铌的碳氮化物对取向硅钢轧制与退火过程中Goss织构和磁性能的作用机理

In this project, the grain oriented silicon steel with niobium by low slab reheating temperature technique will be investigated in order to obtain high magnetic induction oriented silicon steel. On the basis of the existing research results, through optimizing the preparation process and inhibitor composition of the grain oriented silicon steel with niobium, as the object, Goss texture of high orientation degree will be obtained. And, ultimately, the inhibitor program and critical process parameters of the grain oriented silicon steel with niobium will be determined which is suitable for the low slab reheating temperature process. This project will reveal the influence of decarburization annealing process on the decarburization effect of silicon steel with Nb. And also the effects of the changes of niobium carbonitride in decarburization annealing process on the grain boundary character and of primary recrystallization will be studied. The influence of inhibitor behavior and grain boundary character on the abnormal growth of Gauss orientation grains during the high temperature annealing will be investigated. And the adjustment principle and method for refinement of primary recrystallization, stabilization of microstructure and optimum decarburization effect will be obtained. This project will reveal the influence of the evolution behavior of niobium carbonitride during high temperature annealing on the abnormal growth of Gauss orientation grains in the secondary recrystallization process. The mechanism of interaction of inhibitors, process parameters, Goss texture and magnetic properties will be expounded. The results of this research can provide theoretical basis and technical support for the engineering application of grain oriented silicon steel with niobium by low slab reheating temperature technique.

本项目以含铌取向硅钢铸坯低温加热制备高磁感取向硅钢为研究目标，在已有研究成果的基础上，通过优化与调控含铌取向硅钢的抑制剂组成及制备工艺，达到获得高取向度Goss织构的目的，并最终确定适合含铌取向硅钢铸坯低温加热特点的抑制剂方案和关键工艺参数。主要通过研究脱碳退火工艺对含铌硅钢脱碳效果的影响规律，以及铌的碳氮化物在脱碳退火过程中的转变规律与初次再结晶晶界特征和晶界演变规律的关系，抑制剂行为及晶界特征的交互作用对高温退火过程中形成的高斯取向晶粒异常长大的影响，寻求初次再结晶组织细化、微结构组织稳定及脱碳效果好的调控原理和方法；揭示含铌取向硅钢高温退火过程中铌的碳氮化物行为对二次再结晶中高斯取向晶粒异常长大的影响规律；阐明含铌低温取向硅钢抑制剂组成-工艺参数-Goss织构-磁性能之间的相互作用规律。本项目研究成果可为含铌低温取向硅钢的实际工程应用提供理论基础和技术支撑。

本项目以含铌取向硅钢铸坯低温加热制备高磁感取向硅钢为研究目标，通过优化与调控含铌低温取向硅钢的抑制剂组成及其制备工艺，实现铸坯的加热温度低于1250℃，并获得高磁感应强度、低铁损的低温取向硅钢。. 通过实验研究与热力学模拟计算，揭示了含铌取向硅钢抑制剂的固溶与析出行为，确定了适合铸坯低温加热特点的抑制剂组成。研究发现，取向硅钢中加入铌元素可显著降低AlN的开始析出温度，当C含量由0.056%降低至0.042%时，Nb含量可以提高至0.055%，且Nb(N，C)、AlN和（Cu，Mn）S抑制剂的全固溶温度均在1250℃以下。通过研究热轧参数对热轧组织与织构以及冷轧工艺对冷轧织构的影响规律，确定了热轧加热温度为1220℃时，采用后道次大压下率轧制得到的热轧板，沿板厚方向组织不均性最显著，其中间过渡层上{110}<001>Goss织构的强度最强，{100}<011>旋转立方织构强度最弱。将热轧板进行常化处理后分别进行一次冷轧和二次冷轧，发现二次冷轧{111}<112>织构和{114}<841>织构含量均大于一次冷轧，而二次冷轧旋转立方织构{001}<110>含量小于一次冷轧织构，因此二次冷轧工艺要更优于一次冷轧工艺。. 将采用二次冷轧工艺生产的第一次冷轧板试样在25%H2和75%N2气氛下快速加热至850C保温5min，在此工艺进行中间退火得到的高迁移率的高能晶界和大角度晶界含量最高，且初次再结晶晶粒细小均匀，基体中大多为对二次再结晶有利的{411}<148>织构和{111}<112>织构。将中间退火板进行第二次冷轧和回复处理后进行高温退火，将试样以一定的的升温速率加热到1200℃，保温10h，再以一定的降温速率降到600℃，最后随炉冷却至室温，得到的最终成品板中Goss织构的锋锐度很高，位向精准，磁感应强度B800值最高，达到1.9T，铁损P1.7/50值最低，为1.32W/kg。本研究成果通过优化取向硅钢抑制剂的成分及其制备工艺，解决了传统流程铸坯加热温度高带来的加热炉寿命短、晶粒粗大、边裂严重及能耗大的问题。本项目的研究成果丰富和发展了取向硅钢的制备技术与抑制剂的固溶析出理论，可为含铌低温取向硅钢的实际工程应用提供理论基础和技术支撑。