JPH03202459A - Treatment for silicon steel - Google Patents

Abstract

PURPOSE:To improve the mechanical properties and magnetic properties of a silicon steel by embedding a silicon steel having a carburized layer of the prescribed thickness in the surface in a powder mixture of powdered Cr or/and V or/and Ti and catalyst, carrying out heating, and forming a layer of the carbides of the above metals with the prescribed thickness in the surface. CONSTITUTION:Gas carburizing is applied, e.g., to a printing lever composed of a silicon steel with 2.8-6.5% silicon content, by which a carburized layer of 20-200mum thickness is formed in the surface. Subsequently, the above silicon steel having the carburized layer is embedded in a powder mixture of powdered Cr, powdered V, or powdered Ti or a combination of them and catalyst (e.g. NH4Cl) and heated to undergo solid diffusion treatment, by which a layer of the carbides of the above metals of 2-20mum thickness can be formed in the surface of the silicon steel. By this method, the mechanical properties of the silicon steel surface can be sufficiently improved, and also superior magnetic properties can be provided.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a treatment method for improving the mechanical properties of silicon steel.

[Prior Art] In the printer head of a wire dot printer, a printing lever is arranged at the rear end of the printing wire, and the printing lever is driven by magnetic attraction and repulsion to strike the printing wire, and printing is performed using this printing wire. There is. The printing lever has high magnetic permeability as a magnetic property.

Silicon steel and electromagnetic soft iron are used because high magnetic flux density and low coercive force are required. Among them, silicon steel has inferior magnetic properties such as magnetic response, so it can be used for high-speed printing of printers, but silicon steel and electromagnetic soft iron have a base material hardness of 100 to 300 Vickers hardness. Hv
Therefore, in order to use it as a lever for striking the printing wire as described above, it is necessary to improve mechanical properties such as abrasion resistance. However, since silicon steel cannot be subjected to surface carburizing and quenching or carbonitriding, it has conventionally been nickel plated. This nickel plating is, for example, electroless plating containing an appropriate amount of boron or phosphorus, and the plating hardness is increased to 700 by heat treatment after plating.
It was set to about ~1000Hv.

[Problem to be solved] However, a hardness of about 700 to 1000 Hv does not have sufficient durability such as wear resistance, and is not suitable for parts that are subjected to strong impact force such as printing levers or parts that undergo repeated sliding movements. could not be used.

When used as a printing lever, the rear end of a wire with a diameter of 0.3 to 0.2 mm cannot be directly struck, so a wire bin or the like is attached to the rear end of the wire to increase the diameter and the wire bin is struck. was. Therefore, in this case, the weight of the printing wire increases, which hinders an increase in printing speed and increases the cost of the printing wire.

SUMMARY OF THE INVENTION It is therefore an object of the present invention to provide a treatment method for improving the mechanical and magnetic properties of silicon steel.

[Means for Solving the Problems] In order to achieve the above object, the silicon steel treatment method of the present invention carburizes silicon steel with a silicon content of 2.8% to 6.5% to give a surface coating of 20%. A carburized layer with a thickness of ~200 μm is formed, and a solid diffusion treatment is performed to embed the silicon steel in a mixed powder of powdered chromium, powdered vanadium, powdered titanium, or a combination of these and a catalyst, and then heat the surface of the silicon steel. A carbide layer of the above-mentioned metal having a thickness of 2 to 10 μm is formed on the substrate.

[Examples] Hereinafter, specific examples of the present invention will be described in detail.

A commercially available silicon steel with a silicon content of 3% was used as the member to be treated, and a printing lever was manufactured that was driven by magnetic attraction and repulsion to directly strike the printing wire of the printer head, and was subjected to the following processing.

Example 1 This printing lever was gas carburized at 850°C for 45 minutes, and 1
A carburized layer with a thickness of 0.00 μm was formed.

Next, the carburized printing lever was embedded in a mixed powder containing appropriate amounts of powdered chromium, powdered alumina, and ammonium chloride, and heated to 45°C at 1050°C in an argon stream.
A solid diffusion treatment was performed, which was maintained for a minute. Hereinafter, this processing method will be referred to as "processing condition B".
A ~6 μm chromium carbide layer is formed, and the surface hardness is 140
It was 0-1700Hv.

Further, the printing lever on which the carburized layer with a thickness of 100 μm was formed was subjected to solid diffusion treatment in which the print lever was kept at 1050° C. for 90 minutes in an argon stream. Hereinafter, this processing method will be referred to as processing condition C. According to this, 8 to 10
A chromium carbide layer of μm thickness was formed, and the surface hardness was 1400 to 1700 Hv, the same as when the treatment time was 45 minutes.

In addition, under the same conditions, the treatment temperature was 1000℃ and the treatment time was 4.
When the heating time was 5 minutes, a 2 μm thick chromium carbide layer was formed on the surface.

FIG. 1 shows a comparison of the magnetic properties of products obtained under each treatment condition, with the horizontal axis representing the processing conditions and the vertical axis representing maximum magnetic permeability and coercive force. In this graph, processing condition A is vacuum magnetic annealing, which is conventionally used to improve the magnetic properties of silicon steel.
The sample was kept at ℃ for 45 minutes.

In the graph shown in the first figure, under the conventional processing condition A,
Comparing the processing conditions B and C of the present invention,
It can be seen that under treatment conditions B and C, the maximum magnetic permeability increases and the coercive force significantly decreases. In order to use it as a printing lever, the higher the maximum magnetic permeability, the better the magnetic properties, and the lower the coercive force, the better. Therefore, by performing the treatment according to the present invention, both the maximum magnetic permeability and the coercive force are greatly improved, and the magnetic properties are The results showed that the characteristics were improved.

Example 2 A printing lever on which a 100 μm thick carburized layer was formed in the same manner as in the above example was buried in powdered vanadium, and solid diffusion treatment was performed under the same treatment conditions B and C as described above. This treatment forms a vanadium carbide layer on the surface, resulting in a surface hardness of 2
500-2800H■ was obtained.

Example 3 A printing lever on which a 100 μm thick carburized layer was formed in the same manner as in the above example was buried in powdered titanium, and solid diffusion treatment was performed under the same treatment conditions B and C as described above. This treatment forms a titanium carbide layer on the surface, resulting in a surface hardness of 3000H.
v was obtained.

In Figure 2, the horizontal axis is the processing temperature, the vertical axis is the maximum magnetic permeability,
For silicon steel with different silicon components, a printing lever with a 100 μm thick carburized layer formed in the same way as the upper side,
It shows the change in magnetic permeability when solid diffusion treatment was performed for 45 minutes at treatment temperatures of 980°C, 1020°C, and 1050°C. For commercially available 3% silicon steel, the maximum magnetic permeability increases significantly when heated to 1000°C or higher and subjected to solid diffusion treatment, but 2.5% and 1% silicon steel significantly improves maximum permeability.
% silicon steel shows almost no improvement in maximum permeability. When the treatment method of the present invention is applied to silicon steel having a silicon content of 2.8% or more, preferably 3% or more, the magnetic properties are improved. Further, from this graph, it can be seen that the treatment temperature is desirably 1000° C. or higher in order to sufficiently perform the solid diffusion treatment.

In addition to the above examples, the treatment method according to the present invention is most suitable for surface treatment of parts such as magnetizing yokes that are required to have both sufficient magnetic properties and wear resistance.

In the present invention, the silicon component is 2.8% to 6.5%.
As mentioned above, if the silicon content is less than 2.8%, good magnetic properties cannot be obtained, and as the silicon content is increased, the magnetic properties improve. It is known that the silicon content reaches its maximum at 6.5%, and as the silicon content increases, the steel becomes brittle and difficult to use.

The carburizing treatment can be carried out using various methods such as solid carburizing, liquid carburizing, and gas carburizing.

The thickness of the carburized layer is 20 μm to 200 μm.
This is because if it is smaller than 200
If the amount exceeds μm, the carbon that has entered the silicon steel during the carburizing process will not be completely used in the reaction to form metal carbides during the solid-state diffusion process, and the excess carbon that has diffused into the silicon steel will form at the grain interface. Otherwise, the magnetic properties will deteriorate.

As for the metal used in the solid diffusion treatment, any one of powdered chromium, powdered vanadium, or powdered titanium may be used alone, or an appropriate mixture of these may be selected and used. Powdered ammonium chloride or the like is used as the catalyst.

The thickness of the metal carbide layer is 2 to 10 μm.

This is because if the thickness is less than 2 μm, sufficient mechanical properties cannot be obtained for use in parts that are subjected to strong impact forces or parts that undergo repeated sliding motions. This is because 10 μm is sufficient to obtain the desired thickness.

[Effects] When silicon steel is treated by the treatment method of the present invention described above, the mechanical properties of its surface are sufficiently improved, and it can also be made to have excellent magnetic properties.

[Brief explanation of drawings]

Figure 1 shows conventional processing conditions A and processing conditions B and C of the present invention.
FIG. 2 is a graph showing a comparison of the magnetic properties of products according to the above, and FIG. 2 is a graph showing a comparison of magnetic permeability when silicon steels with different silicon components are treated under various temperature conditions. that's all

Claims (1)

[Claims] Silicon steel containing 2.8% to 6.5% of silicon is carburized to form a carburized layer with a thickness of 20 to 200 μm on the surface, and powdered chromium, powdered vanadium, powdered titanium, or these The above silicon steel is embedded in a mixed powder of a combination of and a catalyst.
2 on the surface of the silicon steel by applying a heating solid diffusion treatment.
A method for treating silicon steel, characterized in that a carbide layer of the above metal is formed with a thickness of ~10 μm.