JPH0465899B2 - - Google Patents

Description

[Detailed description of the invention]

[Industrial Field of Application] The present invention relates to a method for manufacturing high-silicon steel materials by silicon leaching treatment. [Prior Art] High-silicon steel sheets are used as electromagnetic steel sheets.
It is known that this type of steel sheet exhibits the most excellent magnetic properties, with iron loss reduced as the Si content increases, and at 6.5% Si, magnetostriction becomes 0 and maximum magnetic permeability reaches its peak. . Conventionally, methods for producing high-silicon steel sheets include the rolling method, direct casting method, and silicon extrusion method. Of these, the rolling method can produce Si steel sheets with a Si content of up to about 4%, but Cold working is difficult because the workability deteriorates significantly. In addition, although the direct casting method, so-called strip casting, does not have workability problems like the rolling method, it is still a technology under development and is prone to shape defects, making it particularly difficult to manufacture high-silicon steel sheets. be. On the other hand, the silicon permeation method produces high-silicon steel sheets by melting low-silicon steel, rolling it into thin sheets, and then infiltrating Si from the surface. A high-silicon steel plate can be obtained without causing any problems. [Problems to be solved by the invention] This infiltration method was proposed by Goyumi and Abe, and was studied in detail by Mitani and Onishi et al. However, all of the previously proposed methods required an infiltration treatment time of 30 minutes.
There is a fundamental problem that the process is long (more than 1 minute) and cannot be applied to industrial continuous production. Also, the processing temperature
Since the temperature is extremely high at around 1230°C, the shape of the thin steel sheet after the penetration treatment is extremely poor, and in addition, because the treatment temperature is too high, there is a risk that the edges may melt due to overheating. The present invention has been made in order to improve the drawbacks of the prior art, and aims to provide a method for producing high-quality high-silicon steel materials in a short processing time. [Means for solving the problem] For this reason, the present invention treats a steel material by a plasma enhanced chemical vapor deposition method using SiCl ₄ or an ion beam irradiation method using Si ions to enrich the surface with Si, Next, by irradiating the steel plate with an Fe ion beam, Si is diffused into the steel material and at the same time
Its basic feature is that Fe is enriched in the surface layer. The details of the present invention will be explained below. In the present invention, the base material steel material includes steel strips, cut plates, and processed materials such as pressed products. Further, the composition of the steel material is not particularly limited, but is preferably determined as follows in order to obtain excellent magnetic properties. For 3-6.5% Si-Fe alloy C: 0.01% or less, Si: 0-4.0%, Mn: 2%
Below, it is desirable that other unavoidable impurities be as low as possible. For Sendust alloy: C: 0.01% or less, Si: 4% or less, Al: 3-8
%, Ni: 4% or less, Mn; 2% or less, Cr, Ti
It is desirable that the content of elements that increase corrosion resistance, such as 5% or less, and other unavoidable impurities be as low as possible. The steel material is not limited to one obtained by hot rolling-cold rolling, but may be one obtained by direct casting or rapid solidification. Note that the thickness of steel material is reduced by CVD treatment, and therefore it is necessary to use a material whose thickness is the final product thickness plus the reduced thickness. The present invention obtains a high-silicon steel material by subjecting such steel material to Si vapor deposition (enrichment by Si injection) and diffusion treatment. First, the Si vapor deposition treatment for steel materials is plasma chemical vapor deposition (hereinafter referred to as plasma chemical vapor deposition) using _SiCl4 gas.
(referred to as CVD) or ion beam irradiation using Si ⁺ ions.By adopting these methods, steel materials can be treated at low processing temperatures. Of these, Si vapor deposition treatment using plasma CVD
The steel material is first heated to the CVD treatment temperature without oxidation, and then subjected to plasma treatment in a non-oxidation gas atmosphere containing _SiCl4 .
A CVD process is performed to deposit Si on the surface (enrichment by implantation). In the plasma CVD process, Si is heated to high temperature (partially ionized) and deposited on the steel strip. In plasma CVD treatment, the higher the temperature of the steel, the faster the reaction and the faster the deposition rate.
A sufficiently satisfactory deposition rate can be obtained even at temperatures of about ~800°C. FIG. 1 shows the relationship between steel material temperature, vapor deposition temperature, and amount of FeCl ₂ produced.
As shown in the figure, when the steel material temperature exceeds 1000℃, the deposition rate increases rapidly, but at such high temperatures, the shape of the steel material tends to be defective, and FeCl ₂ (solid phase) is generated on the surface of the steel material. increases, deteriorating the final surface quality. Further, in the present invention, a diffusion process by ion beam irradiation is performed following the Si vapor deposition process, but this process needs to be performed in a vacuum system. When steel materials are treated at high temperatures, it is difficult to realize the vacuum system described above due to sealing problems, and in this sense, steel materials are processed by plasma CVD at temperatures of 200 to 800 degrees Celsius.
Preferably, it is treated. Figures 2 and 3 show the plasma CVD treatment of a steel strip. Inside the furnace body 6 constituting the CVD treatment zone, there are many gas passages facing each side of the steel strip s. Electrode plates 7a and 7b having holes 8 are arranged, and the reaction gas supplied from the supply port 9 is guided to the steel strip surface through the gas passage hole 8, so that the steel strip S and the electrode plate 7a , 7b, a high voltage plasma is generated, and the Si reaches a high temperature.
is deposited on the steel strip. Note that 10 in the figure is an exhaust port. Further, the Si vapor deposition process by ion beam irradiation is performed by irradiating the steel surface with Si ⁺ ions.
This process is performed by ionizing molecules or atoms, accelerating them in a magnetic field, and causing them to collide with the steel surface, whereby Si is vapor deposited (enriched by implantation) on the steel surface. This treatment can be performed even when the steel material is at room temperature. Note that this ion beam irradiation must be performed under predetermined vacuum conditions. The steel material subjected to the Si vapor deposition treatment as described above is subjected to a diffusion treatment by ion beam irradiation. In other words, immediately after CVD treatment, the Si concentration is high near the steel surface, and the Si concentration remains the same as the base material in the center.
It is necessary to perform soaking and diffusion treatment to obtain a uniform Si concentration or a predetermined concentration distribution. Soaking diffusion is a method for diffusing Si into steel materials, but this method takes a relatively long time for diffusion, lengthens the processing line, and because it is soaked at a high temperature, it may cause poor shape of the steel strip. destabilization of the plate;
Problems such as surface scratches are likely to occur. In contrast, the diffusion process using ion beam irradiation in the present invention can complete the diffusion process in a short time, and in addition, diffusion can be performed even at temperatures below 800°C, and the above-mentioned problems such as the steel strip shape defects etc. problems can be appropriately avoided. In this ion beam irradiation, ions with high kinetic energy collide with the solid surface, and Si is diffused mainly due to the effect of increasing the solid temperature due to the conversion of kinetic energy into thermal energy during the collision. . In this diffusion process, Fe ⁺ ions are used as the ion species to collide with the steel plate for the following reasons. (b) When using inert gas ions such as Ar ⁺ and He ⁺ , there is a problem that Ar, He, etc. remain in the steel surface layer, but since Fe is the same element as the base metal. , does not cause any problems due to residue. (b) The mass of the ions is large, and the collision effect is large. (c) Although Fe in steel is consumed during CVD treatment,
Although it is a small amount, it can compensate for the amount of consumption. (d) FeCl ₂ (boiling point 1023℃) is preferably gaseous and is generated during the CVD process for ionization.
can be used. This diffusion process by ion beam irradiation is also performed under predetermined vacuum conditions. In addition, the above diffusion treatment is performed when Si is applied to steel materials (mainly steel strips).
However, in some cases, the treatment may be stopped while the surface layer Si concentration is higher than the Si concentration in the center of the steel material, so that the Si concentration is uniform throughout the thickness. It may be possible to obtain a uniform steel material. After the above diffusion treatment, the steel material is cooled if necessary. In other words, Si vapor deposition is
When CVD is used, the steel material is heated to a predetermined temperature, and in this case it is usually cooled. On the other hand, when Si vapor deposition is performed by ion beam irradiation, the steel material is not necessarily placed in a heated state, so cooling may not be performed. In addition, in the case of steel strip, it is usually wound in a warm state from room temperature to 300°C. The object of the present invention is not limited to steel strips, but can also be applied to processed materials such as cut plates and pressed products, and when the object is such, the steel material is conveyed through each processing band by a conveyor device etc. will be done. In addition, the raw material gas for the silicon exfoliation treatment is as described above.
In addition to SiCl ₄ , there are halides such as Si ₂ Cl ₆ , SiH ₄ , and SiHCl ₃ . [Example] Figure 4 shows an example of a thin steel plate production line when plasma CVD method is used for Si vapor deposition treatment.
In the figure, 1 is a heating zone, 2 is a CVD treatment zone, and 3 is a heating zone.
4 is a diffusion treatment zone, 4 is a cooling zone, and 5 is an ion beam irradiation device. To explain an example of the manufacturing process using such a line, first, the steel strip S is heated without oxidation to about 600°C in the heating zone 1, and then guided to the CVD treatment zone 2, where it is heated with SiCl ₄ (20%). and H ₂ (80%).
Steel strip S was led to diffusion treatment zone 3 while being maintained at the same temperature, and FeCl ₂ was vaporized and ionized.
Fe ⁺ ions are irradiated with an energy of about 200 keV,
Diffusion processing is performed. After such treatment, the steel strip S
is cooled in a cooling zone to room temperature to around 300°C, and then wound into a coil. Figure 5 shows an example of a thin steel sheet production line when ion beam irradiation is used for Si vapor deposition, where 6 is an ion irradiation zone, 3' is a diffusion treatment zone, and 4' is a non-oxidation cooling zone. . To explain an example of the manufacturing process using such a line, the steel strip S is introduced into the ion irradiation zone 6 at room temperature, and under a vacuum of approximately 10 ^-4 torr, Si ⁺ ions are irradiated with approximately
It is irradiated with an acceleration energy of 500 keV, and Si is vapor deposited (enriched by injection) on the steel strip surface. In this irradiation, the temperature of the steel strip S is also increased by converting kinetic energy into thermal energy. Next, steel strip S
In the diffusion treatment zone 3', Fe ⁺ ions obtained by vaporizing and ionizing FeCl ₂ are irradiated with an acceleration energy of about 200 keV under the same vacuum as above, and Si diffusion treatment is performed. The steel strip S can be heated, for example, after the diffusion treatment zone 3', thereby making it possible to perform the diffusion treatment more effectively. After such a diffusion treatment, the steel strip S is cooled in a non-oxidizing cooling zone 4' and wound into a coil. Hereinafter, specific examples of the present invention will be given. No. 4, which incorporates the plasma CVD device shown in Figure 2.
In the line shown in the figure, the following steel materials were enriched with Si. ●Steel material: 3% Si-containing silicon steel sheet with a thickness of 0.3 mm and a width of 400 mm Composition (wt%):

[Table] The processing conditions are as follows. ●Heating temperature: 400℃ ●CVD processing conditions Processing temperature: 400℃ Reaction gas supply concentration: SiCl ₄ 20%, N ₂ balance ●Diffusion processing conditions Processing temperature: 600℃ Degree of vacuum: 10 ^-4 torr Fe ion irradiation intensity: 200keV ●Cooling zone outlet plate temperature: 60℃ As a result of manufacturing at a line speed of 0.5mpm under these conditions, Cl due to the CVD process
There is almost no decrease in Fe (emission as FeCl ₂ ) due to the low-temperature treatment, and it is due to the diffusion process.
The Fe enrichment resulted in an enrichment of Fe content of approximately 5 g/mm ² . The final product was a high-silicon steel plate containing 6.5% Si in coil form. Further, using the same steel material as above on the line shown in FIG. 5, a 5% silicon steel plate was manufactured by irradiation with a Si ion beam. The processing conditions are as follows. ●Si ion irradiation conditions Irradiation concentration: 500keV Vacuum degree: 10 ^-4 torr ●Diffusion treatment conditions Fe ion irradiation intensity: 200keV Vacuum degree: 10 ^-4 torr As a result of manufacturing under these conditions at a line speed of 0.2mpm, A silicon steel sheet was enriched with approximately 45 g/mm ² of Si and finally had a Si concentration of 4.8%. [Effects of the Invention] According to the present invention described above, the Si vapor deposition treatment can be performed at a relatively low temperature, and the subsequent diffusion treatment can also be performed at a low temperature and in a short time. Problems such as shape defects and edge melting do not occur, and high-quality, high-silicon steel materials can be efficiently manufactured on a short line.

[Brief explanation of the drawing]

Figure 1 shows the steel temperature and Si in plasma CVD.
This shows the relationship between the deposition rate and the amount of FeCl ₂ produced. Figures 2 and 3 show an example of a plasma CVD processing situation, and Figure 2 is a perspective explanatory view;
FIG. 3 is a longitudinal sectional view of the treatment zone. FIG. 4 shows an example of a thin steel sheet manufacturing line using plasma CVD method for Si vapor deposition. Figure 5 shows Si
This figure shows an example of a thin steel sheet production line using ion beam irradiation for vapor deposition.

Claims (1)

[Claims] 1. A steel material is treated with a plasma chemical vapor deposition method using SiCl ₄ or an ion beam irradiation method using Si ions to enrich the surface with Si, and then the steel sheet is irradiated with an Fe ion beam, Si
A method for producing a high-silicon steel material, characterized by diffusing Fe into the interior of the steel material and simultaneously enriching the surface layer with Fe.