阅读说明：本技术 一种通过粉末压烧制备高硅钢薄片的方法 (Method for preparing high-silicon steel sheet through powder pressing and firing ) 是由 杨芳 秦乾 陈明训 郭志猛 陈存广 路新 邵艳茹 孙海霞 汪豪杰 于 2019-11-15 设计创作，主要内容包括：一种通过粉末压烧制备高硅钢薄片的方法,属于粉末冶金技术领域。本发明以气雾化的Fe-6.5wt.％Si粉为原料,通过粉末预置使粉末处于压实状态,并放于真空烧结炉中经高温烧结使其冶金结合,经多道次热轧至一定厚度后再经1-4次冷轧,最后在高温下进行退火得到具有优良性能的高硅钢薄片。相较于采用水雾化粉末,本发明采用气雾化的高硅钢粉末极大地减少了合金体系的氧化物夹杂。同时,采用直接压烧的方法越过了球形的气雾化粉末难以成形的问题,从而避免了因添加成形剂导致的工艺复杂性及后续的脱胶、残碳问题,具有操作简单、生产效率高、产品精度高、工艺流程短、无污染与夹杂、性能优异等优点。(A method for preparing high silicon steel sheets by powder pressing firing belongs to the technical field of powder metallurgy. The method takes gas atomized Fe-6.5 wt.% Si powder as a raw material, the powder is in a compacted state through powder presetting, the compacted powder is placed in a vacuum sintering furnace to be metallurgically bonded through high-temperature sintering, the sintered powder is subjected to multi-pass hot rolling to a certain thickness and then to 1-4 times of cold rolling, and finally the high-silicon steel sheet with excellent performance is obtained through annealing at high temperature. Compared with the method adopting water atomized powder, the method adopting gas atomized high silicon steel powder greatly reduces oxide inclusions in an alloy system. Meanwhile, the problem that spherical gas atomization powder is difficult to form is overcome by adopting a direct pressure sintering method, so that the process complexity caused by adding a forming agent and the subsequent problems of degumming and carbon residue are avoided, and the method has the advantages of simplicity in operation, high production efficiency, high product precision, short process flow, no pollution and impurities, excellent performance and the like.)

1. A method for preparing high silicon steel sheets by powder pressing firing is characterized in that: the powder is directly placed in a vacuum furnace in a compacted state for high-temperature sintering to be alloyed, so that the high-efficiency preparation of the high-silicon steel sheet is realized, and the method comprises the following specific steps:

(1) preparing raw materials: atomizing Fe-6.5 wt.% Si powder by using gas of-200 meshes;

(2) powder presetting: placing the gas atomized powder in two layers of ceramic plates, uniformly compacting, controlling the compacting thickness range to be 2-5mm, and uniformly covering 2-5kg of high-melting-point weight above the upper layer of ceramic plate to obtain a preset powder whole;

(3) and (3) vacuum sintering: sintering the whole preset powder in the step (2) in vacuum at 1150-plus-1300 ℃ for 2-4h to realize metallurgical bonding and element diffusion homogenization, and cooling and then taking away ceramic plates above and below the sintered plate blank and high-melting-point weights above the sintered plate blank to obtain the sintered plate blank;

(4) hot rolling for multiple times: heating the sintered plate blank in the step (3), and then carrying out hot rolling for 4-8 times until the thickness of the plate blank is less than or equal to 0.6 mm;

(5) cold rolling: after acid washing is carried out to remove oxide skin fully, cold rolling is directly carried out for 1-4 times until the thickness of the plate blank is 0.1-0.3 mm;

(6) high-temperature vacuum annealing: and (3) annealing the cold-rolled plate blank in vacuum at 900-1200 ℃ for 1-2h, and cooling along with the furnace to obtain the high-silicon steel sheet with excellent structure and performance.

2. The method for manufacturing high silicon steel sheets by powder press firing according to claim 1, wherein: the powder in the step (1) is high silicon steel powder prepared by gas atomization, and the oxygen content of the powder is lower than 700 ppm.

3. The method for manufacturing high silicon steel sheets by powder press firing according to claim 1, wherein: in the multi-pass hot rolling in the step (4), after each pass of hot rolling, the next pass of hot rolling is carried out after fully heating again, and the heating temperature is 830-960 ℃.

4. The method for manufacturing high silicon steel sheets by powder press firing according to claim 1, wherein: and (5) fully removing the oxide skin layer before cold rolling until a bright metal surface layer appears.

5. The method for manufacturing high silicon steel sheets by powder press firing according to claim 1, wherein: the cold rolling in the step (5) is followed by the hot rolling, and the slab is quenched after the hot rolling, so that the generation of ordered phases is effectively avoided, the brittleness of the slab is reduced, and the slab is directly cold-rolled without cracking after the hot rolling.

6. The method for manufacturing high silicon steel sheets by powder press firing according to claim 1, wherein: and (4) after the high-temperature vacuum annealing, the plate blank in the step (6) must be slowly cooled along with the furnace.

Technical Field

The invention belongs to the technical field of powder metallurgy, and relates to a method for preparing a high-silicon steel sheet by powder pressing firing.

Background

The development of conventional soft magnetic materials has gone through the process from pure iron, silicon steel, permalloy to soft magnetic ferrite. The novel soft magnetic material mainly comprises amorphous alloy (also called metallic glass), nanocrystalline (ultra-microcrystalline) soft magnetic alloy, soft magnetic composite material and the like, which are all manufactured by adopting powder metallurgy technology. The novel soft magnetic material has excellent magnetic performance and also has a plurality of limiting factors, such as low material strength, poor device stability and the like. Therefore, nowadays, silicon steel is still an important magnetic material for manufacturing generators, motors, transformers, relays, transformers and other electrical instruments in the power, electronic and telecommunication industries, and is one of the most productive metallic functional materials.

The development of silicon steel sheets has been over 100 years old and plays an important role in industrial production processes. In the beginning of the 20 th century after the 19 th century, Hadfield and the like research Fe-Si alloy, namely silicon steel sheets, and become the first historically soft magnetic material applied to an alternating strong magnetic field, and the research on the silicon steel sheets successfully leads the research on the soft magnetic material to take a new step. The magnetic performance of the silicon steel is positively correlated with the Si content, and along with the increase of the Si content, the resistivity of the silicon steel is obviously improved, the eddy current loss is reduced, and the relative magnetic conductivity is improved. Compared with the traditional 3 wt.% silicon steel, when the Si content is increased to 6.5 wt.%, the resistivity of the material is increased from 48 mu omega cm to 82 mu omega cm, the alternating current iron loss is greatly reduced, the magnetostriction coefficient is almost zero, and the best soft magnetic performance is achieved. Therefore, the high-silicon electrical steel is an ideal magnetic material for manufacturing the iron core and the rotor, can realize high efficiency, low noise and small and light weight of the motor in the fields of power equipment elements, electric automobiles and high frequency, and has important significance for energy conservation, emission reduction, noise reduction, environmental protection and the like.

However, high-silicon steel has serious room temperature brittleness, is seriously strengthened by solid solution, forms an ordered structure and obviously increases deformation resistance, so the traditional production process of thermalization, cold rolling and annealing has great difficulty and is difficult to prepare by a conventional rolling method, thereby restricting the production and the application of the high-silicon steel. No enterprises for producing 6.5% Si silicon steel on a large scale are available in the world except for the Japan NKK company, but the demand for 6.5% Si silicon steel is increasing day by day, and the production capacity is far from meeting the market demand. Therefore, it is very important to research and develop a simple, economical, efficient, and mature high silicon steel process route.

Aiming at the problems that the traditional rolling is difficult to carry out due to the existence of high content of Si and the forming is difficult in the powder metallurgy method, the invention aims to provide a technical means which adopts a powder pressing and burning method to avoid the forming problem so as to efficiently obtain the high-silicon steel sheet with excellent magnetic property.

Disclosure of Invention

The invention aims to provide a method for preparing high-silicon steel sheets by powder pressing and firing. The powder pressure sintering method effectively shortens the process flow for preparing the high silicon steel sheet. In the traditional process, water atomized alloy powder with good formability is generally used as a raw material, but because of the inherent defect of high oxygen content of the water atomized powder, a large amount of oxide inclusions exist in the material; meanwhile, when the mixed powder of Fe powder and Si powder or FeSi powder is adopted for preparation, the formability of a powder system is greatly reduced due to the addition of high-content Si, so that an organic forming agent is required to be added to realize good combination and forming, and the process complexity is increased; in addition, the addition of a forming agent also leads to the inevitable problem of carbon residue in subsequent degumming and sintering.

The invention innovatively provides a method for burning the atomized alloy powder, and the problem that spherical atomized powder is difficult to form is directly overcome, so that the problems of process complexity, subsequent degumming, carbon residue and the like caused by adding an organic forming agent are solved. Meanwhile, the aerosol alloy powder with extremely low oxygen content is adopted, so that no inclusion or little inclusion of the material is ensured.

The method has the advantages of simple operation, high production efficiency, high product precision, no pollution and impurity, and ensures the excellent magnetic and mechanical properties of the high silicon steel sheet.

A method for preparing high silicon steel sheets by powder pressing firing comprises the following specific steps:

(1) preparing raw materials: atomizing Fe-6.5 wt.% Si powder by using gas of-200 meshes;

(2) powder presetting: placing the gas atomized powder in two layers of ceramic plates, uniformly compacting, controlling the compacting thickness range to be 2-5mm, and uniformly covering 2-5kg of high-melting-point weight above the upper layer of ceramic plate to obtain a preset powder whole;

(3) and (3) vacuum sintering: sintering the whole preset powder in the step (2) in vacuum at 1150-plus-1300 ℃ for 2-4h to realize metallurgical bonding and element diffusion homogenization, and cooling and then taking away ceramic plates above and below the sintered plate blank and high-melting-point weights above the sintered plate blank to obtain the sintered plate blank;

(4) hot rolling for multiple times: heating the sintered plate blank in the step (3), and then carrying out hot rolling for 4-8 times until the thickness of the plate blank is less than or equal to 0.6 mm;

(5) cold rolling: after the scale is sufficiently removed by acid washing, cold rolling can be directly carried out for 1-4 times until the thickness of the plate blank is 0.1-0.3 mm;

(6) high-temperature vacuum annealing: and (3) annealing the cold-rolled plate blank in vacuum at 900-1200 ℃ for 1-2h, and cooling along with the furnace to obtain the high-silicon steel sheet with excellent structure and performance.

Further, the powder in the step (1) is high silicon steel powder prepared by gas atomization, and the oxygen content of the powder is lower than 700 ppm.

Further, in the multi-pass hot rolling in the step (4), after each pass of hot rolling, sufficient heating is required again, and then the next pass of hot rolling is performed, wherein the heating temperature is 830-960 ℃.

Further, the oxide skin layer is sufficiently removed before the cold rolling in the step (5) until a bright metal surface layer appears.

Further, the cold rolling in the step (5) is immediately followed by the hot rolling, and because the slab is quenched after the hot rolling, the generation of ordered phases is effectively avoided, the brittleness is reduced, and the slab is directly cold-rolled without cracking after the hot rolling.

Further, the slab described in step (6) must be slowly cooled with the furnace after high temperature vacuum annealing.

The invention has the advantages that:

(1) the aerosol alloy powder with extremely low oxygen content is used as a raw material, so that no inclusion or little inclusion of the material is ensured;

(2) the problem that spherical powder is difficult to form is solved by adopting the preset powder to directly sinter; meanwhile, the problems of process complexity, subsequent degumming, carbon residue and the like caused by the addition of a forming agent are avoided;

(3) the process flow for preparing the high-silicon steel sheet can be effectively shortened by using the powder press-sintering method;

(4) the brittleness is reduced due to the disorder of the hot rolled structure, so that the hot rolled structure can be directly cold rolled, and the seamless combination of hot rolling and cold rolling processes is realized;

(5) simple operation, high production efficiency, high product precision, short process flow, no pollution and impurity and being beneficial to realizing industrial production.

Detailed Description