50tUHP(EBT)50tLF精炼工艺生产轴承钢

莱钢特殊钢厂采用５０ｔＵＨＰ（ＥＢＴ）５０ｔＬＦ精炼工艺生产的轴承钢,其高、低倍组织达到ＹＢ９６８标准要求,一次检验合格率１００％,其中点状夹杂物出现率为零,钢中氧含量小于２０×１０－３％;为执行更高级别的标准打下了基础。低碱度精炼渣可有效地消除钢中点状夹杂物,实践证明,碱度控制在２０～２５范围内,渣量为２％时,脱硫率可达７０％。钢中酸溶铝含量最佳值为００２８％～００４０％。５０ｔＬＦ精炼轴承钢的吹氩量为６０００～８５００Ｌ／炉。50tUHP(EBT)50tLF精炼工艺生产轴承钢@刘力力…     

50tUHP（EBT）电炉—LF精炼工艺参数优化及合成渣系研究

针对从德国引进的５０ｔＵＨＰ（ＥＢＴ）电炉－ＬＦ精炼生产线在试生产中存在的工艺参数不稳定、生产效率低、消耗高及钢品种开发少等问题,莱钢特钢厂从优化生产工艺参数和稳定操作入手,通过设计合理的精炼渣系,使脱硫率提高了３０％以上,轴承钢中钢的含氧量降低到２．０×１０－３％以下,成本降低了３５．５２元／ｔ钢。     

LF（钢包炉）固体合成渣脱硫工业性试验研究

以３０ｔＥＢＴ超高功率电炉为初炼炉和４０ｔＬＦ（钢包炉）作为精炼炉，使用ＣａＯ－ＣａＦ２系固体合成渣对Ｑ２３５钢进行钢包炉内脱硫工业试验，在本试验条件下，当ＥＢＴ电炉初炼钢液（Ｓ）初＝０．０３５％～０．０８１％时，最佳精炼渣碱度Ｒｂ＝（％ＣａＯ）／（％ＳｉＯ２）为２．０～２．６或Ｒｆ＝（％ＣａＯ）＋（％ＭｇＯ）／（％ＳｉＯ２）＋（％Ａｌ２Ｏ３）为１．５～２．０，渣指数（ＣａＯ）／（ＳｉＯ２）：（Ａ     

精炼渣发泡性能的实验研究和渣发泡条件的理论分析

对碱度为１．５～２．５，ＦｅＯ〈０．５％～１．０％的精炼渣进行了发泡性能的研究，实验在竖式电阻炉和中频感应炉内进行，分别测试了精炼渣碱度，助熔剂含量和发泡剂成分等因素对渣起泡率和发泡指数的影响，从理论上对渣的发泡行为进行了分析，导出了渣发泡南非要气体量的计算公式。     

70 t EAF-LF冶炼低、中碳钢快速脱硫的工艺实践

在70 t EAF-LF冶炼20MnSi钢过程中,通过EAF出钢时加石灰400～450 kg和合成渣80-250 kg,控制EAF出钢温度1 580～1 630℃,增加精炼渣量,保证精炼渣碱度为1．5-2．8,吹Ar搅拌流量为180～280 L/min, (TFe)平均≤1．0％,可使钢中平均硫含量由0．060％降至0．015％,精炼时间由30～45 min降低至20-30 min。     

精炼渣发泡性能的实验研究

对碱度为１．５￣２．５，ＦｅＯ％〈０．６￣１．０的精炼渣进行了发泡性能的研究。实验在竖式电阻炉和２００ｋｇ中频感应炉内进行，分别测试了精炼渣碱度，精炼渣中助熔剂含量和发泡剂组成等因素对渣起泡率η，发泡持续时间τ和发泡指数Σ的影响。     

铁矿石铝热还原形成精炼渣的条件

铁矿石铝热还原形成精炼渣的条件捷克和斯洛伐克进行了该项试验。在实验室试验中，由铝－铁矿石－石灰及其它精炼原料混合配成精炼剂。当精炼渣中Ａｌ２Ｏ３的量为５０％～４５％时，混合精炼剂中的铝：铁矿石：石灰应为１：２：３或１：２：３．５，金属液的温度则应低于...     

LF(VD)精炼工艺对控制28MnCr5齿轮钢中硫和硫化物的影响

试验了45 t LF精炼渣的碱度、喂硫线和脱氧工艺对28MnCr5钢(％:0.25～0.30C、0.60～0.80Mn、0.020～0.035S、0.80～1.00Cr)硫含量的控制、氧化物含量和钢中硫化物的影响。结果表明,LF精炼渣碱度控制在2.8～5.1喂硫线,VD后硫的回收率达80％～90％;钢中氧化物级别≤1.5级;精炼结束喂适量CaSi线可改善钢中硫化物的形貌。     

管线钢LF精炼效果分析

对某钢厂管线钢LF精炼效果进行了分析,包括精炼渣的碱度及其对钢中T．O的影响、渣中（MnO＋FeO）含量的变化、炉渣的曼内斯曼指数以及炉渣的脱硫效果。结果表明：LF精炼渣碱度在5．47～7．53,符合高品质钢所要求的碱度范围;LF精炼后渣中w（MnO＋FeO）偏高,平均为2．0%;LF精炼渣曼内斯曼指数MI（MI=R／w（A1203））偏低,影响渣的流动性及吸附夹杂物的能力;LF精炼过程脱硫率平均为62．5％,脱硫效果较好。     

精炼炉熔渣泡沫化的实验研究

对精炼炉深渣的泡沫化进行了实验室研究了半工业性的实验研究。实验在硅化钼棒炉和１０００ｋｇ感应炉内进行,考究了熔渣碱度、熔渣中ＣａＦ２含量及发泡剂配比对发泡效果的影响。在分析大量实验数据的基础上,对熔渣发泡机理进行了探讨。研究结果表明：所研究的ＣａＯ－ＳｉＯ２－ＭｇＯ－Ａ１２Ｏ３渣系,在碱度为１．０～１．２、ＣａＦ２含量为６％～８％和碳加入量过剩指数为１．４～１．５时,发泡效果较好。     

150 t BOF-LF-VD-CC流程无铝脱氧工艺高速轨钢冶炼过程的夹杂物行为

时速350 km高速钢轨要求钢中全氧含量T[O]≤20×10^-6,非金属夹杂物B、C、D类≤1.0级。国内在重轨钢冶炼中,通常采用无铝脱氧工艺,即采用SiCaBa合金强化脱氧,形成了低熔点的Mn-Al-Si-Ba-Ca多元型氧化物夹杂,该类夹杂物在精炼中全部排出钢液。研究了铁水预处理脱硫-150 t顶底复吹转炉-LF-VD-280 mm ×380 mm连铸流程冶炼钢轨钢U71MnG时的夹杂物行为,包括无铝脱氧工艺钢轨钢中氧化物夹杂的组成及特征,转炉终点[C]对钢水氧活度的影响以及LF精炼渣碱度和VD后期软吹氩搅拌对钢氧含量和夹杂物的影响。结果得出,钢轨头部的≤20μm氧化物夹杂为精炼时二次脱氧产物,通过控制转炉终点[C]＞0.15%,控制精炼渣碱度(CaO)/(SiO₂)=2.5~3,∑(FeO+MnO)≤1.0%可有效降低钢轨钢中氧化物的数量和尺寸。     

170 ~190tLF精炼过程脱硫影响因素分析

为了分析船板钢和低碳钢LF精炼过程脱硫效率,对各影响因素进行了分析研究,结果表明,在LF平均处理周期35 min以内,钢水中的硫脱除至0.010%以下,初始硫含量要低于0.027%;炉渣（FeO+MnO）含量控制在0.5%以下,碱度控制在4,Al2O3与MgO分别控制在20%和12%,脱硫效率最佳;硫含量脱除至0.010%以下,处理前钢水中的溶解氧尽量控制在16×10^-6以下,硫含量脱除至0.003%以下,钢水中的溶解氧尽量控制在5×10^-6以下;渣量控制在15～20 kg/吨钢,吹氩量控制在0.6～0.8m³/min比较适宜;前20 min内硫含量的降低速度最快,能够将钢水中的硫控制在0.010%以下,之后硫含量降低速度趋于平缓,为使硫脱至0.005%,精炼处理时间通常需要30 min以上。     

45 t AOD精炼304不锈钢的造渣工艺实践

为降低AOD精炼的渣料和还原剂硅铁用量,对高铬钢液脱碳及还原过程渣碱度控制进行热力学分析,并进行45 t AOD冶炼304不锈钢造渣工艺试验。试生产结果表明,降低AOD精炼304不锈钢脱碳期炉渣碱度可减少钢水铬的氧化,同时有效减少AOD精炼渣料和还原剂消耗;AOD精炼过程石灰加入量平均从104.2 kg/t降至84.2~93.1 kg/t时,脱碳期炉渣碱度由平均13.44降低到10.64,AOD冶炼过程石灰、萤石、硅铁单耗分别平均降低14.7、5.4、4.4 kg/t,钢中Cr收得率、Ni收得率和硫含量分别为99.0%、98.3%和0.0025%。     

弹簧钢100 t DC EAF-LF-VD流程无铝脱氧工艺实践

EAF-LF-VD冶炼60Si2MnA和55CrSiA弹簧钢时EAF出钢过程加17～23 kg/t低铝硅铁(Al含量≤0.50%)脱氧,LF补加3～6 kg/t硅铁,并控制精炼渣的碱度≤2.5,可控制[Als]≤60×10^-6,总[O](9～20)×10^-6,A类夹杂级别≤0.5,B类≤0.5,C类≤1.5,D类≤0.5。用该脱氧工艺冶炼的钢水可浇注性强,适合大批量工业性生产。     

100t转炉-LF(VD)工艺冶炼轴承钢的氧含量控制

通过铁水预脱硫-100 t顶底复吹转炉-吹Ar-LF(VD)-方坯连铸工艺生产轴承钢的实践,得出冶炼终点钢水碳含量为0.2%~0.6%时,钢水氧含量在50×10^-6到150×10^-6之间;经出钢时脱氧、吹氩、LF(VD)精炼后,中间包钢水中的全氧含量为(14~16)×10^-6,铸坯中的全氧量<12×10^-6。分析表明,加强熔池搅拌,使钢渣充分反应,控制转炉下渣量<5 kg/t钢,加强吹氩搅拌,控制LF顶渣碱度在2.0~2.5之间,(FeO)+(MnO)小于0.5%,可使轴承钢中全氧量进一步降低。     

120 t BOF-LF-VD-CC工艺生产GCr15轴承钢的氧含量控制

采用铁水预处理-120 t顶底复吹转炉-LF-VD-φ180 mm连铸工艺生产GCr15轴承钢.统计分析了轴承钢转炉终点[C]对钢水氧活度的影响,LF精炼渣碱度对T[O]的影响,LF末钢中铝含量对VD过程铝损和T[O]的影响.通过控制转炉终点[C]≥0.06％、出钢用铝锰铁强化脱氧;控制LF离位时[Al]0.020％ ～0.040％,( FeO+MnO)≤1％,碱度2.8～4.5;VD软吹时间≥15 min,轴承钢中全氧含量为(6～12) ×10-6.     

Industrial Application of Desulfurization Using Low Basicity Refining Slag in Tire Cord Steel

Desulfurization performance with low binary basicity refining slag in 72 grade tire cord steel was calculated using FactSage and it is found that sulfur content in steel decreases with the increase of basicity of slag, MgO content in slag and slag/steel ratio while sulfur partition ratio between slag and steel increases gradually with the increase of basicity of slag as well as MgO content. Experiments were carried out and the results are of great agreements with theoretical calculation. Then industrial application tests were performed in a domestic plant and good results were achieved. Sulfur content in steel decreases gradually during refining process, as a result, sulfur content in the billets is controlled in the range of 0.007 1%-0.008 1%. Sulfur content in steel refined with slag basicity of 1.21 is lower than that of 1.02, while the plasticity of oxide compound inclusions is a little better controlled in low basicity heats. Using refining slag with basicity of 1.0-1.2 and MgO content of 5%-10% and reducing the slag takeover of LD are favorable for improving the desulfurization performance and the plasticity of inclusions during the industrial production.     

Control of Ultra Low Titanium in Ultra Low Carbon Al-Si Killed Steel

 Titanium is the impurity in some special steel grades. The existence of titanium decreases the grain size, depresses the yield strength, and results in the low quality of these steels in various properties. Thus, titanium should be removed to the minimum. Based on the industrial production of ultra low carbon Al-Si killed steel, the physical-chemical behavior of titanium was investigated in vacuum degassing refining (RH) process with and without desulfurization. The influences of titanium content in hot metal, ladle slag composition, and ladle slag quantity, etc, on titanium content of refined liquid steel were discussed. The results showed that the partition ratio of titanium between ladle slag and liquid steel is in inverse proportion to the 4/3 square of aluminum content. The maximum partition ratio of titanium between top slag and liquid steel can be obtained by adjusting an optimum slag composition including contents of FeOx and Al2O3 and the slag basicity, and the suitable range of them should be controlled higher than 6%, less than 20%, and within 1. 5 to 3. 0, respectively. Moreover, desulfurization refining by RH decreases the partition ratio of titanium between ladle slag and liquid steel significantly. To ensure the titanium content stably less than 15×10-6 in a 300 t ladle, the titanium content in hot metal must be less than 500×10-6 and the thickness of basic oxygen furnace (BOF) slag carrying over must be less than 50 mm.     

Inclusion evolution in 50CrVA spring steel by optimization of refining slag

In order to control the CaO-Al2O3 -SiO 2 -MgO system inclusions in 50CrVA spring steel in a lower melting temperature region, high temperature equilibrium experiments between steel and slag were performed in the laboratory, under the conditions of the initial slag basicity within 3-7 and the con-tent of Al2O3 between 18-35 mass%, to investigate the formation and evolution of this type of in-clusion.The results indicate that the total oxygen content in the steel decreases with the increase of slag basicity and the decrease of Al2O3 content in slags, and CaO-Al2O3 -SiO 2 -MgO inclusions tend to deviate from the low melting point region with the increase of Al2O3 content in slags.The most fa-vorable composition for the refining slag is composed of 51-56 mass% CaO, 9-13 mass% SiO2 , 20-25 mass% Al2O3 and 6 mass% MgO.In this case, the inclusions in 50CrVA spring steel are mostly in the low melting point regions, in which their plasticities are expected to improve during steel roll-ing.The MgO-based inclusions were observed in the steel matrix and the formation mechanism was theoretically and schematically revealed.It is also found that adding around 11 mass% of MgO into the refining slags is beneficial to reducing the refractory corrosion.Further work should be carried out focusing on the evolution rates of MgO-based inclusions.     

淮钢80t BOF-90t LF-RH-CC流程开发特殊钢的生产实践

通过转炉采用高拉碳操作,控制出钢[P]≤0.012%,终渣碱度2.8～3.5;双挡渣工艺,LF精炼渣碱度≥4,(TFe+MnO)≤1.0%;应用低铝洁净钢精炼技术和含钡洁净钢生产技术专利;RH-MFB真空处理,连铸全程保护浇铸及二冷技术优化等措施,淮钢开发了127个特钢新产品,总氧含量(T[O]):轴承钢≤10×10-6,60Si2CrVAT弹簧钢≤12×10-6,CM490锚链钢≤15×10-6,37Mn5油井管坯钢≤18×10-6,SAE1022A冷镦钢和15CrMoG高压锅炉管坯钢≤20×10-6。