12CaO·7Al2O3基精炼渣脱硫试验

在试验室用MoSi₂井式电阻炉试验研究了12CaO·7Al₂O_O3的预熔工艺和含10%～20%BaO、2%～6%MgO、1%～3%Li₂O,（12CaO·7Al₂O₃）/SiO₂=8～10的12CaO·7Al₂O₃基精炼渣对成分为（%）0.23C、1.29Mn、0.44Si、0.026P、0.023S、0.04Mo、0.02Cr、0.06Cu的低碳钢的脱硫能力。结果表明,12CaO·7Al₂O₃基预熔精炼渣具有较好的脱硫能力,在1 590℃加入量为3%的条件下,能将钢液中的硫含量从0.030%降低到0.006%,脱硫率80.00%。通过运用正交方法对渣成分进行优化,得出12CaO·7A国₂O₃基精炼渣的优化渣系为:15%BaO,4%MgO,3%Li₂O,（12CaO·7Al₂O₃）/SiO₂=9。     

高强度管线钢精炼渣系的开发与实践

根据马钢生产高强度管线钢的需求,结合CaO-Al₂O₃-SiO₂相图12CaO·7Al₂O₃生成区域,开发了管线钢用钢包精炼渣系(%:55～60CaO、7～12SiO₂、25～30Al₂O₃、4～8MgO)。300 t LF精炼实践表明,该精炼渣的平均脱硫率为73.2%,钢中终点硫含量可控制在0.002%以下;而且该渣系具有较好的吸收夹杂物的能力,精炼后钢中Alt-Als含量较低,为0.002%～0.013%。     

低碳低硅铝镇静钢LF顶渣硫分配比预报模型

根据钢厂100 t BOF-吹氩-LF-RH-Ca处理流程生产优质深冲(DDQ)级深冲热轧带钢SPHE(%:≤0.07C、≤0.03Si、0.20～0.30Mn、≤0.020P、≤0.010S、0.02～0.06Als)时Ca处理过程S含量过高的情况,通过KTH硫容量模型,分析了CaO/SiO₂、Al₂O₃和MgO对精炼渣硫分配比LS的影响,建立了CaO-MgO-SiO₂-Al₂O₃四元渣系脱硫模型,优化LF脱硫的精炼渣成分。结果表明,使用优化后的精炼渣(%:50CaO、6MgO、≤5SiO₂、30～35Al₂O₃),LF精炼钢水的脱硫率≥80%。模型预测值与实测值误差为±5%的占80%。     

无铁水预处理超低硫管线钢L245NCS的生产实践

LF精炼渣系控制在CaO 50%～58%、Al₂O₃ 27%～35%、SiO₂≤10%、MgO≤10%、（TFe+MnO）≤1.0%,MI范围0.25～0.30,R范围8～9.5,（CaO）/（Al₂O₃）范围1.6～1.9,Als含量0.010%～0.020%。渣系脱硫效果好,化渣快,可在无铁水预处理的情况下,满足生产成品S≤15×10^-6超低硫管线钢L245NCS的要求。     

B2O3作助熔剂对CaO基精炼渣系熔化温度的影响

研究了B₂O₃对低碱度[(CaO)/(SiO₂)=3～4]和高碱度[(CaO)/(SiO2)=5～7.5]两个系列CaO基精炼渣熔化温度的影响。结果表明,用B₂O3比用Al₂O₃和CaF₂更有效降低CaO基精炼渣系的熔化温度,对低碱度渣系,B₂O₃替代渣中的部分CaF₂、Al₂O₃以及SiO₂,都能有效降低渣的熔化温度;对高碱度渣系,B₂O₃替代CaF₂作助熔剂时,可实现在高(CaO)/(SiO₂)和(CaO)/(Al₂O₃)下造具有超低熔化温度的CaO基精炼渣,既可提高造渣速度,又可提高渣的脱硫磷能力和吸收硅、铝脱氧产物的能力。     

低钛高炉渣应用于HRB400E螺纹钢100t LF精炼的工业试验

采用喷吹CO₂法对低钛高炉渣进行脱硫处理,低钛高炉渣中硫的脱除率为66.59%~78.01%,渣中残硫含量为0.137%~0.283%,所制备的低硫低钛高炉渣中硫含量基本满足HRB400E钢LF精炼渣要求。低硫低钛高炉渣LF精炼终渣成分为/%:37.40~46.50CaO,12.30~15.10MgO,21.70~26.70SiO_2,5.74~17.00Al₂O_3,2.44~3.39TiO_2,0.36~1.42MnO,0.75~1.62Fe₂O_3,0.200~0.597S,钢水脱硫率为10.0%~41.5%,HRB400E钢终点[S]为0.008%~0.029%,与现工艺精炼渣（折渣和钢包渣终渣成分/%:34.30~42.90CaO,13.60~18.10MgO,24.00~26.50SiO_2,4.88~11.00Al₂O_3,0.71~1.12TiO_2,0.47~1.47MnO,0.81~1.72Fe₂O_3,0.245~1.132S）的脱硫效果相当（HRB400E钢终点[S]0.027%~0.032%）。     

精炼渣组成对钢渣硫分配比的影响

采用二次正交回归实验设计方法在中频感应炉内进行碱度R(CaO/SiO₂)2～7的CaO-SiO₂-MgO- Al₂O₃精炼渣系的脱硫实验,建立渣系组分与钢-渣硫分配比Ls关系的数学模型,实验渣碱度、渣指数MI (R:Al₂O₃)、CaF₂、MgO和FeO含量对硫分配比Ls的影响。结果表明,渣碱度R 3.5～5.0、渣指数MI 0.25～0.40时脱硫效果较好;精炼渣最佳组分为(%):9CaF₂、8MgO、13Al₂O₃、<0.5FeO,R值=4。     

60t LF精炼终点GCrl5轴承钢中氧化物夹杂特性的研究

通过电弧炉出钢加铝铁、硅铁脱氧,LF精炼初渣的组分为(/%:27.39~37.34 Al₂O_3,38.42~38.68 CaO,14.20~18.38 SiO_2,8.50~10.72 MgO,0.82~0.89 FeO,0.27~0.33 MnO,0.69~0.74 S,0.66~0.75TiO₂,（CaO）/（SiO₂）=2.09~2.72,（CaO）/（Al₂O₃）=1.04~1.40),LF终点T[O]为0.0012%~0.0019%,T[N]为0.0043%~0.0050%,[Ti]0.002%和[Ca]0.006%~0.009%。GCr15轴承钢LF精炼终点氧化物夹杂分析结果表明,钢中主要氧化物夹杂为镁铝尖晶石（MgO·Al₂O₃）和钙镁铝尖晶石氧化物（CaO·MgO·Al₂O₃）。镁铝尖晶石平均尺寸低于0.5μm,当有MnS、TiN等在其上析出后平均尺寸增大。钙镁铝尖晶石平均尺寸通常在2μm以上,在精炼温度下呈液态,易在钢中聚集长大,其尺寸（1.39~2.12μm）比固态的钙镁铝尖晶石-MnS夹杂物大,且更被精炼渣吸收并上浮去除。随着精炼过程钢液中的硫含量降低,以这两类尖晶石为核心的含MnS的复合夹杂物的平均尺寸降低。适当降低精炼终点渣中MgO的含量、光学碱度和黏度可以减少钢中夹杂物的数量并降低其平均尺寸。     

65Mn钢LF精炼渣系优化及工业试验

为了研究适合高洁净度高碳钢的LF精炼渣渣系,通过FactSage热力学软件计算精炼渣碱度(R)、(CaO)/(Al₂O₃)对精炼渣熔点的影响,得出最合适的精炼渣成分。根据热力学计算的精炼渣成分,降低原有渣系的钙铝比,并将优化的渣系成分用于65Mn钢工业试验。结果表明：优化后的精炼渣系成分质量分数为CaO52%～58%、Al₂O₃28%～33%、SiO₂8%～12%、MgO5%～7%、R=4～6、(CaO)/(Al₂O₃)=1.5～2;使用该渣系进行工业试验,LF出站时的T.[O]可达7×10^-6～13×10^-6,RH出站时的T.[O]可达6×10^-6～12×10^-6;钢中全氧质量分数基本可控制在10×10^-6内;65Mn钢卷中的B类细系夹杂均不大于1级,达到高级优质钢要求。     

20钢管LF精炼渣系优化的工业试验

通过对中天钢铁公司电炉厂20钢管现行精炼渣系（/%:4～17Si0₂,17～34Al₂O₃,40～65CaO)的动力学以及热力学分析,在确保炉渣粘度1.5～2.0 Pa·s的前提下,设计出较高吸附夹杂物能力的LF精炼渣系:（/%:6～15SiO₂,24～34Al₂O₃, 58～65CaO）。试验结果表明,该渣系能够很好地满足20钢管的质量要求,达到了去除钢中夹杂物的目的,其B类夹杂评级均≤1.0。     

等温状态下新型动压推力轴承承载力计算

根据流体力学有限元理论 ,对新型动压推力轴承的承载力作了计算 ,并在可逆式动压推力轴承实验台上进行了验证     

提高振动筛轴承润滑质量延长轴承工作寿命

针对烧结矿生产线中的振动筛轴承使用寿命过短的现象,通过对润滑脂的粘度、极压性和使用温度以及轴承温度监测记录的分析,找到一种大幅延长轴承寿命的方法。     

大型轴承修复的实践

介绍了大型轴承修复再造工艺方法在韶钢板材厂的实践,这方法改变传统的轴承异常直接报废的处理方式,根据轴承具体受损情况,制定切实可行的修复方案,实现了废旧轴承的修复再造.     

轴承钢线材的开发

轴承钢线材的市场需求量不断增大，同时在生产上存在很大的难度。高线厂对影响质量的孔型系统、料型制度、生产管理等方面进行了优化，实现了逐渐扩大南钢轴承钢线材市场影响力的目的。     

Bearing materials from steel chips

Powder Metallurgy and Metal Ceramics -     

Bearing Materials by Powder Metallurgy

Abstract

The dependence of green strength on green density and on compacting pressure was investigated for the bidirectional die pressed and isostatically pressed Cu powder compacts. The breaking strength of the pressed Cu compact was found to increase with green density and also with compacting pressure. The green strength seemed to be directly proportional to the contact area between powder particles. A theoretical equation for the relationship between green density and contact area was derived from a geometrical consideration, and agreed well with experimental findings. PM/0272     

轴承边界单元在分析轧机滚动轴承载荷分布中的应用

针对滚动轴承接触的特点,提出一种新的单元模式———轴承边界单元,用来解决轴承接触单元中面力不连续的问题。在三维弹性无摩擦接触边界元法的基础上,针对轴承边界单元给出了计算接触区位移和面力影响系数的流程。以某二辊实验轧机的四列圆锥轴承系统为例来说明方法的正确性和高效性。     

Bearing Capacity of Circular Footings

Numerical computations using FLAC are reported to evaluate the soil-bearing capacity for circular smooth and rough footings. The effect of nonassociativity of the soil is investigated. The results indicate a decrease in the bearing capacity-factors value when the soil displays high nonassociativity. The bearing capacity factors Nγ′ obtained from the computations are significantly lower than those reported by Bolton and Lau in 1993. The results compare favorably with experimental data reported by de Beer in 1970. The sources of possible inaccuracies in numerical simulations are discussed.     

Bearing Capacity of Desiccated Tailings

The development of matric suctions in soils contributes to their shear strength, resulting in an enhanced factor of safety against bearing-capacity failure. In this paper, matric suction profiles of desiccated mine tailings are predicted from a steady-state solution for evaporative conditions, and from an isothermal mathematical model that simulates liquid and vapor water flow through soils. The shear-strength envelope with respect to matric suction is established by testing reconstituted tailings samples in a modified triaxial cell, in which matric suction can be controlled. The contribution of matric suction to the shear strength is interpreted as an additional apparent cohesion for use in bearing-capacity calculations. Because of the nonlinearity of the shear-strength profile, a numerical method of analysis is adopted to predict the ultimate bearing capacity of the desiccated tailings. A subsequent decrease in bearing capacity following 2D water infiltration into a partially capped tailings deposit and accompanying suction loss is investigated.