Effects of Primary Annealing Condition on Recrystallization Texture in a Grain Oriented Silicon Steel

The recrystallization texture in grain oriented silicon steel sheets, which were annealed at different primary annealingtemperatures with and without an electric field, was investigated. An automated electron backscattered diffraction(EBSD) technique was used to analyze the recrystallization texture. It was found that recovery and application ofelectric field in primary annealing lead to an increase of {001} component and a decrease of {111} component afterannealing at 900℃. The development of recrystallization texture can be explained in terms of the effects of electricfield and primary annealing temperature on recovery.

STUDY ON REDUCING THE CORE LOSS OF GRAIN ORIENTED SILICON STEEL AND IMPROVING ITS AGING PROPERTY BY LASER NITRIDING TECHNIQUE IN ATMOSPHERIC AMBIENT

CW-CO2 laser nitriding technique was applied to improve the properties （such as aging property and the core loss） of grain oriented silicon steel. The samples were nitrided with regular space. Laser power density and scanning speed were chosen as 7.8×10^5W·cm^-2 and 100mm·min^-1. By some laser irradiation, Fe4N and Fe3N were formed in the nitrided zone. The nitrided samples were annealed at the temperatures ranged from 100 to 90℃. The core loss of some interested samples was tested. The results show that the core loss of the nitrided samples with different thickness of 0.23 and 0.30mm decreased by 14.9% and 9.4% respectively, and the aging property were improved up to 800℃. The mechanism of laser nitriding to improve the properties of grain oriented silicon steel is discussed.

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.

Analysis of oxide layer structure in nitrided grain-oriented silicon steel

The production of low-temperature reheated grain-oriented silicon steel is mainly based on the acquired inhibitor method.Due to the additional nitriding process,a high nitrogen content exists in the oxide layer,which changes the structure of the oxide layer.In this study,the structure of the surface oxide layer after nitriding was analyzed by scanning electron microscopy(SEM),electron back-scattered diffraction(EBSD),glow discharge spectrometry(GDS),and X-ray diffraction(XRD).The size and orientation of ferritic grains in the oxide layer were characterized,and the distribution characteristics of the key elements along the thickness direction were determined.The results show that the oxide layer of the steel sample mainly comprised particles of Fe2SiO4 and spherical and lamellar SiO2,and Fe4N and fcc-Fe phases were also detected.Moreover,the size and orientation of ferritic grains in the oxide layer were different from those of coarse matrix ferritic grains beneath the oxide layer;however,some ferritic grains exhibited same orientations as those in the neighboring matrix.Higher nitrogen content was detected in the oxide layer than that in the matrix beneath the oxide layer.The form of nitrogen enrichment in the oxide layer was analyzed,and the growth mechanism of ferritic grains during the oxide layer formation is proposed.

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.

Texture Characteristics of Thin Grain Oriented Silicon Steel Sheet Produced by Cross Shear Rolling

Commercial grain oriented silicon steel was cold rolled to thickness from 0.06 to 0.10 mm by cross shear rolling, then annealed in vacuum or a hydrogen atmosphere furnace. Deformation textures of the sheets were researched by ODF method and reverse pole figure quantitative analyses. The results indicate that: in the condition of the cross shear rolling, the deformation texture of rolled sheet is generally similar to that of conventional rolled sheet, however, the texture distribution through the thickness is asymmetrical. With mismatch speed ratio increasing, the amount of Goss texture increases. With reduction ratio increasing, the intensity of γ-fiber becomes strong.

Effect of Magnesia Blending on the Magnetic Properties of Grain Oriented Silicon Steel

Decarburized samples of grain oriented silicon steel were coated with alone and blended magnesias and submitted to the high temperature annealing. The magnesias and their blendings were characterized using granulometry measurements, ignition loss and reactivity tests. After high temperature annealing, forsterite film morphology, magnetic properties and Goss deviation were also analyzed. Better magnetic properties and sharper Goss orientation were found in samples which had used blended magnesias. These results are explained by the magnesias particle size distributions, forsterite film formation and rate of inhibitors release.

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.

Optimizing Domain Distribution of Grain Oriented Silicon Steel by Using Antimony as the Laser Surface Alloying Element

For reducing the core loss of grain oriented silicon steel and improving its aging property, a new method, the LLSA by using Sb as the laser surface alloying element, was investigated, and at proper technique conditions rather good result was obtained.

Effect of Ball Scribing on Power Loss Separation of Fe-3%Si Grain-oriented Silicon Steel

Power loss of Fe-3%Sigrain-oriented silicon steelwas measured after ballscribing with different spacing using a self-designed tool.Three different sections of power loss,including hysteresis loss,abnormalloss,and eddy current loss,were measured and calculated,respectively.The loss variation and ratio were analyzed based on the experimentaldata.At 1.0 T,hysteresis loss of tested steelwith scribing spacing of 8 mm descends by 8.2% compared to samples without scribing,which is similar to the totalloss variation,and abnormalloss descends by 16.8%.At 1.0 T,hysteresis loss ratio of the steelwith scribing spacing of 16 mm ascends from 55.7% to 57.9%,and eddy current loss increases from 17.4% to 24.1%,while abnormalloss descends from 26.9% to 23.7%.The experimentalresults show that the reduction of power loss after scribing is mainly due to decreasing of hysteresis loss and abnormalloss.

Fe-3%Si平面流铸带平整轧制退火过程中组织织构演变

采用平面流铸技术制备了Fe-3%Si无取向硅钢极薄带,研究了平面流铸Fe-3%Si薄带平整轧制与退火处理的组织织构演变规律。结果表明,平面流铸带具有大比率的柱状晶组织,{100}取向晶粒占比高于30%,也即存在对磁性能有益的{100}织构。小压下率冷轧平整过程中,晶粒取向变化及晶内取向分裂程度整体不高,形变行为存在取向依赖性。{100}取向晶粒形变储能积累程度相对较低,经退火处理后该组分体现出遗传优势,在退火组织中占比仍超过30%。退火组织中小尺寸晶粒有所增加,且绝大部分小尺寸晶粒偏离{100}取向,这导致了退火组织平均晶粒尺寸降低,并在一定程度上弱化{100}织构。

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。

取向硅钢常化及其对二次再结晶影响的研究进展

取向硅钢是重要的铁芯材料,而常化是目前生产高磁感取向硅钢不可或缺的工业生产工序,它可以调整热轧板的组织、织构和抑制剂析出从而改善硅钢磁性能。本文综述了取向硅钢热轧与常化组织的遗传性规律与常化过程中抑制剂的演变规律,重点讨论了常化对初次再结晶和二次再结晶组织与织构的影响规律,指出常化组织中细小γ-晶粒群有利于二次再结晶,而大的变形α-晶粒与λ-晶粒不利于二次再结晶。最后针对低温加热渗氮型高磁感取向硅钢推荐了能最优化磁性能的三段式常化工艺及其参数。而如何在保证获得同等织构组分与抑制剂含量的基础上进一步简化工艺以及常化工艺在薄板坯连铸连轧和薄带连铸生产取向硅钢中的合理应用将是未来常化发展的重点方向。

Goss取向铁素体钢中形变孪晶的产生行为研究

采用电子背散射衍射(EBSD)技术,研究了Goss取向铁素体钢在不同冷轧压下率(10%~34%)下形变孪晶的演变行为。结果显示,在冷轧压下率为10%的样品中观察到了形变孪晶,孪生面为{112},孪生方向为〈111〉,孪晶晶界为Σ3晶界(〈111〉60°),形变孪晶在变形初始阶段的取向为{114}〈221〉。随着冷轧压下率从10%增大至17%,Goss晶粒逐渐向{221}〈114〉取向转变,形变孪晶逐渐向{001}〈110〉取向转变。当冷轧压下率从17%继续增大至34%时,形变孪晶的取向保持{001}〈110〉,孪晶与基体逐渐偏离理论取向差关系,即孪晶界取向差角逐渐偏离60°。

取向硅钢热轧板中纤维织构及Goss织构的形成和演变

在热轧过程中,取向硅钢热轧板形成了不均匀的微观组织和织构梯度,其中热轧板表层和次表层中的Goss织构对取向硅钢的磁性能有重要影响。因此,热轧板微观组织和织构沿厚度方向的形成和演变,特别是Goss织构的形成,仍然是一个值得讨论的课题。为了研究热轧板组织和织构的形成及其演变,使用光学显微镜和扫描电镜(SEM-EBSD)观察了热轧板不同厚度层(表层、次表层和中心层)组织,研究了热轧板组织形貌沿厚度方向的演变,并使用XRD测量了热轧板各厚度层(从表层s=1到中心层s=0)的宏观织构。结果表明,在高剪切力的作用下,热轧板表层s=1形成了大量等轴晶粒(晶粒长宽比为1.0~1.5)和具有一定随机性的织构。表层以下,随着剪切力从表层向中心层逐渐减小,等轴晶粒(晶粒长宽比为1.0~1.5)占比逐渐降低,再结晶晶粒的晶粒长宽比沿着厚度方向逐渐增大,再结晶晶粒形状倾向于沿轧向延伸和呈不规则状。最后,在中心层s=0中,一些大尺寸再结晶晶粒的晶粒长宽比可以达到3.0~6.5。在压缩力和沿厚度方向逐渐减小的剪切力的共同作用下,热轧板次表层s=0.5~0.9形成由众多特定取向组成的纤维织构,而中心层s=0~0.4形成典型的α纤维织构,纤维织构中的一些典型的特定位向包括{100}〈011〉、{112}〈111〉、{110}〈112〉、{213}〈364〉、{441}〈104〉和{110}〈100〉Goss。热轧板次表层s=0.5~0.9中的纤维织构沿厚度方向逐渐演变,并且在次表层s=0.5中有稳定的Goss织构形成。然而,次表层s=0.5中形成的高强度的Goss织构,而次表层中形成的Goss织构只是纤维织构的一小部分。

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。

取向硅钢生产技术发展

介绍了取向硅钢生产技术发展历程及特点,重点阐述了渗氮法取向硅钢生产技术控制原理,诠释了锋锐的Goss{110}<001>织构选择生成、定向遗传、择优长大的择优环境是抑制剂近恒量,本质是先天抑制剂AlN近恒量、后天渗氮形成的AlN近恒量,结合Goss织构的定向遗传完成了二次再结晶。

高磁感取向硅钢Goss织构形成机制的研究进展

基于Goss织构异常长大可获得良好磁性能和工业生产高磁感取向硅钢产品工艺流程的背景,系统分析了Goss织构异常长大理论研究进展,着重剖析了Goss织构异常长大选择生成、定向遗传、择优长大的机制,阐述了抑制力近恒量取向硅钢生产技术的特征,为取向硅钢生产工艺技术提供理论支撑。

热轧加热对无取向硅钢中AlN和MnS析出相的影响

AlN和MnS等析出相对无取向硅钢的磁性能有重要影响,受热轧加热工艺影响,无取向硅钢中的析出相与免常化工艺实现的效果紧密相关。以1.5%Si-0.3%Al无取向硅钢锻造坯为研究对象,利用热力学软件计算钢中可能的析出相,使用箱式电阻炉在不同温度和保温时间下对实验钢进行热轧加热实验,利用光学显微镜(OM)、扫描电子显微镜(SEM)表征分析析出相的形貌、尺寸及样品晶粒尺寸,研究热轧加热温度和保温时间对实验钢中AlN和MnS析出相的影响。结果表明:实验钢中夹杂物主要为AlN和MnS,当加热温度为1050℃时,保温时间由1h延长至3 h,细小的AlN和MnS析出相(直径小于1μm)占比由33%降至19%,平均晶粒尺寸从100.0μm增加到149.7μm;保温时间为1h时,加热温度由1050℃提高至1150℃,细小的AlN和MnS析出相占比由33%降至7%,平均晶粒尺寸从100.0μm增加到124.3μm。不改变其他实验条件,热轧加热温度的提高与保温时间的延长都会使实验钢中AlN和MnS析出相与晶粒尺寸变大,有利于绿色低碳的无取向硅钢免常化生产工艺的实现。