JP3520840B2 - Austenitic stainless steel sheet and manufacturing method - Google Patents

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 Austenitic stainless steel sheets or austenitic stainless steel strips (hereinafter collectively referred to as austenitic stainless steel sheets in the present specification) have a dull gloss and appear whiter than ferritic stainless steel sheets. For this reason, in applications such as building materials and kitchen equipment where appearance is important, it is common to buff the surface and use it in order to give the luster of stainless steel.

In the buff polishing, a steel plate is prepared by adding abrasive grains having a predetermined roughness such as # 400, # 600, # 700, # 800 to a rotating polishing roll having a linen or cotton coating layer on the surface thereof. This is a method of polishing the surface. The properties of the steel plate surface have a strong effect on the polishing property, and when the unevenness of the steel plate surface is deep, the effect of this is removed to reduce the stripping speed and increase the number of passes in the buffing process. It requires a great deal of time and labor, and there is a problem that the workability is significantly reduced.

Japanese Unexamined Patent Publication (Kokai) No. 6-280064 discloses a stainless steel plate having a microgroove depth of 1.0 μm or less and excellent in buffing property, and a manufacturing method thereof. here,
“Microgrooves” are grain boundary oxidation by annealing and grain boundary erosion by subsequent pickling.
Deep microgrooves are generated in the pickling process,
In the above-mentioned publication, as a manufacturing method for reducing microgrooves, annealing of hot-rolled steel sheet is omitted and only pickling is performed, then cold rolling is performed, and final annealing is performed at 1050 ° C. or more and 1170 ° C. or less, and further predetermined A method of pickling with an acid solution is shown.

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

This method prevents grain boundary oxidation by omitting the annealing of the hot rolled steel sheet, and is wound up at a low temperature of 650 ° C. or lower to form a sensitization due to the formation of Cr carbides at the grain boundaries. To prevent the annealing of hot rolled steel sheets.
It is intended to produce a steel sheet which has no micro-grooves generated by pickling and has excellent polishing properties.

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

On the other hand, the hot rolled steel sheet is annealed, and the steel sheet whose grain boundaries are oxidized is appropriately pickled,
The following proposals have already been disclosed as to methods for preventing microgrooves from remaining on the surface of a steel sheet.

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

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

[0011]

However, in these prior arts, a steel plate excellent in abrasiveness is stably and
And it cannot be manufactured economically.

For example, in order to avoid annealing the hot-rolled steel sheet so as to prevent the formation of microgrooves by pickling, Japanese Patent Publication No.
As shown in Japanese Patent No. 50810, it is necessary to prevent erosion of grain boundaries generated by annealing pickling of hot-rolled steel sheet. Especially, in order to prevent intergranular corrosion due to pickling, 650 ℃ or less after hot rolling. However, if the winding temperature is lowered to 650 ° C or lower, the cooling of the steel sheets in the width direction and the longitudinal direction becomes uneven, and the formability deteriorates, causing the steel sheets to rub against each other during winding. Scratch marks 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-rollability is remarkably inferior to that of the steel sheet obtained by annealing the hot-rolled steel sheet. On the other hand, the method of removing the microgrooves formed on the surface of the steel sheet by pickling, as disclosed in Japanese Patent Publication No. 3-60920 and Japanese Patent Application Laid-Open No. 11-131271, is carried out by immersing in a highly concentrated acid solution for a long time. There is an instability factor such as increase of Fe ion, change of concentration of hydrofluoric acid and nitric acid with time, generation of iron fluoride by combining Fe ion and fluorine ion, and decrease of fluorine ion involved in dissolution. , It becomes difficult to stably dissolve the microgrooves.

In addition, in these methods, the amount of dissolution is large, so that the yield loss is large, and the cost of the acid solution and the waste treatment related to the pickling are also increased, and there is a problem in economic efficiency. It was

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

Further, a detailed examination of the buffing property of the austenitic stainless steel sheet revealed that the polishing property was inferior even if the microgroove depth was 1.0 μm or less, or conversely, the microgrooves having a depth of 1.0 μm or more were found. It was found that the buffing property may be excellent even if there is.

An object of the present invention is to provide an austenitic stainless steel sheet suitable for buff polishing and an effective method for producing it stably and economically.

[0018]

As a result of various studies, the inventors of the present invention have found that the surface properties of a steel sheet before polishing, particularly the shape-area ratio of the surface irregularities, that is, the defect area ratio, are The present invention has been completed by finding that it greatly affects the buffing property.

That is, the present invention defines the steel plate having excellent buffing property and the manufacturing conditions thereof, and the summary thereof is as follows. (1) The maximum surface roughness Rmax is 2 μm or less, and the average flat area ratio AFp expressed by the following formula (1) is 0.5 μ from the maximum peak height.
AFp (0.5 μm) ≥80% at m depth and cutting level P
(%) = 20%, flat area ratio AFp (P (%)) at 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
The length of the flat portion appearing in (%) (2) In the hot rolling of austenitic stainless steel containing 0.02 to 0.08% by mass of C: 0.02 to 0.08%, in the hot rolling according to the amount of C contained. The temperature is specified within 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
The total reduction ratio is applied to the hot-rolled hot-rolled steel sheet that has been annealed and pickled, which is obtained by subjecting the resulting hot-rolled steel sheet to a thickness of 2 μm or more by subsequent pickling and then performing a pickling.
The present invention is characterized in that cold rolling is performed at 50% or more, and the obtained cold rolled steel sheet is further annealed and pickled.
Method of manufacturing that austenitic stainless steel.

( I ) When 0.02% ≤ C ≤ 0.04% Winding temperature (Tc): 600 ° C ≤ Tc ≤ 800 ° C (2) (ii) 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 carried out in a mixed aqueous solution of nitric acid: 20-100 g / l, hydrofluoric acid: 50-200 g / l. The method for producing an austenitic stainless steel sheet according to the above (2), characterized in that the method is performed.

(4) The method for producing an austenitic stainless steel sheet according to the above (1) or (3), characterized in that the final annealing of the annealing performed on the cold rolled steel sheet is performed at a temperature of 900 ° C. or higher and 1100 ° C. or lower. .

[0022]

BEST MODE FOR CARRYING OUT THE INVENTION In the method for producing a stainless steel sheet according to the present invention, the area of the recess remaining after buffing is determined by appropriately defining the production conditions in each step from hot rolling to final annealing and pickling. It is possible to obtain a stainless steel plate having excellent buff polishing property by reducing to a level that cannot be visually detected.

The reasons for limiting the present invention will be described below. The inventors have found that the average surface roughness R of the No. 2B steel plate surface before polishing
a, maximum roughness Rmax, PPI indicating the number of irregularities above a certain height
The relationship between the surface roughness index such as Pλa indicating the average interval of the unevenness and the polishing property and the polishing property was investigated, but when manufactured under the conventional conditions, the variation was large. This is because the quality of the buff polishing is strongly influenced not only by the depth and the number of concaves and convexes remaining after the polishing but also by its size and area.

[0024] When a method of adding abrasive grains to a rotary polishing apparatus that combines sisal linen and cotton for buffing that is commonly used, or polishing with a Scotch buff to which abrasive grains are added in advance is 0.2 μm or more. Grinding is done.

However, in addition to the setting of the polishing conditions such as the type of abrasive grain and its count, the combination of hemp and cotton, etc., the grinding amount varies depending on the number of revolutions of the polishing device, the plate passing speed, and the number of plate passing. Although it is difficult to specify the amount, if the buffing from # 400 to # 800 is performed without performing the base polishing, the grinding of more than 2 μm will significantly increase the number of steps.

Therefore, in the present invention, the Rmax of the steel sheet is specified to be 2 μm or less. It is preferably 1.5 μm or less. Grinding the steel plate prepared in this way by buffing, but if no polishing is done at all, the area of the recesses on the surface of the steel plate is large because the fine pits in the crystal grains and the rolls of cold rolling and skin pass are strongly retained. Cannot be calculated accurately. 0.2 μ is used to evaluate the buffing property by removing fine pits that are not affected by roll eyes and general buffing.
It is necessary to grind more than m.

However, if the amount of grinding is increased, the concave portion is removed regardless of whether it is good or bad, and it becomes impossible to judge the good or bad of the polishing property. Therefore, the surface of the sample that was buffed in this way was visually observed, and the relationship between the glossiness and the minute dot-like or linear defects remaining on the surface was sorted out. When the appearance is different and many fine defects remain, the glossiness is low. When relatively large defects remain sparsely, the specular glossiness is relatively high, but white spots appear to remain spotty. It was found that such a non-uniform pattern was formed, and the visual glossiness was remarkably reduced.

Therefore, the roughness of the surface of the 2B steel plate manufactured by various manufacturing methods was determined, and the shape and the polishability of the roughness curve were investigated in detail. As a result, the surface cut in parallel with the average line of the roughness curve was examined. It was found that there is a strong correlation between the area of the flat part appearing in Fig. And the specular gloss after polishing.

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

In order to obtain a high gloss after polishing with a slight polishing allowance, the area ratio AF of the flat portion at the cutting level of 0.5 μm is used.
It is necessary to secure p at 80% or more. Small cutting level
The higher the ratio of the area ratio of the flat portion at the 20% cutting level to the 30% cutting level, the higher the gloss of the steel sheet obtained with a small amount of polishing.

It was found that AFp (30) / AFp (20) should be 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 the number of spot-shaped or linear recesses remaining on the surface of a certain area or more.

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. To specify the C content to 0.02% or more, the C content should be 0.
This is because if it is specified to be less than 02%, the steelmaking cost involved in decarburization for refining will increase accordingly and the economic efficiency will decrease. Further, if the amount of C exceeds 0.08%, product characteristics such as deterioration of corrosion resistance and workability are deteriorated. Therefore, the amount of C is set to 0.02% or more and 0.08% or less.

Next, the influence on the surface properties will be described below. There are mainly four possible causes of the recesses remaining on the product plate. (1) Unevenness caused by non-uniform oxide scale thickness formed on the surface of hot-rolled steel sheet (2) Intergranular corrosion caused by corrosion of the vicinity of grain boundary precipitation of Cr carbide during pickling (3) Heat Grain boundary oxidation by annealing of rolled steel sheet and subsequent corrosion by pickling (4) Grain boundary oxidation by final annealing after cold rolling and subsequent corrosion by pickling Corrosion of hot rolled steel sheet according to the C content in steel The reason for defining is to suppress intergranular corrosion in (2) above and to suppress erosion due to hot-rolled sheet annealing and pickling in (3).

That is, Cr that precipitates at the grain boundaries according to the amount of C
Since the amount of carbide and the precipitation size change, the volume of Cr carbide is large when the coiling temperature is high, and it does not solidify in a short time at low temperature.

By annealing the hot-rolled steel sheet at a low temperature while preventing the growth of Cr carbide after winding the hot-rolled steel sheet, grain boundary oxidation and acid erosion in the subsequent pickling are suppressed.

The smaller the amount of C, the less precipitation of Cr carbide in the grain boundaries even when wound at a high temperature, and the small volume, so that the temperature of hot-rolled sheet annealing can be lowered. 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, the precipitation of Cr carbide at the grain boundaries is further reduced, and the grain boundary corrosion can be reduced. It will be possible. When 0.02% ≤ C ≤ 0.04%, the occurrence of intergranular corrosion becomes extremely small when the coiling temperature is 800 ° C or less.
However, when the coiling temperature is less than 600 ° C, the occurrence of scratches increases remarkably. Therefore, the winding temperature is 600 ℃ or more 800
Keep below ℃.

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

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

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

In the subsequent pickling, the main purpose is to remove the scale of the hot-rolled steel sheet and also to remove the layer having a low Cr fraction directly below the scale (hereinafter referred to as Cr-deficient layer) generated by the annealing of the hot-rolled steel sheet. However, it is necessary to dissolve a part of the surface because the scale unevenness and the unevenness such as shot blasting before the descaling cannot be sufficiently smoothed only by the descaling.

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 deficient layer immediately below the oxide scale formed during annealing is shallow.

Since the grain boundary groove is very shallow and slight, 10
High surface quality and corrosion resistance can be secured even when the amount of dissolution by pickling is small compared to the case of performing hot-rolled steel sheet annealing at a temperature above 00 ° C. It is dissolved by 2 μm or more in order to secure the surface quality, but it is preferably 2 μm to 5 μm from the viewpoint of yield loss and reduction of productivity.

The acid used to dissolve the surface of the steel sheet may be commonly used sulfuric acid, hydrofluoric acid, nitric acid and an aqueous mixed solution thereof. The concentration of these acids is not particularly limited, and for example, commonly 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 it accelerates the dissolution rate of the steel sheet composition relatively close to the Cr fraction of the base metal and improves productivity. Therefore, nitric acid may be set 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 produced under the above production conditions, grain boundary oxidation due to annealing / 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, in order to smooth the unevenness due to it, and to crush the oxide scale and improve pickling efficiency, before pickling Shot blasting or alumina blasting may be performed as the treatment.

Next, cold rolling is performed, but in order to smooth the surface irregularities due to shot blasting or alumina blasting as described above, the total rolling reduction is 50% or more. Even in the final annealing / pickling, deep grain boundary erosion grooves are generated by the same generation mechanism as in annealing / pickling of hot-rolled steel sheets, but the Cr carbides found in hot-rolled steel sheets on the surface of cold-rolled steel sheets. By Cr
Since there is no decrease in the fraction or the Cr-deficient layer generated by slab heating and it is smooth, it is covered with a dense, highly protective oxide scale with a high Cr fraction by the final annealing.

During cold rolling, annealing in the middle
The pickling is performed, but the cold rolling is performed again for this, and therefore the treatment conditions are not particularly limited. Therefore,
Owing to the protective effect of the oxide scale having a high protective property, the grain boundary erosion groove becomes shallow even when the heat treatment is performed at a higher temperature than the 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 at grain boundaries where the atomic diffusion rate is high deepens. For this reason, the grain boundary erosion grooves after pickling become deep, and the buffing property is deteriorated. On the other hand, if the temperature is lower than 900 ° C, recrystallization takes a long time and the productivity is lowered.

Therefore, the final annealing temperature is 900 ℃ or more and 1100 ℃
It is specified below. The Cr-deficient layer immediately below the oxide scale formed in the final annealing has 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. Therefore, it is sufficient that the generated oxide scale can be removed by pickling following the final annealing, and the method is not particularly specified.

The pickling method at this time is 10% to 20% after the steel sheet after the final annealing is immersed in a high temperature alkali molten salt.
Method of electrolytic pickling in a ₂ % Na ₂ SO ₄ or 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 fluorinated nitric acid), or combining neutral salt electrolysis without mixed molten alkali salt immersion, mixed acid immersion and electrolytic pickling in 5-20% nitric acid, Either may be used.

After pickling, if necessary, temper rolling is performed to finish. Next, the working effects of the present invention will be described more specifically by way of examples.

[0050]

[Example 1] SUS304 2B steel sheets of various sizes produced on an actual production 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 into lengths, buffing of the same sample was performed.

For buffing, a disk-shaped sisal buff and a cotton cloth were alternately laminated, and a polishing agent: a mixture of chromium oxide and oil and fat, rotation speed: 1200 rpm, plate passing speed: 10 mpm,
Number of polishing: 1 round trip.

The reduction in plate thickness due to polishing (unit: mm) was calculated by the following formula, assuming that the entire surface of the steel plate was ideally polished uniformly. [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 was μm.

The characteristics of the polished steel plate thus obtained were evaluated as follows. <Abrasivity evaluation method> The surface roughness was measured in the rolling direction of the SUS 304 2B steel plate 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 %) Was calculated.

The specular glossiness measurement was evaluated using a steel plate after polishing. Specular gloss measurement: 60 degree specular gloss specified in JIS Z8741. The light source was reflected in a direction parallel to the rolling longitudinal direction of the steel sheet.

Good (○): ≧ Gloss500 Pass (△): 500 ＞ Gloss ≧ 400 Bad (×): <Gloss400 AFp (0.5 μm) is 80% or more, and AFp (30) / AFp (20) ≧ 1.05
The steel sheet of No. 3 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 x 200 mm width x 250 mm length was taken from the surface layer part of a SUS304 steel slab produced in an actual production line, and this slab piece was hot-rolled in a laboratory mill. A hot-rolled steel sheet having a thickness of 3.0 mm was manufactured.

At this time, in order to simulate the winding after the hot rolling, the steel sheet immediately after the hot rolling is finished at 800 ° C, 750 ° C, 700 ° C.
It was put into a furnace preheated to 650 ° C, 650 ° C, 600 ° C, and 550 ° C, gradually cooled to 400 ° C or less at a cooling rate of 50 ° C / hr, and then taken out and air-cooled.

Further, these hot-rolled steel sheets were formed into a plate 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. The pickling conditions 1 to 4 are shown in Table 2.

[0061]

[Table 2] Cold rolling is from 3.0 mm to 1.0 mm on a 4-high laboratory mill 9
A sample having a thickness of 50 mm in width and 50 mm in length was cut out from the steel sheet after each pass, and various characteristics were evaluated by the same method as in Example 1.

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

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

For steel sheets with a total reduction of 50% or more in cold rolling,
The C content is 0.04% or less, the hot-rolled steel sheet winding temperature is 800 ° C or less, the annealing temperature of the hot-rolled steel sheet is 1000 ° C or less, and the pickling lapping amount is 2
If the thickness is not less than μm and the final annealing temperature is 1050 ° C., it is possible to obtain the gloss after polishing at a pass level. At the final annealing temperature of 1120 ° C, the oxidation during the final annealing becomes severe and the gloss after polishing becomes low.

Steel plates with a C content of 0.04% or more cannot secure sufficient polishing property when the coiling temperature after hot rolling is 750 ° C. or more, and the coiling temperature of the hot-rolled steel plate is set to 600 to 700 ° C. By doing so, it is possible to obtain a steel plate having excellent gloss after polishing.

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

[0067]

[Table 3]

[0068]

[Table 4]

[0069]

According to the manufacturing method of the present invention, it becomes possible to economically and stably manufacture an austenitic stainless steel sheet and a steel strip having excellent buff grindability, and its practical significance is significant. I understand.

[Brief description of drawings]

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

─────────────────────────────────────────────────── ─── Continuation of the front page (56) Reference JP-A-11-140545 (JP, A) JP-A-11-131271 (JP, A) JP-A-62-253732 (JP, A) JP-A-6- 280064 (JP, A) (58) Fields surveyed (Int.Cl. ⁷ , DB name) C22C 38/00 302 C21D 9/46 C23G 1/08

Claims (4)

(57) [Claims] 1. A maximum surface roughness Rmax of 2 μm or less, and an average flat area ratio AFp expressed by the following formula (1): AFp (0.5 μm) ≧ 80% at a depth of 0.5 μm from the maximum peak height, and a cutting level P. (%) = Flat area ratio AFp at 20% and 30%
(P (%)) is AFp (30) / AFp (20) ≧ 1.05, an austenitic stainless steel sheet. AFp = (ΣXi / L) × 100 (1) However, L: Extraction length from the roughness curve of the steel plate surface P (%): Maximum peak of extraction length from roughness curve-Maximum valley depth Depth level from the maximum peak when the height is 100% Xi: Cutting length P at the extraction length L from the roughness curve
Length of flat part appearing in (%) 2. In the hot rolling of an austenitic stainless steel containing C: 0.02 to 0.08% by mass, the coiling temperature of the hot rolling depends on the amount of C contained in the following (2).
The hot-rolled steel sheet is annealed at a temperature of 1000 ° C or less after the hot rolling, and is then subjected to pickling to a thickness of 2 µm or more, and the resulting annealed pickling is performed. claims already perform cold rolling to hot-rolled steel sheet with a total rolling reduction of 50% or more, further annealing the resulting cold-rolled steel sheet, and performing a pickling
1. The method for producing an austenitic stainless steel sheet according to 1 . ( i ) Winding temperature (Tc) when 0.02% ≤ C ≤ 0.04%: 600 ℃ ≤ Tc ≤ 800 ℃ ... (2) (ii) Winding temperature (Tc) when 0.04% <C ≤ 0.08% : 600 ℃ ≤ Tc ≤ 700 ℃ (3) 3. The pickling performed on the hot rolled steel sheet is nitric acid: 20 to 10
The method for producing an austenitic stainless steel sheet according to claim 2, which 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, which is performed at a temperature of 900 ° C or more and 1100 ° C or less.