Effect of normalizing cooling process on microstructure and precipitates in low-temperature silicon steel

Microstructure, precipitate and magnetic characteristic of fmal products with different normalizing cooling processes for Fe-3.2%Si low-temperature hot-rolled grain-oriented silicon steel were analyzed and compared with the hot-rolled plate by optical microscopy （OM）, transmission electron microscopy （TEM）, and energy dispersive spectrometry （EDS）. The results show that, the surface microstructure is uniform, the proportion of recrystallization in matrix increases, and the banding textures are narrowed; the precipitates, whose quantity in normalized plate is more than that in hot-rolled plate greatly, are mainly A1N, MnS, composite precipitates （Cu,Mn）S and so on. Normalizing technology with a temperature of 1120 ℃, holding for 3 min, and a two-stage cooling is a most advantaged method to obtain oriented silicon steel with sharper Goss texture and higher magnetic properties, owing to the uniform surface microstructures and the obvious inhomogeneity of microstructures along the thickness. The normalizing technology with the two-stage cooling is the optimum process, which can generate more fine precipitates dispersed over the matrix, and be beneficial for finished products to get higher magnetic properties.

Effect of aluminum on secondary recrystallization texture and magnetic properties of grain-oriented silicon steel

The slab low-temperature reheating grain-oriented silicon steel was prepared in the laboratory,and the high-temperature annealing interruption tests were carried out.The effects of aluminum(which meant acid-soluble aluminum)on the grain size texture,precipitate,magnetic properties and their correlations were studied.The results showed that with the increase in aluminum element,the grain size decreased,while the intensity of{114}<481>and{111}<112>textures increased in the primary recrystallization structure.Meanwhile,the pinning force during the secondary recrystallization and the onset secondary recrystallization temperature were increased.The precipitates were concluded to have a more important role on determining the onset secondary recrystallization temperature than the primary grain size.The higher onset temperature resulted in sharper Goss texture and the better magnetic properties,but when the aluminum content came up to a certain extent,a fine-grain structure was developed.The most suitable aluminum content for present study was 0.025 wt.%,while the onset secondary recrystallization temperature and the primary texture were considered to be conducive to the sharpness of Goss texture.

Effect of Ball Scribing on Magnetic Shielding Efficiency of Grain-oriented Silicon Steel

Magnetic shielding of grain-oriented silicon steel was investigated. Ball scribing with spacing of 2 to 16 mm was performed at peak flux densities of 8.0 mT to 1.3 T. Magnetic shielding efficiency was calculated, including absorption, reflection and inner multi-reflection shielding efficiencies. Magnetic shielding efficiency （MSE） increase ratios after different scribing spacing were compared, and thickness requirement to achieve absorption shielding of 50 dB was also calculated. The results show that magnetic shielding efficiencies of C711 and H668 silicon steels increase by 4.79 and 3.15 dB respectively after scribing of 16 mm. Before scribing, shielding efficiency of H668 steel was higher than that of C711 steel, while after scribing, both absorption and shielding efficiency gaps were largely abridged between C711 and H668 steels. Plate thickness of C711 steel could be reduced from 3.18 mm without scribing to 2. 20 mm after scribing of 16 mm. There is no apparent thickness reduction at lower flux densities; while the peak flux density is above 0.3 T, the shielding effect becomes apparent, and the thickness could be reduced from 2.28 mm without scribing to 1.70 mm with scribing spacing of 16 ram. Magnetizing process and its effect on variation of magnetic shielding were also analyzed.

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.

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。

高牌号无取向硅钢生产流程中织构控制研究现状

在节能减排的背景之下,水电、风电和核电等清洁能源行业得到了快速发展。高牌号无取向硅钢是上述发电机组应用最普遍的铁芯材料。因此,开发低铁损和高磁感的高牌号无取向硅钢是清洁能源产业高质量发展的前提条件。织构是影响高牌号无取向硅钢磁感和铁损的主要因素之一,受到生产工艺的影响。然而,高牌号无取向硅钢工艺流程长,影响织构控制的工艺因素众多。为了满足高牌号无取向硅钢在低铁损时实现高磁感,在产品加工时应尽量避免对磁性能不利的{111}织构的形成,促进对其有利的{100}和{110}织构形成。本文首先介绍了高牌号无取向硅钢的工艺流程,对比了国内外钢铁企业产品的磁性能(P_(15/50)和B_(50))。其次,阐述了高牌号无取向硅钢在炼钢、热轧、常化、冷轧和成品退火过程中促进有利织构形成的影响因素。最后,归纳出能促进高牌号无取向硅钢有利织构形成的生产工艺,并对织构控制的发展方向提出了建议。

加工方式对含Cu高强度无取向硅钢力学和磁性能的影响

采用光学显微镜、电子背散射衍射、万能拉伸试验机和磁性能测量仪等研究了线切割和激光切割两种加工方式对含Cu高强度无取向硅钢组织及力学、磁性能的影响。结果表明:激光切割会使试样加工边缘晶粒粗化,而线切割则会细化加工边缘晶粒,并且影响区域均约为0.21 mm。此外,在线切割加工试样边缘还观察到应力集中现象。由于加工方式对试样晶粒尺寸及应力状态的影响,导致线切割加工试样加工边缘区域硬度值高于激光切割试样,并且抗拉强度与屈服强度均高于激光切割试样。同时,线切割加工试样磁感略低于激光切割试样,铁损显著高于激光切割试样。

“双碳”背景下新能源汽车电机用软磁材料发展趋势与应用现状

大力发展电动汽车产业进而促进节能环保,是实现双碳目标的一个重要举措。新能源汽车驱动电机在半导体和永磁材料的基础上,很难通过结构优化突破效能瓶颈。随着多学科交叉融合和跨行业协调发展,新型软磁材料的应用将是带动电机技术创新的重要手段。针对驱动电机对软磁材料的性能需求,介绍了晶粒取向硅钢、极薄无取向硅钢、高强硅钢及非晶合金4种在电机中极具应用潜力的软磁材料,并对其应用在电机中的性能表现进行了分析。结合驱动电机发展对软磁材料的需求,总结了新能源汽车电机利用软磁材料的发展和应用趋势。

低温HiB钢全流程组织、织构演变及成品磁性能

以低温高磁感取向硅钢(HiB钢)全流程生产过程中各工序段的热轧板、常化板、冷轧板、脱碳渗氮板和成品板为研究对象,采用光学显微镜、X射线衍射仪(XRD)和电子背散射衍射仪(EBSD)表征其组织与织构,分析低温HiB钢生产全流程组织与织构的演变规律,探究其对低温HiB钢成品板磁性能的影响。结果表明:低温HiB钢热轧板、常化板的组织和织构在厚度方向上存在显著差异,Goss晶粒起源于热轧板1/4次表层,热轧板与常化板的织构种类相同,仅织构强度存在差异,中心层主要织构为{118}<110>;冷轧板为纤维状变形组织,形成了较强的α纤维织构和γ纤维织构,{111}<110>的织构强度最高,为14.4;脱碳渗氮板以α^(*)纤维和γ纤维织构为主,分别集中在{114}<481>和{111}<112>处,Goss晶粒周围主要为{114}<481>和{111}<112>取向晶粒,尺寸小于其他晶粒,不具有数量和生长优势。磁性能为B_(8)≥1.89 T,P_(1.7/50)≤0.97 W/kg的成品板Goss晶粒发展完善,晶粒尺寸达到厘米级,晶界呈锯齿状,Goss织构锋锐;磁性能为B_(8)=1.83 T,P_(1.7/50)=1.27 W/kg的成品板中多为异常长大的非高斯与高斯位向偏离角较大的取向晶粒,且晶界光滑;大部分晶粒未发生二次再结晶的成品板组织为细晶组织,磁性能B_(8)=1.77 T,P_(1.7/50)=1.48 W/kg。

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。

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。

常化处理对无取向硅钢组织及磁性能的影响

利用金相显微镜、SEM&EDS和TEM研究了不同常化温度对无取向硅钢样品的组织结构和析出行为,并利用VSM研究了它们对磁性能的影响。结果表明,温度达950℃常化处理样品的晶粒发生了完全再结晶,并随着常化温度升高,晶粒逐渐长大,形成等轴晶,其成品退火板晶粒平均尺寸最大。样品中的析出相主要为AlN,并伴有少量AlN-MnS复合相。理论计算发现微米级析出相的钉扎力均小于其晶界生长的驱动力,因此析出相难以起到阻碍晶粒长大的作用。不同常化温度处理的样品的饱和磁感应强度均低于热轧板的,但随着常化温度的升高,饱和磁感应强度在950℃达到峰值。

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。

渗氮温度对低温高磁感取向硅钢氮化物析出行为的影响

采用扫描电子显微镜(SEM)、透射电子显微镜(TEM),结合能谱仪(EDS)与选区电子衍射(SEAD)对渗氮条件下低温高磁感取向硅钢析出相进行表征分析,探讨渗氮过程氮化物析出与转变的机制。结果表明:渗氮处理前,硅钢中固有氮化物以AlN,AlN+MnS与AlN+CuxS为主,尺寸分布在40~150 nm,析出相在基体中的分布较为弥散,主要在晶粒内部析出,晶界上的析出量较少;经750,900℃渗氮处理,渗氮板表层出现大量新析出的氮化物,析出相均分布于晶界及附近与晶粒内部,随渗氮温度的升高,析出相的种类与形貌更复杂多样,尺寸分布范围由50~150 nm减至20~100 nm,其中在120 nm以下析出相的分布密度由9.449×10^(8)个/cm^(2)增至1.649×10~9个/cm^(2),平均尺寸由90 nm减至55 nm,体积分数由5.55%减至3.63%;氮化物析出相沿整个渗氮板厚度方向分布不均匀,但900℃渗氮板中心层析出相的分布密度与含量明显更高,平均尺寸明显更小,提高渗氮温度可大幅改善渗氮板中的氮含量与氮化物在板厚方向上分布的均匀性;渗氮温度由750℃升高至900℃,氮化物析出种类由非晶结构富Mn的Si3N4→正交晶体结构的MnSiN2或(Si,Mn)N→(Si,Mn,Al)N或(Si,Al,Mn)N→(Al,Si,Mn)N或(Al,Si)N进行转变;渗氮温度对氮化物的热稳定性、氮原子的扩散路径与扩散系数的影响是造成氮化物种类与分布发生变化的主要原因。

新能源汽车驱动电机用无取向硅钢技术开发与应用研究

首钢智新从新能源汽车实际需求出发,自2016年起陆续攻克了高牌号无取向硅钢超低铁损及磁感提升控制技术、超高强度硅钢制造成套关键技术,成功研发出低铁损系列、高磁感系列、超高磁感系列、高强度系列、高强低铁损系列共计5个系列20余款专用无取向硅钢产品,并实现35SWYS900和25SW1250H两个牌号产品全球首发。应用研究表明,首钢智新新能源汽车驱动电机用无取向硅钢产品有助于提升驱动电机的效率、转矩和功率密度。

热轧板厚度对高牌号无取向硅钢磁性能的影响

基于高牌号无取向硅钢现场生产实验,将相同炉次的连铸板坯热轧至不同厚度(2.1,2.3,2.6 mm)的板卷,经常化均热工艺调控,获得晶粒较为均匀的常化板组织,再经85.7%~88.5%压下率冷轧,得到相同厚度(0.3 mm)的冷轧板,最终采用相同的退火工艺得到退火板;结合组织、织构和磁性能的相关检测分析,研究热轧板增厚对高牌号无取向硅钢产品磁性能的影响。结果表明:随高牌号无取向硅钢热轧板厚度的增加(在2.1~2.6 mm范围,即冷轧压下率降低),退火板组织中{111}晶粒占比提高,γ纤维织构强度逐渐增强,织构发生恶化;随热轧板厚度的增加,磁性能中铁损P_(1.0/400)线性增加,磁感强度B_(50)线性降低。热轧板厚度由2.1 mm增至2.3 mm时,P_(1.0/400)平均恶化0.20 W/kg,P_(1.5/50)平均恶化0.04 W/kg,B_(50)平均恶化0.005 T;热轧板厚度由2.3 mm增至2.6 mm时,P_(1.0/400)平均恶化0.24 W/kg,P_(1.5/50)平均恶化0.04 W/kg,B_(50)平均恶化0.009 T。

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.

高强度钢方管局部感应加热数值模拟及实验研究

为了解决高强度钢方管难变形、易开裂等成形难题,在传统冷成形工艺基础上,引入局部感应加热技术.基于矢量磁位法和物理环境法,利用ANSYS参数化设计语言建立局部感应加热电磁-温度场耦合模型.在不同加热工艺参数下进行数值模拟,并采用优化后参数进行实验研究.模拟结果表明,导磁体通过增大磁场强度,可以明显提升感应加热效率.加热频率越高,外圆角区域加热速度越快,但与内圆角区域之间的温差也越大.加热功率越高,高温区域和温度峰值越大,但外圆角区域更容易过热.实验结果表明,采用优化后的加热工艺参数,可以获得圆角半径极小、角部厚度增加且没有裂纹缺陷的高强度钢尖角方管.加热温度模拟值与实测值的误差均值约为7.57%,说明有限元模型具备良好预测精度.