JPH0739627B2 - Manufacturing method of high Al content stainless steel plate - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial field of application] The present invention has high-temperature oxidation resistance, corrosion resistance, and electric heat resistance, and can be suitably used for a catalytic metal substrate for treating heat generated by an electric heater and polluting gas. The present invention relates to an industrial manufacturing method of a high Al stainless steel alloy plate.

[Conventional technology]

Since stainless steel sheets are excellent in oxidation resistance and corrosion resistance, they are widely used in various industrial fields by taking advantage of this characteristic. However, in order to impart further oxidation resistance, it is effective to add Al to the steel. Is. However, the addition of a large amount of Al makes the material very brittle, making it difficult not only for cold rolling but also for hot rolling.
It is extremely difficult to manufacture a stainless steel plate. For this reason, high-Al stainless steel sheets have high electrical resistance, and although they are materials with excellent oxidation resistance and corrosion resistance, their productivity is extremely poor, so they have not been fully utilized.

[Object of the Invention]

An object of the present invention is to establish a method for easily and inexpensively producing such a useful high Al stainless steel sheet, and to contribute to the widespread use of the high Al content stainless steel sheet.

[Structure of Invention]

The gist of the present invention, which is intended to achieve the above-mentioned object, is to stack an Al thin plate or a thin strip on at least one surface of a stainless steel plate or a steel strip so as to have a ratio corresponding to the amount of Al to be contained. It is passed between rolls to form a laminated rolled sheet, and the obtained laminated rolled sheet may be further rolled to a target sheet thickness (in that case, before or during rolling, an intermediate annealing of 250 to 550 ° C is performed. It is advantageous that a diffusion treatment is performed at a temperature in the range of 600 to 1300 ° C under the condition that the Al layer is not melted but alloyed, Exist.

Further, according to the present invention, a laminated pressure-bonded plate, an annealing pressure-bonded plate or a rolled plate obtained in the course of the above-mentioned manufacturing method is used as a material to be processed into a product shape or an intermediate product shape according to the application. Process for producing a processed product or a semi-processed product of Al-containing stainless steel, characterized by subjecting the semi-processed product to a diffusion treatment under a condition that an Al layer is not melted and alloyed at a temperature in the range of 600 to 1300 ° C Will be provided.

According to the method of the present invention, a stainless steel sheet containing 3% or more of Al, which is difficult in the past, and in some cases, 10% or more of Al can be industrially produced. Moreover, industrial production as a steel strip is possible as in the case of producing ordinary stainless steel sheets. The high Al content stainless steel sheet obtained by the method of the present invention is an alloy steel sheet having a uniform concentration in the thickness direction in which Al is uniformly diffused, depending on the degree of diffusion treatment,
High Al stainless steel sheets with different Al concentration distributions in the thickness direction, with a special structure having a layered alloy layer interposed or an outermost surface layer having an oxide film of Al or Cr, can be manufactured. The feature is that it is relatively easy to manufacture a product suitable for the purpose. Further, it is possible to easily manufacture a processed product or a semi-processed product made of high Al stainless steel having a complicated shape, which was difficult to manufacture in the past.

[Detailed Description of the Invention]

The stainless steel plate or steel strip used in the method of the present invention (hereinafter,
The composition of steel sheet) is not particularly limited, and the C content is> 0.
Ordinary stainless steel plate of 03% can be used, but if the Cr content is high, it becomes difficult to obtain a pressure-bonded plate.
% Or less, it is desirable to use a stainless steel plate. Although it is desirable that the C content is as low as possible, one of the objects of the present invention is to produce a stainless steel sheet containing a high amount of Al at a low cost, and a cheap stainless steel sheet having a C content of more than 0.03% is used as a starting material. Even when used, it has excellent heat resistance
It was found that an Al-containing stainless steel plate can be manufactured.

On the other hand, the Al plate used in the method of the present invention (Al foil or ribbon can also be used) is preferably a pure Al plate, but a normal Al plate.
The plate contains some Fe, Si, etc. Since these elements are also contained in the stainless steel sheet, there is no problem even if such elements are contained, and an Al plate containing up to 3% of such elements is also advantageous in the present invention. Can be used for

On one or both sides of such a stainless steel plate, an Al plate,
The rolls are overlapped with each other to achieve the target Al content and pressed against each other using a roll. In both cases, it is desirable to clean the overlapped surface. In the pressure welding process of the laminated plates by this roll, it is usually difficult to obtain a good pressure welding state between the stainless steel and Al when the pressure welding reduction ratio is less than 30%. Therefore, it is necessary that the pressure contact reduction ratio be 30% or more.
A laminated pressure contact plate with Al can be obtained.

It is preferable to perform an annealing treatment to improve the adhesiveness of the laminated pressure-bonded plate. This annealing treatment is not necessary for all, but when the thickness of the pressure contact plate exceeds about 1.5 mm,
When the plate thickness is reduced by further cold rolling in the next step, peeling may occur on the adhesive surface, and it is advantageous to perform annealing to prevent this. This intermediate annealing is not effective unless a temperature of 250 ° C or higher is adopted. However, 5
If the temperature exceeds 50 ° C, a thick alloy layer develops at the interface between the stainless steel layer and the Al layer of the pressure-bonded plate, and cracks may occur near this alloy layer during cold rolling in the next step, which may cause delamination. As the annealing method for this intermediate annealing, batch annealing with a tight coil can be used. In this case, the annealing time should be about 1 to 20 hours. Other annealing methods may be used, but in any case, in order to prevent peeling during cold rolling, it is necessary to carry out in the temperature range of 250 ° C to 550 ° C.

In this way, the target Al content of the laminated pressure-bonded plate as it is after the pressure-bonding process, the annealing pressure-bonded plate subjected to the intermediate annealing, or the cold-rolled pressure-bonded plate further cold-rolled with or without the intermediate annealing is performed. Once manufactured, it is then diffusion treated. This diffusion treatment is a treatment for mutually diffusing the stainless steel layer and the Al layer, and must be performed in the temperature range of 600 to 1300 ° C. When the diffusion treatment temperature is less than 600 ° C, Al diffusion does not proceed sufficiently, and when it exceeds 1300 ° C, a molten layer is formed in the diffusion alloy layer. If the heating rate during this diffusion treatment is increased to a temperature higher than the melting point of Al, the
l Layer may melt. When this Al layer melts, it causes the concentration of Al to change in the plate surface direction due to sagging and accumulation. Therefore, it is necessary to prevent such melting of the Al layer as much as possible. For this reason, heating at a temperature below the melting point of Al, for example, to a temperature of 550 to 680 ℃
It is recommended to hold for more than a minute to make the Al layer an alloy layer with a high melting point, and then heat it to a higher temperature to perform sufficient diffusion treatment. That is, it is necessary to perform the diffusion treatment under the condition that the Al layer is alloyed without melting at a temperature in the range of 600 to 1300 ° C.

By selecting the diffusion treatment temperature and diffusion treatment time and adjusting the atmosphere, steel sheet products of various configurations can be manufactured.
In other words, if sufficient diffusion is performed in a non-oxidizing atmosphere, a stainless steel plate with high AI content that has a uniform AI concentration in the plate thickness direction can be manufactured. Also, if diffusion annealing is performed without avoiding surface oxidation, a special high-Al stainless steel sheet for heat resistance, which has a rich oxide layer such as Al and Cr in the surface layer, can be manufactured. If the surface of the steel sheet becomes inferior in quality after the diffusion treatment, light cold rolling can remove the strain, or the surface can be polished or gloss-finished to obtain good surface properties.

In this way, according to the method of the present invention, it is possible to industrially manufacture a high Al stainless steel plate, which is difficult to manufacture by the ordinary steel plate manufacturing method. In particular, it is difficult to roll not only cold rolling but also hot rolling with high Al content stainless steel, but with the method of the present invention, a stainless steel plate having good workability and an Al plate are welded in a pressure welded state before Al is alloyed. Alternatively, since the plate thickness is reduced by rolling after pressure welding, it is possible to satisfactorily cold-roll down to a target thin plate, and in some cases, it is possible to cold-form into a product shape or a semi-finished product shape. The Al content can be 10% or more as required. Therefore, not only for special applications, such as electric resistance heating materials and catalyst-supporting metal substrates used at high temperatures, but also high Al-containing stainless steel plates or strips having even higher heat resistance and corrosion resistance can be manufactured at low cost. The oxidation resistance of the high Al content stainless steel obtained by the method of the present invention is 20 at 1200 ° C. as shown in Examples below.
It is sufficient even under severe conditions such as heating for 00 hours. Conventionally, it has been attempted to achieve this by repeating rolling and annealing of stainless steel containing Al for the purpose of imparting further oxidation resistance to the stainless steel. It will be appreciated how useful the method of the present invention is in view of the fact that is limited to 3% or less.

Typical examples of the present invention will be described below to show how excellent the heat resistance of the steel sheet obtained by the method of the present invention is.

[Example 1] JIS / SUS43 with both surfaces polished by a roll with a wire brush
A steel sheet was used as a core material, and an Al sheet of JIS alloy number 1050 was spray-degreased with trichlorethane as a skin material.

On both sides of this core material, the skin material with the plate thickness constitution shown in Table 1 is piled up, and it is bitten into the 4-high rolling mill, and pressed to the plate thickness shown in Table 1 at the indicated reduction rate. It was rolled and wound on a coiler. The rolling speed was 10 to 30 m / min. The obtained pressure-bonded plate coil was placed in a batch annealing furnace, subjected to intermediate annealing at 350 ° C for 10 hours, and then cold-rolled to a plate thickness of 0.30 mm. A 60 mm disc-shaped sample was taken from the cold-rolled cold-rolled sheet obtained, and the disc-shaped sample was heat-treated at 650 ° C for 1 hour, and subsequently heated to 1100 ° C and 1200 ° C in air. The oxidation test of heating at was carried out. The results are shown in Table 1.

As is clear from Table 1, the SUS430 steel sheet, which is the comparative material, shows an oxidation increase of 10 mg / cm ² or more at the test time of 25 hours at both the oxidation test temperatures of 1100 ° C and 1200 ° C, whereas the invention material shows 1200 hours. Even in the course of, the amount of oxidation increase was much smaller than that of the former, showing good oxidation resistance.

The oxidation weight gain of the material of the present invention at 1200 ° C was
Differences are recognized depending on the composition ratio of the Al plate. Sample No. 1 showed about 700 hours for the time to show an increase in oxidation of 10 mg / cm ² or more.
2 shows about 1200 hours, and samples No. 3 and No. 4 show very good oxidation resistance of less than 10 mg / cm ² even after about 2000 hours.
The Al of the cold-rolled pressed sheet diffused uniformly during the oxidation test, but the condition was 2 hours at 1100 ° C.

[Example 2] The pressure-contact rolled plates of Samples No. 1 and No. 3 in Example 1 had a plate thickness of 0.3.
Cold rolled to 0 mm, put a step of 650 ℃ × 1 hour, and continuously perform a diffusion treatment of 1100 ℃ × 2 hours in vacuum.
A high-Al stainless steel plate in which l was uniformly diffused. After that, light cold rolling with an elongation of 1.0% was performed to modify the plate shape. A 60 mm disc-shaped sample was taken from the obtained high-Al stainless steel plate and heated at 1100 ° C and 1200 ° C in the atmosphere for an oxidation experiment. The results are shown in Table 2.

In this example, the oxidation resistance of a high Al stainless steel plate in which Al of the pressure contact plate was uniformly diffused was examined. As is clear from Table 2, the SUS430 steel sheet shows an oxidation increase of 10 mg / cm ² or more in less than 25 hours at both oxidation temperatures of 1100 ° C and 1200 ° C. Is more than 1200 hours at 1100 ℃ and about 700 hours at 1200 ℃. 120 for sample No. 3a
It was less than 10 mg / cm ² even after 2000 hours at 0 ° C, indicating extremely good oxidation resistance.

Front page continuation (72) Inventor Tetsumitsu Midomaru 2-3-1 Tsuiya, Amagasaki City, Hyogo Prefecture Nisshin Steel Co., Ltd. Osaka Works Kanzaki Manufacturing Division (72) Inventor ▲ Makimoto Mamoru Amagasaki City, Hyogo Prefecture Ya 2-3-1 Nisshin Steel Co., Ltd. Osaka Works Kanzaki Manufacturing Division (56) Reference JP-A-50-11942 (JP, A) JP 54-9985 (JP, B2)

Claims (4)

[Claims] 1. A laminated pressure-bonding plate obtained by stacking Al plates on at least one surface of a stainless steel plate so as to have a ratio corresponding to the amount of Al to be contained, and passing this between rolls to form a laminated pressure-bonding plate. A method for producing a high Al-containing stainless steel sheet, which comprises subjecting a steel sheet to a diffusion treatment under the condition that the Al layer is not melted and alloyed at a temperature in the range of 600 to 1300 ℃. 2. A laminated pressure-bonding plate obtained by stacking Al plates on at least one surface of a stainless steel plate so as to have a ratio corresponding to the amount of Al to be contained and passing this between rolls to form a laminated pressure-bonding plate. Is further rolled to the target thickness and then 600
A process for producing a high Al-containing stainless steel sheet, which comprises subjecting a diffusion treatment to a temperature in the range of up to 1300 ° C to form an alloy without melting the Al layer. 3. A laminated pressure-bonding plate obtained by stacking Al plates on at least one surface of a stainless steel plate so as to have a ratio corresponding to the amount of Al to be contained, and passing this between rolls to form a laminated pressure-bonding plate. Is further rolled to the target plate thickness,
Before or during this rolling, intermediate annealing at 250 to 550 ℃ is performed, and then diffusion treatment is performed at a temperature in the range of 600 to 1300 ℃ under the condition that the Al layer is not melted but alloyed. Steel plate manufacturing method. 4. A stainless steel plate laminated with an Al plate has C>
The method for producing a high Al-containing stainless steel sheet according to claim 1, 2 or 3, wherein the stainless steel sheet has 0.03% by weight and Cr ≤ 30% by weight.