JP2649590B2 - Manufacturing method of Fe-Al alloy thin plate - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to an industrial method for producing an Fe—Al alloy thin plate that can be formed at room temperature and has excellent oxidation resistance, magnetic properties, and corrosion resistance.

[Conventional technology]

Fe-Al alloys are known to have excellent high temperature oxidation resistance and magnetic properties. In particular, Fe12% Al and Fe16% Al have very good magnetic properties.

However, conventionally, it has been extremely difficult to industrially produce such Fe-Al alloy thin plates. This is because the inclusion of Al at a high concentration in Fe makes the material very brittle, making it difficult to manufacture thin sheets by a combination of ordinary rolling and sintering. Because of the fact that cold rolling is almost impossible and processing into thin sheets is difficult, such Fe-Al alloys are industrially available despite their excellent oxidation resistance and magnetic properties. The fact is that it has not been widely used.

As a means for solving the poor workability of this alloy, a method of performing a special warm rolling than before (for example, JF Naehman;
J. Appl. Physics, 25 (1959), p. 307), a method of diffusing and infiltrating powder Al from the surface of a steel sheet (Japanese Patent Laid-Open No. 54936/1979), and an ultra-thin Fe-Al alloy by a liquid quenching method A method for obtaining the same (Japanese Patent Application Laid-Open No. 57-6024) has been proposed.

However, all of the methods need to be manufactured using a special manufacturing apparatus. Therefore, it cannot be denied that mass production is lacking as in the production of ordinary steel sheets, and production costs are increased. It has also been proposed to use an aluminum clad steel sheet as a material and alloy it by diffusion hardening.
There is a problem that voids and cracks occur near the interface with the Al plate, and a technique for obtaining a high-quality Fe-Al alloy thin plate has not been established.

[Object of the invention]

An object of the present invention is to produce such a useful thin plate of Fe-Al alloy industrially at low cost using ordinary equipment.
In particular, Fe-
When using an aluminum laminated pressure-welded plate as a material and diffusing and refining it to form an alloy, a good-quality Fe-Al alloy with no cracks near the interface between the steel layer and the Al layer and little void formation It is to manufacture a thin plate.

[Configuration of the invention]

According to the present invention, the C content is 0.02% by weight or less and Ti, N
Al having a thickness corresponding to the amount of Al to be contained in the steel sheet is superimposed on at least one side of a steel sheet (excluding stainless steel sheet) containing one or more kinds of b or Zr in an amount of 0.01 to 0.8% by weight. Then, pass this between the rolls and apply a reduction of 30% or more to form a laminated pressure-welded plate.
Fe-contained by performing a diffusion treatment under the condition that the Al layer is alloyed with the steel without melting at a temperature in the range of 600 to 1300 ° C
Provided is a method for manufacturing an Al alloy sheet.

Further, the above-mentioned laminated pressure-welded plate is used as a raw material, which is further rolled to a target plate thickness, and before or during this rolling, an intermediate refining at 250 to 550 ° C. is performed.
Provided is a method for producing an Fe-Al alloy thin plate, which comprises performing a diffusion treatment under a condition where an Al layer does not melt at a temperature in a range of 300 ° C and alloys with the steel.

Further, after the above-described laminated pressure-welded plate is subjected to ingot at 250 to 550 ° C., it is formed into a desired shape (including a semi-finished product shape),
Next, there is provided a method for producing a thin Fe-Al alloy sheet product, which comprises performing a diffusion treatment under a condition where the Al layer is not melted and alloyed with the steel at a temperature in the range of 600 to 1300 ° C.

[Action]

In the method of the present invention, since the operations of clad pressure welding and diffusion treatment are performed, more than 3% of Al, and
% Of Al in Fe can be industrially manufactured as a steel strip in the same manner as a normal steel plate.

In the diffusion process, by adjusting the degree, the uniform concentration of Fe-
An Al alloy plate can be obtained, and an Fe-Al alloy plate having an Al-rich portion having a different Al concentration distribution in the thickness direction can be obtained. In addition, it is relatively easy to manufacture products that are suitable for applications, such as a special structure Fe-Al alloy plate with an Al oxide film on the outermost surface and a layered Fe-Al alloy layer interposed inside. it can. Further, if processing is performed before alloying by diffusion processing, a processed or semi-processed product of an Fe-Al alloy having a complicated shape, which has been conventionally difficult to manufacture, can be easily manufactured.

In the present invention, a steel sheet containing 0.01% to 0.8% of C: 0.02% or less and one or more of Ti, Nb, and Zr is used as the Fe-based material. Voids and cracks that may be generated near the interface between the steel plate and the Al plate during diffusion processing of the pressure contact plate with the Al plate are prevented. That is, after making the C content in the steel 0.02% or less, one or more of Ti, Nb, and Zr are contained in the steel in the range of 0.01 to 0.2%.
When 8% is contained, these elements function to prevent the generation of voids and cracks according to the present invention, whereby a high-quality Fe-Al alloy sheet having excellent heat resistance and magnetic properties can be produced.

[Detailed Description of the Invention]

The present invention uses, as one of the starting materials, a steel sheet or a steel strip containing C: 0.02% by weight or less and one or more of Ti, Nb, and Zr in an amount of 0.01 to 0.8% by weight. . It should be noted that a stainless steel sheet containing a large amount of chromium is not included in the present invention. In carrying out the present invention, C
When a steel sheet with a high content is used, voids are likely to be formed near the interface between the steel plate and the aluminum plate when the pressure-welded plate is subjected to diffusion treatment, which may cause cracks at the interface. Therefore, it is desirable that the C content in the steel sheet is as low as possible, but in the present invention, the C content is allowable up to 0.02%. When Ti, Nb, or Zr is contained in steel in an appropriate amount, voids near the interface between the steel layer and the Al layer during the diffusion treatment of the welded plate,
It was found that the generation of cracks could be prevented. If the content of one or more of these components is less than 0.01%, the effect is not recognized. On the other hand, the effect is saturated even if it is contained in a large amount, and the workability is deteriorated, making it difficult to obtain a press-contact plate, so that the content is limited to 0.8% or less. Although it is not always clear why the inclusion of these components can prevent voids and cracks generated near the interface, these components are related to fixing C to form stable carbides. Conceivable.

The Al plate (usually a thin plate or ribbon) used as the other starting material in the method of the present invention is desirably a pure Al plate, but a normal Al plate contains some Fe, Si, and the like.
These elements are also contained in the steel sheet, and therefore there is no particular problem even if such elements are contained.

Such an Al plate is superimposed on one or both surfaces of the steel plate with a thickness selected so as to have a target Al content in the product alloy thin plate, and this is pressed using a roll.
In that case, it is desirable that both surfaces are subjected to a cleaning treatment. It is usually difficult to obtain a good pressed state between the steel plate and the Al plate if the rolling reduction of the pressed plate is less than 30% in the pressing process of the superposed plates using the rolls. Therefore, it is necessary that the rolling reduction of the welding be 30% or more, whereby a laminated welding plate of a steel plate and an Al plate can be obtained.

In order to further enhance the adhesiveness of the laminated press-contacting plate, it is preferable to perform an appropriate refining treatment. Although this refining process is not necessary for all cases, when the thickness of the press contact plate exceeds about 1.5 mm, the plate is further cold-rolled in the next process to reduce the thickness. When forming or processing into a semi-finished product or a semi-finished product, peeling may occur on the bonding surface, but this can be prevented by performing appropriate sintering. The effect of this intermediate sintering is not recognized unless a temperature of 250 ° C. or higher is employed. However, when the temperature exceeds 550 ° C, a thick intermetallic compound layer develops at the interface between the steel layer and the Al layer of the welded plate, and cracks occur near this alloy layer during the next cold rolling, resulting in delamination. Or Batch refining using a tight coil can be used as the refining method. In this case, the baking time is preferably about 1 to 20 hours. Although any other refining method may be used, in any case, it is necessary to carry out the treatment in a temperature range of 250 to 550 ° C. in order to prevent peeling at the time of cold pressure or the like.

In this way, the laminated pressure-welded plate,
After producing a pure pressure welded plate with intermediate sintering, or a cold rolled plate with intermediate sintering before cold rolling or with intermediate sintering in the middle of cold rolling, with the target Al content, This is subjected to diffusion processing. This diffusion process is a process for mutually diffusing the steel layer and the Al layer. In carrying out this diffusion treatment, if the treatment temperature is lower than 600 ° C., the diffusion of Al does not proceed sufficiently. When the temperature exceeds 1300 ° C., a molten layer is formed in the diffusion alloy layer. Therefore, it is necessary to perform in the temperature range of 600 ° C to 1300 ° C. In this diffusion process, if the heating rate is increased and the material is rapidly heated to a temperature higher than the melting point of Al, the Al layer may melt at about 700 ° C. When this Al layer is melted, it causes a change in the concentration of Al in the plate surface direction due to dripping or accumulation. Therefore, it is necessary to prevent such melting of the Al layer as much as possible.
At a temperature below the melting point of
It is preferable that the Al layer is kept at a temperature of ° C for 1 minute or more to turn the Al layer into an alloy layer having a high melting point, and then further heated to a high temperature to perform a sufficient diffusion treatment. In the present invention, "the diffusion treatment is performed under the condition that the Al layer is alloyed without being melted" means such a content.

In carrying out this diffusion treatment, by appropriately selecting the temperature and the treatment time within the above-mentioned treatment temperature range, and further by adjusting the atmosphere, it is possible to produce steel sheet products having various structures. For example, if sufficient diffusion is performed in a non-oxidizing atmosphere, an Fe-Al alloy thin plate having a uniform Al concentration in the thickness direction can be manufactured. A Fe-Al alloy thin plate having a high Al concentration can be manufactured. Also, if diffusion sintering is performed without particularly avoiding surface oxidation, a special heat-resistant Fe-Al alloy thin plate having a rich Al oxide layer on the surface layer can be manufactured. If the surface properties of the Fe-Al alloy sheet become poor after the diffusion treatment, remove the strain by light cold rolling or polish or gloss finish the surface to obtain good surface properties. Can be.

In this way, according to the method of the present invention, an Fe-Al alloy thin plate which is difficult to produce by a normal production method can be produced industrially. Especially
It is difficult to roll Fe-Al alloys not only by cold rolling but also by hot rolling.However, according to the method of the present invention, a steel sheet and an Al sheet having good workability can be welded in a pressed state before or after Al alloying. Since the thickness is reduced by rolling, it is possible to cold roll well to the target thin plate, and in some cases it can be cold-processed into a product or semi-finished product, and the Al content is required. It is also possible to make it 10% or more according to it.
Therefore, it is possible to manufacture an Fe—Al alloy thin plate or a thin alloy ribbon having excellent heat resistance and corrosion resistance as well as an Fe—Al alloy thin plate which is a high magnetic permeability alloy or a metal substrate for supporting a catalyst used at a high temperature.

The oxidation resistance of the Fe-Al alloy sheet obtained by the present invention is superior to that of a stainless steel sheet (ferrite type) even under severe conditions such as heating at 1000 ° C., as shown in Examples described later. Is less than 0.02%, and one of Ti, Nb and Zr
By using a steel sheet containing 0.01% to 0.8% of one or more species, voids and cracks are prevented from being generated at the interface between the steel layer and the Al layer during the diffusion treatment.
Al alloy thin plate can be manufactured.

The characteristics of the steel sheet obtained by the method of the present invention will be described below with reference to typical examples of the present invention.

[Example 1] Table 1 shows the chemical component value (% by weight) and a sheet thickness of 0.6 m.
m steel plate, both surfaces of which are polished with a roll with a wire brush and used as a core material. A 0.15 mm thick Al plate of JIS alloy number 1050 is spray-degreased with trichlorethane to be used as a skin material. did.

Laminated materials were superposed on both sides of each core material in the thickness configuration shown in Table 2 and bitten by a four-high rolling mill, and pressed and rolled to the thickness shown in Table 2 at the indicated reduction rate. And wound it around a coiler. The rolling speed was 10-30m / min. The obtained pressure contact plate coil was placed in a batch refining furnace, subjected to intermediate refining at 350 ° C. for 10 hours, and then cold rolled to a plate thickness of 0.10 mm. A 60mmφ disk-shaped specimen was collected from the obtained cold-welded coil.
This disk-shaped specimen was subjected to a heat treatment of holding at 650 ° C. × 1 hour. Next, an oxidation test was performed in which the sample was heated to a temperature of 1000 ° C. to 1500 ° C. in the air for the indicated time, and the oxidation increase was measured. The results are shown in Table 2. During the high-temperature oxidation test, the diffusion of Al progressed, but the diffusion was completed uniformly at 1100 ° C. for about 1 hour in the present invention.

Sample No. 4 and N after heat treatment of 1100 ° C. × 25 hours
Samples of o.5 were taken and their cross sections were observed under a microscope. The photographs are shown in FIG. 1 and FIG.

As is clear from Table 2, in Comparative Sample No. 5 which does not contain Ti, Nb and Zr, 10 mg / cm at 1100 ° C. × 200 hours.
Sample N, which is the material of the present invention, exhibits an oxidation weight increase of ² or more.
o.1, No.2, No.3 and No.4 show good oxidation resistance with an oxidation weight gain of less than 10 mg / cm ² even at an oxidation test of 1100 ° C. × 200 hours. As shown in the photograph of FIG. 2, the sample No. 5 of the comparative material not containing Ti, Nb, and Zr has voids and cracks near the interface between the steel sheet layer and the Al layer. On the other hand, when a steel sheet having the composition specified in the present invention is used, no voids or cracks are seen and the interface is uniform as shown in the photograph of FIG.

[Example 2] Samples No. 4 and No. 5 of Example 1 were pressed and rolled.
It was cold-rolled to 0.55 mm, heat-treated at 650 ° C for 1 hour, and subsequently subjected to diffusion at 1100 ° C for 2 hours in a vacuum to obtain a Fe-Al alloy sheet in which Al was uniformly diffused. After that, light cold rolling with an elongation of 1.0% was performed to correct the shape of the sheet. From the obtained Fe-Al alloy thin plate, a disk-shaped specimen of 600 mmφ was sampled and heated to 1000-1150 ° C in the atmosphere to perform an oxidation experiment. The results are shown in Table 3. Example 1 In this example, the oxidation resistance of a Fe—Al alloy thin plate in which Al of a pressure contact plate was diffused uniformly was examined.

As is evident from Table 3, the comparative material No.6 SUS430
Stainless steel sheet is 25 at oxidation temperature of 1100 ℃ and 1150 ℃.
Less than 10 mg / cm ^{2 in} less than 10 hours
In Comparative Sample 5a, which used a steel sheet containing no b and Zr, the oxidation gain was smaller and better than that of SUS430 steel sheet of Sample No. 6, but 10 mg / cm ^{2 at} less than 1100 ° C × 200 hours and 1150 ° C × 50 hours. In contrast to the above oxidation increase, Sample No. 4a according to the present invention
At 1100 ℃ × 200 hours and 1150 ℃ × 50 hours
The oxidation weight gain is less than 10 mg / cm ² , indicating good oxidation resistance.

In Comparative Sample No. 5a, when the cold-rolled sheet was subjected to the diffusion treatment, voids and cracks were generated near the interface between the steel layer and the Al layer as shown in FIG. Therefore, it was confirmed that the sheet was liable to be cut during light cold rolling, and that cracking occurred during working such as punching and bending.

[Effects of the Invention] As described above, according to the present invention, a thin sheet of an Fe-Al alloy, which was extremely difficult to be thinned, can be manufactured in good quality without cracks or voids. Since it can be easily and inexpensively manufactured using the above production line, its industrial significance is enormous.

[Brief description of the drawings]

Fig. 1 is a metallographic micrograph showing the metallographic structure of a cross section of a steel sheet after diffusion treatment using a steel sheet containing Ti as a core material.
4 is a metal micrograph showing a metal structure of a cross section of a steel sheet after a diffusion treatment using a steel sheet containing no b and Zr as a core material.

Claims (3)

(57) [Claims] 1. The amount of Al to be contained in at least one surface of a steel sheet having a C content of 0.02% by weight or less and containing 0.01 to 0.8% by weight of one or more of Ti, Nb and Zr. Laminated Al plates having a thickness equivalent to that of the above are passed between the rolls and subjected to a reduction of at least 30% to form a laminated pressure-welded plate. The obtained laminated pressure-welded plate is heated at a temperature in the range of 600 to 1300 ℃. A method for producing an Fe-Al alloy thin plate, comprising performing a diffusion treatment under conditions in which an Al layer is alloyed with the steel without melting. 2. The amount of Al to be contained in at least one surface of a steel sheet having a C content of 0.02% by weight or less and containing at least one of Ti, Nb and Zr in an amount of 0.01 to 0.8% by weight. Laminated Al plates having a thickness equivalent to that of above are passed through the rolls and subjected to a reduction of 30% or more to form a laminated pressed plate. The obtained laminated pressed plate is further rolled to a target plate thickness.
250-550 ° C before or during this rolling
A method for producing a thin Fe-Al alloy sheet, comprising subjecting the intermediate layer to the above-mentioned intermediate sintering, and then performing a diffusion treatment under conditions in which the Al layer is not melted and alloyed with the steel at a temperature in the range of 600 to 1300 ° C. 3. The amount of Al to be contained in at least one surface of a steel sheet having a C content of 0.02% by weight or less and containing 0.01 to 0.8% by weight of one or more of Ti, Nb and Zr. Laminated aluminum plates having a thickness equivalent to that of the above are passed through the rolls and subjected to a reduction of 30% or more to form a laminated pressure-welded plate. After forming, it is formed into a desired shape, and then subjected to a diffusion treatment under the condition that the Al layer does not melt and alloys with the steel at a temperature in the range of 600 to 1300 ° C. Manufacturing method.