Japanese Patent Hei 3-146615 is that when the iron core releases heat, a heat absorbing body is placed in a furnace, and the ultra-microcrystal iron core is brought into contact with the iron core to prevent the iron core from overheating. The use of this method because the heat absorption body to occupy a certain space, and with the increase in the number of iron cores and increase, on the one hand, affect the iron core of the furnace, on the other hand, will slow down the heating and cooling speed, extend the production cycle, the same impact on productivity, and long-term processing, so that the iron core is easy to oxidize.
, the purpose of the present invention is to provide a heat treatment method for iron-based ultrafine crystal iron core that can ensure product performance, ensure performance consistency and high yield. That is, the amorphous alloy iron core is the object of treatment, and the ultra-fine crystal iron core with the best performance is obtained after heat treatment.
temperature range is only the reference temperature for the ultrafine crystallization treatment in general. In practice, it is difficult to control the optimum heat treatment temperature of the ultrafine crystalline iron core only by measuring the furnace temperature of the heat treatment furnace. Because amorphous alloys produce heat release during crystallization transformation, for large quantities of iron cores, due to the difference of amorphous preparation conditions, it is difficult to determine the crystallization heat release, heat release rate and heat release temperature rise in advance. Therefore, in the process of superfine crystallization treatment, the actual temperature of the iron core suddenly exceeds the predetermined superfine crystallization treatment temperature due to the crystallization heat release phenomenon, resulting in deterioration of the performance of the iron core.
In order to solve the above difficulties, Japanese Patent Hei 3-141615 discloses a two-stage heat treatment method suitable for batch heat treatment of ultra-fine crystal iron cores. In this method, the amorphous iron core is pretreated by holding the amorphous iron core at a temperature of tens of degrees lower than the crystallization temperature for a period of time, or when the crystallization of the iron core releases heat, it is brought into contact with the heat absorber to reduce the temperature of the iron core due to the crystallization heat to exceed the optimal ultrafine crystallization temperature, and then the temperature is raised to the second stage-the optimal ultrafine crystallization temperature for heat preservation, and then cooled with the furnace. This method provides a basic idea to solve the problem of over-temperature caused by iron core heat release during batch processing of ultra-crystalline iron cores, but there are still some problems to be solved in actual batch production, that is, there are still some shortcomings, one is to use this method to extend the entire processing cycle, the first stage processing time is several hours, therefore, resulting in a decrease in productivity; the more important problem is the uncertainty of the pretreatment temperature in the first stage. Due to the large number of amorphous strip in the preparation process, the spraying time is longer, the change of the conditions during the spraying (such as the change of the cooling roll temperature and the thickness of the belt), will lead to the same batch of preparation of the strip section is actually made at different cooling speed, that is to say, the amorphous degree is different. The core made of this strip, due to the difference in cooling speed, leads to the uncertainty of the core starting heat release temperature and heat release during the subsequent ultrafine crystallization treatment, the different sizes of iron cores processed in each batch (mainly referring to the volume and specific surface of the iron core), the furnace loading of the iron core, the ambient temperature, and even the type of protective atmosphere added (the initial heat release temperature of the iron core treated in nitrogen is significantly higher than that in hydrogen) will affect the heat release size and heat dissipation conditions of the iron core and determine the actual temperature in the iron core. Therefore, it is very incomplete and impractical to determine the superfine crystallization treatment temperature only according to the crystallization temperature, and it cannot be guaranteed that each batch of iron cores is at the optimal superfine crystallization treatment temperature, thus the blindness is very large, and the finished product rate and performance consistency of the treated iron cores are very poor. It is difficult to achieve a more satisfactory effect of ultrafine crystallization treatment.
ultrafine crystalline iron core is made of amorphous alloy as raw material (or based on), by ultra-microcrystallization heat treatment. After its heat treatment, the amorphous tissue is crystallized to produce fine grains of nano-scale size to obtain the best performance required. In the ultra-fine crystallization heat treatment, the most important thing is to control the ultra-fine crystallization treatment temperature. In the prior art, the usual ultra-fine crystallization treatment temperature (T) is controlled to be higher than the crystallization temperature Tx and lower than the precipitation temperature Tx′ of the combined phase (crystal phase), because below the temperature Tx, no ultra-fine crystal can be formed, and above the temperature Tx′, the precipitated compound phase and the microcrystalline grains are coarsened, resulting in serious deterioration of the magnetic properties. For this reason, the ultrafine crystallization treatment is carried out in a temperature range between the crystallization temperature Tx and the compound phase precipitation temperature Tx′. Generally, the ultrafine crystallization treatment is carried out in a temperature range of the crystallization temperature Tx (30 to 80 ° C.).
For the above purpose, the main technical measures of the present invention are to measure and track the actual temperature of the processed amorphous iron core during the heat treatment process, take the temperature of the iron core as the main basis for controlling the furnace temperature, and take the tested furnace temperature as the reference basis for controlling the furnace temperature, to ensure that the actual temperature of the iron core is at a predetermined optimal ultra-fine crystalline iron core processing temperature, and ensure the performance and performance consistency of the ultra-fine iron core.
