Amorphous alloys have the advantages of high saturation magnetic induction, small coercive force, low loss, etc., so they are widely used in power transformers with high efficiency, energy saving, and environmental protection. However, before 2009, almost all the amorphous strips used in the amorphous alloy transformers in the entire industry market in my country were produced by Hitachi Metals Corporation of Japan. In 2010, my country's Antai Technology Co., Ltd. built a 10,000-n grade amorphous alloy strip production line with independent intellectual property rights, which broke the passive situation of relying on imports for amorphous raw materials and accelerated the development of low-carbon economy in my country's power industry.

The current amorphous alloy core adopts a nearly rectangular lap winding structure. The internal stress of the formed core is very large, and the magnetic properties are severely damaged. These stresses must be eliminated by heat treatment and annealing. Heat treatment The annealing process is the most critical and difficult control process in the entire production process of amorphous alloy cores. The domestic amorphous alloy strip is arc-shaped in the transverse direction, and its internal stress is larger than that of the imported strip. Coupled with the difference in composition, it is more sensitive the temperature during heat treatment. Therefore, it is necessary formulate a suitable heat treatment annealing process. The performance and quality of the final core of the domestic amorphous alloy strip is very important.

1. Heat treatment annealing temperature. A suitable iron core annealing temperature must not only ensure the elimination of the core's internal stress and resre its magnetic properties, but also reduce the brittleness of the amorphous alloy strip as much as possible and reduce the risk of breakage in the subsequent operation of the iron core. Tests show that the final annealing temperature of domestic amorphous alloy strip cores is best controlled at 375～380℃.

2. Heat preservation time. Experiments show that the unit excitation power decreases with the annealing time, and the unit no-load loss of the core increases with the annealing time. Moreover, the brittleness of the core strip also increases with the annealing time. . Therefore, the best holding time must be selected according the user's requirements for the performance of the core.

3. Protective atmosphere for heat treatment. The iron core is easily oxidized during high temperature heat treatment and annealing. After the surface of the iron core is oxidized, in addition the rust on the surface, the more important thing is that the no-load loss of the iron core will increase significantly. Therefore, the core must be protected by atmosphere during the entire heat treatment and annealing process. At present, the commonly used process protection gas is nitrogen or argon.

Fourth, the rate of heating and cooling. Since iron cores are subjected multiple loading and batch heat treatment during mass production, reasonable heating and cooling speeds not only affect the performance results of amorphous alloy iron cores, but also affect production efficiency and production costs. Generally speaking, the faster the heating rate, the greater the dispersion. However, experiments have shown that the temperature dispersion of domestic amorphous alloy strip cores when they reach the high temperature zone and approach the optimal annealing temperature is small, and can almost be controlled within 3°C. Therefore, in the heating stage, the domestic amorphous alloy strip core can be directly heated up quickly. In addition, the fast cooling speed is beneficial for reducing the no-load loss of the iron core, but at the same time it will increase the excitation power of the iron core. Therefore, the best cooling rate needs accumulate empirical data make the best choice.

5. Apply a magnetic field. The formed amorphous alloy core needs be annealed with a DC magnetic field obtain a good magnetic domain orientation, so as improve its magnetic properties. The test shows that the field strength of the domestic amorphous alloy strip core during annealing needs be about 2000A/m or the magnetic field current is 1400A ensure that the core material is saturated during annealing, so as achieve the best annealing effect.