【作者】 孙颖；

【导师】 连法增； 赵宇；

【作者基本信息】 东北大学 ， 材料学， 2009， 博士

【摘要】 以高效、节能,环保的工艺方式生产取向硅钢是当前世界各大电工钢生产厂家降低成本、提高产品市场竞争力的重要手段；在各种有效措施中,采用降低板坯加热温度的方式生产取向硅钢已成为该领域的研发热点。本论文即采用低温板坯加热工艺于实验室进行0.30mm厚度取向硅钢的研制。通过不同成分方案及系列工艺实验对比,根据磁性能测量结果总结出合理的成分与制备工艺。文章对取向硅钢板坯加热、热轧、冷轧以及退火等工艺进行了研究；考察了部分工艺阶段取向硅钢抑制剂的构成与特点,微观组织与织构的演变规律,讨论了取向硅钢成品磁性能的影响因素,进而探索低温板坯加热工艺制备取向硅钢的机理。通过大量实验可知,取向硅钢的成分范围窄,工艺参数限制严格,成分与工艺密切相关,各步工艺之间也互相制约。经过系列对比实验所得的合理工艺流程如下：将取向硅钢板坯于1250℃温度下加热30min后热轧至2.3mm厚度；然后将热轧板进行一次冷轧达到0.65mm厚度；将一次冷轧板于840℃温度下脱碳退火后,再进行第二次冷轧,达到0.30mm的成品厚度；随后进行550℃回复处理、涂MgO隔离剂后开始高温退火,即以50℃/h的速率由室温缓慢升温至1200℃,其后的高温净化处理、降温工艺以及退火气氛均与传统CGO钢的生产工艺相同。由该低温工艺制备的取向硅钢成品可以达到良好稳定的磁性能。实验表明,抑制剂在高温退火过程中发挥重要作用,即抑制取向硅钢初次再结晶晶粒长大,促使位向准确的Goss晶核在达到二次再结晶开始温度后充分发展成为高强度分布的Goss二次晶粒。通过对取向硅钢中析出第二相质点的观察分析可知,低温工艺的抑制剂以Cu2S为主,(Cu, Mn)S及(Mn, Cu)S为辅,从热轧阶段开始大量析出。Cu2S颗粒尺寸细小,分布密度高,抑制能力能够满足取向硅钢的生产要求,并且超过传统CGO钢的常用抑制剂MnS。实验证明,本成分方案取向硅钢在一定情况下能够形成细小弥散分布的AlN析出相,但在本文低温工艺条件下并不能独立地大量弥散析出。低温工艺取向硅钢的微观组织和织构的演变规律从脱碳退火后开始与高温工艺有着明显差别。低温工艺于中间退火过程中完成脱碳反应。回复处理后,钢中的冷轧态组织及织构特征延续至高温退火的初次再结晶开始之前。在高温退火的升温阶段中,采用缓慢速率的加热方式能够延缓取向硅钢初次再结晶和晶粒长大过程,使得成品的二次再结晶发展完善,Goss织构组分占有率高,位向准确,成品晶粒尺寸远远大于传统工艺生产的CGO钢,获得理想的磁性能。更多还原

【Abstract】 Efficient manufacturing processes of grain-oriented silicon steel considering energy conservation and environmental protection requirements have been developed recently in the world, as important methods of reducing production cost and increasing competitiveness on the market. And the production process by reducing slab reheating temperature has been attracted more attention in the field of electrical steel. In this dissertation, the grain-oriented silicon steel (0.30mm) prepared in the laboratory by low temperature slab reheating technique was studied. Reasonable chemical composition and producing processes were determined according to magnetic properties after experimental research with different compositions and a series of process schemes. The producing processes of low temperature slab reheating method were researched in detail. The characteristic of inhibitors in grain-oriented silicon steel, and the evolution of microstructure and texture during producing as well as their influence on magnetic properties were analyzed systematically, so that the mechanism of low temperature slab reheating technique for grain-oriented silicon steel was explored.It’s known that the composition must be fully corresponded with the producing processes, because of limited range of composition and strict process parameters in grain-oriented silicon steel production. Grain-oriented silicon steel with definite composition was prepared as followed:the slab was hot rolled to 2.3mm thickness after being reheated at 1250℃for 30 minutes; the hot rolled band was cold-rolled to 0.65mm thickness for the first time and then decarburization annealed at 840℃; then the decarburized strip was cold-rolled to 0.30mm thickness for the second time and then recovered at 550℃; after being applied by MgO preparation, the high temperature batch annealing was employed, heating up from room temperature to 1200℃at 50℃/h warming-up velocity, and the other process parameters were the same as those of conventional procedures of CGO steel. Then ideal magnetic properties were obtained by the process.It’s shown that inhibitors influence the magnetic properties of grain-oriented silicon steel by grain growth inhibition, which is a key requirement in the development of sharp Goss texture via secondary recrystallization during the high temperature batch annealing. It has been investigated from second phase particles that the inhibitors in grain-oriented silicon steel prepared by low slab reheating temperature method were mostly Cu2S, and some (Cu, Mn)S and (Mn, Cu)S precipitates. They were precipitated from hot rolled band with considerable amount. Typical inhibitor Cu2S particles have some advantages such as smaller grain size, higher distribution density and have more inhibition ability than those of CGO steel produced by conventional process. They are competent in grain-oriented silicon steel production by the process mentioned.The evolution of microstructure and texture in steel from decarburization annealing was different obviously from that of conventional high slab reheating temperature technique. In the production mentioned, decarburization happened during the intermediate annealing. Cold rolled microstructure and texture inherited after recovery treatment. Primary recrystallization and grain growth course of low slab temperature grain-oriented silicon steel were prolonged at the stage of high temperature batch annealing at slow warming-up velocity. It benefited to the development of secondary recrystallization, so that grain-oriented silicon steel strip had more proportion of sharp Goss texture and quite larger size grains than those of CGO steel, which determined fine magnetic properties of product.更多还原