采用电渣重熔工艺冶炼高质量轴承钢

文献[1,2]证实：钢中非金属夹杂物的聚集是导致疲劳破坏的根源,特别是氧化铝、氮化钛等脆性夹杂物,所以控制轴承钢的夹杂物是保证轴承钢质量的关键。我们对电渣重熔工艺的提纯过程进行了试验研究,并根据研究结果制定了电渣重熔工艺参数、生产实践证明效果很好。     

钢中非金属夹杂物的测定

本文介绍利用电解非金属夹杂物粉末制备成供图象分析仪分析试样的方法,以定量测定钢中非金属夹杂物的形状、大小等参数。将金相试片、夹杂物的电解粉末试样与图象分析仪测定方法有机结合,测定了两种电渣重熔高碳铬轴承钢中非金属夹杂物的数量、形状和大小等参数,探讨了在图象分析仪上利用金相试片与本人所述方法制备的试样对测定结果准确性的影响。     

提高铁铬铝合金寿命的新途径

稀土元素的加入方法对铁铬铝合金性能有显著的影响。稀土氧化物渣系,在电渣重熔过程中顺利地实现了OCr25A15合金的稀土化,有效地去除了合金中的非金属夹杂物,大大地降低了合金的成本,提高了合金的使用寿命。     

Cr20Ni80电热合金铸锭与电渣锭的对比研究

研究了电渣重熔对Cr20Ni80铸锭组织和力学性能的影响。结果表明,电渣重熔后铸锭大头柱状晶区的范围扩大,中心等轴晶区所占比例为半径的1/2左右;小头靠近型壁的细晶粒区范围扩大,柱状晶范围扩大,晶粒出现一定的圆度。扫描电镜分析结果表明,铸锭中夹杂物主要有5类,其中以第3类夹杂物为主要夹杂物;夹杂物在上浮过程中被结晶雨所捕获并沉降到底部。电渣重熔后,锭子的夹杂物面积比减小了48.3%,并且分布更加均匀。其塑性提高了8~9倍,韧性提高了5~6倍。     

电渣精炼去除铝中夹杂物的研究

采用电渣精炼法去除工业纯铝中的夹杂物,研究了电渣精炼去除夹杂物的效果及机理。结果表明,工业纯铝中夹杂物的去除效率随着电渣重熔速率的减小不断提高;当电渣重熔速率为108g·min~(-1)时,夹杂物的去除效果最佳,达到97.6%。在电渣精炼过程中,工业纯铝中的夹杂物被熔融渣剂所捕获。夹杂物-铝熔体-熔融渣剂体系的吉布斯自由能计算结果表明,在铝熔滴中的夹杂物具有从铝熔体中自发迁移到熔融渣剂中的趋势。     

磁控电渣重熔对LD冷作模具钢电渣锭组织及性能的影响

研究了横向稳恒磁场对磁控电渣重熔LD冷作模具钢微观组织和力学性能的影响,分析了电渣锭的碳化物微观形貌、冲击韧性和维氏硬度的变化。研究结果表明:在电渣重熔过程中施加横向稳恒磁场能够有效地细化电渣锭凝固组织,减小碳化物的尺寸以及提升电渣锭的维氏硬度,从而提升电渣产品的质量。     

不同冶炼方式生产的超高强度钢洁净度研究

对真空自耗重熔(VAR)和电渣重熔(ESR)生产的超高强度钢洁净度进行对比研究。利用化学分析、相分析、定量金相和扫描等方法,获得了钢中非金属夹杂元素含量,以及夹杂物的类型、数量和形状特征参数。结果表明,真空自耗重熔钢中的硫、磷、氧和氮含量均低于电渣重熔钢。电渣重熔钢中硫化物呈条状,尺寸较大,夹杂物平均自由程较小。真空自耗重熔钢中,硫化物呈细小球状,夹杂物平均自由程较大。从钢中非金属夹杂元素和夹杂物情况可以看出,真空自耗重熔钢的洁净度水平高于电渣重熔钢。     

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对真空自耗重熔(VAR)和电渣重熔(ESR)生产的超高强度钢洁净度进行对比研究。利用化学分析、相分析、定量金相和扫描等方法,获得了钢中非金属夹杂元素含量,以及夹杂物的类型、数量和形状特征参数。结果表明,真空自耗重熔钢中的硫、磷、氧和氮含量均低于电渣重熔钢。电渣重熔钢中硫化物呈条状,尺寸较大,夹杂物平均自由程较小。真空自耗重熔钢中,硫化物呈细小球状,夹杂物平均自由程较大。从钢中非金属夹杂元素和夹杂物情况可以看出,真空自耗重熔钢的洁净度水平高于电渣重熔钢。     

工程机械用30CrNi3MoV钢的热处理与组织性能

对比分析了锻态和调质态电渣重熔和非电渣重熔30CrNi3MoV钢的显微组织和力学性能,在此基础上,研究了Mn和Si含量对非电渣重熔钢组织、力学性能和耐腐蚀性能的影响。结果表明:电渣重熔并不能改善锻态试验用钢的晶粒度,但是贝氏体组织会有所细化;经过调质热处理后,电渣重熔钢和非电渣重熔钢的晶粒都有明显细化,组织都为细小回火索氏体;调质态电渣重熔钢和非电渣重熔钢具有相似的力学性能,且都满足工程机械用钢的使用要求。Mn含量的提高有利于细化调质态非电渣重熔钢的晶粒,而Si含量的提高对晶粒度的影响较小;适当增加Mn和Si元素含量有助于提高试验用钢的抗拉强度、屈服强度和布氏硬度,但是塑性和低温冲击韧性会有所降低;调质态非电渣重熔钢中增加Mn含量会降低材料的耐腐蚀性能,而增加Si含量有助于提高材料的耐腐蚀性能。同时增加Mn和Si含量的调质态非电渣重熔钢具有较好的强塑性、-40℃冲击韧性和耐蚀性能。     

电磁场对5082铝合金铸轧板材组织的影响

进行了5082铝合金的常规铸轧、静磁场铸轧、交流电场铸轧以及电磁振荡铸轧试验,对比分析各试验条件下获得的铸轧板材的显微组织。结果表明,在5082铝合金板材铸轧过程中施加静磁场可以抑制树枝晶生长、细化晶粒,使晶粒大小分布均匀;施加交流电场使得晶粒分布均匀,但晶粒细化效果不明显,且有助于树枝晶的生长;同时施加静磁场和交流电场,产生电磁振荡效应,使得晶粒细小均匀,晶粒细化效果显著,不再有明显的树枝晶。     

Effect of Transverse Static Magnetic Field on Droplets Transient and Inclusions Evolution During the Electroslag Remelting Process of GCr15 Ingots

The voltage was recorded to investigate the influence of the static magnetic field on droplet evolution during the magnetically controlled electroslag remelting(MC-ESR) process. MC-ESR experiments were carried out under different remelting current, and transverse static magnetic fields(TSMF) of 85 mT, 130 mT and 160 mT were superimposed.Statistical work was performed to obtain the quantitative data of the droplets. The ASPEX Explorer was utilized to investigate the inclusions evolution of GCr15 ingots. The number of the droplets was 31 in 20 s during the traditional ESR process and reached 50 and 51 under the MC-ESR process with the TSMF of 85 mT and 130 mT, respectively. When compared the traditional ESR process with the MC-ESR process, the inclusions amount reduced 67%.     

Improving the Solidified Structure by Optimization of Coil Configuration in Pulsed Magneto-Oscillation

Using both numerical and experimental methods, we studied the effect of coil configuration of pulsed magneto-oscillation (PMO) on distribution of electromagnetic field, flow field and solidification structure with the same pulse current parameters in Al ingots. We designed and constructed three types of coils: surface pulsed magneto-oscillation, hot-top pulsed magneto-oscillation (HPMO) and combined pulsed magneto-oscillation (CPMO). PMO treatment refined the solidification structure in all the ingots. The configuration of the PMO, however, introduced differences in magnetic field intensity, electromagnetic force, Joule heat, flow field, equiaxed grain zone, grain size and growth direction of columnar grains. The largest equiaxed grain zone was found in CPMO treated ingot, and the smallest grain size was found in both HPMO and CPMO treated ingots. Numerical simulation indicated that difference in electromagnetic field and flow field resulted in differences in solidification structure. HPMO is more advantageous over others for large ingot production.     

Phenomena at three-phase electroslag remelting

The electroslag remelting (ESR) process is widely used to produce high-quality ingots and billets for high-alloyed steels and alloys.Both the single-phase and three-phase alternating current diagram with bifilar and monofilar connection are in use for heavy ingot manufacturing.The numerical simulation of the three-phase bifilar circuit for the 120 t three-phase bifilar six-electrode ESR furnace at different variants of electric connection was presented and discussed.At the bifilar diagram of power supply,the geometrical location of electrodes in a mould holds critical importance for performances:the close location of bifilar pair electrodes provides the highest heat productivity,but the equidistant location of electrodes gives a much more uniform heat distribution.The monofilar mulit-electrode diagram of three-phase connection without phase shift shows the most uniform distribution of potential and heat generation as well as a favorable magnetic field that makes this kind the most promising for providing a high quality of heavy ingots.     

A study on elimination of alumina particles in molten aluminum using direct electromagnetic force

From the viewpoint of energy reduction, the recovery of metal scrap and its recycling have been rising as an important global subject. However, it is difficult to remove deleterious impurities, which have detrimental effects on the mechanical properties. In particular, it is difficult to eliminate nonmetallic inclusions such as alumina(Al₂O₃) in aluminum alloys when they are subject to recycling. In this study, an experiment on the elimination of the impurities in the melt by imposing electromagnetic force to molten aluminum was conducted. The principle behind these electromagnetic methods is that as the electromagnetic force induced in metal scarcely acts on non-metallic inclusions due to low electric conductivity, the non-metallic inclusions are moved to the direction opposite the electromagnetic force and can be separated from the melt. The prediction based on the theoretical analyses was confirmed through the visualization of the polystyrene particle motion in an NaCl aqueous solution. We also proposed optimum electromagnetic conditions such as current density, magnetic field intensity and particle size for eliminating the inclusion particles continuously found through numerical analysis and experiments.     

静磁场对铝硅合金Na变质处理的影响

分别对亚共晶Al-6Si合金和共晶Al-12．6 Si合金进行Na变质处理，发现对于亚共晶Al-6 Si合金，重熔使N。变质失效，而施加静磁场条件下，重熔没有使Na变质失效。对于共晶Al-12．6 Si合金，同样在变质剂反应温度保温20min，施加静磁场的条件下，共晶硅细化，并呈现一定程度的粒状化，其变质效果明显优于不施加静磁场的情况。延长保温时间至40 min，不施加静磁场时出现了变质衰退现象。但在施加静磁场条件下，变质衰退现象相对较轻，即静磁场具有延长变质有效时间的作用。分析认为这是静磁场抑制对流作用的结果。     

VAR工艺参数对Ti-10V-2Fe-3Al铸锭凝固行为的影响

采用真空自耗电弧熔炼(VAR)工艺制备Ti-10V-2Fe-3Al铸锭,研究了熔炼电流和搅拌磁场等工艺参数对铸锭凝固行为的影响,并对真空自耗电弧熔炼过程中起弧、熔炼、补缩等阶段的凝固组织及熔池形貌进行了分析。结果表明,在未加搅拌磁场时,熔池较窄,铸锭组织粗大,而施加搅拌磁场后,熔池变宽且旋转明显,铸锭宏观组织中的晶粒变小;随熔炼电流增大,熔池加深,凝固组织中的晶粒变得粗大。     

18—18护环用钢的电渣重熔技术研究与应用

针对18-18型护环用钢的特点和重熔条件,研究了不同N含量特别是超高N的行为及影响冶金质量的工艺因素、开发了18—18型护环钢的电渣重熔技术。试生产了4根8t 18—18型护环电渣锭。钢锭冶金质量优良,N=0.63％,O=10ppm,S=20ppm～40ppm。钢锭已制成300MW发电机护环。     

Inclusion counting of steel residues as means of assessing the hot working performance of steel

A new technique, Coulter Counter Particle Size Analysis, has been applied to the study of oxide inclusions in seamless ingots and their effect on defect occurrence in the finished product. The volume of oxide inclusions in representative small steel samples is a measure of hot working quality within ingots and between seamless heats. Furthermore, oxide inclusion distribution by size is a log-normal function indicating that most large and small inclusions have a similar morphology. A series of calculations were made on the number of hot working defects to be expected from the oxide inclusion population of the subject steels. Close agreement between the number of calculated defects and observed defects was obtained.     

Effects of electrode configuration on electroslag remelting process of M2 high-speed steel ingot

The electrode configuration determines the thermophysical field during the electroslag remelting(ESR) process and affects the final microstructure of the ingot. In this work, ingot with a diameter of 400 mm was prepared with two electrode configuration modes of single power ESR process, namely one electrode(OE) and two series-connected electrodes(TSCE). Finite element simulation was employed to calculate the electromagnetic field, flow field and temperature field of the ESR system. The results show that the temperature of the slag pool and the metal pool of the TSCE process is lower and more uniform than that of the OE process.The calculated temperature distribution of the ingot could be indirectly verified from the shape of the metal pool by the experiment. The experimental results show that the depth of the metal pool in the OE ingot is about 160 mm, while the depth of the TSCE ingot is nearly 40 mm shallower than that of the OE ingot. Microstructural comparisons indicate that coarse eutectic carbides are formed in the center of the OE ingot, whereas more even eutectic carbides appear in the center of the TSCE ingot. In general, compared with the OE process, the TSCE process is preferred to remelt high speed steel ingots.