Soft magnetic material vacuum heat treatment process

Soft magnetic material means that when magnetization occurs at Hc of not more than 1000 A/m, such a material is called a soft magnetic body. Soft magnetic materials are widely used in magnetic antennas, inductors, transformers, magnetic heads, earphones, relays, vibrators, TV deflection yokes, cables, delay lines, sensors, microwave absorbing materials, electromagnets, accelerator high frequency acceleration.Cavity, magnetic field probe, magnetic substrate, magnetic field shielding, high frequency quenching energy, electromagnetic chuck, magnetic sensitive components (such as magnetocaloric materials for switching).

The raw materials of soft magnetic alloys are mainly bars, strips and plates, and the parts are cut, punched, stamped or wound by cold working. During the processing, the original grain structure of the material will be destroyed, so that the magnetic permeability of the material will decrease, and the processing stress generated during the processing will lead to instability of the part size. Therefore, the parts made of soft magnetic alloy must be annealed after processing to re-obtain the regular equiaxed grain structure, reduce the impurity content in the material, restore and improve the magnetic properties of the material, and eliminate the processing stress. Stabilize part size. Depending on the material and the requirements of use, the annealing of soft magnetic alloy parts can be performed by high temperature annealing (1150 ~ 1250 °C) and medium temperature annealing (800 ~ 850 °C). Among them, the permalloy of high magnetic permeability material is usually annealed at a high temperature, sometimes to further improve the magnetic permeability, and magnetic field annealing is also used; and for a transformer, a transformer or a motor, a stacked or rolled silicon steel sheet (commonly called a core) ) uses medium temperature annealing.

Before the vacuum furnace was used, many manufacturers used a well-type external thermal atmosphere furnace, which was treated by nitrogen or hydrogen protection. This treatment method has obvious defects, especially when nitrogen is used as a protective atmosphere. First, when the treatment is carried out by means of nitrogen gas protection, the atmosphere obtained by nitrogen replacement in the furnace is not pure enough, and the flow direction of nitrogen has a great influence on the surface quality of the workpiece, and the color of the same furnace parts is often inconsistent. This is due to the slight oxidation of some of the workpieces in the furnace where there is a poor flow of nitrogen. Secondly, the temperature uniformity of the external heat furnace is poor, and the performance of the parts after treatment is greatly different, and the pass rate is low. In addition, in terms of energy consumption, the furnace lining of the external heating furnace is thick, the power consumed in the furnace lining during heating is large, and the thermal efficiency is low; in the heating process, high-purity nitrogen gas is continuously charged, and the consumption of nitrogen is large; heat-resistant steel The low service life of the furnace at high temperatures leads to higher operating costs for the external furnace. If hydrogen is used as the protective atmosphere, the performance and surface quality of the workpiece can be improved by relying on the strong decarburization ability and reduction of hydrogen, but the problem of uneven temperature and high operating cost is still unavoidable. The use of an internal thermal vacuum annealing furnace is of great significance for the annealing of soft magnetic alloy parts. The internal thermal vacuum furnace has obvious advantages in terms of workpiece processing effect, operating cost, production efficiency and production environment.