JP6758179B2 - Ferrite-austenitic two-phase stainless steel sheet with excellent polishability and its manufacturing method - Google Patents

Description

The present invention relates to a stainless steel sheet having excellent polishability and a method for producing the same, which is used in various fields where a mirror surface having high glossiness and high image quality is required.

Recently, the orientation of beauty is increasing, and mirror-finished stainless steel with excellent design and beauty is used for general building materials, interior materials, exterior materials such as exterior panels, mirror surface materials such as decorative mirrors and curved mirrors, and commercial kitchens. It is used in kitchen equipment such as countertops, sink tops, refrigerator doors, and cooking utensils such as square bats and pots. Among these applications, for example, in the case of mirror-related applications, conventionally used glass-based products are easily damaged when subjected to impact, and the damage may lead to injury. Due to its high price, it is widely used to use mirror-finished stainless steel as a mirror to replace glass.

Austenitic stainless steel, which has been conventionally used for the above purposes, has an annealed structure and is therefore soft, and is liable to have flaws during cleaning and handling, which spoils the aesthetic appearance. Also, during polishing, if Al-based oxides or Si-based oxides, which are deoxidizing products, are present on the surface, it causes ground defects and increases the polishing process.

In Patent Document 1, the amount of Al added as a deoxidizing element is reduced at the steelmaking stage, and the formation of Al ₂ O ₃ contained in the product is suppressed to eliminate ground defects during polishing and improve polishability. Steel is listed.

Patent Document 2 describes the production of steel in which the crystal grain size and the Al concentration of the base material are limited in order to suppress fine rough skin caused by temper rolling, which is the final process, and improve polishability by using a bright annealed material. The method is described.

On the other hand, in ferritic stainless steel, Patent Document 3 states that the rolling speed is reduced to suppress the formation of oil pits caused by rolling lubricating oil, and the white streaks caused by the oil pits are reduced to improve the polishability. Is described.

Further, Patent Document 4 describes a steel in which a ferrite phase + martensitic phase double-phase steel sheet is applied to mirror polishing to achieve both ferrite-based workability and martensitic-based flaw resistance.

However, in Patent Document 1, although austenitic stainless steel with few ground defects can be obtained, the defects that occur during handling cannot be eliminated. In Patent Document 2, the surface waviness after temper rolling is eliminated and the polishing process can be reduced, but the process is limited to the BA process. In Patent Document 3, although the formation of oil pits during rolling is suppressed and the deterioration of polishability due to the material is suppressed, since it is a ferritic stainless steel, it is soft and when the grinding flaw during rough polishing becomes deep, it is finished. Since the load of the polishing process increases, the polishability is deteriorated.

As a countermeasure against these, the steel described in Patent Document 4 was invented, but the duplex stainless steel of ferrite phase + martensite phase has a fine mixed structure consisting of soft ferrite phase and hard martensite phase. Therefore, the advantages of both are utilized, the glossiness after mirror finishing is excellent, and the workability and strength are moderate, and the flaw resistance is better than that of the austenitic stainless steel. Further, since it is a fine mixed structure, in the case of a mirror surface having a curvature such as a curved mirror, the surface rough surface after plastic working is small, and the polishing load for removing the rough skin is small. However, since the hardness of the material is remarkably high, about HV350, there is a problem that the polishing grain is hard to be attached and the load of the polishing apparatus and the consumption of the grindstone are increased.

Japanese Unexamined Patent Publication No. 4-99215 Japanese Unexamined Patent Publication No. 8-309405 Japanese Unexamined Patent Publication No. 2-173215 Japanese Unexamined Patent Publication No. 11-152550

The present invention has been devised to solve such a problem, and even when mirror polishing for accurately reflecting a reflected image is performed, the glossiness is high and the load of the polishing apparatus is high. To provide a mirror-finished stainless steel plate which is a ferrite / austenitic two-phase stainless steel plate capable of suppressing the consumption of a grindstone, is less likely to cause scratches and cracks even after long-term use, and can be reduced in weight by increasing its strength. The purpose is. In addition, general building materials using the mirror-finished steel plate, interior materials, exterior materials such as exterior panels, mirrors such as decorative mirrors and curved mirrors, kitchen countertops for commercial kitchens, sink top plates, and kitchen equipment such as refrigerator doors. , Square bats, pots and other cooking utensils.

The ferrite-austenitic two-phase stainless steel sheet of the present invention and its manufacturing method are as follows.

(1) In mass%, C: 0.03% or less, Cr: 19.0 to 22.0%, N: 0.06 to 0.20%, Ni, Mn, Cu: 1 type or 2 or more types. 5.0-7.5% in total, Si, Al: 1 or 2 in total 1.0% or less, P: 0.045% or less, Mo: 1.0% or less, S: 0.005 % Or less, O: 0.01% or less, the balance has a composition of Fe and unavoidable impurities, has a double-phase structure of ferrite phase and austenitic phase, and the particle size difference ΔGs between ferrite and austenite is 15 μm or less. A ferrite / austenitic two-phase stainless steel plate with excellent polishability.

(2) The composition further comprises, in mass%, Sn: 0.005 to 0.2%, Nb: 0.01 to 0.2%, Ti: 0.01 to 0.2%, B: 0. The ferrite-austenitic two-phase stainless steel plate having excellent polishability according to (1) above, which comprises one type or two or more types of 01% or less.

(3) The composition further comprises, in mass%, Y: 0.01 to 0.20%, REM: 0.01 to 0.20%, V: 0.005 to 0.20%, Al: 0. The ferrite-austenitic two-phase stainless steel plate having excellent polishability according to the above (1) or (2), which contains one or more of 005 to 0.20%.

(4) The ferrite / austenitic two-phase stainless steel sheet having excellent polishability according to any one of (1) to (3) above, which is used for a mirror surface material.

(5) The ferrite-austenitic two-phase stainless steel sheet having excellent polishability according to any one of (1) to (3) above, which is used for exterior materials.

(6) The ferrite-austenitic two-phase stainless steel sheet having excellent polishability according to any one of (1) to (3) above, which is used for kitchen equipment.

(7) The ferrite-austenitic two-phase stainless steel sheet having excellent polishability according to any one of (1) to (3) above, which is used for cooking utensils.

(8) A steel slab having the composition according to any one of (1) to (3) above is hot-rolled, then annealed with a hot-rolled sheet and pickled, and then the final pass is performed at a rolling ratio of 80% or more. After cold rolling to a plate temperature of 80 ° C. or higher, final annealing is performed at a temperature of 1000 to 1100 ° C., and then the cooling rate to 500 ° C. is set to 25 ° C./s or higher, and pickling is performed. The method for producing a ferrite-austenite-based two-phase stainless steel sheet having excellent polishability according to any one of 1) to (7).

Since the double-phase structure stainless steel sheet of the present invention has a mixed structure of a ferrite phase and an austenite phase, it has a high hardness that does not impair the fine particle size and polishability, and can be used as various mirror-finished products that are less likely to have surface defects. used. Further, the mirror-finished double-phase structure stainless steel sheet has a high glossiness, and the austenitic stainless steel sheet represented by SUS304 and the ferritic stainless steel sheet represented by SUS430 are liable to cause surface defects and cannot be used. It can also be used for mirror surface materials, exterior materials, kitchen equipment, and cooking utensils in various fields.

It is a figure which shows the relationship between the particle size difference of ferrite and austenite, and the surface roughness after one pass of polishing. It is a figure which shows the relationship between the surface roughness and glossiness after one pass of polishing.

Hereinafter, the alloy components, content, etc. contained in the stainless steel targeted by the present invention will be described. In addition,% of the content rate of a component shows mass%.

C: 0.03% or less C is a strong austenite-forming element and has a large strengthening ability, so that it effectively acts to increase the strength. However, if a large amount of C exceeding 0.03% is contained, a large amount of carbides will be generated after the heat treatment, and the corrosion resistance and toughness will be lowered. Therefore, it was set to 0.03% or less. Desirably, it is in the range of 0.01 to 0.02%.

Cr: 19.0 to 22.0%
Cr is an important element in maintaining the corrosion resistance of stainless steel. In a two-phase stainless steel composed of a ferrite phase and an austenite phase, Cr distribution to the austenite phase is suppressed, so that 19.0% or more is required to ensure the corrosion resistance of the austenite phase. However, if an excess of Cr exceeding 22.0% is contained, the toughness decreases. Excessive Cr content causes a decrease in manufacturability. Desirably, it is in the range of 20.0 to 21.0%.

Ni, Mn, Cu: 1 type or 2 or more types in total 5.0-7.5%
Both are alloying elements that act as austenite-forming elements and are necessary to obtain a ferrite + austenite structure at room temperature. As the content of Ni, Mn and / or Cu increases, the austenite phase increases and the hardness (strength) increases. When one or more of Ni, Mn, and Cu are contained in a total amount of 5.0% or more, the hardness of the austenite phase becomes a value equal to that of the ferrite phase. However, if an excess of Ni, Mn and / or Cu exceeding 7.5% is contained, the amount of austenite at high temperature becomes too large and the hot workability is lowered. Desirably, it is in the range of 5.5 to 6.5%.

N: 0.06 to 0.20%
Like C, N is an austenite-forming element, and therefore the N content needs to be determined from the component content in consideration of other ferrite-forming elements. Further, this N also has an effect of improving the pitting corrosion resistance, and the content of N needs to be at least 0.06%. However, if it exceeds 0.20%, the hot workability deteriorates, so the ratio was set to 0.06 to 0.20%. It is preferably in the range of 0.10 to 0.18%.

Si, Al: 1.0% or less in total of 1 or 2 types Si and Al are known as elements required for deoxidation, and are very important for improving the cleanliness of steel and reducing burrs. It is an important element. On the other hand, Si promotes the precipitation of the σ phase and causes embrittlement, and Al also causes the formation of AlN by combining with N in the steel. Therefore, these elements are in the range of 1.0% or less, preferably 0.2 to 0.6% in total. However, excessive reduction leads to an increase in refining cost and poor deoxidation, so the lower limit is preferably 0.05% or more.

P: 0.045% or less P is an element harmful to corrosion resistance, so the smaller the amount, the better. However, in order to excessively reduce the content, a special smelting technique is required, which leads to an increase in manufacturing cost. Therefore, P needs to be controlled to 0.045% or less.

S: 0.005% or less S is an element that precipitates at the grain boundaries of ferrite and austenite to deteriorate hot workability and adversely affect corrosion resistance, so the lower the value, the better. In particular, when the S content exceeds 0.005%, the effect becomes remarkable, so S is set to 0.005% or less. Preferably, it is 0.002% or less.

Mo: 1.0% or less Mo is an element that contributes to the improvement of corrosion resistance such as pitting corrosion resistance and crevice corrosion resistance, and to the solid solution strengthening of the ferrite phase. On the other hand, if it exceeds 1.0%, the ductility and toughness deteriorate with hardening, which leads to an increase in manufacturing cost. Therefore, Mo is contained in the range of 1.0% or less. Desirably, it is 0.5% or less. Although Mo exerts an effect depending on the amount of Mo added, it is preferably contained in an amount of 0.01% or more in order to sufficiently obtain the effect of improving the corrosion resistance of Mo.

O: 0.01% or less O exists as an oxide in steel. Oxides are generally high in hardness and easily cause scratches on the steel surface during polishing, so it is desirable that the amount is small. However, the deoxidation time and the elements required for deoxidation have a great influence on productivity and cost. Therefore, it was set to 0.01% or less. Desirably, it is 0.006% or less.

The above is the basic component of the stainless steel targeted by the present invention, and it is composed of the balance and unavoidable impurities, and the following components can be contained as necessary.

Sn: 0.005-0.2%
Sn is an element that improves corrosion resistance, but it is also a solid solution strengthening element of the ferrite phase, and the upper limit was set to 0.2% due to the decrease in hardness difference. Since the effect of improving the corrosion resistance is exhibited from 0.005%, it was set to 0.005 to 0.2%. Desirably, it is in the range of 0.03 to 0.1%.

Nb: 0.01 to 0.2%, Ti: 0.01 to 0.2%
Both Nb and Ti are stabilizing elements in the ferrite phase and are effective elements for improving local corrosion resistance. However, addition of 0.01% or less has no effect, while if it exceeds 0.2%, a large amount of precipitates are precipitated, resulting in deterioration of toughness, which deteriorates hot workability and manufacturing cost. It becomes disadvantageous. Therefore, the amount of Nb and Ti added is in the range of 0.01 to 0.2%, preferably 0.05 to 0.12%.

B: 0.01% or less B is an element that exists at the grain boundaries of the alloy with a small amount of addition and improves hot workability. However, at the same time, it is also an element that deteriorates corrosion resistance such as intergranular corrosion. Therefore, the content of B was set to 0.01% or less.

In addition to the above alloy components, the stainless steel targeted by the present invention has 0.01 to 0.20% Y and 0.01 to 0.20% REM, which are effective for improving oxidation resistance. Rare earth metal excluding Y), 0.005 to 0.20% V effective for improving oxidation resistance, and 0.005 to 0.20% Al effective for deoxidation can be contained.
In addition, other elements can be added as long as the effects of the present invention are not impaired.

In the present invention, the content of various alloy components contained in stainless steel is regulated as described above, and the alloy components are mutually adjusted so that a double phase structure of a ferrite phase + an austenite phase can be obtained at room temperature. .. As the multiphase structure obtained at room temperature, a structure composed of substantially 50 to 60% by volume of a wrought ferrite phase and 40 to 50% by volume of a granular austenite phase is preferable.

Difference in particle size between ferrite and austenite ΔGs is 15 μm
Using the steels of the components shown in Table 1 as test materials, cold-rolled products of two-phase stainless steel consisting of ferrite phase and austenite phase having various particle sizes were manufactured as shown in Examples described later, and ferrite was used as a test material. The particle size of austenite was measured by electron backscatter diffraction (EBSD). The particle size was measured by converting the particle sizes of all ferrites and austenites in a 1000-fold visual field into circle-equivalent diameters. The average values of the measured ferrite and austenite particle sizes were obtained and used as the ferrite average particle size and the austenite average particle size, respectively. The difference between the ferrite average particle size and the austenite average particle size was defined as ΔGs in the field of view. This was performed for any 5 visual fields, and the average value of ΔGs in the 5 visual fields was taken as ΔGs of the steel sheet. Next, the surface roughness Rz and the glossiness Gs60 before and after one pass of # 400 buffing were measured, and the relationship between the particle size difference and the surface roughness was compared. As shown in FIG. 1, when the particle size difference ΔGs between ferrite and austenite (ferrite particle size-austenite particle size) is 15 μm or less, the surface roughness is stably reduced. The relationship between the surface roughness and the glossiness is shown in FIG. 2. The lower the surface roughness, the better the glossiness. From FIGS. 1 and 2, when the particle size difference is within 15 μm, the glossiness is 350 or more.

The phenomenon that the surface roughness after polishing is stably reduced due to such a difference in particle size is considered as follows. It is presumed that the factors that hinder the decrease in surface roughness when the cold-rolled product is polished are the grain boundary erosion grooves caused by the pickling treatment and the ground defects caused by the inclusions. This grain boundary erosion groove is a phenomenon in which grain boundaries are selectively dissolved and generally occurs in the austenite phase. About 50% of the austenite phase is present on the product surface of the steel of the present invention, and the surface roughness after polishing is improved by reducing the intergranular erosion grooves in this portion. However, it is not possible to control only the austenite particle size.

Therefore, it is important to control the particle size difference between ferrite and austenite. In order to reduce the intergranular erosion groove of austenite, it is desirable that the austenite particle size is 8 μm or less, but at the same time, ferrite grows. Since the ferrite phase of the steel of the present invention is softer than the austenite phase, the presence of coarse particles tends to cause ground flaws. In order to achieve both of these, the particle size difference needs to be within 15 μm.

Next, a manufacturing method for obtaining the duplex stainless steel sheet of the present invention will be described.
A steel slab adjusted to the above component content is hot-rolled, then annealed and pickled on a hot-rolled plate, then cold-rolled, and then finally annealed and pickled. However, in order to obtain a two-phase stainless steel having a particle size difference of 15 μm or less, cold rolling and final annealing are performed as follows.

Cold rolling rate: 80% or more and plate temperature after final pass 80 ° C or higher When manufacturing cold rolled steel strips, the cold rolling rate (rolling rate in cold rolling) is 80% or more in order to reduce the difference in crystal grain size. Must be. This is because the coarse ferrite texture is crushed by cold rolling to obtain fine recrystallized grains. If the cold rolling ratio is less than 80%, residual coarse ferrite grains can be confirmed, so the cold rolling ratio was set to 80% or more.

Further, the introduction of strain during cold rolling becomes a nucleation of recrystallized grains, but in a high-strength steel such as the present invention, a large load is generated in the cold rolling process as work hardening progresses. Therefore, the load is reduced by raising the plate temperature during cold rolling. This effect is useful not only for increasing the load on the cold rolling process but also for controlling the crystal grain size because it does not overstate the recrystallized nuclei. It is necessary to control the plate temperature after passing to 80 ° C. or higher. The upper limit of the plate temperature is about 300 ° C. The plate temperature after the final pass can be controlled by changing the rolling rate and rolling speed per pass.

Final annealing: 1000-1100 ° C
A finish heat treatment is performed by heating to a temperature range of 1000 to 1100 ° C. The temperature range of 1000 to 1100 ° C. was found as a result of various investigations and studies by the present inventors regarding the grain growth behavior of crystal grains, and is a ferrite and austenite crystal grains necessary for improving polishability. It is an important requirement for controlling the difference in diameter and hardness. At a heating temperature of less than 1000 ° C., the recrystallization of austenite cannot be completed sufficiently, and some austenite remains as recovery swelling granules. Since the intergranular erosion grooves of the coarse grains become deep, the surface roughness after polishing is deteriorated. On the other hand, when heated to a high temperature exceeding 1100 ° C., the material is softened and ferrite is coarse-grained, so that the difference in crystal grain size and hardness becomes large, the scratch resistance is lowered, and the surface roughness is deteriorated. This leads to a significant decrease in polishability.

Cooling rate: 25 ° C / s or more (up to 500 ° C)
When the ferrite phase is heated to a temperature range of 1000 to 1100 ° C. and then slowly cooled, the grain boundary N increases as the N solid solution limit of the ferrite phase decreases, and Cr nitride precipitation occurs. This Cr nitride causes intergranular erosion grooves in the subsequent descaling process and deteriorates polishability. Therefore, the cooling rate was set to 25 ° C./s. Further, since the precipitation of Cr nitride is suppressed at 500 ° C. or lower, the temperature is set to 500 ° C. or lower.

By this finish heat treatment, a fine mixed structure composed of about 50 to 60% by volume of the ferrite phase and about 40 to 50% by volume of the austenite phase is obtained, and the material has a ferrite and austenite particle size difference ΔGs of 15 μm or less.

The finish heat-treated stainless steel is subjected to rough polishing finish, medium finish polishing, and final mirror polishing finish to obtain a product having a mirror surface. Since the product thus obtained is not damaged by an impact like a glass mirror, troubles such as injury due to the damage can be prevented. In addition, since the surface hardness is high, surface defects that tend to occur during cleaning and handling can be reduced. Therefore, transportation-related products such as automobiles, motorcycles, and various vehicles, aircraft-related products, construction / civil engineering-related products such as houses, buildings, stores, and roadside facilities, chemical equipment-related products such as optics and medical care, machinery, electricity, and electronics. It is a material suitable for a wide range of fields such as equipment-related, general household equipment, kitchen equipment, cooking equipment, and office equipment-related.

A stainless steel made of steel A satisfying the component range of the present invention shown in Table 1 and steel B not satisfying the component range of the present invention is melted and hot-rolled to a hot-rolled steel strip having a plate thickness of 6.0 mm. I made it. Next, the hot-rolled steel strip was annealed with a hot-rolled plate at 980 ° C. for 60 minutes, the plate thickness was changed so as to have various cold-rolling ratios, and cold rolling was performed. The obtained cold-rolled steel sheet was introduced into an annealing furnace and heat-treated at the temperatures shown in Table 2 as a finish heat treatment to produce a stainless steel strip having a double-phase structure of a ferrite phase and an austenite phase.

A test piece was cut out from each double-phase structure stainless steel strip and subjected to 1 pass of # 400 buffing to obtain a mirror-polished finish. Since the hardness of the test piece was about HV250, the load on the polishing apparatus was small, and the consumption of the grindstone could be suppressed. The surface roughness of each mirror-polished test piece was measured according to the ten-point average roughness Rz of JIS B0601'1994, and the glossiness was measured according to the mirror glossiness measurement method of JIS Z8741. The results are shown in Table 2.

As is clear from Table 2, Example Test No. of the present invention in which the component range and the production conditions satisfy the range of the present invention. For 1, 2, 5, 6, 8, 9, 12, 16, 17, 19, 20, 22, 23, 24, 25, and 26, the particle size difference between the ferrite phase and the austenite phase is within 15 μm, and after polishing, The glossiness Gs60 was as good as 350 or more. On the other hand, Comparative Example Test No. of Steel B whose component range is out of the range of the present invention. In Nos. 1 to 15, the particle size difference between the ferrite phase and the austenite phase was more than 15 μm even if the production conditions were satisfied, and the glossiness after polishing was also inferior.

On the other hand, even if steel A whose composition satisfies the invention range is used, if the production method deviates from the present invention, the glossiness after polishing may be inferior. Comparative Example Test No. of Steel A In Nos. 3, 14 and 27, the plate temperature after the final pass was low and the particle size difference was large, and as a result, the surface roughness after polishing was coarse and the glossiness was low. Comparative Example Test No. of Steel A In No. 4, the cooling rate after annealing was slow, and the γ-phase grain boundaries formed grain boundary erosion grooves after pickling, so that the surface roughness after polishing was coarse and the glossiness was low. Comparative Example Test No. of Steel A Nos. 7 and 21 have a low cold rolling ratio and a high annealing temperature, and the comparative example test No. of steel A. No. 10 and 28 have a low cold rolling ratio, and Steel A has a comparative example test No. Since the annealing temperature of No. 15 was high, coarse graining of the α phase was remarkable, the particle size difference exceeded the range of the present invention, and the glossiness after polishing was not improved. Comparative Example Test No. of Steel A In No. 13, the annealing temperature was low, the recrystallization of the γ phase was insufficient, and the expanded grains remained, so that the intergranular erosion grooves were deep and the surface roughness after polishing was deteriorated. Comparative Example Test No. of Steel A In Nos. 11 and 18, the heat treatment conditions after the final pass and the cold rolling ratio exceed the range of the invention, and the cooling rate is slow and the intergranular erosion grooves are prominent, so that the surface roughness after polishing is rough and the polishing is performed. The later gloss was poor.

As described above, since the double-phase structure stainless steel sheet of the present invention has a mixed structure of a ferrite phase and an austenite phase, it has a fine particle size and a high hardness that does not impair polishability, and has surface defects. It is used as various mirror surface products that are difficult to attach. Further, the mirror-finished double-phase structure stainless steel sheet has a high glossiness, and the austenitic stainless steel sheet represented by SUS304 and the ferritic stainless steel sheet represented by SUS430 are liable to cause surface defects and cannot be used. It can also be used as a mirror surface material in other fields.

If the stainless steel of the present invention is used, it is related to transportation such as automobiles, motorcycles, and various vehicles, aircraft-related, construction / civil engineering-related such as houses, buildings, stores, road incidental facilities, chemical equipment-related such as optics and medical equipment, and machinery. It is possible to prevent troubles such as injuries caused by damage to mirror surface materials such as electric and electronic equipment, general household equipment, kitchen equipment, cooking equipment, office equipment, etc., and to reduce clean surface defects. The industrial effect of the present invention is extremely remarkable.

Claims (8)

By mass%, C: 0.03% or less, Cr: 19.0 to 22.0%, N: 0.06 to 0.20%, Ni, Mn, Cu: 1 type or 2 or more types in total 5 .0 to 7.5%, Si, Al: 1 or 2 in total 1.0% or less, P: 0.045% or less, Mo: 1.0% or less, S: 0.005% or less, O: 0.01% or less, the balance has a composition of Fe and unavoidable impurities, has a dual phase structure of a ferrite phase and an austenite phase, and the particle size difference ΔGs between ferrite and austenite is 15 μm or less. A ferrite austenite-based two-phase stainless steel plate having excellent polishability, characterized in that the particle size of austenite is 5 μm or less. The composition further includes Sn: 0.005 to 0.2%, Nb: 0.01 to 0.2%, Ti: 0.01 to 0.2%, B: 0.01% or less in mass%. The ferrite-austenitic two-phase stainless steel plate having excellent polishability according to claim 1, which comprises one or more of the above-mentioned. The composition further includes Y: 0.01 to 0.20%, REM: 0.01 to 0.20%, V: 0.005 to 0.20%, Al: 0.005 to 0 in mass%. The ferrite / austenite-based two-phase stainless steel sheet having excellent polishability according to claim 1 or 2, which comprises 20% of one or more. The ferrite-austenitic two-phase stainless steel sheet having excellent polishability according to any one of claims 1 to 3, which is used for a mirror surface material. The ferrite / austenitic two-phase stainless steel sheet having excellent polishability according to any one of claims 1 to 3 for exterior materials. The ferrite-austenitic two-phase stainless steel sheet having excellent polishability according to any one of claims 1 to 3, which is used for kitchen equipment. The ferrite-austenitic two-phase stainless steel sheet having excellent polishability according to any one of claims 1 to 3 for cooking utensils. The steel slab having the composition according to any one of claims 1 to 3 is hot-rolled, then annealed and pickled, and then the plate temperature after the final pass at a rolling ratio of 95% or more. After cold rolling to a temperature of 80 ° C. or higher, final annealing is performed at a temperature of 1000 to 1100 ° C., and then the cooling rate to 500 ° C. is set to 25 ° C./s or higher, and pickling treatment is performed to obtain a ferrite phase. Any one of claims 1 to 7 to obtain a stainless steel sheet having a double-phase structure with an austenite phase, a particle size difference ΔGs between ferrite and austenite of 15 μm or less, and an austenite particle size of 2 μm or less. A method for producing a ferrite / austenite-based two-phase stainless steel sheet having excellent polishability as described in 1.

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