6.5 wt%Si high silicon steel sheets prepared by composite electrodeposition in magnetic field

A new preparation method of near-net-shape 6.5 wt% Si high silicon steel sheets was proposed by combining composite electrodeposition(CED) and diffusion annealing under magnetic field. The obtained sheets were characterized by scanning electron microscopy, energy dispersive spectrometry, analytical balance and a silicon steel material measurement system. The results show that the surface morphology,the elemental distribution, the cathode current efficiency and the silicon content of coatings were obviously influenced by the micro and macro magnetohydrodynamics(MHD) flows under magnetic field.With the effect of magnetic field, the silicon particles content of coatings showed an increasing trend and the diffusion process showed that an approximately uniform 6.5 wt% silicon steel sheet has been successfully obtained. The magnetism measurement showed that the high silicon steel sheet has the lower iron loss, and the iron loss further decreased under magnetic field. The new method proposed in this article,which is more environmentally friendly and low energy consumption, is feasible to prepare high silicon steel sheets.

Characterization of Microstructure and Texture in Grain-Oriented High Silicon Steel by Strip Casting

Grain-oriented 4.5 wt% Si and 6.5 wt% Si steels were produced by strip casting, warm rolling, cold rolling, primary annealing, and secondary annealing. Goss grains were sufficiently developed and covered the entire surface of the secondary recrystallized sheets. The microstructure and texture was characterized by OM, EBSD, TEM, and XRD. It was observed that after rolling at 700 ℃, the 6.5 wt% Si steel exhibited a considerable degree of shear bands, whereas the 4.5 wt% Si steel indicated their rare presence. After primary annealing, completely equiaxed grains showing strong y-fiber texture were presented in both alloys. By comparison, the 6.5 wt% Si steel showed smaller grain size and few favorable Goss grains. Additionally, a higher density of fine precipitates were exhibited in the 6.5 wt% Si steel, leading to a ~ 30-s delay in primary recrystallization. During secondary annealing, abnormal grain growth of the 6.5 wt% Si steel occurred at higher temperature compared to the 4.5 wt% Si steel, and the final grain size of the 6.5 wt% Si steel was greater. The magnetic induction B8 of the 4.5 wt% Si and the 6.5 wt% Si steels was 1.75 and 1.76 T, respectively, and the high- frequency core losses were significantly improved in comparison with the non-oriented high silicon steel.

Preparing High Silicon Steel by Sintering Fe-6.5%Si Powder Compacts in Static Magnetic Field

In this research,sintering Fe-6.5wt%Si Compact specimen in static magnetic field is proposed for preparing high silicon steel.It is found that the densifications of the compacts are affected remarkably by superimposing magnetic field.The density of the compacts can be increased when the MFD is higher than 0.2 T.The highest relative density of the samples is 97.2%.The magnetic property of silicon steel could be improved when superimpose static magnetic field in sintering process,the permeability of the compact are two times of that without magnetic field,and the magnetic property parallel to the direction of the magnetic field was evidently higher than that in perpendicular direction.

Punchability and Punching Fracture Behavior of High Silicon Steel Sheets

The 0.2-0.3mm thick cold-rolled sheets and annealed sheets of high silicon steel were produced by rolling process,then punching tests were carried out at room temperature to 150℃.The punchability and punching fracture behavior were investigated by means of scanning electron microscope（SEM）and electron back-scattered diffraction（EBSD）.It is found that cold-rolled sheets of high silicon steel show good punchability under the condition of 0.01 mm punch-die clearance and at the temperature of 100℃;the punchability of annealed sheets with fine grain size is better than that of annealed sheets with coarse grain size;the punching temperature of 150℃is suitable for annealed high silicon steel sheets especially with coarse grain size on account of punching edge quality.The major cleavage planes of annealed high silicon steel sheets are{100}crystallographic planes on which brittle fracture occurs at low temperatures.The cleavage systems include{100}〈110〉and{100}〈100〉,and cleavage fracture is completed by one or both of them.The punchability of high silicon steel sheets is related with punching temperature,grain size and ordering degree.Reducing ordering degree,increasing punching temperature,as well as refining grain size can improve the ductility and punchability of high silicon steel sheets.

Microstructure and mechanical properties of a new type of austempered boron alloyed high silicon cast steel

In the present paper, a new type of austempered boron alloyed high silicon cast steel has been developed, and its microstructures and mechanical properties at different temperatures were investigated. The experimental results indicate that the boron alloyed high silicon cast steel comprises a dendritic matrix and interdendritic eutectic borides in as-cast condition. The dendritic matrix is made up of pearlite, ferrite, and the interdendritic eutectic boride is with a chemical formula of M2B (M represents Fe, Cr, Mn or Mo) which is much like that of carbide in high chromium white cast iron. Pure ausferrite structure that consists of bainitic ferrite and retained austenite can be obtained in the matrix by austempering treatment to the cast steel. No carbides precipitate in the ausferrite structure and the morphology of borides remains almost unchanged after austempering treatments. Secondary boride particles precipitate during the course of austenitizing. The hardness and tensile strength of the austempered cast steel decrease with the increase of the austempering temperature, from 250 oC to 400 oC. The impact toughness is 4-11 J?cm-2 at room temperature and the impact

Pulsed Nd:YAG laser cladding of high silicon content coating on low silicon steel

A pulsed Nd：YAG （yttrium aluminum garnet） laser-based technique was employed to clad low silicon steel with preplaced Si and Fe mixed powders for high Si content. The surface morphology, microstructural evolution, phase composition, and Si distribution, within the obtained cladding coatings, were characterized by optical microscopy （OM）, field emission scanning electron microscopy （FE-SEM）, with associated energy dispersive spectroscopy （EDS）, transmission electron microscopy （TEM）, and X-ray diffraction （XRD）. The microhardness was also measured along the depth direction of the specimens, A crack- and pore-free cladding coating through excellent metallurgical bonding with the substrate was successfully prepared on low silicon steel by means of optimized single-track and multi-track laser cladding. The phases of the coating are a-Fe, T-Fe, and FeSi. The high microhardness of the lasercladding zone is considered as an increase in Si content and as the refined microstructure produced by the laser treatment. The Si contents of the cladding coatings were about 5.8wt% in the single-track cladding and 6.5wt% in the multi-track cladding, respectively.

Development of top high-grade non-grain-oriented silicon steels at Baosteel

The development, production and application of top high-grade non-grain-oriented （NGO） silicon steels at Baosteel were introduced in this paper. Top high grades refer to the highest grades in the intemational silicon steel product standard and above. B35A230 and B50A250 were developed at Baosteel in 2009 and have been used in inverter compressors for air-conditioners, small transformers and big hydropower generators in the Three Gorges project. Small- batch production of B35A210 and B50A230, which exceed the highest grades listed in the intemational silicon steel product standard,began in 2010. That was a breakthrough in the silicon steel making history in China. Presently,Baosteel＇ s high- grade NGO products have passed the strict qualifications of the three major electric power equipment manufacturers in China and the leading international power equipment suppliers like ALSTOM, GE, SIEMENS, VESTAS, etc. These products are characterized by low iron loss, low anisotropy, good punchability and a high lamination factor. They have been used in the 770 MW hydropower generator at Xiluodu Power Station in the three gorges area, 1 000 MW thermal power generators and 2.5 MW wind power generators.

Recent progress of high silicon electrical steels

This paper summarized recent progress of high silicon grain-oriented and non-oriented electrical steels. Technical development in composition adjustment, inclusion control and process optimization was introduced, and future development trend was explored. In addition, a brief introduction was provided to technical progress of high silicon thingauge strips with a Si content of 6.5%.

In-situ SEM observation on fracture behavior of austempered silicon alloyed steel

Crack initiation, propagation and microfracture processes of austempered high silicon cast steel have been investigated by using an in-situ tensile stage installed inside a scanning electron microscope chamber. It is revealed that micro cracks always nucleate at the yielding near imperfections and the boundary of matrix-inclusions due to the stress concentration. There are four types of crack propagations in the matrix: crack propagates along the boundary of two clusters of bainitic ferrite; crack propagates along the boundary of ferrite-austenite in bainitic ferrite laths; crack propagates into bainitic ferrite laths; crack nucleates and propagates in the high carbon brittle plate shape martensite which is transformed from some blocky retained austenite due to plastic deformation. Based on the observation and analysis of microfracture processes, a schematic diagram of the crack nucleation and propagation process of high silicon cast steel is proposed.

硅含量对9Cr-1.5W钢在550℃下蠕变性能的影响

在550℃下对硅质量分数分别为0.34%,0.60%,0.90%的9Cr-1.5W钢进行拉伸试验以及不同应力下的蠕变试验,研究了硅含量对试验钢高温拉伸性能和蠕变性能的影响。结果表明:随着硅含量的增加,试验钢在550℃下的屈服强度和抗拉强度均降低,但断后伸长率增大,应变硬化指数先升后降,含质量分数0.60%硅的试验钢具有最大的应变硬化指数;含质量分数0.60%硅的试验钢在不同应力下均具有较长的蠕变时间,表现出最佳的高温蠕变性能,应力指数最小,最小蠕变速率对外加应力敏感性最低;试验钢的蠕变行为均受位错攀移控制。

喷嘴尺寸对Fe-6.5 %Si高硅钢薄带组织和性能的影响

研究了快速凝固单辊甩带过程中喷嘴尺寸(Φ2 mm、Φ1.5 mm、Φ1 mm和Φ0.7 mm)对Fe-6.5%Si高硅钢薄带组织和性能的影响。结果表明,随着喷嘴尺寸的减少,有序相减少,薄带的连续长度明显提高,而薄带的厚度和宽度减小,晶粒尺寸减小,显微硬度也随之减小。薄带饱和磁化强度(M s)随着喷嘴尺寸的减小逐渐变小,而矫顽力(H c)逐渐变大,但磁性能总体变化不大。在Φ1 mm喷嘴下制得的高硅钢薄带质量较好。

高硅钢不同脱氧工艺下精炼渣系控制

针对“转炉→RH精炼→连铸”工艺流程生产的高硅钢精炼渣精准控制的难题,借助FactSage7.2商业热力学计算软件,计算了两种不同脱氧工艺下合理的精炼渣系控制范围。采用A脱氧工艺(铝脱氧硅合金化工艺)时,合理精炼渣系控制范围为氧化钙含量为53%~55%,二氧化硅含量在15%~18%,三氧化二铝含量为25%~30%,氧化镁含量为3%~5%,碱度为3~5;采用B脱氧工艺(硅脱氧铝合金化工艺)时,合理的精炼渣系的主要成分范围为:氧化钙含量为53%~56%,二氧化硅含量为12%~17%,三氧化二铝含量为25%~30%,氧化镁含量为3%~5%,碱度为3~4.5。采用工业两种对不同脱氧工艺精炼渣系吸附夹杂能力进行分析,结果表明B脱氧工艺下夹杂物数量、尺寸分布方面均优于A脱氧工艺。

Cu对含Ce高强高效无取向硅钢磁性能的影响

无取向硅钢作为新能源汽车电机系统的核心部件材料,要求其磁性能和力学性能同时优异,但两者往往不能兼顾。如何获得强度和磁性能的良好匹配是高性能无取向硅钢需要解决的关键问题之一。对此,本工作通过Cu、Ce合金化研制了高强高效无取向硅钢样品,但是,目前Cu在硅钢中的作用尤其是对磁性能的影响机理尚不十分明确。因此,本工作采用光学显微镜、扫描电镜、背散射电子衍射和透射电镜等方法研究了Cu对含Ce高强高效无取向硅钢磁性能的影响及机理。结果表明,适量Cu的添加在显著提高强度的情况下同时降低高频铁损,较多Cu的添加使磁感降低、铁损升高。这主要是因为,适量的Cu以富Cu相析出,具有尺寸小、分布分散等特点,一方面促使再结晶的发生,提高晶粒均匀性,并且高温再结晶退火过程中Cu以固溶形式存在不会明显阻碍晶粒长大,对磁性能有利;另一方面促使有利织构的产生,抑制不利织构出现,提高磁感,从而在一定程度上抵消富Cu析出相阻碍磁畴转动对磁性能的不利影响。Cu含量较高时,富Cu析出相不仅尺寸较大,而且形态呈长条状或短棒状,恶化了磁性能。

稀土处理对高牌号无取向硅钢中夹杂物的影响

通过工业试验研究了不同稀土含量对高牌号无取向硅钢中夹杂物的影响。研究结果表明,当稀土质量分数为0.0021%时,稀土元素主要形成(La,Ce)AlO_(3)夹杂物,从而进行脱氧、变质钢中Al_(2)O_(3)夹杂物;随着钢中稀土含量的增加,稀土主要形成以(La,Ce)AlO_(3)-(La,Ce)_(2)O_(2)S类和(La,Ce)_(2)O_(2)S类稀土夹杂物,主要降低了钢中硫化物的析出量,但是此时生成的稀土夹杂物对钢中大量温降过程析出和二次氧化产生的Al2O3类夹杂物的改性作用较弱,这导致稀土含量高时钢中Al_(2)O_(3)夹杂物的数密度明显增加。此外,夹杂物长宽比的统计结果表明,稀土处理使铸坯中夹杂物发生明显球化,但在随后的热轧工序中,常规处理与稀土处理的热轧板中夹杂物的平均长宽比差异较小。即在工业生产实际中,稀土处理对成品组织中的夹杂物的长宽比影响很小,影响夹杂物长宽比的主要因素主要是轧制过程的相关工艺参数。

3.3%Si高强无取向电工钢再结晶组织演变及其对性能的影响

探究3.3%Si高强无取向硅钢再结晶组织与织构的演变及其对磁性能与力学性能的影响规律与机理。借助光学显微镜,扫描电镜分析冷轧-退火在不同阶段再结晶组织与织构,利用磁性能设备测试铁损与磁感应强度,万能拉伸试验机测试力学性能。结果表明,3.3%Si高强无取向硅钢冷轧后组织沿轧向呈纤维状分布,主要织构是{001}<110>织构,在900℃退火30s发生部分再结晶,随着退火时间的延长,纤维状组织消失,得到等轴状铁素体,晶粒尺寸由7.8μm增大到25.1μm,{111}<112>与{111}<110>织构逐渐增强,退火时间为240s时,形成了较强的{114}<481>织构,该织构能对织构有一定的抑制作用。实验钢在900℃退火120s时,磁性能与力学性能均最佳,屈服强度为527MPa,高频铁损P_(1.0/400)为18.79W/kg,磁感应强度B_(5000)为1.644T。

取向硅钢高温退火工艺研究进展

高温退火是冷轧取向硅钢生产过程中的重要工序,几十年来,许多从业者在这一领域进行了大量的研究工作,并取得诸多进展。本文根据取向硅钢高温退火工艺的特征,结合国内外研究,对取向硅钢高温退火设备、工艺和组织生长机理等方面进行了总结,并提出高温退火今后有待进一步研究的部分方向。

高温环形退火炉内罩压力控制研究

详述了硅钢高温环形退火炉旋转周期内及旋转前后内罩压力控制系统工作原理。根据操作人员在实际生产过程中的操作经验和生产中遇到的一些实际情况进行分析,对现场操作遇到的问题进行梳理,并制定内罩压力预检测控制法和操作规范,实现高温环形退火炉内罩压力全自动预警技术,有效提高了内罩压力合格率。

大功率低速直驱电机电磁特性对比分析

针对大功率低速直驱电机,对其电磁特性进行对比研究,以设计的一台36槽30极极槽数相近的大功率低速直驱电机为例,在空载和负载两种状态下,对比不同定子硅钢材料对该种电机的电磁特性及效率的影响。有限元分析表明,采用取向硅钢定子材料的大功率低速直驱永磁电机与常规硅钢定子材料的该种电机相比,电磁特性更优,空载时取向硅钢材料会削弱齿部饱和现象,负载时提高了电机的输出转矩,降低了电动势波形畸变率;降低了永磁体涡流损耗幅值,两部电机效率相差不大,为该类电机工程上实际生产提供参考。

Improving Corrosion Resistance of Stainless Steel by Yttrium Addition: An AES Analysis

The influence of Y addition on the distribution of element concentrations in the passive film of high silicon stainless steel formed in 93% H2SO4 was comparatively studied by using auger electron spectroscopy (AES). The results show that 0.2%Y addition increases the SiO2 proportion in the passive film of stainless steel so that the formation of SiO2 enriched passive film from silicon in the alloy is brought into full play.

新能源汽车驱动电机用高强无取向硅钢力、磁性能调控研究进展

新能源汽车能够有效缓解传统汽车行业对化石燃料的严重依赖和全球所面临的环境问题,是未来发展的必然趋势.驱动电机作为新能源汽车的动力核心,不仅需要具有优异的磁性能提高能源转换效率,同时需要具有高强度来抵抗高速运转时的离心力.然而,无取向硅钢的强度和磁性能难以兼顾,因此无取向硅钢力、磁性能的协同调控是新能源汽车驱动电机发展过程中的一个关键科学问题.本文综述了国内外有关高强无取向硅钢力学性能和磁性能调控的相关研究现状,分析了不同强化方式对无取向硅钢磁性能的影响,指出了新能源汽车驱动电机用高强无取向硅钢力学性能和磁性能协同调控的未来发展趋势,即多种强化方式共同作用或利用细小弥散的纳米共格析出相实现高强无取向硅钢力、磁性能的最佳匹配,为新能源汽车驱动电机用高强无取向硅钢的发展提供借鉴.