相变法制备｛100｝织构电工钢的研究

发布时间：2019-06-28 11:05

【摘要】：随着电气设备高速化和高效化时代的来临,传统无取向电工钢的磁性能,特别是中高牌号高铁损、低磁感的性能已经很难满足人们的需要。工业大生产中,一般采用净化钢水、减少杂质和获得均匀的晶粒尺寸等方法来提高无取向电工钢的磁性能,而很少通过控制织构的方法来获得良好的磁性能。由于具有两个易磁化方向,{100}织构能够同时降低铁损并提高磁感,因此在无取向电工钢中获得强{100}织构是制备低铁损、高磁感新型无取向电工钢的最佳途径,才能真正解决目前无取向电工钢进一步发展所面临的窘境。制备{100}织构的方法主要有表面能法、应变能法、两阶段脱碳退火法、两阶段冷轧退火法、交叉轧制法、双辊薄带连铸法等,其中表面能法又包括真空脱锰法、化学反应诱导法和高温退火法。由于工期长、工艺复杂、设备要求高等一系列的劣势,使得{100}织构无取向电工钢的生产到目前为止还很难应用于社会化大生产。本文通过成分和工艺改进,以低碳中硅和超低碳两种成分体系的无取向电工钢为研究材料,分别采用脱碳退火工艺和缓慢冷却相变工艺来尝试制备具有强{100}织构的无取向电工钢。对于低碳中硅体系无取向电工钢,采用湿氢气氛脱碳退火难以获得{100}织构,最终在0.50mm厚的成品板中获得了强{111}织构柱状晶组织,成品磁性能较差,其铁损和磁感分别达到4.49W·kg-1和1.69T；改进工艺,首先将热轧板在高温奥氏体相区保温退火,随后进行冷轧并变换湿氢脱碳气氛为纯氢气氛,最终在0.35mm厚的成品板中获得了{100}织构近似的柱状晶组织,磁性能较相同成分的35A550(P15/50=3.50Wkg-1, B50=1.69T)牌号工业大生产成品得到了极大的改善,其铁损和磁感分别达到2.60W·kg-1和1.76T。对于超低碳体系无取向电工钢,在纯氢气气氛中进行缓慢冷却γ→α相变退火,获得了完整的{100}织构柱状晶组织,并在成分为Fe-0.5%Mn的0.50mm无取向电工钢中成功的制备出了强{100}织构无取向电工钢,其铁损和磁感分别达到4.30W·kg-1和1.80T,较相同成分的50WW1000(P15/50=6.7W@kg-1, B50=1.74T)牌号工业大生产成品,不仅铁损提高了近3个牌号,磁感也有大幅度的提升。对于低碳中硅体系无取向电工钢,一方面,由于其相变点较低,两相区较宽,热轧后形成了明显的带状组织,这对后续组织的均匀性和织构的改善极为不利；另一方面,在湿氢气氛脱碳退火过程中,由于硅在表面发生氧化形成SiO2氧化膜,抑制了有利织构的形成和发展,故最终获得了磁性能较差的强{111}织构柱状晶组织；改进工艺,首先将热轧板在高温奥氏体相区保温退火以粗化初始晶粒并消除热轧带状组织对后续织构演变的不利影响,随后进行冷轧并改变湿氢脱碳退火气氛为纯氢气氛以弱化硅元素在表面氧化的影响,最终在应变能各向异性的驱动下获得了{100}织构近似的柱状晶组织。对于超低碳成分体系无取向电工钢,通过在纯氢气气氛中进行缓慢冷却相变退火,由于氢气高的热传导系数能够产生大的温度梯度和沿ND方向分布的应变能,在相变过程中,应变能各向异性驱动{100}取向核心在试样表面形成,并且沿ND方向不断向内生长,最终形成完整的{100}织构柱状晶组织。此外研究还发现,不同气氛条件下Fe-0.5%Mn钢的表面氧化行为不同,这对最终相变方式、组织和织构均有显著的影响；纯氢气氛下为“定向型相变”,气氛流量较大时获得{100}织构柱状晶组织,而流量较小时获得{100}+{110}织构柱状晶组织；纯氮气氛下为“整体型相变”,最终获得{111}织构等轴晶组织。相比于之前的方法,相变法制备{100}织构柱状晶无取向电工钢具有磁性能优良、工艺简单易操作等优点,为未来无取向电工钢的发展指明了方向。
[Abstract]:With the advent of high speed and high efficiency of electrical equipment, the magnetic performance of traditional non-oriented electrical steel, especially the high-grade high-speed iron loss, has been difficult to meet the needs of people. In the industrial mass production, the method of purifying the molten steel, reducing the impurity and obtaining the uniform grain size is generally adopted to improve the magnetic properties of the non-oriented electrical steel, and a good magnetic property is rarely obtained by controlling the texture. Due to the two easy-to-magnetization directions, the {100} texture can reduce the iron loss and improve the magnetic sense, therefore, obtaining the strong {100} texture in the non-oriented electrical steel is the best way to produce low iron loss, high magnetic induction and non-oriented electrical steel. In ord to solve that problem of the further development of the current non-oriented electrical steel. The method for preparing {100} texture mainly includes surface energy method, strain energy method, two-stage decarbonization annealing method, two-stage cold rolling annealing method, cross rolling method, double-roll thin strip continuous casting method, etc., wherein the surface energy method also includes vacuum demanganization process, chemical reaction quenching method and high-temperature annealing Due to a series of disadvantages such as long construction period, complex process and high equipment requirement, the production of {100} texture non-oriented electrical steel is very hard to be applied to the socialization of great students. In this paper, through the improvement of composition and process, the non-oriented electrical steel of low-carbon medium silicon and ultra-low-carbon two-component system is used as the research material, and the non-orientation with strong {100} texture is tried by means of a decarburization annealing process and a slow cooling phase change process, respectively. For the non-oriented electrical steel of the low-carbon medium silicon system, it is difficult to obtain {100} texture with a wet hydrogen atmosphere, and a strong {111} texture is obtained in the finished plate with a thickness of 0.50 mm. The magnetic performance of the finished product is poor. The iron loss and the magnetic induction of the finished product reach 4.49 W 路 kg-1 and 1.69T, respectively. The process comprises the following steps of: firstly, carrying out heat preservation and annealing on a hot-rolled plate in a high-temperature austenite phase region, then carrying out cold-rolling and transforming the wet-hydrogen decarburization atmosphere into a pure hydrogen atmosphere, finally obtaining a {100}-texture approximate columnar crystal structure in a 0.35-mm-thick finished product plate, and the magnetic energy of 35 A550 (P15/50 = 3.50 Wk) with the same composition G-1, B50 = 1.69T), and the iron loss and magnetic induction of the finished product were 2.60 W 路 kg-1 and 1, respectively. 76 T. For the non-oriented electrical steel of the ultra-low carbon system, a complete {100} texture amorphous structure was obtained in the pure hydrogen atmosphere, and the {100} texture was not oriented successfully in the 0.50 mm non-oriented electrical steel with the composition of Fe-0.5% Mn. The iron loss and magnetic induction of the electrical steel respectively reach 4.30W 路 kg-1 and 1.80T, and the 50 WW1000 (P15/50 = 6.7W@kg-1, B50 = 1.74T) of the same component is a large-scale production of the finished product, not only has the iron loss increased by nearly 3 brands, but also has a large magnetic feeling As for the non-oriented electrical steel of the low-carbon medium-silicon system, on the one hand, because the phase change point is lower, the two-phase region is wider, and after hot rolling, the obvious strip-shaped tissue is formed, which is extremely disadvantageous for the improvement of the uniformity and the texture of the follow-up tissues; and on the other hand, in the wet-hydrogen atmosphere, In the annealing process, the formation and development of the favorable texture are inhibited by the oxidation of the silicon on the surface, so that the strong {111} texture columnar crystal structure with poor magnetic properties is finally obtained. and the process is improved, the hot-rolled plate is first insulated and annealed in the high-temperature austenite phase region to coarsen the initial crystal grain and eliminate the adverse effect of the hot-rolled strip-shaped tissue on the subsequent texture evolution, The effect of oxidation, finally, obtained the {100} texture approximation under the drive of the strain energy anisotropy for the non-oriented electrical steel of the ultra-low carbon component system, the slow cooling phase change annealing is carried out in a pure hydrogen atmosphere, During the phase change, the strain energy anisotropic drive {100} orientation core is formed on the sample surface and grows continuously in the ND direction, resulting in a complete {100} texture In addition, the surface oxidation behavior of the Fe-0.5% Mn steel under different atmosphere conditions is different, which has a significant effect on the final phase change, the microstructure and the texture, and the {100} texture is obtained when the atmosphere flow is large. The crystalline structure of {100} + {110} texture is obtained with the flow rate of {100} + {110} texture; in pure nitrogen atmosphere, the {111} texture is obtained. Compared with the previous method, the phase-change method has the advantages of excellent magnetic performance, simple process and easy operation and the like, and is a non-oriented electrical steel in the future.
【学位授予单位】：北京科技大学
【学位级别】：博士
【学位授予年份】：2015
【分类号】：TG142.1;TF76

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