JPH0452283A - Production of material having ferromagnetic area - Google Patents

Abstract

PURPOSE:To enable accurate poatting of a fine pattern which gives high magnetic variation rate by melting ferrite-producing material provided on the surface of an austenite steel base body with a heat source of high energy density to make an alloy so that a ferrite phase is partially formed on the surface. CONSTITUTION:The surface of an austenite steel base body is coated with a ferrite-producing material. Then at least the surface of the base body is molten along a specified pattern C with a heat source of high energy density. Thereby, the ferrite-producing material is changed into an alloy with the base body, which partially gives a ferrite phase. Thus, an alloy area having high ferrite content and little variation in the ferrite content in the area can be formed.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Field of Application 1] The present invention relates to a method for producing materials having partially different magnetic properties.

[Prior art] By partially modifying the surface of a material with uniform properties or by joining materials with different properties, the physical and chemical properties of the material can be partially modified. Change. This characteristic change is utilized in sensing technology. For example, a material with uniform magnetic properties that has regions or patterns with different magnetic properties formed on it can be used as a magnetic sensor to detect position and measure length by detecting the amount of change in magnetism. has been done.

A common method for forming regions or patterns with different magnetic properties is to bond a material of a predetermined shape to the surface or a part of a material serving as a base. However, with this method, the resulting product has a thick wall, and it is not possible to draw a complicated pattern.

Therefore, recently, a method has been developed in which a non-magnetic material such as austenitic stainless steel is made magnetized by cold working, and then the part is made non-magnetic by irradiation with a laser (Plasticity and Processing Vol. 1.30. No.347
．． p1593-15999).

Another method is to melt the ferrite-forming element into the non-magnetic material and make that part ferromagnetic by irradiating the surface of the non-magnetic material with high-energy rays while supplying the ferrite-forming element in the form of powder or wire. , Japanese Patent Publication No. 62-22
This is proposed in Publication No. 7095.

[Problems to be Solved by the Invention] A method in which austenitic stainless steel that has been magnetized by cold working is partially irradiated with a laser to make it nonmagnetic has the advantage of being able to draw complex patterns. but,
Compared to methods of joining dissimilar materials, this method has the disadvantage that the amount of magnetic change obtained is small.

On this point, in the method of melting the ferrite-forming element by supplying the ferrite-forming element to a non-magnetic material in the form of powder or wire and irradiating it with high-energy rays, it is possible to increase the amount of magnetic change and create complex patterns. It is also possible to draw.

However, when supplying the ferrite-forming element in powder form, it is difficult to supply the powder while suppressing fluctuations in the supply amount. Therefore, due to fluctuations in the supply amount, the amount of ferrite formed on the base body also tends to fluctuate. In addition, since the powder is directly irradiated with the laser beam, a part or most of it is evaporated and wasted, which not only lowers the yield, but also does not work effectively on ferrite formation, reducing the amount of ferrite to the target range. It is difficult to fit it into Furthermore, since the laser beam is blocked by the powder, there is a problem that the amount of energy irradiated to the base is insufficient, making it impossible to obtain the desired melt penetration. Moreover, a certain width is required when supplying the powder, and when irradiating the laser beam, it is necessary to shift the focus and melt the powder over a relatively wide width. Therefore, it has been impossible to draw fine patterns with high precision.

On the other hand, the method of supplying the ferrite-forming element as a wire also requires uniformity in the amount of wire supplied, and therefore requires an expensive feeding mechanism. Additionally, since wire tends to reflect laser beams, there is a limit to the amount of wire that can be supplied, which poses a problem in terms of productivity. Furthermore, as with powder, it was impossible to accurately draw fine patterns.

The present invention was devised to solve these problems, and the ferrite-generating material is coated on a non-magnetic substrate in advance and then alloyed with a high energy density heat source to form a predetermined pattern. The purpose of the present invention is to form a ferrite phase with high precision and to manufacture a material having a ferromagnetic region with a large amount of magnetic change compared to the base material.

[Means for Solving the Problems] In order to achieve this object, the method for manufacturing a material having a ferromagnetic region of the present invention coats the surface of an austenitic steel substrate with a ferrite-forming material, and at least The ferrite-forming material is alloyed with the substrate by melting the surface along a predetermined pattern with a high-energy-density heat source to partially form a ferrite phase.

The austenitic steel substrate used in the present invention includes:
Various materials can be used as long as they are non-magnetic.

Typically, an austenitic stainless steel such as 5US304 whose austenite phase has been stabilized by solution heat treatment is used. Further, the shape of the base body is not particularly limited, and various shapes such as a plate shape, a rod shape, and a pipe shape can be used.

As the ferrite-forming material coated on the austenitic steel substrate, there is used a material that is dissolved in the substrate and has a tendency to precipitate a ferrite phase at room temperature. Specifically, AI2. which is known as a ferrite forming element. Si
, Cr, Mo, Nb.

Fe, etc., or an alloy or mixture containing these elements as main components is used. Among them, A℃ or A!
An alloy or mixture mainly composed of is effective because it has a strong effect of producing ferrite and can form ferrite in a small amount compared to other alloys.

The ferrite-generating material is coated onto predetermined portions of the substrate by methods such as plating, adhesion, cladding, vapor deposition, thermal spraying, and the like. At this time, the area to be coated may be the entire surface or a part of the substrate. For example, a ferrite-generating material may be coated on the surface of the substrate depending on the pattern of ferromagnetic regions to be formed.

The amount of coating of ferrite-forming material influences the magnetic properties of the ferrite phase formed in subsequent steps. Therefore, the relationship between the amount of coating and the amount of magnetic change is
The amount of coating of the ferrite-generating material is determined in accordance with the target amount of magnetic change.

The coated ferrite-forming material is melted and alloyed to the substrate by a high energy density heat source. The high energy density heat source used at this time is T
There are arcs such as IG welding, light energy such as laser beams, electron beams, etc. These heat sources locally apply heat to the base and ferrite-forming material, melting only those parts.

Alloying occurs. Note that when using a device equipped with an NC control function, melting and 5-alloying can be performed not only along a simple linear pattern but also along an arbitrary pattern.

Furthermore, the melting depth and width of the substrate can be controlled by adjusting the amount of heat output and the focus position of the beam. At this time, by oscillating the heat source itself within a predetermined width,
It is possible to control the melting depth in 9 widths. Regarding the melting depth of the base, either method may be adopted in which the entire thickness of the base is melted or only a part of the base is melted in the thickness direction.

By melting and alloying, a ferrite phase is precipitated in a predetermined portion of the austenitic base, and a ferromagnetic region is formed. At this time, as mentioned above, the magnetic properties and size of the ferromagnetic region can be controlled by appropriately selecting the ferrite-generating material and energy irradiation conditions, so a product with the targeted amount of magnetic change can be created. Obtainable.

The ferrite-generating material melted and alloyed can be used as a product as it is. Alternatively, if necessary, the ferrite-generating material remaining without being alloyed is ground, or the surface of the substrate after alloying treatment is polished. This post-processing means is appropriately selected depending on the usage pattern of the product.

[Function j] When the ferrite-forming material and the austenitic substrate are alloyed by a high-energy-density heat source, the alloying reaction occurs when the ferrite-forming material is irradiated with energy (limited to only a portion of the material. Under these conditions, the ferrite-forming material Since a ferromagnetic region is produced by alloying the ferromagnetic region, the boundary between the ferromagnetic region and the non-magnetic region becomes clear.In addition, since the ferromagnetic region is composed of a ferrite phase, it is difficult to compare with the austenite phase. The magnetic properties change greatly.

In alloying the ferrite-forming material and the austenitic substrate with a high energy density heat source, the ferrite-forming material is previously coated on the austenitic substrate. Therefore, the ferrite-generating material can be uniformly added to the melted part. As a result, variations in magnetic properties in the alloyed portion can be significantly reduced compared to a method in which a ferrite-generating material is added externally in the form of powder or wire during energy irradiation.

Furthermore, the irradiated energy beam reaches the surface of the substrate coated with the ferrite-generating material without being interrupted on the way, unlike when the ferrite-generating material is supplied from the outside in the form of powder or wire. Therefore, energy usage efficiency is improved (and fluctuations in energy reaching the surface can be extremely small. Also from this point of view, variations in magnetic properties in the alloyed portion can be extremely reduced).

Furthermore, it is not necessary to widen the width of the energy beam, as is the case when ferrite-generating materials are supplied externally in the form of powder or wire, and the energy beam can be irradiated with the focus of the energy beam located on the surface. In this case, the melting width can be very narrow, making it possible to create fine patterns that were not possible with conventional methods of supplying ferrite-forming materials in the form of powder or wire. You can also draw.

Note that coating can also improve the corrosion resistance of the substrate itself. That is, there are cases where the corrosion resistance is improved by exerting a sacrificial anticorrosion effect on the substrate, such as AJ2, and there are cases where the corrosion resistance is improved by coating with something that has better corrosion resistance than the substrate, such as Cr or Ti.

Which material to select can be determined as appropriate depending on the usage environment.

[Example] Examples will be described below.

5U stainless steel plate with a thickness of 1mm that has been subjected to one-place type uni-solution heat treatment
The surface of S304 was plated with aluminum to a thickness of 20 μm.

This aluminized stainless steel plate was placed close to the oscillator by 1 mm from the focal point. Then, a laser beam was irradiated onto the surface of the aluminized stainless steel plate using a carbon dioxide laser oscillator at an output of IKW and a speed of 1 m. The irradiation part has a width Q of 7 mm and a depth of 0.4 mm.
The structure was 100% ferrite phase.

Next, the surface portions of adjacent aluminized steel plates were irradiated with a laser so that the ends of the molten parts overlapped by about 0.2 mm. In this way, an alloyed portion with a width of 30 mm was provided.

When the components of the alloyed part were analyzed, as shown in Table 1, it contained about 6% aluminum.

Table 1: Composition of alloyed part (% by weight) The magnetic properties of the obtained products were also investigated. As a result, the initial magnetic permeability μ of the alloyed part and the base metal part. were as shown in Table 2.

In addition, in the conventional method listed in Table 2, a stainless steel plate 5US304 with a thickness of 1 mm is subjected to 50% cold working to become magnetized, and the material is irradiated with a laser beam under the same conditions as above. This is an example in which a non-magnetic material is formed on a magnetic material. In this case, the base has magnetism because martensite is precipitated by cold working. On the other hand, the laser irradiated part is rapidly solidified after being melted to become non-magnetic.

Table 2: Initial permeability μ. As is clear from Table 2 of the measurement results, it can be seen that when the method of the present invention is used, products exhibiting a larger change in magnetic properties are obtained compared to the conventional method. Further, at the boundary between the magnetic region and the non-magnetic region, only an extremely narrow transition phase of several microns was formed.

Implementation flameout: 1mm thick stainless steel plate 5U subjected to solution heat treatment
The surface of S304 was plated with aluminum to a thickness of 20 LLm. This aluminized stainless steel plate was placed at the focal point of a carbon dioxide laser oscillator, and irradiated with a laser beam under the same conditions as in Example 1. Table 3 shows the shape and ferrite content of the obtained alloyed part. When the method of the present invention was used, the irradiated area was melted with a width of 0.4 mm and a depth of 0.5 mm, and the structure was 100% ferrite phase.

The conventional method listed in Table 3 involves supplying A°C powder to the energy irradiation part of a similar stainless steel plate that has been subjected to solution heat treatment, at a speed of 1 m/min, at a speed of 2 mm from the focal point.
Alloying was performed by irradiating the steel plate surface with a laser beam under the condition that the steel plate was placed on the oscillator side.

Table 3 - Shape of melted zone and ferrite content As is clear from Table 3, in the conventional method, the melting width became wider, and variations in the melting width depending on the position were also observed. Further, the ferrite content rate also varied depending on the position, and the rate also showed a low value of 25 to 40%.

A: Aluminum plating with a thickness of 7 μm was applied to the surface of a stainless steel plate 5US316 with a thickness of 1.5 mm that had been subjected to solution heat treatment. This base body was irradiated with an arc using a DC TIG welding machine so that a molten layer having a depth of about 0.5 mm was obtained from the surface layer.

Adjacent surface portions were then irradiated with an arc so that the ends of the molten zone overlapped each other by about 0.5 mm. Arc irradiation was repeated in this manner to alloy the square portion with a negative side of 100 mm. After the alloyed portion was formed, the steel plate was immersed in a caustic soda solution to peel off the aluminum layer that was not used for alloying.

For the obtained product, the center point A of the alloyed part.

The magnetic properties were investigated at three points: a midpoint B around the alloyed part and a corner part C. As a result, as shown in Table 4, the initial magnetic permeability was the same at all of the measurement positions A, B, and 0 points. From this, it can be seen that the magnetic properties of the alloyed part obtained according to the method of the present invention do not change depending on the position, but have constant magnetic properties over the entire area of the alloyed part.

Table 4: Measurement results of initial magnetic permeability In the above examples, an aluminum layer, which is a ferrite-generating material, was formed on the surface of the substrate by plating. However, even when a substrate coated with other ferrite-forming materials such as Cr, Si, Mo, and Fe is melted using a high-energy-density heat source, ferromagnetic regions with a large magnetic change rate can be formed in a predetermined pattern. could be formed accurately according to the following.

[Effects of the Invention] As explained above, in the present invention, the ferrite-generating material is coated on the base in advance and then heated with a high energy density heat source to melt and alloy the ferrite-generating material onto the austenitic steel base. As a result, a ferrite phase along a predetermined pattern is formed within the structure of the base body. Therefore, compared to conventional methods, it is possible to form an alloy part with a high ferrite content and extremely small variations depending on the location of the ferrite content. Moreover, compared to conventional methods, fine patterns with a high rate of magnetic change can be drawn with high precision.

The materials thus obtained can be used in a wide range of fields, including magnetic materials for mechatronics, various sensors, actuators, and the like.

Claims (1)

[Claims] (1) Coating the surface of an austenitic steel substrate with a ferrite-forming material, and alloying the ferrite-forming material with the substrate by melting at least the surface of the substrate along a predetermined pattern with a high-energy density heat source. A method for producing a material having a ferromagnetic region characterized by partially forming a ferrite phase.