidation (metal deoxidized by aluminum) is accompanied by the opposite transition of FeO from the lining to the metal, which causes its secondary oxidation. This secondary oxidation mechanism can be critical for the production of a high-quality high-reliability structural steel, especially at a large specific lining surface area.     

Distribution of metal particles in a slag during argon blowing of a melt in a ladle

The distribution of metal particles in a slag is studied during argon blowing of steel in a ladle. It is established that the fraction of the metallic phase in the top slag layer is 3.5–5 times smaller than that in the middle and bottom layers. A microscopic analysis of the fraction composition and the geometric shape of the metallic particles show that all portions of the slag part of samples contain significantly larger amounts (by a factor of approximately 4–5) of irregular plane particles along with fine spherical particles.     

Interaction between tungsten monocarbide and an iron-based metallic melt

A technique and results of investigation of compacted tungsten carbide substrates by scanning microscopy are reported. Samples are prepared in the course of studies of the wettability of tungsten carbide substrates with the iron melt, which are performed in accordance with the sessile drop method using two different heating strategies, namely, contact and noncontact heating of metal.     

150 t钢包底吹氩工艺优化

对梅山钢铁公司150 t钢包建立水力学模型,试验研究不同喷嘴布置方式(单喷嘴、双喷嘴90°夹角布置和双喷嘴 180°夹角布置)、布置位置(喷嘴距包底中心0.40R、0.55R、0.70R)和吹气量(35～60m3/h)对钢包内钢液混匀时间及卷渣的影响,得出150 t钢包底吹氩的优化工艺参数为单喷嘴0.55R布置,吹气量控制在45 m3/h.应用生产后,单包钢水在中间包两次测温的平均温差仅2.66℃,吹氩处理前后夹杂物含量下降了30.1%,Al收得率较工艺优化前提高了50%.     

Ultrasonic effect on the penetration of the metallic melt into submicron particles and their agglomerates

Deagglomeration and wetting of submicron particles in a metal melt under ultrasonic exposure are considered based on the theory of acoustic cavitation and capillary phenomena. Basic dependences linking the exposure time with physicochemical properties of the particles and the melt, as well as with acoustic radiation characteristics, are found. The experimental and calculated times of ultrasonic treatment of the aluminum melt containing submicron aluminum oxide particles are compared, and a satisfactory agreement of results is found.     

300 t转炉底吹位置优化及其效果

介绍了马鞍山钢铁股份有限公司第四钢轧总厂300 t转炉的底吹特点.为了提高转炉底吹的冶金效果,需要对转炉底吹元件位置进行优化选择.通过水模拟试验,并综合考虑顶枪、副枪位置和转炉砌筑状况,确定了转炉透气元件的最佳位置.生产实践证明,其底吹效果良好.     

Macrosegregation during growth of a dendrite array into a stirred melt at near steady-state conditions

Solidification experiments on tin alloys have been carried out where the interface morphology consisted of an array of dendrites advancing at near steady-state conditions. It was found that a fairly severe degree of mixing changed the dendrite morphology at low temperature gradients but not at higher gradients. In both cases the mixing was relatively ineffective at producing a macrosegregation in the presence of the dendrite array. The results may be interpreted as evidence that in some cases one would expect very little macrosegregation in columnar growth under near steady-state conditions even in the presence of severe liquid convection.     

马钢120t顶底复吹转炉底吹工艺优化

马钢第一钢轧总厂通过对120 t转炉底吹工艺不断优化与改进,将供气强度逐步提高到0.09 m3/(t·min),瞬间高强度达0.15 m3/(t·min),保证了底吹的效果,促进终点碳氧反应,终点碳氧积从0.0040逐步降低至0.0025左右;降低了转炉冶炼渣中带铁,渣中TFe含量平均值为17.01％;Mn合金收得率明显高于2#和3#转炉,平均值为95.19％.脱磷率变化不明显,平均值为77.11％,脱磷效果满足要求,并未出现回磷情况,通过转炉底吹工艺的优化,降低转炉冶炼的成本,减少了钢液的过氧化.     

优化过程枪位控制减少复吹转炉炼钢喷溅

喷溅是转炉炼钢过程中常见的危害现象,主要分为金属喷溅、泡沫渣喷溅、爆发性喷溅,控制喷溅的关键就是控制枪位,所以合理的枪位在整个吹炼过程中尤为重要。根据莱钢特钢事业部90t复吹转炉实际生产情况,分别从吹炼前期、中期和后期喷溅进行原因研究分析,主要通过优化过程枪位控制的应用措施,使渣中聚集适当的（FeO）含量,有效减少了喷溅。并总结出优化后的大致枪位图,可供生产者参考借鉴。     

复吹转炉低磷钢生产工艺的优化

在济钢条件下,采用常规的铁水脱硫加转炉双渣的冶炼工艺生产低磷钢,很难将成品w(P)稳定控制在0.010%以下。基于转炉双渣大渣量生产试验,采用回归分析研究了影响冶炼过程脱磷效率的主要因素,确定了最佳的双渣吹炼时间、过程温度和炉渣成分控制,大幅度提高了冶炼过程的脱磷效率。该工艺在9Ni、高级别管线(X90/X100)的生产中得到广泛应用,成品w(P)稳定控制在0.006%以下,最低达到了0.004%,实现了低磷钢的批量生产。     

200t提钒复吹转炉氧枪喷头优化

 针对攀钢西昌钢钒200 t提钒复吹转炉在底吹布置一定的条件下,通过优化顶吹氧枪喷头的结构来增加熔池搅混能力的问题,采用物理模拟的方法在顶吹流量一定的条件下优化了氧枪喷头尺寸参数(包括喷孔夹角、喷孔数和马赫数Ma),并进行了工业性应用。结果表明,反映熔池搅拌能的混匀时间随喷孔夹角减小先减小后增大,在喷孔夹角为12°时最小;反映熔池液面活跃度的1/3大波波高随喷孔夹角减小先增大后减小,在喷孔夹角为12°时最大。5孔喷头混匀时间比4孔减小1.88%,波高减小3.35%,熔池中死区增大。Ma数为2.10和2.20的喷头比Ma数为1.99的喷头混匀时间分别减小7.36%和14.31%,波高分别增加8.68%和14.57%。3种参数对熔池搅拌影响程度的排序为Ma数>喷孔夹角>喷头孔数,且在底吹流量低时更为显著。工业应用结果表明,底吹效果差时优化喷头(4孔喷孔夹角为12°,Ma数为2.10)的应用加强了熔池反应的动力学条件,使半钢残w(［V］)降低18.8%,残钒合格炉次(不大于0.05%)比例提升26.7%,钒渣w((V2O5))增加了6.5%,w((TFe)) 降低了6.6%,达到了良好的冶金效果。     

Effects of BOF top blowing and bottom stirring conditions on suppressing excessive oxidation

Abstract

The effects of top blowing and bottom stirring conditions during steelmaking in a 6 t basic oxygen furnace (BOF) were investigated in studies with the aim of suppressing excessive oxidation. With low oxygen feed rate and high stirring energy, the apparent partial pressure of CO P′_CO was calculated from the equilibrium of carbon and oxygen in molten steel as being <1 atm. The relationship between top blowing/bottom stirring conditions and mass transfer at the slag/metal interface was analysed. It is proposed that mass transfer at the hot spot is significantly affected by the reaching rate of oxygen to the steel bath and bottom stirring. Mass transfer at the slag/metal interface, outside the hot spot, is sufficient to allow equilibrium to be attained in combined blowing BOF processes. Thus, the oxygen that is not consumed for decarburisation is distributed between steel and slag, i.e. deoxidation from steel to slag takes place, which makes it possible to obtain P′_CO <1 atm under atmospheric conditions. The decarburisation model developed based on the analysis reproduces the suppression of excessive oxidation under a decreased, top blown oxygen feed rate and is in good agreement with results from both 6 t BOF experiments and 350 t commercial BOF operation.     

快淬NdFeB磁粉粒度分布的优化

研究了粒度分布对快淬NdFeB磁粉性能的影响,采用正交法对磁粉的粒度分布进行优化,获得具有最佳性能的磁粉粒度配比是（颗粒度目数）：（100～150）：（150～200）：（200～250）：（250～325）：（〉325）=12：3：1：3：1．     

300 t复吹转炉底吹系统优化模拟

顶底复合吹炼转炉炼钢法是当下主流的炼钢方法,底部供气元件的种类、支数、排布方式和底吹供气强度直接影响着转炉熔池的混匀效果,合理的流场不仅可以降低生产成本,更能缩短冶炼周期,增加企业效益.基于冷态水模拟以及CFD数值模拟手段各自的研究特点,以某钢厂300 t转炉为原型,将不同底吹条件下熔池的混匀时间、死区以及弱流区体积作...