JP2002004010A - Austenitic stainless steel sheet and its manufacturing method - Google Patents

Abstract

(57) [Abstract] [Problem] To provide an austenitic stainless steel sheet excellent in buffing property. SOLUTION: An austenitic stainless steel sheet satisfying the following conditions. The maximum surface roughness Rmax is 2 μm or less, Equation (1)
AFp (0.5 μm) ≧ 80 at average flat area ratio AFp indicated by
%, AFp (30) / AFp (20) ≧ 1.05 where, AFp = (ΣXi / L) × 100 (1) where L: length of extraction from roughness curve of steel sheet surface P (%) Depth level Xi from the maximum peak assuming the maximum peak-to-valley depth of the extraction length from the roughness curve to 100%: Cutting level P at the extraction length L from the roughness curve
(%) (P = 20%, 30%) Length of flat part appearing

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an austenitic stainless steel sheet suitable for buffing, for example, and a method for economically and stably producing them.

[0002]

2. Description of the Related Art An austenitic stainless steel sheet or an austenitic stainless steel strip (hereinafter abbreviated as an austenitic stainless steel sheet in the present specification) is duller and whiter than a ferritic stainless steel sheet. For this reason, in applications where the appearance is emphasized, such as building materials and kitchen equipment, it is common to buff-polish the surface to provide a glossy appearance as stainless steel before use.

Here, the buffing is performed by adding abrasive grains having a predetermined roughness such as # 400, # 600, # 700, and # 800 to a rotary polishing roll provided with a coating layer of hemp or cotton on its surface. This is a method of polishing the surface. The properties of the steel sheet surface have a strong influence on the abrasion, and when the unevenness of the steel sheet surface is deep, measures to reduce the threading speed and increase the number of passes in the buffing process have been made to eliminate the influence of this. Requires a great deal of time and labor, and there is a problem that workability is significantly reduced.

Japanese Patent Application Laid-Open No. 6-280064 discloses a stainless steel plate having a microgroove depth of 1.0 μm or less and excellent in buffing properties, and a method for producing the same. here,
"Microgroove" refers to grain boundary oxidation due to annealing and subsequent grain boundary erosion during pickling.
Deep microgrooves are generated in the pickling process,
As a manufacturing method for reducing microgrooves in the above-mentioned publication, cold rolling is performed after only pickling, omitting annealing of a hot-rolled steel sheet, performing final annealing at 1050 ° C. or more and 1170 ° C. or less, and furthermore, a predetermined method. A method of pickling with an acid solution is shown.

Japanese Patent Publication No. 2-50810 discloses that austenitic stainless steel slab is hot-rolled, then wound at 650 ° C. or lower, annealing of a hot-rolled steel sheet is omitted, and after preheating, 20 to 200 g / l.
Mixed solution of nitric acid and 15-100 g / l hydrofluoric acid, or nitric acid 20-20
A method of pickling in an aqueous solution which is a mixed solution of 0 g / l, 20 to 200 g / l hydrochloric acid and 30 to 250 g / l ferric chloride is disclosed.

In this method, oxidation of grain boundaries is prevented by omitting annealing of a hot-rolled steel sheet, and sensitization caused by the formation of Cr carbide at grain boundaries is achieved by winding at a low temperature of 650 ° C. or less. It is characterized by preventing the annealing of hot rolled steel sheets.
The purpose is to produce a steel sheet that is free of microgrooves generated by pickling and has excellent polishing properties.

As described above, in the inventions disclosed in the two publications, the abrasion is improved by omitting annealing of the hot-rolled steel sheet and not generating microgrooves generated by annealing and pickling of the hot-rolled steel sheet. That is.

On the other hand, a hot-rolled steel sheet is annealed, and the steel sheet whose grain boundaries are oxidized is appropriately subjected to subsequent pickling,
The following proposal has already been disclosed for a method for preventing microgrooves from remaining on the steel sheet surface.

For example, in Japanese Patent Publication No. 3-60920, after hot rolled steel sheet is mechanically pre-scaled, nitric acid 100 to 40 is added.
A production method has been proposed in which descaling is performed with an pickling solution containing 0 g / l and hydrofluoric acid of 75 to 400 g / l, and bright annealing (BA) is performed after cold rolling so that oxide scale is not generated.

Japanese Unexamined Patent Publication No. 11-131271 proposes a method of descaling with a pickling solution containing 20 to 100 g / l of nitric acid and 100 to 300 g / l of hydrofluoric acid.

[0011]

However, according to these prior arts, a steel plate having excellent abrasiveness is stably used.
And it cannot be manufactured economically.

For example, in order to omit annealing of a hot-rolled steel sheet so as not to generate microgrooves by pickling, Japanese Patent Publication No.
As shown in Japanese Patent No. 50810, it is necessary to prevent the erosion of grain boundaries generated by annealing and pickling of hot-rolled steel sheets, and in particular, to prevent intergranular corrosion due to pickling, 650 ° C or less after hot rolling. However, if the winding temperature is lowered to 650 ° C or less, the cooling in the width and longitudinal directions of the steel sheet will be uneven, resulting in deterioration of the shape, and the steel sheets will rub each other during winding. Scratches occur.

Further, there is a problem that the hot-rolled steel sheet wound at a low temperature is hard as it is, and the cold-rolling property is remarkably inferior to that of the steel sheet annealed to the hot-rolled steel sheet. On the other hand, a method of removing microgrooves formed on the surface of a steel plate by pickling, as disclosed in Japanese Patent Publication No. Hei 3-60920 and Japanese Patent Application Laid-Open No. H11-131271, is to immerse in a highly concentrated acid solution for a long time. There are instability factors such as an increase in Fe ions, a change over time in the concentration of hydrofluoric acid and nitric acid, and a decrease in the number of fluorine ions involved in the formation and dissolution of iron fluoride due to the combination of Fe ions and fluorine ions. It is difficult to stably dissolve the microgrooves.

In addition, in these methods, the amount of dissolution increases, resulting in a large yield loss, an increase in the cost of an acid solution and an increase in the cost of disposal of wastes associated with the pickling, and there is a problem in economy. Was.

As described above, conventionally, it has been considered that deep microgrooves remaining after final annealing and pickling are generated by annealing and pickling of a hot-rolled steel sheet. Even if the microgrooves of the hot-rolled steel sheet are completely removed by performing sufficient grinding, deep micro-grooves may be generated in the final annealing and pickling. It is difficult to stably and economically manufacture a steel plate or a steel strip having excellent abrasiveness only by devising it.

Further, when the buffing property of the austenitic stainless steel sheet was examined in detail, the polishing property was poor even when the microgroove depth was 1.0 μm or less, or conversely, the microgrooves having a depth of 1.0 μm or more were found to be poor. It was found that buffing properties were excellent even in some cases.

It is an object of the present invention to provide an austenitic stainless steel sheet suitable for buffing and an effective method for stably and economically producing the same.

[0018]

In order to solve the above problem, the present inventors have made various studies and found that the surface properties of the steel sheet before polishing, particularly the shape-area ratio of the surface irregularities, that is, the defect area rate, were reduced. The inventors have found that the present invention greatly affects the buffing property, and completed the present invention.

That is, the present invention specifies a steel plate having excellent buffing properties and its manufacturing conditions, and its gist is as follows. (1) The maximum surface roughness Rmax is 2 μm or less, and the average flat area ratio AFp represented by the following equation (1) is 0.5 μm from the maximum peak height.
m AFp (0.5 μm) ≧ 80% at depth, cutting level P
(%) = Flat area ratio AFp (P (%)) at 20% and 30% is AF
Austenitic stainless steel sheet characterized by p (30) / AFp (20) ≧ 1.05 AFp = (ΣXi / L) × 100 (1) where L: Extraction from roughness curve of steel sheet surface Length P (%): Maximum peak of extraction length from roughness curve-Depth level from maximum peak when maximum valley depth is 100% Xi: At extraction length L from roughness curve Cutting level P
(%) Length of flat part appearing in (%) (2) In hot rolling of austenitic stainless steel containing 0.02 to 0.08% by mass of C: hot rolling according to the amount of C contained The temperature is defined in the range of the following formulas (2) and (3), and after the hot rolling, annealing of the hot-rolled steel sheet is performed for 10 hours.
Performed at a temperature of 00 ° C. or less, and then hot-rolled steel sheets having a thickness of 2 μm or more by pickling, and the resulting annealed and pickled hot-rolled steel sheets were subjected to total rolling reduction.
A method for producing an austenitic stainless steel sheet, comprising performing cold rolling at 50% or more, and further annealing and pickling the obtained cold-rolled steel sheet.

When 0.02% ≦ C ≦ 0.04% Winding temperature (Tc): 600 ° C. ≦ Tc ≦ 800 ° C. (2) When 0.04% <C ≦ 0.08% Winding temperature (Tc): 600 ° C. ≦ Tc ≦ 700 ° C. (3) (3) The pickling performed on the hot-rolled steel sheet is performed in a mixed aqueous solution of nitric acid: 20 to 100 g / l and hydrofluoric acid: 50 to 200 g / l. The method for producing an austenitic stainless steel sheet according to the above (2).

(4) The method for producing an austenitic stainless steel sheet according to (1) or (3), wherein the final annealing of the annealing performed on the cold-rolled steel sheet is performed at a temperature of 900 ° C. or more and 1100 ° C. or less. .

[0022]

BEST MODE FOR CARRYING OUT THE INVENTION The method for producing a stainless steel sheet according to the present invention is characterized in that the production conditions in each of the steps from hot rolling to final annealing and pickling are properly defined, so that the area of the recesses remaining after buffing is reduced. Is reduced to a level that cannot be visually detected, thereby obtaining a stainless steel sheet having excellent buffing properties.

The reasons for limiting the present invention will be described below. The present inventors have determined that the average surface roughness R of the steel sheet surface of No. 2B before polishing is
a, maximum roughness Rmax, PPI indicating the number of irregularities above a certain height
The relationship between the abrasiveness and the surface roughness index such as Pλa, which indicates the average spacing between the irregularities, and the like, was examined. The reason for this is that the quality of the buff polishing is affected not only by the depth and the number of concaves and convexes but also by the size and area of the concaves remaining after polishing.

A method of adding abrasive grains to a generally used rotary polishing apparatus using a combination of sisal or cotton for buffing, or polishing with a scotch buff or the like to which abrasive grains have been added in advance is 0.2 μm or more. Grinding is performed.

However, in addition to the setting of the polishing conditions such as the type and number of abrasive grains and the combination of hemp and cotton, the amount of grinding differs depending on the number of rotations, the speed of passing the plate, and the number of times of passing the polishing device. Although it is difficult to define the amount, when buffing from # 400 to # 800 is performed without performing base polishing, grinding more than 2 μm will greatly increase the number of steps.

For this reason, in the present invention, Rmax of the steel sheet is specified to be 2 μm or less. Preferably it is 1.5 μm or less. The steel sheet prepared in this way is subjected to buffing grinding, but if no polishing is performed, the fine pits in the crystal grains and the cold rolling or the roll of the skin pass remain strong, so the area of the recess on the steel sheet surface is strong. Cannot be calculated accurately. 0.2 μm to remove fine pits that do not affect the roll and general buffing and evaluate buffing ability
m or more.

However, if the grinding amount is increased, the concave portion is removed regardless of the quality, so that it is impossible to determine the quality of the polishing. Thus, the surface of the buffed sample was visually observed, and the relationship between the glossiness and the minute point-like or linear defects remaining on the surface was organized. The appearance is different, the glossiness is low when many fine defects remain, and the mirror glossiness is relatively high when relatively large defects remain sparsely, but white spots remain patchy. It was found that the resulting pattern became a non-uniform pattern and markedly reduced the visual glossiness.

Then, the roughness of the surface of the 2B steel sheet manufactured by various manufacturing methods was determined, and the form and the abrasiveness of the roughness curve were examined in detail. As a result, the surface cut parallel to the average line of the roughness curve was obtained. It was found that there was a strong correlation between the area of the flat portion appearing in the above and the mirror gloss after polishing.

FIG. 1 schematically shows the procedure for measuring the average flat area ratio AFp in the present invention. FIG. 1 shows the procedure for calculating AFp from a roughness curve. First, a roughness curve is determined, and an average line X is determined. Distance between the highest mountain height and the maximum valley depth is 100
%, The total cut length (ΣX _i = X ₁ + X ₂ +... X _n ) of the convex portion when cut at an arbitrary depth level P is obtained as a ratio to the unit length (L). AFp with
That is. The level P may be defined by the depth (μm) from the top of the projection or by the ratio (%) to the entire depth.

In order to obtain high gloss after polishing even with a slight polishing margin, the flat area ratio AF at a cutting level of 0.5 μm
It is necessary to secure p over 80%. Cutting level is small
The higher the ratio of the area ratio of the flat portion at the 20% cut level to the 30% cut level, the higher the gloss of the steel sheet can be obtained with a small amount of polishing.

It has been found that AFp (30) / AFp (20) should be set to 1.05 or more in order to obtain high gloss after light buffing. In order to obtain a stainless steel sheet having excellent buffing properties according to the present invention, it is necessary to reduce point-like or linear concave portions having a certain area or more remaining on the surface.

Next, the reason for defining the manufacturing conditions will be specifically described. First, the reason for defining the C content in steel and the manufacturing conditions will be described. The C content is specified as 0.02% or more when the C content is set to 0.
If the content is less than 02%, the cost of steel making for decarburization in refining is increased, and the economic efficiency is reduced. On the other hand, if the C content exceeds 0.08%, the product characteristics such as deterioration of corrosion resistance and workability are deteriorated. Therefore, the C content is set to 0.02% or more and 0.08% or less.

Next, the effect on the surface properties will be described below. The following four causes are considered mainly as the causes of the concave portions remaining on the product plate. (1) Irregularities caused by uneven thickness of oxide scale formed on the surface of hot-rolled steel sheet (2) Intergranular corrosion caused by erosion near the grain boundary precipitation of Cr carbide during pickling (3) Heat Grain boundary oxidation by annealing of rolled steel sheet and subsequent erosion by pickling (4) Grain boundary oxidation by final annealing after cold rolling and subsequent erosion by pickling Winding condition of hot rolled steel sheet according to C content in steel The reason for defining (1) is to suppress the intergranular corrosion described in (2) above and the erosion due to hot-rolled sheet annealing and pickling described in (3).

That is, Cr that precipitates at the grain boundary according to the amount of C
Since the amount of carbide and the precipitation size change, when the winding temperature is high, the volume of Cr carbide is large and the solution does not form a solid solution at a low temperature for a short time.

The annealing of the hot-rolled steel sheet is carried out at a low temperature so that the Cr carbide after the winding of the hot-rolled steel sheet does not grow, thereby suppressing the grain boundary oxidation and the acid erosion in the subsequent pickling.

The smaller the amount of C, the less precipitation of Cr carbides at the grain boundaries even if the film is wound at a high temperature, and the small volume makes it possible to lower the temperature of hot-rolled sheet annealing. That is, when a steel having a C content of less than 0.04% or a steel having a C content of more than 0.04% is wound at a lower winding temperature, precipitation of grain boundaries of Cr carbide is further reduced, and grain boundary corrosion can be reduced. It becomes possible. When 0.02% ≦ C ≦ 0.04%, at a winding temperature of 800 ° C. or less, the occurrence of intergranular corrosion becomes very slight.
However, when the winding temperature is lower than 600 ° C., the occurrence of scratches increases remarkably. Therefore, the winding temperature is more than
℃ or below.

On the other hand, for steel having a C content exceeding 0.04%, by controlling the winding temperature Tc at 600 to 700 ° C., it is possible to suppress intergranular corrosion equivalent to steel having a C content of 0.04% or less. The hot-rolled steel sheet manufactured under these conditions does not have continuous grain boundary precipitation of Cr carbide, so even if pickling without annealing the hot-rolled steel sheet, the intergranular corrosion is slight and the effect on the surface properties is not affected. small.

However, if the film is wound at a very low temperature, the shape may be non-uniform, and the workability of the subsequent cold rolling may be reduced. Annealing of a hot-rolled steel sheet is necessary to correct such a shape. The shape correction of the hot-rolled steel sheet is achieved by tension applied to the steel sheet during the annealing of the hot-rolled steel sheet, and is desirably performed at a high temperature. However, it is necessary to lower the temperature from the viewpoint of suppressing oxidation due to annealing of the hot-rolled steel sheet. In particular, from the viewpoint of suppressing grain boundary oxidation of the surface layer, the upper limit of the annealing temperature of the hot-rolled steel sheet is set to 1000 ° C.

In the annealing of a hot-rolled steel sheet, it is important to perform the correction by applying a heating tension. When the temperature is low and the strength is high, the tension may be increased. Therefore, the lower limit is not particularly specified. is there.

The main purpose of the subsequent pickling is to remove the scale of the hot-rolled steel sheet and to remove a layer having a low Cr fraction immediately below the scale generated by annealing of the hot-rolled steel sheet (hereinafter, Cr-deficient layer). However, only descaling cannot sufficiently smooth the unevenness of the scale and the unevenness such as shot blast of the descaling pre-treatment, so it is necessary to partially dissolve the surface.

Since the winding temperature is low, the growth of oxide scale after winding is small, and since the annealing temperature for the hot-rolled steel sheet is low, the Cr-depleted layer immediately below the oxide scale generated during annealing is shallow.

Further, since the grain boundary grooves are very shallow and slight,
High surface quality and high corrosion resistance can be ensured even if the pickling dissolution amount is small as compared with the case where the hot-rolled steel sheet is annealed at a temperature exceeding 00 ° C. Although 2 μm or more is dissolved in order to ensure surface quality, it is preferably 2 μm to 5 μm from the viewpoint of yield loss and suppression of reduction in productivity.

The acid used for dissolving the surface of the steel sheet may be generally used sulfuric acid, hydrofluoric acid, nitric acid, and a mixed aqueous solution thereof. The concentration of these acids is not particularly limited, and for example, generally used nitric acid: 10
It can be carried out in a mixed aqueous solution of 0 to 200 g / l and hydrofluoric acid: 10 to 50 g / l, but the dissolution rate of the steel sheet composition relatively close to the Cr content of the base material is increased to improve productivity. For this purpose, nitric acid may be reduced to 100 g / l or less, and the concentration of hydrofluoric acid may be increased to 50 to 200 g / l.

On the surface of the steel sheet manufactured under the above manufacturing conditions, grain boundary oxidation due to annealing and pickling of the hot-rolled steel sheet and shallow grain boundary erosion grooves (microgrooves) due to acid erosion may be observed. In addition, since the oxide scale on the surface of the hot-rolled steel sheet has a non-uniform thickness, the unevenness due to the unevenness is smoothed, and the oxide scale is crushed to improve the pickling efficiency. As a treatment, shot blasting or alumina blasting may be performed.

Next, cold rolling is performed. In order to smooth the surface irregularities caused by shot blasting or alumina blasting as described above, the total draft is set to 50% or more. Even in the final annealing and pickling, deep grain boundary erosion grooves are generated by the same generation mechanism as in the annealing and pickling of hot-rolled steel sheets, but the Cr carbide found in the hot-rolled steel sheets appears on the cold-rolled steel sheet surface. By Cr
Since there is no decrease in the fraction and there is no Cr-depleted layer generated by slab heating, it is covered with an oxide scale that is uniform, has a high Cr fraction, and is highly protective by the final annealing.

In cold rolling, intermediate annealing and
The pickling is performed, but the processing conditions are not particularly limited since the cold rolling is performed again. Therefore,
Due to the protective effect of the highly protective oxide scale, the grain boundary erosion groove becomes shallower even when heat treatment is performed at a higher temperature than annealing of the hot-rolled steel sheet. However, when the final annealing temperature is higher than 1100 ° C., the number of oxygen atoms passing through the oxide scale and reacting with the base metal atoms increases, and the oxidation particularly at the grain boundaries where the diffusion rate of atoms is fast increases. For this reason, the grain boundary erosion grooves after the pickling are deepened, and the buffing property is reduced. If the temperature is lower than 900 ° C., recrystallization takes a long time and the productivity is reduced.

Therefore, the final annealing temperature is 900 ° C. or higher and 1100 ° C.
It is specified below. The Cr-depleted layer immediately below the oxide scale formed in the final annealing has only a very shallow depth due to the dense and highly protective oxide scale formed in the surface layer, and can be easily removed by light pickling. For this reason, it is sufficient that the generated oxide scale can be removed in the pickling subsequent to the final annealing, and the method is not particularly limited.

As a pickling method at this time, the steel sheet after the final annealing is immersed in a high-temperature alkali molten salt and then dipped in 10% to 20%.
Method of performing electrolysis pickling% of Na ₂ SO ₄ and NaCl aqueous solution
(Hereinafter referred to as neutral salt electrolytic pickling) or 1% to 5% hydrofluoric acid and 5% to 2%
A method of immersing in a mixed aqueous solution of 0% nitric acid (hereinafter referred to as hydrofluoric acid), or a combination of neutral salt electrolysis, mixed acid immersion and electrolytic pickling in 5 to 20% nitric acid without performing alkali molten salt immersion, Any of them may be used.

After the pickling, if necessary, temper rolling is performed to finish. Next, the operation and effect of the present invention will be described more specifically with reference to examples.

[0050]

[Example 1] SUS304 2B steel sheets of various sizes manufactured on an actual manufacturing line were sampled, and the sheet thickness x 100 mm width x 100 mm
After measuring the average flat area ratio of the sample cut to length, the same sample was buffed.

The buffing is performed by using a polishing apparatus in which disk-shaped sisal buffs and cotton cloth are alternately stacked. Abrasives: a mixture of chromium oxide and oil, rotation speed: 1200 rpm, passing speed: 10 mpm,
Polishing frequency: 1 reciprocation.

The thickness reduction (unit: mm) by polishing was calculated by the following equation, assuming that the entire surface of the steel plate was ideally and uniformly polished. [Weight before polishing (g)-Weight after polishing (g)] /
｛(100mm × 100mm) × 7.75 (g / cm ³ )｝ × 10 ⁶ The difference between the weight before polishing and the weight after polishing is between 0.037 g and 0.052 g, and the depth removed by polishing is 0.48 μm to 0.67 g. μm.

The characteristics of the polished steel sheet were evaluated in the following manner. <Abrasiveness evaluation method> The surface roughness was measured in the rolling direction of the SUS 304 2B steel sheet surface.

Surface roughness measurement: L = 12.5 mm length was measured according to the roughness curve measurement of JIS B0601, and AFp (0.5 μm), AFp (20%), AFp (30%) were obtained from the obtained curves. %) Were calculated respectively.

The specular gloss was measured using a polished steel sheet. Specular gloss measurement: 60-degree specular gloss specified in JIS Z8741. The light source was reflected in a direction parallel to the rolling direction of the steel sheet.

Good (○): ≧ Gloss500 Pass (△): 500> Gloss ≧ 400 Poor (×): <Gloss400 AFp (0.5 μm) is 80% or more, and AFp (30) / AFp (20) ≧ 1.05
Has a high visual gloss after polishing and a high specular gloss.

[0057]

[Table 1]

[0058]

Example 2 A slab piece of 50 mm thickness × 200 mm width × 250 mm length was sampled from the surface layer of a SUS304 steel slab manufactured in an actual manufacturing line, and this slab piece was hot-rolled in a test room mill. To produce a hot-rolled steel sheet having a thickness of 3.0 mm.

At this time, in order to simulate winding after hot rolling, the steel sheet immediately after completion of hot rolling was heated at 800 ° C., 750 ° C., 700 ° C.
C., 650.degree. C., 600.degree. C., and 550.degree. C., were put into a furnace which had been preheated, cooled slowly at a cooling rate of 50.degree.

Further, these hot-rolled steel sheets were subjected to sheet thickness × width × 200
The hot-rolled steel sheet was annealed and pickled under the conditions shown in Table 1 to obtain a cold-rolled base material. Table 2 shows pickling conditions 1 to 4.

[0061]

[Table 2] Cold rolling is performed from 3.0 mm to 1.0 mm in a four-stage laboratory mill.
Each sample was cut out from the steel sheet after each pass, and samples having a thickness of 50 mm and a length of 50 mm were cut out, and various characteristics were evaluated in the same manner as in Example 1.

The pass schedule of the cold rolling in this example is 3.0 mm → 2.4 mm → 2.1 mm → 1.8 mm → 1.5 mm → 1.4 mm →
1.3mm → 1.2mm → 1.1mm → 1.0mm. In order to adjust the effect of the cold rolling reduction, the total reduction was reduced to 40% and 50%.
When it reached%, it was stopped. Table 3 shows the relationship between the final thickness and the rolling reduction in cold rolling.

Table 4 shows the characteristic evaluation results in this example.
When the total rolling reduction of the cold rolling is less than 50%, there is an effect of hot skin, and gloss after polishing reaching the acceptable level cannot be obtained.

For a steel sheet having a total reduction of 50% or more in cold rolling,
C content is 0.04% or less, hot-rolled steel sheet winding temperature is 800 ° C or less, annealing temperature of hot-rolled steel sheet is 1000 ° C or less, and pickling cutting amount is 2
By setting the final annealing temperature at 1080 ° C. to at least μm, an acceptable level of polished gloss can be obtained. At a final annealing temperature of 1120 ° C., oxidation during the final annealing becomes severe, and the gloss after polishing decreases.

When the coiling temperature of the steel sheet having a C content of 0.04% or more is higher than 750 ° C., sufficient abrasion cannot be ensured, and the coiling temperature of the hot-rolled steel sheet is set to 600 to 700 ° C. By doing so, a steel sheet having excellent gloss after polishing can be obtained.

Further, by performing pickling conditions 2, 3, and 4 in which the HF concentration is further increased and the HNO ₃ concentration is reduced, a large amount of abrasion can be obtained in a short time, and more excellent polishing properties can be obtained. Obtainable.

[0067]

[Table 3]

[0068]

[Table 4]

[0069]

According to the production method of the present invention, it is possible to economically and stably produce an austenitic stainless steel sheet and a steel strip excellent in buffing property, and its practical significance is large. I understand.

[Brief description of the drawings]

FIG. 1 is an explanatory diagram of a method of measuring an average flat area ratio.

 ────────────────────────────────────────────────── ─── Continued on the front page (72) Inventor Shinji Tsuge 4-5-33 Kitahama, Chuo-ku, Osaka-shi, Osaka F-term in Sumitomo Metal Industries, Ltd. (reference) 4K037 EA05 EA12 EA15 EA21 EA23 EA25 EA27 FE02 FE03 FF01 FF02 FF03 FJ06 FJ07 HA05 4K053 PA04 PA12 QA01 RA05 RA16 RA17 SA06 SA13 TA02 ZA10

Claims (4)

[Claims] An AFp (0.5 μm) ≧ 80% at a depth of 0.5 μm from the maximum peak height at an average flat area ratio AFp represented by the following formula (1), wherein the maximum surface roughness Rmax is 2 μm or less, and the cutting level P (%) = Flat area ratio AFp at 20% and 30%
An austenitic stainless steel sheet wherein (P (%)) satisfies AFp (30) / AFp (20) ≧ 1.05. AFp = (ΣXi / L) × 100 (1) where: L: length of extraction from roughness curve of steel sheet surface P (%): maximum peak-to-valley depth of extraction length from roughness curve Depth level from the maximum peak when X is 100% Xi: Cutting level P at extraction length L from roughness curve
Length of flat part appearing in (%) 2. In hot rolling of austenitic stainless steel containing 0.02 to 0.08% by mass of C in mass%, the coiling temperature of hot rolling is set according to the content of C in the following (2):
After the hot rolling, annealing is performed on the hot-rolled steel sheet at a temperature of 1000 ° C. or less, and the thickness of the steel sheet is adjusted to 2 mm by pickling.
It is characterized in that the hot-rolled steel sheet which has been ablated by μm or more and which has been annealed and pickled is cold-rolled at a total reduction rate of 50% or more, and the obtained cold-rolled steel sheet is further annealed and pickled. For producing austenitic stainless steel sheets. When 0.02% ≦ C ≦ 0.04% Winding temperature (Tc): 600 ° C ≦ Tc ≦ 800 ° C ... (2) When 0.04% <C ≦ 0.08% Winding temperature (Tc): 600 ° C ≦ Tc ≦ 700 ° C ・ ・ ・ (3) 3. The pickling performed on a hot-rolled steel sheet is nitric acid: 20 to 10
3. The method for producing an austenitic stainless steel sheet according to claim 2, wherein the step is performed in a mixed aqueous solution of 0 g / l and hydrofluoric acid: 50 to 200 g / l. 4. The final annealing of the annealing performed on a cold-rolled steel sheet,
The method for producing an austenitic stainless steel sheet according to claim 2 or 3, wherein the method is performed at a temperature of 900 ° C to 1100 ° C.