Preparation method of large-size directional aluminum-nickel-cobalt magnetic steel

The invention relates to the field of permanent magnet materials, and discloses a preparation method of large-size directional aluminum-nickel-cobalt magnetic steel, which comprises the following steps: (1) preheating a sand mold; (2) smelting to obtain molten steel; (3) bidirectional directional cooling is conducted, specifically, the two sides of the sand mold are clamped through water cooling plates for cooling, and molten steel is poured into the sand mold; after casting is completed, the surface of the sand mold is subjected to heat preservation; (4) carrying out sand cleaning and rough machining to obtain a blank; (5) carrying out heat treatment-magnetization-tempering treatment to obtain a semi-finished blank; and (6) finish machining is conducted, and the large-size directional aluminum-nickel-cobalt magnetic steel is manufactured. According to the method, a bidirectional directional cooling process is adopted, completely-oriented isometric crystals can be obtained, the success rate of manufacturing d