Assimilation of Steel Contemporary Extra-Furnace Treatment Technology with the Aim of Reducing Metal Contamination with Nonmetallic Inclusions

Metallurgist - Contemporary technology of steel extra-furnace treatment that makes it possible to reduce scrap with respect to non-metallic inclusions is considered. Improvement of steel...     

大型氧化物夹杂在钢锭底部锥中聚积机理的研究

用NH₄Cl水溶液和塑料粒子模拟了钢中大型夹杂物在钢锭底部锥聚积过程,提出了聚积机理,并导出了夹杂聚积量的数学方程:
$Q = \\frac{{A{\\rm{\\cdot}}b}}{{1 - \\alpha }}(\\int_{{t_1}}^{{t_0}} {(\\overline V - {U_S})} {C_0}dt + \\int_{{t_0}}^{t + {t_s}} {(\\overline V - {U_S})} k{C_0}dt)$
实验结果在生产中得到了验证。减少钢锭底部夹杂物的有效措施是向钢锭帽部加发热剂和适当的注温。加发热剂时,要注意加入时间和加入方法。     

<Emphasis Type="Italic">In Situ</Emphasis> Observation of the Formation and Interaction Behavior of the Oxide/Oxysulfide Inclusions on a Liquid Iron Surface

Inclusion formation and its behavior at the early stage of deoxidation and alloying operation has a considerable influence on steel cleanliness. In the present work, steel alloying, such as Mn, Al, FeSi, and FeMn additions to the liquid steel with different oxygen and sulphur content was simulated with a confocal scanning laser microscope combined with a special addition device. The inclusion formation and the inclusion interaction behavior immediately after the alloying and/or deoxidation were observed in situ. The inclusions were characterized based on both the in situ observation and the quenched sample. The effect of the sulphur and oxygen content in liquid iron, as well as that of the deoxidant type on the formation of oxides/oxysulfides is discussed taking consideration of the thermodynamics of the system. The inclusion behavior on the liquid iron surface, i.e., the interaction after its formation, the dissolution during the high temperature iso-thermal holding, and growth during the cooling was investigated. The dissolution of Mn(O,S) inclusions at 1843 K (1570 °C) was found to be driven by Mn diffusion through the inclusion/liquid iron boundary layer, and its growth during cooling was significantly affected by Marangoni flow.     

大型钢锭锭重兼容设计的适用性研究和应用

基于锭重兼容设计了插板式(C)、套圈式(T)和垫圈式(D)三种锭型,并运用有限元软件模拟10～15 t、20～27 t、29～35 t、39～45 t、50～60t42CrMo4钢锭在三种锭型下的凝固特性.结果表明,在10～60 t锭重内,随兼容量增大,凝固末期液相穴愈加深入锭身,在D锭型中表现尤为明显.当兼容量占原始...     

Metal Contamination Characteristics of Lepidium sativum in a Phosphate-, Saline-, and Nitrate-Contaminated Media

In this research we investigated the ability of cress seeds (Lepidium sativum L.) to grow in an aqueous media with metal toxicities. The toxicity of Cd, Co, Cr, Cu, Fe, Mn, Ni, Pb, and Zn ions were examined in blank, nitrate (N–NO3)–, phosphate (KH2PO4)–, and saline (NaCl)–contaminated media. The acute toxicity of the tested metal ions in the blank media according to their IC50 (50% inhibitory concentration) values increased on the order of Pb相似文献   

大型扁型钢锭模的裂纹分析及结构优化设计

针对大型灰铸铁扁型钢锭模早期裂纹报废问题，采用计算机模拟计算技术对ＦＺ２５ｔ钢锭模使用过程的温度场、热应力和裂纹敏感系数的变化过程进行了数值计算分析，并优化了结构设计。     

用KH计算法模拟大铸锭的热轧压下规程

文章分析了热轧大铸锭的特点,提供了快捷模拟现行热轧压下规程的步骤,为进一步创新和优化热轧压下规程创造条件,为工厂节能创造条件。     

Thermodynamics of Modifying Effect of Rare Earth Oxide on Inclusions in Hardfacing Metal of Medium—High Carbon Steel

The modifying effect of rare earth(RE)oxide on inclusions in hardfacing metals of medium-high carbon steel was investigated by means of thermodynamics,The thermodynamic analsys for inclusion formation shows that RE oxide can be reduced to RE element by carbon,then the RE element can react with oxygen and sulfur to form the RE oxide,RE sulfide and RE oxide-sulfide in hardfacing molten pool.The deoxidization and the desulphurization can be carried otu and the liquid metal can be purified.In addition,RE oxide can also react with sulfur to form RE oxide-sulfide dirdctly.Therefore,the harmful effect of sulfur can be decreased.     

大规格纯钛铸锭脱氧现象及对策

利用真空自耗电弧炉进行了大规格纯钛铸锭的工业生产,研究并分析Ф1040 mm大规格高氧含量纯钛铸锭的底部脱氧现象和氧元素均匀性的问题。纯钛铸锭底部脱氧的原因是海绵钛中的Mg与添加剂TiO₂在一次铸锭熔炼时反应引起的。采用真空自耗电弧炉对梯度加氧自耗电极进行两次熔炼,结果表明:通过梯度加氧的方式可以有效解决纯钛铸锭脱氧的问题,并显著改善纯钛铸锭氧元素成分均匀性,使生产出的Ф1040 mm高氧含量纯钛铸锭头部、尾部氧含量的偏差控制在0.011%范围内。     

管线钢硫化物夹杂及钙处理效果研究

系统分析了硫化物夹杂形貌、组成,并采用氧化物变性指标及硫化物变性指标对管线钢钙处理效果进行了全面评价,分析结果表明:管线钢经过钙处理后,没有发现沿晶界分布的MnS塑性夹杂,少量的硫化物夹杂由(Ca,Mn)S夹杂、CaS均匀分布的CaO-Al2O3-CaS复合夹杂和内核为CaO-A12O3外壳为CaS的复合夹杂组成,这对于提高钢板抗HIC性能非常有利;在现有工艺条件下,硅钙线加入量为0.7kg/t时夹杂物变性效果不理想,应适当增加硅钙线的加入量.     

Analysis of Largest Sulfide Inclusions in Low Carbon Steel by Using Statistics of Extreme Values

The statistics of extreme values was applied for the determination of the largest sulfide inclusions with different morphology in low carbon steel samples by using both two‐dimensional (2D) observations on the polished cross section and three‐dimensional (3D) observations on a surface of a film filter after electrolytic extraction of the samples. It was found that the globular, rod‐like and dendritic sulfides in the molten steel sample as well as the elongated sulfides in the rolled steel sample can be successfully extracted from the both samples, and analyzed precisely by using extreme value analysis in 3D. Based on the geometrical considerations of the probability for measurement of the true length of rod‐like and elongated inclusions on a cross section, it was found that this probability for inclusions decreases dramatically with an increasing real aspect ratio value of them. Particularly for the determination of the true length for elongated inclusions in the rolled steel sample by 2D investigations on a metal cross section, it is required to be cut investigating section of steel sample within ± 1 degree against rolling direction. Therefore, a 3D observation is considered to be more preferable and accurate than the conventional cross sectional observation in 2D, due to the possibility for the measurements of the real size of them.     

Origin of Nonmetallic Inclusions and Ways of Alleviating Their Contamination of Steel

The use of a new technology that involves inoculating tube steel during casting can save money by eliminating the need for vacuum degassing (production cost $25/ton) and treating the steel on a ladle-furnace unit (production cost $15.70/ton). The cost of such treatment is ∼$4–5/ton. Inoculation of the steel during casting does not require complex equipment and can easily be done in any steelmaking shop. Rolling of the inoculated steel results in a larger yield of useable tubes, and the finished rolled product has better mechanical characteristics and greater corrosion resistance than steel made by the usual technology.__________Translated from Metallurg, No. 4, pp. 73–77, April, 2005.     

Understanding the Formation and Evolution of Oxide Inclusions in Si-Deoxidized Spring Steel

Metallurgical and Materials Transactions B - To illustrate the mechanism of the formation and evolution of inclusions in Si-deoxidized spring steel, pilot trials and systematic samplings were...     

等离子体光谱仪定量分析低合金钢中稳定氧化夹杂物

钢中非金属夹杂物对钢的力学性能和工艺性能的影响,主要是降低材料的塑性、韧性和疲劳性能,尤其当夹杂物以不利的形状及分布特征存在时,对材料机械性能的影响更为严重。以往氧化夹杂物分量测定采用化学法和原子吸收法,测定周期长,且Ca、Cr、Mn、Fe等元素的氧化物含量很低,化学法测定有一定局限性。而采用等离子体光谱分析(ICP-AES)定量测定氧化夹杂物,由于夹杂物含量低,相对干扰少,此法具有速度快,灵敏度高,并可同时测定多元素等特点,从而大大缩短了分析周期,降低了分析成本和劳动强度。     

Mn-Si-Ti-Mg复合脱氧对钢中氧化物夹杂的影响

从氧化物冶金观点出发,研究了Mn-Si-Ti-Mg复合脱氧对钢中氧化物夹杂的影响.利用扫描电镜和Qwin图像分析软件,观察和分析了各种复合脱氧条件下钢中夹杂物的形貌、组成以及粒度分布,并研究了Ti,Mg含量变化对夹杂物的影响.结果表明,Mn对钢中夹杂物的形态和尺寸起到了重要作用;在W[Ti]>0.138%时,Mg含量的...     

大型钢锭电渣重熔工艺数学模型的建立及模拟计算

 基于传热学基本理论,建立了80 t级三相电渣炉大型钢锭电渣重熔过程数学模型,并通过工业生产75t TP316LN奥氏体不锈钢钢锭验证模型,研究了大型电渣钢锭温度场分布情况及二次晶间距的变化情况。结果表明：渣池中心部位温度达1800℃,自上而下沿着传热方向中心线温度逐渐降低;金属熔池最深处达1500mm,大约等于钢锭直径的0.8倍;金属熔池上方具有50mm圆柱段以保证渣皮薄而均匀;二次枝晶间距大小由钢锭外侧边缘向中心部位呈递增趋势,模拟结果与实际生产情况吻合。     

Oxide Inclusions in Ferromanganese and Its Influence on the Quality of Clean Steels

Low and medium carbon ferromanganese produced by oxygen decarburization process and electric silicothermic process was briefly introduced, and the quality of products by these two processes was analyzed. Results showed that the total oxygen content in medium carbon ferromanganese by electric silicothermic process in China, which ranged from 0.039% to 0.171%, was between those of the common and refined products by oxygen decarburization process outside of China. The increments of total oxygen content in liquid steel were estimated when ferromanganese was added for the purpose of Mn element adjustment at the end of smelting. Refined low and medium carbon ferromanganese, which had low total oxygen content, was recommended for composition adjustment of clean steels during final stage of a heat. It is possible that the inclusions in the ferromanganese alloy greatly influenced the quality of clean steel indirectly by affecting the amount, size and composition of inclusions in steel.