Domestic amorphous alloy iron core and the key technologies of strip heat treatment

Amorphous alloy with high saturation magnetic induction intensity, the coercive force is small, and low loss, so the effect with high efficiency, energy saving, environmental protection is widely used in power transformer.

The amorphous alloy iron core adopts the lap of the approximate rectangle type winding structure, forming the core of internal stress is very large, magnetic properties were severely damaged, must be eliminated by annealing heat treatment to the stress. Heat treatment of annealing process is the most critical crystal alloy iron core of the whole production process is also the most difficult to control the process. Domestic amorphous alloy strip transverse an arc, the internal stress is larger than import strip, plus the composition of different, more sensitive to heat treatment temperature, therefore, make appropriate annealing heat treatment process, amorphous alloy strip on domestic final core is very important to the quality and performance.

A, heat treatment of annealing temperature. Appropriate annealing temperature of the core, to ensure that not only eliminate the internal stress of core, restore its magnetic properties, and to be able to reduce the brittleness of amorphous alloy strip, as far as possible to reduce the risk of breakage in the core processing. Amorphous alloy strip test shows that domestic core final annealing temperature control in 375 ~ 380 ℃ is the best.

Second, the time of heat preservation heat treatment. Experiments show that the unit excitation power with the annealing time is reduced, and the core unit of no-load loss increases with annealing time, and the core of strip brittleness, and increases with the increase of annealing time. Therefore, must be based on user requirements, the performance of the core to choose the best heat preservation time.

Third, protective atmosphere heat treatment. Core is easily oxidized in high temperature annealing heat treatment. Core surface is oxidized, in addition to the surface have rust, more major is core no-load loss will lead to increased obviously. Therefore, the core in the whole atmosphere protection must be used in the process of annealing heat treatment. At present the commonly used technology to protect for nitrogen or argon gas.

Fourth, heating and cooling speed. Because of the core are multiple loading, when mass production batch heat treatment, so the reasonable heating and cooling speed, not only affects the performance of the amorphous alloy iron core as a result, but also affect the production efficiency and production cost. In general, the faster the speed, the greater the discreteness. However, the experimental results show that domestic amorphous alloy strip core arrive in high temperature and close to the optimum annealing temperature point of discrete small, almost can be controlled within 3 ℃. In heating stage, therefore, domestic core of amorphous alloy strip can be directly for rapid warming. In addition, the cooling speed, no-load loss is beneficial to reducing core, but at the same time will increase the excitation power of the core. So, the best cooling speed need to accumulate experience data to make the best choice.

Five, plus a magnetic field. After forming of amorphous alloy iron core, at the time of annealing need additional dc magnetic field for good magnetic domain orientation, in order to improve the magnetic properties. Annealing amorphous alloy strip test showed that domestic core of field strength should be around 2000 a/m current or magnetic field when in 1400 a, can guarantee to annealing when saturated core material, so as to achieve the best annealing effect.