稀土Y微合金化6.5%Si高硅钢增韧增塑机制及磁性能优化调控机理

6.5% Si high-silicon steel has a broad application prospect in the field of energy conservation, noise reduction and other fields, because of its low core loss, high permeability, and near-zero magnetostriction. However, the brittleness of the material at room temperature caused by the ordering transformation hinders its production and application. At present, the preparation of high silicon steel sheet has made great progress based on the "gradual toughening and plasticizing rolling method" , but the toughness, plasticity and magnetic properties still need to be improved. Considering the rare earth (RE) with deep purification of molten steel, deterioration of harmful inclusions and its unique micro-alloying effect, this project intends to improve the toughness, plasticity and magnetic properties of high-silicon steel by adding yttrium (Y). The effects of Y on the modification, microstructure evolution, mechanical and magnetic properties of high-silicon steel will be studied by means of thermodynamic software calculation and advanced analysis testing technology. The mechanism of toughening and plasticizing, the effect of Y on the texture evolution of the high-silicon steel and the relationship between Y and the magnetic properties of high-silicon steel will be clarified, and theoretical models will be established. The optimization mechanism of the magnetic properties of Y micro-alloyed high-silicon steel will be clarified, which provides theoretical support for the development of RE micro-alloyed high-silicon steel sheet with better magnetic properties.

6.5%Si高硅钢具有低铁损、高磁导率和近乎为零的磁致伸缩系数的优异软磁性能，在节能降噪等领域具有广阔的应用前景。然而材料本身有序化转变所造成的室温脆性阻碍了其生产与应用。目前基于“逐步增韧增塑轧制法”制备高硅钢薄带虽取得了长足进步，但其韧塑性与磁性能仍有待提高。稀土具有深度净化钢液，变质有害夹杂物及微合金化作用，本项目拟通过在6.5%Si高硅钢添加微量稀土Y元素，旨在改善韧塑性并提高磁性能。基于热力学计算及先进分析测试技术，系统研究稀土Y对高硅钢夹杂物改性、微观组织结构演变、力学性能及磁性能的影响，探明含稀土Y高硅钢有序结构无序化与晶界强化协同作用下的增韧增塑机制，揭示稀土Y对高硅钢形变与再结晶组织织构遗传演变的影响规律，澄清稀土Y元素特性与高硅钢磁性能内在关联性并建立理论模型，阐明稀土Y微合金化高硅钢磁性能优化调控机理，为开发磁性能优良的稀土微合金化高硅钢薄板带制备技术提供理论支撑。

6.5wt%Si高硅钢具有低铁损、高磁导率和近乎为零的磁致伸缩系数的优异软磁性能，在节能降噪等领域具有广阔的应用前景。然而材料本身有序化转变所造成的室温脆性阻碍了其生产与应用。鉴于稀土具有深度净化、变质有害夹杂及微合金化作用，本项目通过添加微量稀土Y，改善了高硅钢韧塑性并提高了磁性能。基于逐步增韧增塑轧制法制备高硅钢薄板带，系统研究了稀土Y对高硅钢夹杂物改性、微观组织结构演变、力学性能及磁性能的影响。研究结果表明，Y 在高硅钢中主要以Y2O2S、Y2O3等稀土夹杂物形式存在，含0.0056~0.023wt% Y合金基体中S和O含量明显下降，随着Y含量继续增加，稀土夹杂物数量明显增多，作为异质形核剂起细化晶粒作用。高温拉伸及热变形行为研究结果表明，稀土Y微合金化高硅钢韧塑性有显著提高，主要是因为稀土添加导致高硅钢有序结构无序化、位错密度提高导致有序畴细化，阻碍了微裂纹扩展，对塑性提高起到了关键作用。Y对高硅钢形变与再结晶组织织构演变的影响研究表明，添加微量稀土Y可以促进高硅钢温轧及冷轧过程中剪切带变形，进而有利于退火过程中剪切带形核，对磁性能有利；Y含量增加至0.03wt%时，细小弥散的稀土Y氧化物阻碍晶界迁移，导致高硅钢再结晶晶粒细化，同时γ取向晶粒形核增多，对磁性能不利。Y含量对高硅钢磁性能影响研究结果表明，随着Y含量增加，高硅钢退火成品板磁感值先增加后降低，50~1000 Hz频率下铁损值先降低后升高。最终得到高硅钢中最合适的稀土Y含量为0.012wt%，获得了通过添加微量稀土Y促进剪切带形核的组织织构优化策略，可为开发新一代磁性能优良的高硅钢薄板制备技术提供理论支撑与实践指导。本项目研究成果为重稀土元素Y在电工钢中的应用提供基础实验数据，对于开拓高牌号无取向电工钢成分设计思路、调整产品的品种结构和提高产品性能具有较大的理论和实践意义。