JPH02133562A - Production of high al-content stainless steel sheet - Google Patents

Abstract

PURPOSE:To obtain the high-Al stainless steel sheet having high-temp. oxidation resistance, corrosion resistance and electric heating property by subjecting the laminated and rolled sheets, which are obtd. by passing a stainless steel sheet superposed with Al sheets between rolls, to a diffusion treatment under alloying conditions without melting the Al layers. CONSTITUTION:The Al sheets or strips are superposed on one or both surfaces of the stainless steel sheet contg., preferably <=30% Cr so as to attain the ratio corresponding to the ratio of the Al to be incorporated into the steel sheet. The superposed sheets are passed between the rolls and are press-welded at >=30% draft to obtain the laminated and rolled sheet. The laminated and rolled sheet is preferably subjected to intermediate annealing at 250 to 550 deg.C in order to improve the adhesiveness. The laminated and rolled sheet after the intermediate annealing is then subjected to the diffusion treatment under the conditions to alloy the Al layers without melting the same in a 600 to 1300 deg.C range. The high-Al stainless steel sheet which has the above-mentioned characteristics and is adequately usable for the heating zone of an electric heater and a catalyst metal base plate for treating polluted gases is obtd. in this way.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention improves high temperature oxidation resistance, corrosion resistance, and electrical heating property by +1.
High Ai that can be suitably used for the generation zone of a 1-ton heater or a catalytic metal substrate for treating polluted gas! This article relates to an industrial manufacturing method for stainless steel alloy plates.

[Prior art] Stainless steel plate r1↑ has excellent oxidation and corrosion resistance, and is widely used in various industrial fields to take advantage of these characteristics. Adding Al is effective. However, the addition of a large amount of Al greatly degrades the material, making it difficult not only to cold-roll but also to hot-roll.1 It is extremely difficult to produce high-Al stainless steel sheets by a combination of ordinary rolling and annealing. be. For this reason, although high-Al stainless steel sheets are a material with high electrical resistance, excellent oxidation resistance, and corrosion resistance, they have very poor manufacturability and are not fully utilized.

[Object of the Invention] The object of the present invention is to establish a method for manufacturing such a useful high-Al stainless steel sheet in a simple and inexpensive manner, and to contribute to the widespread use of high-Al-containing stainless steel sheets.

[Structure of the invention]

The gist of the present invention, which aims to achieve the above object, is to stack an Al thin plate or ribbon on at least one side of a stainless steel plate or steel strip in a proportion corresponding to the amount of AlI to be contained, and then roll this. The laminated press-welded plates are passed between the blocks, and the obtained stacked stone press-welded plates are further rolled to the target thickness depending on the case (at that time, intermediate annealing at 250 to 550"C is performed before or during rolling. A high Al-containing stainless steel sheet or steel strip characterized in that it is subjected to a diffusion treatment at a temperature in the range of 600 to 1300°C under conditions in which the Al layer is alloyed without melting. It depends on the manufacturing method.

Further, according to the present invention, the laminated press-welded plate, annealed press-welded plate, or rolled plate obtained during the above manufacturing method is processed into a product shape or intermediate product shape according to the application from now on as a raw material, and this processed product or Manufacture aluminum-containing stainless steel processed or semi-finished products by subjecting the semi-finished products to a diffusion treatment at a temperature in the range of 600 to 1300°C under conditions in which the Al layer is alloyed without melting. A method is provided.

According to the method of the present invention, 3% or more Al
Contains. In some cases, stainless steel sheets containing 10% or more Al can be produced industrially. Moreover, it can be industrially manufactured as a steel strip in the same way as ordinary stainless steel sheets.

The high Al-containing stainless steel sheet obtained by the method of the present invention has a uniform distribution of Al depending on the degree of diffusion treatment.
There are alloy steel sheets with a uniform concentration of Ae in the thickness direction, and sheets with a different concentration distribution of Ae in the thickness direction, and in some cases, a striped alloy layer is interposed or the outermost surface layer is made of Al or Cr.
It is possible to manufacture a specially purchased high-Al stainless steel plate with an oxide film, and it has the advantage that it is relatively easy to manufacture a sheet suitable for the intended use. Furthermore, processed or semi-processed products of high-Al stainless steel plates with complex shapes, which have been difficult to manufacture in the past, can be easily manufactured.

[Stainless steel plate or belt used in the detailed description of the invention (hereinafter referred to as m
There are no particular limitations on the components of
Ordinary stainless steel tJA temporary containing 0.03% can be used, but if the Cr content is large, it will be difficult to obtain a press-welded plate, so it is desirable to use a stainless steel plate containing 30% or less Cr. Although it is desirable that the C content be as low as possible, one of the purposes of the present invention is to inexpensively manufacture merchant 2-containing stainless steel sheets, and to produce inexpensive stainless steel sheets and steel sheets with a C content of more than 0.03%. It was found that a high-Al-containing stainless steel sheet with excellent heat resistance properties could be produced even if the following materials were used as the starting material.

On the other hand, the Al plate used in the method of the present invention (Al foil or thin strip can also be used) is pure Al, preferably temporary, but 1
A normal /12 plate contains some amount of Fe, 34, etc. These elements are also contained in stainless steel sheets, so there is no problem even if these elements are contained in A steel sheet containing up to 3% of these elements.
42 can be advantageously used in the present invention.

Temporary Al is superimposed on one or both sides of such a stainless steel plate so as to have a target Al content, and is pressed using a roll.

It is desirable that the overlapping surfaces of both be subjected to purification treatment. In this pressure welding process of the overlapping plates using rolls, it is normal to obtain a good welding condition between the stainless steel and Al when the welding reduction rate is less than 30%. It is difficult. Therefore, it is necessary to set the pressure reduction ratio to 30% or more, and thereby a laminated pressure-welded plate of stainless steel and A1 can be obtained.

It is preferable to perform an annealing treatment to improve the adhesion of this laminated press-welded plate. This annealing treatment is not necessary for all cases, but if the thickness of the press-welded plate exceeds approximately 1.511+ m, it may be necessary to reduce the thickness by further cold rolling in the 0th step. In order to prevent this, annealing is performed to prevent this from occurring. This intermediate annealing is not effective unless the temperature is 250°C or higher. However, when the temperature exceeds 550°C, a thick alloy layer develops at the interface between the stainless steel layer and the A1 layer of the press-welded plate, and cracks occur near this alloy layer during the first cold rolling process, which causes delamination. or As an annealing method for this intermediate annealing, batch annealing using a tight coil can be used. In this case, the annealing time is preferably about 1 to 20 hours. Other annealing methods may be used, but in any case, the annealing time is about 1 to 20 hours. II 250°C to 5 to prevent gates
It is necessary to carry out in a temperature range of 50°C.

In this way, we aim to produce a laminated press-welded plate that has undergone the press-welding process, an annealed press-welded plate that has been subjected to intermediate annealing, or a cold-rolled press-welded plate that has been further cold rolled with or without intermediate annealing.2 Once produced in quantity, it is first subjected to a diffusion treatment. This diffusion treatment is a treatment for mutually diffusing the stainless steel layer and the A1 layer, and must be performed at a temperature range of 600-1300°C. If the diffusion treatment temperature is less than 600°C, the diffusion of Al will not proceed sufficiently, and if it exceeds 1300°C, a molten layer will be formed in the diffusion alloy layer. Note that if the heating rate during this diffusion treatment is increased to a high temperature that is higher than the melting temperature of AP, the A1 layer may melt at around 700°C. When this Al layer is melted, it causes a change in Al concentration in the direction of the plate surface due to sag or accumulation. Therefore, it is necessary to prevent such melting of the Al layer as much as possible, and for this purpose, it is heated at a temperature below the melting point of A1 and held at a temperature of, for example, 550 to 680°C for more than 1 minute. It is preferable to form the AP kidney into an alloy layer with a high melting point and then heat the layer to a high temperature to perform a sufficient diffusion treatment. That is, it is necessary to carry out the diffusion treatment at a temperature in the range of 600 to 1300° C. under conditions where the Al layer is alloyed without melting.

By selecting the diffusion treatment temperature and diffusion treatment time, and by adjusting the atmosphere 311, thin plate products of various configurations can be manufactured. In other words, if sufficient diffusion is performed in an oxidizing atmosphere, a high A7! Containing stainless steel sheets can be manufactured, and -■- minute diffusion can be achieved.
If the treatment is finished midway through the process, the surface layer will have high A.1. It is possible to produce stainless steel sheets containing high Al and high concentrations. In addition, without particularly avoiding surface oxidation,
Eight on the surface! It is possible to produce a special heat-resistant, high-AP, stainless steel sheet that is rich in oxide layers such as and Cr.

In addition, if the surface properties of the steel sheet become poor at the diffusion treatment temperature, it is possible to improve the surface properties by removing the distortion by light cold rolling or by polishing or polishing the surface. Can be done.

In this manner, according to the method of the present invention, high Ae stainless steel needles, which are difficult to manufacture using normal batten manufacturing methods, can be manufactured industrially. In particular, high Al-containing stainless steel is difficult to roll, not only in cold 11E rolling but also in hot rolling.
In the method of the present invention, a stainless steel plate and an Al plate, which have good workability, are pressed together before being alloyed with AI, or the plate thickness is reduced by rolling after rolling, so that the target thin plate can be cold-rolled well. It can be rolled and, in some cases, cold formed into a product shape or an “I”-product shape,
Moreover, the A72 content can be increased to 10% or more, if necessary. Therefore, in addition to special applications 5, such as materials for electrical resistance heating and metal substrates for supporting catalysts used at high temperatures, it is also possible to
High Al-containing stainless steel Y1 plate can be manufactured at low cost. The oxidation resistance of the high Al-containing Sudyu/L Suyi obtained by the method of the present invention is 12 as shown in the examples below.
It is sufficient even under severe conditions such as heating at 00°C for 2000 hours. In the past, attempts have been made to achieve this by repeatedly rolling and annealing stainless steel to which Al has been added in order to impart greater oxidation resistance to stainless steel. It will be understood how useful the method of the present invention is in view of the fact that it is limited to 3% or less.

The following is a typical example of the present invention to show how excellent the heat resistance properties of the steel plate obtained by the method of the present invention are.

[Example 1] JIS 5 polished both surfaces with wire brushed roll
US430 steel plate is used as core material, JIS alloy number 1050
The skin material was made by spray degreasing an Al plate with trichloroethane.

(2) Skin on both sides of this core material (under the plate thickness configuration shown in Table 1)
The sheets were stacked on top of each other, placed in a four-high rolling mill, pressure-rolled at the indicated rolling reduction to the thickness shown in Table 1, and wound up on a coiler. The rolling speed was 10-30 m7 minutes. The obtained pressure welding machine coil was charged into a punch annealing furnace, and the coil was heated to 350"
After intermediate annealing for C×10 hours, the plate thickness was 0.30 mm.
It was cold rolled to . From the obtained pressure-welded cold-rolled sheet, 6
A disk-shaped specimen of 0 mm was collected, and this disk-shaped specimen was heated to 650 mm.
Heat treatment was performed for 1 hour at 1100 °C.
An oxidation test was carried out by heating in air to a temperature of 1200"C. The results are shown in Table 1.

As is clear from Table 1, the comparative material 5tlS430
Steel plates show an oxidation weight gain of 10 mg/cm" or more at both oxidation test temperatures of 1100°C and 1200°C over a 25-hour test time, whereas the oxidation weight gain of the inventive material is much greater than the former even after 1200 hours. (, showing good oxidation resistance.

The oxidation weight gain of the present invention material at 1200"C differs depending on the composition ratio of stainless steel plate and Al plate. 10
The time required to show an oxidation increase of more than mg/cmz was $4 N.

1 for about 700 hours, sample Nα2 for about 1200 hours, and samples Nα3 and N(L4) for about 2000 hours, showing very good oxidation resistance of less than 10 mg/cm''.

Note that Al in the pressure-welded cold-rolled sheet was uniformly diffused during the oxidation test, but the conditions were 2 hours at 1100'c.

[Example 2] The pressure-welded rolled plates of samples N11l and Nn3 in Example 1 were cold rolled into plates 1'X 0 and 30I, and heated to 650°C
After 1 hour of step and treatment, continue to heat to 1100℃
A 2-hour diffusion process was carried out in a vacuum, and A7! This is a high-aluminum stainless steel net plate with uniformly diffused aluminum. After that, the board was stretched for $1 to correct its shape. Light cold rolling of 0% was performed. A disk-shaped specimen of 6 (Jan) was taken from the obtained high-Al stainless steel mesh plate, and an oxidation experiment was conducted by heating it in the atmosphere to 1100 ° C and 1200 ° C. The results are shown in Table 2. .

In this example, the oxidation resistance of a high-Al stainless mesh plate in which Al was uniformly diffused was investigated.

As is clear from Table 2, the S[l3430i plate shows an oxidation increase of 10 mg/c+++'' or more in less than 25 hours at both oxidation temperatures of 1100°C and 1200'C, while an oxidation increase close to this is 11 for sample Nα1a.
It is more than 1200 hours at 00℃ and about 700 hours at 1200''C.For sample No. 3a, it is 20 hours at 1200℃.
Even at 00 hours, it was less than lomg/cn+'', indicating extremely good oxidation resistance.

Claims (4)

[Claims] (1) Overlap an Al plate on at least one side of a stainless steel plate in a proportion corresponding to the amount of Al to be contained, pass this between rolls to make a laminated press-welded plate, and make the obtained laminated press-welded plate, A method for producing a high Al-containing stainless steel sheet comprising performing a diffusion treatment at a temperature in the range of 600 to 1300°C under conditions in which the Al layer is alloyed without melting. (2) Overlap an Al plate on at least one side of the stainless steel plate in a proportion corresponding to the amount of Al to be contained, pass this between rolls to make a laminated press-welded plate, and further Rolled to target thickness, then 600
A method for producing a high Al-containing stainless steel sheet, which comprises performing a diffusion treatment at a temperature in the range of ~1300°C under conditions in which the Al layer is alloyed without melting. (3) Overlap an Al plate on at least one side of the stainless steel plate in a proportion corresponding to the amount of Al to be contained, pass this between rolls to make a laminated press-welded plate, and further The plate is rolled to the target thickness, then intermediate annealing is performed at 250 to 550°C before or during this rolling, and then diffused at a temperature in the range of 600 to 1300°C under conditions that alloy the Al layer without melting. A method for producing a high Al-containing stainless steel sheet, which comprises subjecting it to a treatment. (4) The stainless steel plate to be overlapped with the Al plate has C>0.
4. The method for producing a high Al-containing stainless steel sheet according to claim 1, 2 or 3, wherein the stainless steel sheet has a content of 0.3% by weight and Cr≦30% by weight.