Primary Recrystallization of Grain Oriented Silicon Steel Strip Rolled by CSR and Annealed in Magnetic Field

The magnetic properties and textures of grain oriented silicon steel with different thickness rolled by cross shear rolling （CSR） of different mismatched speed ratio （MSR） and annealed in magnetic field under hydrogen were presented.Effects of the factors such as thickness and mismatched speed ratio on the magnetic properties and recrystallization texture were analyzed and the recrystallization principles in magnetic field annealing were discussed. The study would provide a new route for mass production of high quality ultra-thin grain oriented silicon steel strip.

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.

New process for production of ultra-thin grain oriented silicon steel

The Hi-B silicon steels were cold rolled by cross shear rolling (CSR) with different mismatch speed ratio(MSR)s and conventional rolling(CR) respectively, followed by primary recrystallization annealing. The effects of MSR and annealing temperature on magnetic properties of ultra-thin grain oriented silicon steel were analyzed. Experimental results show that, with the increase of MSR, the magnetic properties can be remarkably improved. The higher the annealing temperature is, the higher the magnetic induction and the lower the iron loss in ultra-thin silicon steel is.

The Mechanism of Heating Rate on the Secondary Recrystallization Evolution in Grain Oriented Silicon Steel

Grain-oriented silicon steels were prepared at different heating rates during high temperature annealing,in which the evolution of magnetic properties,grain orientations and precipitates were studied.To illustrate the Zener factor,the diameter and number density of precipitates of interrupted testing samples were statistically calculated.The effect of precipitate ripening on the Goss texture and magnetic property was investigated.Data indicated that the trend of Zener factor was similar under different heating rates,first increasing and then decreasing,and that the precipitate maturing was greatly inhibited as the heating rate increased.Secondary recrystallization was developed at the temperature of 1010℃when a heating rate of 5℃/h was used,resulting in Goss,Brass and{110}<227>oriented grains growing abnormally and a magnetic induction intensity of 1.90T.Furthermore,increasing the heating rate to 20℃/h would inhibit the development of undesirable oriented grains and obtain a sharp Goss texture.However,when the heating rate was extremely fast,such as 40℃/h,poor secondary recrystallization was developed with many island grains,corresponding to a decrease in magnetic induction intensity to 1.87 T.At a suitable heating rate of 20℃/h,the sharpest Goss texture and the highest magnetic induction of 1.94 T with an onset secondary recrystallization temperature of 1020℃were found among the experimental variables in this study.The heating rate affected the initial temperature of secondary recrystallization by controlling the maturation of precipitates,leading to the deviation and dispersion of Goss texture,thereby reducing the magnetic properties.

Goss Texture Evolution of Grain Oriented Silicon Steel by High-Energy X-ray Diffraction

High energy synchrotron diffraction offers great potential to study the recrystallization kinetics of metallic materials. To study the formation of Goss texture （{ [10}（001）） of grain oriented （GO） silicon steel during secondary recrystallization process, an in situ experiment using hi gh energy X-ray diffraction was designed. The results showed that the secondary recrystallization began when the heating temperature was 1,494 K, and the grains grew rapidly above this temperature. With an increase in annealing temperature, the large grains with 7 orientation [〈111〉//normal direction] formed and gradually occupied the dominant position. As the annealing temperature increased even further, the grains with Goss orientation to a very large size by devouring the 7 orientation grains that formed in the early annealing stage. A single crystal with a Goss orientation was observed in the GO silicon steel when the annealing temperature was 1,540 K.

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.

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.

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.

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。

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。

不同厚度低温渗氮型取向硅钢初次再结晶组织、织构差异分析

以0.27 mm、0.23 mm和0.20 mm三种厚度且磁性能都较好的取向硅钢样品为研究对象,通过EBSD技术对其对应的初次再结晶晶粒尺寸及织构进行研究,从而探索不同板厚度对应的最佳初次再结晶组织和织构是否存在异同。结果表明:三种厚度对应的最佳一次再结晶晶粒平均尺寸均在20~22μm范围内,沿板厚侧面的平均晶粒尺寸基本接近,约为21.4μm;0.27 mm的中心层区域的平均晶粒尺寸比表层更大,而随厚度继续减小,表层和中心层平均晶粒尺寸逐渐接近。随板厚度的减小,初次再结晶织构增强,主要织构{114}〈481〉、{111}〈112〉以及{100}〈021〉织构均在一定程度上增强,其中{114}〈481〉织构的强度又显著高于其他织构;{114}〈481〉组分面积百分比增加,Goss以及{210}〈001〉组分减少。在这三种厚度样品中,表层区域的Goss、{210}〈001〉和{114}〈481〉组分比例都高于中心层,{100}〈021〉以及黄铜组分比例都低于中心层。随着厚度的减薄,表层和中心层区域的{114}〈481〉、{111}〈112〉织构以及中心层区域的{100}〈021〉织构都明显增强。

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。

时效轧制温度对低温取向硅钢组织、织构及磁性能的影响

通过在不同温度下保温5 min的时效轧制实验,研究了时效轧制温度(150、200、250、300℃)对低温取向硅钢组织、织构及磁性能的影响。结果表明,时效轧制温度对低温取向硅钢的冷轧及初次再结晶组织形貌没有明显的影响。但随着时效轧制温度的升高,初次再结晶组织中{111}<112>和Goss织构含量均先增加后减少,{111}<112>织构在200℃时具有较高的含量,Goss织构在250℃时含量较高,此时{411}<148>和{100}<012>初次再结晶织构的占比相对较低。初次再结晶组织中,有利的Goss及{111}<112>织构含量增加和不利的{100}<012>织构含量减少,使得试样在高温退火过程中能够发生较完善的二次再结晶,经高温退火后,细小晶粒及岛状晶粒较少,成品板具有优异的磁性能。

“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。

耐热型取向硅钢涂层特性与磁性能

本工作对耐热型取向硅钢薄板进行了分析,研究了退火温度对其涂层的影响,探索了复杂工况条件、拉应力及压应力对薄板磁性能的影响规律。结果表明:选取的耐热型取向硅钢薄板涂层附着性为C级和D级,涂层包含绝缘涂层和硅酸镁底层,刻痕区硅酸镁底层被严重破坏。退火对耐热型取向硅钢涂层表面绝缘电阻无明显影响,但影响涂层的附着性,耐热型取向硅钢带材表面的绝缘涂层不具备耐热性。过励磁与直流偏磁工况比谐波工况对带材损耗、噪声、磁致伸缩的影响更为明显。压应力对耐热型取向硅钢磁性能、噪声均产生不利的影响,而拉应力在一定范围内对损耗具有降低作用,同时不影响噪声。

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。

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。