超低硫钢精炼工艺

在感应炉上进行了一系列对比实验,研究结果表明:顶渣+喂线工艺比完全顶渣工艺具有更快的脱硫效果,含BaO精炼渣系比传统的CaO-CaF₂渣系具有更强的脱硫能力;当钢中氧和硫都很低时,CaSi合金能起到显著的深脱硫作用.由研究结果得出超低硫钢(w_s<0.0010%)钢液精炼的主要工艺参数.     

马钢超低硫钢的生产工艺研究

在马钢生产X70、X80管线钢为平台的超低硫钢生产工艺的基础上,分别对转炉、LF精炼过程钢水硫含量控制进行了分析研究,研究结果表明转炉吹炼过程增硫主要来自于铁水脱硫渣和废钢中带入的硫,LF炉深脱硫主要取决于钢包顶渣的控制和强搅脱硫的搅拌功。通过工艺调整,使生产X70、X80管线钢时LF炉终点w[S]可稳定控制在0.005 0%以下,平均w[S]为0.001 1%。     

超低硫钢生产工艺技术

在铁水和钢水脱硫反应的热力学、动力学分析的基础上提出了适用于脱氧出钢———LF精炼和未脱氧出钢———RH喷粉两种冶炼超低硫钢 ([S]≤ 1 0× 1 0 -6 )的工艺。     

济钢超低硫钢生产实践探索

介绍了济钢210t转炉超低硫钢生产工艺技术,通过控制转炉入炉铁水S含量,在转炉出钢过程中加入一定量的顶渣对钢水进行"渣洗"脱硫,控制LF炉渣碱度、氧化性、温度、渣量等,实现了转炉渣洗平均脱硫率达到61.41%,LF平均脱硫率78.2%,精炼结束平均S含量达到了0.00174%。     

超低硫钢冶炼技术的研究

含硫量小于30 ppm的超低硫钢是发展石油工业等的紧缺钢材。为开发这种钢的冶炼技术,作者用在英国BSC公司做的试验数据作了统计分析,并相应地进行了一些基础研究。研究指出,不能单独用B=(％CaO)/(％SiO_2)或MI(Mannesmann Index)来说明顶渣的脱硫效果。它们有一最佳匹配,即B≈7,MI=0.33。最佳的顶渣组成是58～62 ％CaO+24～28 ％Al_2O_3+8～12 ％SiO_2。在MI较大时,(％FeO)+(％MnO)对脱硫效果的影响较弱。文中对喷吹方案,Ca利用率和回硫问题进行了分析。     

超低硫钢生产工艺的研究与应用

莱钢银山型钢炼钢厂在超低硫钢([S]≤30 ppm)生产过程中,受原料、工艺条件等因素影响,终点钢水硫含量控制较不稳定,通过系统分析原料、转炉等工序对脱硫效果的影响,细化工艺流程,同时研究开发钢水固硫剂,使终点硫含量稳定在0.002%以下,满足了低硫钢生产需要。     

RH工艺精炼超低硫钢的冶炼技术

在RH工艺精炼超低硫钢的热力学分析的基础上 ,用MoSi2 电阻炉进行了CaO Al2 O3 SiO2 MgO CaF2 渣系预熔渣和机混固体渣对钢液脱硫的试验 ,得出预熔渣脱硫速率较机混固体渣快 ,使用预熔渣时在 30min以内即可将钢中的硫含量从 116 7× 10 -6降低到 2 0× 10 -6以下 ,钢中最低终点硫含量可达 2 9× 10 -6。在30 0tRH装置上工业试验表明 ,使用预熔渣后 ,当RH精炼前钢中平均硫含量为 4 0 5× 10 -6时 ,RH精炼终点钢中平均硫含量降至 2 8 7× 10 -6,最低硫含量为 2 2× 10 -6,平均脱硫率为 2 8.9%。     

氧气转炉出钢脱硫-LF精炼生产超低硫钢的工艺

因210tBOF冶炼终点NVA32(%:0.12～0.18C、1.30～1.60Mn)钢中硫含量由0.005%升高至0.020%,通过BOF出钢过程加入1000kg二元合成渣CaO-CaF₂、200kg铝粒,并加入硅锰和硅铝钡合金,可使钢中硫含量降低0.007%～0.008%,脱硫率达30%。在LF精炼时,通过进一步加入合成渣800kg,600～900L/min吹氩,加热后喂600m硅钙线,30～45L/min吹氩10min,终渣碱度R=4.5～5.5,钢中硫含量进一步降低至0.001%～0.002%。     

高硫容量含BaO超低硫钢精炼脱硫渣系

通过500g钼丝炉和10kg感应炉进行了顶渣CaO-SiO2-MgO-Al2O3-CaF2渣系和喂线渣CaO-BaO-CaF2渣系在钢-渣平衡状态的硫容量和钢水脱硫试验。结果表明，该顶渣 喂线渣具有高的硫容量(logC5为-1．6～0．5)，适用于超低硫钢的精炼脱硫；CaO-BaO-CaF2中BaO/CaO为5/3时，硫的分配系数L5达到极大值，CaO-SiO2-MgO-Al2O3-CaF2渣系的碱度3．1，炉渣指数MI0．31时，硫的平衡分配系数L5最高。     

Production technology for low-carbon,low-sulfur boron steel

A technology for slag formation in the ladle–furnace unit is considered; the slag is based on the CaO–SiO₂–MgO–Al₂O₃–B₂O₃ system. This technology permits both microalloying of the steel with boron (reduced from the oxide phase) and desulfurization of the steel. The resulting boron content in the steel is 0.001–0.008%; the sulfur content in low-alloy steel and pipe steel is low (0.004–0.010%); and the consumption of manganese ferroalloys is reduced to 0.5 kg/t for 08кп steel and 1.4 kg/t for 09Г2C steel. In addition, the proposed technology increases the strength of the rolled steel, without loss in its plasticity; and reduces the environmental impact thanks to the replacement of fluorspar by colemanite.     

Study on control technology of slag composition for low-sulfur ＆ low-oxygen steel

为实现高品质低硫、低氧钢的生产，有效降低钢中T．0、S含量，在考虑转炉下渣、炉渣氧化性以及钢水氧活度的条件下，研究确定了用于低硫、低氧钢冶炼的CaO-Si02-A1：03精炼渣系，并结合转炉下渣改质技术以及LF精炼钢包渣成分控制技术等工艺措施，制定了低硫、低氧钢的钢包渣改质制度。采用该技术生产的27CrMoNbV等圆管坯钢达到了成品w（T．0）≤15×10，w（S）≤0．005％的水平，实现了低硫、低氧钢的生产。     

Production of low-sulfur steel with limited hydrogen content

The converter production of steel with low sulfur content is analyzed. Existing desulfurization methods greatly increase the hydrogen content in the steel. Options for reducing the hydrogen content associated with the solid slag-forming mixture are outlined. The influence of the storage time and conditions on the quality of fluidized lime and correspondingly on the steel’s hydrogen content is discussed.     

A technique for obtaining shock-wave parameters using wave superposition in low-carbon steel

A novel experimental set-up for obtaining shock-wave superposition is described. Detonation is simultaneously initiated at the two opposite sides of an explosive layer placed directly in contact with a steel block. It was possible to take advantage of thea (bcc) → ε (hcp) →α (bcc) transformation occurring in iron at approximately 13 GPa in a unique fashion. The pressure of the two converging pulses is approximately 13 GPa, resulting in little or no transformation. However, in the region of superposition of the two waves the pressure is much higher.Post explosionem observation of the microstructure allowed an easy identification of the region of superposition, because of the profuse transformation “debris”. Events conducted for three thicknesses of the explosive layers allowed conclusions to be drawn about the changes of rarefaction and attenuation rates. The interactions occurring between the waves due to simultaneous superposition and transformation are thought to be responsible for internal spalling. Formerly with the Department of Metallurgical Engineering, South Dakota School of Mines and Technology     

Luders deformation of low-carbon steel

The development of Chernov–Luders bands on elastoplastic transition in low-carbon steel is investigated. The main factors responsible for the creation and development of the bands are identified. The kinetics of the mobile band boundaries (fronts) is of particular interest. The characteristic speeds are determined. The nucleation rate of Chernov–Luders bands exceeds their expansion rate by more than an order of magnitude. The simultaneous development of more than one band, with the appearance of several moving fronts, is considered. In all cases, the fronts of the Chernov–Luders bands move at matched speeds, so that, at any time, the generalized expansion rate of the deformation zone is constant. The influence of the strain rate on the kinetics of the band fronts is analyzed. Both the generalized expansion rate of the deformed zone and the speeds of individual fronts increase with increase in the loading rate. This is a nonlinear dependence (a power law). The fronts of the Chernov–Luders bands are complex in structure. Different sections of the front may move at nonuniform speeds, so that the front is locally distorted and split. Ahead of the front, in the undeformed sample, precursors whose configuration resembles that of the incipient Chernov–Luders bands may be observed. When they meet, the fronts of adjacent bands cancel out. Annihilation of the band fronts is a complex process, characterized by the formation of precursors and secondary diffuse Chernov–Luders bands. These findings indicate that the simplified concept of the Chernov–Luders bands as a deformed region in a loaded sample, as the front of a band, or as the boundary between deformed and undeformed zones must be revised. A microscopic theory of Luders deformation is based on the cascade growth in density of mobile dislocations on account of their breakaway from the points of attachment and their subsequent multiplication, which occurs instantaneously at the upper yield point within the crystallite (grain). At the same time, the formation of a mobile macroscopic strain front calls for the transfer of plastic deformation by adjacent grains, without strengthening. In other words, grain-boundary accommodation is required. The results obtained suggest that the Chernov–Luders band is such an accommodation zone, and so it has a complex structure.     

低碳钢中硼的损失机理研究

根据南钢低碳含硼钢BOF-LF-CC工艺制定取样方案,跟踪硼含量的变化.通过试验结果及理论热力学计算,分析了含硼低碳钢在生产过程中硼的损失机理,并提出了优化方案.结果表明:精炼过程中[B]与[O]、[N]、N2的反应不能自发进行,造成硼损失的主要原因是硼与空气中的O2发生氧化反应.因此,避免钢液中[B]与空气直接接触成为提高硼收得率的重要手段,从而提出了3点优化方案:①控制搅拌,防止钢液面与空气接触反应;②在精炼结束至中间包运输过程中对钢包采用加盖操作;③浇铸过程中加强钢液由中间包至结晶器之间密封保护.     

Study of the kinetics of the recrystallization of cold-rolled low-carbon steel

The suitability of the differential scanning calorimetry (DSC) technique for the quantitative study of the recrystallization process in cold-rolled steels is demonstrated, the recrystallization kinetics was described with a semiempirical model, and the transformation of a cold-rolled steel submitted to an industrial-batch thermal cycle was appropriately simulated. It was found that the activation energy for the recrystallization process depends on the heating-rate range, having values of 522 ± 13 and 259 ± 12 kJ/mole for low and high heating rates, respectively. It was concluded that the smallest value corresponds to the recrystallization process alone, while the largest one contains an additional contribution from the aluminium nitride precipitation. It is also shown that the X-ray diffraction (XRD) line-width measurement is a useful complementary method to determine the temperature regions where recovery and recrystallization occur.