Ferritic stainless steel with improved workability and ridging resistance and manufacturing method thereof

Abstract

The present invention pertains to a ferritic stainless steel with improved workability and ridging resistance, and a manufacturing method thereof. A ferritic stainless steel with improved workability and ridging resistance according to an embodiment of the present invention contains, in wt%, 0.0005-0.02% of carbon (C), 0.01-0.2% of nitrogen (N), 0.01-1.0% of silicon (Si), 0.01-1.0% of manganese (Mn), 0.001-0.05% of phosphorus (P), 13.0-20.0% of chromium (Cr), and 0.05-0.2% of titanium (Ti), with the remainder comprising iron (Fe) and inevitable impurities, satisfies expression (1), and may have a grain size of 20 to 25 µm. Expression (1): 2*[Ti] / [N] ≤ 2.3 In expression (1), [Ti] and [N] refer to the content (in wt%) of the respective elements.

Description

[Technical Field]

[0001] The present invention relates to a ferritic stainless steel with improved workability and ridging resistance and a method of manufacturing method thereof.[Background Art]

[0002] Ferritic stainless steels are steels that have excellent corrosion resistance while containing a lower amount of expensive alloying elements, offering superior cost competitiveness than austenitic stainless steels. Ferritic stainless steels are used in construction materials, transportation equipment, home appliances, and kitchen appliances.

[0003] Ferritic stainless steel cold-rolled products have ridge defects appearing as stripe-like patterns during forming processes such as deep drawing. Such ridging defects not only degrade the appearance of the product, but also increase the manufacturing costs because severe ridging defects require an additional polishing process after forming.

[0004] In order to address the ridging defects, various manufacturing methods such as hot rolling at extremely low temperatures, low-speed rolling, and additional cold rolling have been proposed. However, the manufacturing methods proposed in the conventional technology are difficult to apply in the field, and increase manufacturing costs, thereby reducing the productivity of products.[Disclosure][Technical Problem]

[0005] The present invention aims to provide a ferritic stainless steel with improved workability and ridging characteristics achieved by optimizing the steel composition and the manufacturing process to control the grain size of the final cold-rolled annealed material such that workability is enhanced, and a method of manufacturing the same.

[0006] The technical objectives of the present invention are not limited to the above, and other objectives that are not described above will be clearly understood by those skilled in the art from the above detailed description.[Solution to Problem]

[0007] A ferritic stainless steel with improved workability and ridging resistance according to an aspect of the present invention includes, in percent by weight (wt%), 0.0005 to 0.02% of carbon (C); 0.01 to 0.2% of nitrogen (N); 0.01 to 1.0% of silicon (Si); 0.01 to 1.0% of manganese (Mn); 0.001 to 0.05% of phosphorus (P); 13.0 to 20.0% of chromium (Cr); 0.05 to 0.2% of titanium (Ti); and the balance being iron (Fe) and inevitable impurities, and satisfying Expression (1) below, and satisfying a grain size in a range of 20 to 25 µm: 2 * Ti / N ≤ 2.3

[0008] In Expression (1), [Ti] and [N] represent the content (wt%) of each element.

[0009] The ferritic stainless steel with improved workability and ridging resistance according to an embodiment may have a ridging height of 10 µm or less measured after 15% tension.

[0010] The ferritic stainless steel with improved workability and ridging resistance according to an embodiment may have an elongation of 32% or more.

[0011] A method of manufacturing a ferritic stainless steel with improved workability and ridging resistance according to an aspect of the present invention includes: preparing a slab comprising, in percent by weight (wt%), 0.0005 to 0.02% of carbon (C), 0.01 to 0.2% of nitrogen (N), 0.01 to 1.0% of silicon (Si), 0.01 to 1.0% of manganese (Mn), 0.001 to 0.05% of phosphorus (P), 13.0 to 20.0% of chromium (Cr), 0.05 to 0.2% of titanium (Ti), and the balance being iron (Fe) and inevitable impurities, and satisfying Expression (1) below; reheating the slab; hot-rolling the reheated slab, followed by hot-rolled annealing; and cold-rolling the hot-rolled steel sheet, followed by cold-rolled annealing at 800 to 850°C, 2 * Ti / N ≤ 2.3

[0012] In Expression (1), [Ti] and [N] represent the content (wt%) of each element.

[0013] In the method of manufacturing a ferritic stainless steel with improved workability and ridging resistance according to an embodiment, the reheating may be performed at 1,000 to 1,300°C.

[0014] In the method of manufacturing a ferritic stainless steel with improved workability and ridging resistance according to an embodiment, the stainless steel may have a grain size satisfying a range of 20 to 25 µm.

[0015] In the method of manufacturing a ferritic stainless steel with improved workability and ridging resistance according to an embodiment, the stainless steel may have a ridging height of 10 µm or less measured after 15% tension.

[0016] In the method of manufacturing a ferritic stainless steel with improved workability and ridging resistance according to an embodiment, the stainless steel may have an elongation of 32% or more.[Advantageous Effects]

[0017] The present invention can provide a ferritic stainless steel with improved workability and ridging characteristics and a method of manufacturing the same by optimizing the steel composition and the manufacturing process to control the grain size of the final cold-rolled annealed material such that the workability of a cold-rolled product is enhanced.[Description of Drawings]

[0018] FIG. 1 is a graph showing a ridging height (a solid line) and an elongation (a dotted line) as a function of the annealing temperature in a manufacturing of a stainless steel according to an embodiment. FIG. 2A is a photograph showing the grain size of a stainless steel manufactured at a cold-rolled annealing temperature of 750°C. FIG. 2B is a photograph showing the grain size of a stainless steel manufactured at a cold-rolled annealing temperature of 800°C. FIG. 2C is a photograph showing the grain size of a stainless steel manufactured at a cold-rolled annealing temperature of 850°C. FIG. 2D is a photograph showing the grain size of a stainless steel manufactured at a cold-rolled annealing temperature of 900°C. FIG. 2E is a photograph showing the grain size of a stainless steel manufactured at a cold-rolled annealing temperature of 950°C. [Best Mode of the Invention]

[0019] A ferritic stainless steel with improved workability and ridging resistance according to an embodiment may include, in percent by weight (wt%), 0.0005 to 0.02% of carbon (C); 0.01 to 0.2% of nitrogen (N); 0.01 to 1.0% of silicon (Si); 0.01 to 1.0% of manganese (Mn); 0.001 to 0.05% of phosphorus (P); 13.0 to 20.0% of chromium (Cr); 0.05 to 0.2% of titanium (Ti); and the balance being iron (Fe) and inevitable impurities, and satisfy Expression (1) below, and satisfy a grain size in a range of 20 to 25 µm: 2 * Ti / N ≤ 2.3

[0020] In Expression (1), [Ti] and [N] represent the content (wt%) of each element.[Modes of the Invention]

[0021] Hereinafter, embodiments of the present disclosure will be described in detail with reference to the accompanying drawings. The embodiments of the present disclosure may, however, be embodied in many different forms and should not be construed as being limited to the embodiments set forth herein. Rather, these embodiments are provided so that this disclosure will be thorough and complete, and will fully convey the concept of the invention to those skilled in the art.

[0022] Also, the terms used herein are merely used to describe particular embodiments. An expression used in the singular encompasses the expression of the plural, unless otherwise indicated. Throughout the specification, the terms such as "including" or "having" are intended to indicate the existence of features, operations, functions, components, or combinations thereof disclosed in the specification, and are not intended to preclude the possibility that one or more other features, operations, functions, components, or combinations thereof may exist or may be added.

[0023] Meanwhile, unless otherwise defined, all terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this disclosure belongs. Thus, these terms should not be interpreted in an idealized or overly formal sense unless expressly so defined herein. As used herein, the singular forms are intended to include the plural forms as well, unless the context clearly indicates otherwise.

[0024] The terms "about", "substantially", etc. used throughout the specification means that when a natural manufacturing and a substance allowable error are suggested, such an allowable error corresponds the value or is similar to the value, and such values are intended for the sake of clear understanding of the present invention or to prevent an unconscious infringer from illegally using the disclosure of the present invention.

[0025] A ferritic stainless steel with improved workability and ridging resistance according to an aspect of the present invention, may include, in percent by weight (wt%), 0.0005 to 0.02% of carbon (C); 0.01 to 0.2% of nitrogen (N); 0.01 to 1.0% of silicon (Si); 0.01 to 1.0% of manganese (Mn); 0.001 to 0.05% of phosphorus (P); 13.0 to 20.0% of chromium (Cr); 0.05 to 0.2% of titanium (Ti); and the balance being iron (Fe) and inevitable impurities.

[0026] Hereinafter, the reason for limiting the composition range of each alloy element is described in more detail below. Unless otherwise specified, the units thereof are expressed in weight percent (wt%).

[0027] The content of carbon (C) may be 0.0005 to 0.02 wt%, preferably 0.01 to 0.02 wt%.

[0028] C is an element that greatly affects the improvement of the strength of a steel. When the amount of carbon (C) is less than 0.0005 wt%, the refining cost for producing a high-purity product may increase. However, when the carbon content exceeds 0.02 wt%, corrosion resistance and formability may be degraded.

[0029] The content of nitrogen (N) may be 0.01 to 0.2 wt%, preferably 0.04 to 0.2 wt%.

[0030] Nitrogen is an element that forms nitrides and is present as an interstitial form, and thus excessive amounts of N may degrade impact toughness and formability. Considering this, the upper limit of the nitrogen content is limited to 0.2 wt% or less. However, when the content of nitrogen (N) is too low, TiN crystallization may decrease, which may reduce the equiaxed crystallinity of the slab.

[0031] The content of silicon (Si) may be 0.01 to 1.0 wt%, preferably 0.05 to 0.60 wt%.

[0032] Si may be added to deoxidize molten steel during steelmaking, and is an effective element for stabilizing ferrite. When the amount of silicon (Si) is less than 0.01 wt%, the refining cost may increase. However, when the silicon content exceeds 1.0 wt%, the amount of impurities may increase and formability may be degraded.

[0033] The content of manganese (Mn) may be 0.01 to 1.0 wt%, preferably 0.20 to 0.95 wt%.

[0034] Mn is an element that is effective in improving corrosion resistance. When the amount of manganese (Mn) is less than 0.01 wt%, the refining cost may increase, and when the amount of manganese (Mn) exceeds 1.0 wt%, the amount of impurities increase and thus the formability may be degraded.

[0035] The content of phosphorus (P) may be 0.001 to 0.05 wt%, preferably 0.001 to 0.020 wt%.

[0036] When the amount of phosphorus (P) is less than 0.001 wt%, the refining cost may increase. However, when the content of phosphorus exceeds 0.05 wt%, the amount of impurities increases and the formability may be degraded.

[0037] The content of chromium (Cr) may be 13.0 to 20.0 wt%, preferably 13.5 to 17.5 wt%.

[0038] Cr is an element that is effective in ensuring the corrosion resistance of steel. When the amount of chromium (Cr) is less than 13.0 wt%, the corrosion resistance degrades. However, when the content of chromium exceeds 20.0 wt%, the formability may be degraded.

[0039] The content of titanium (Ti) may be 0.05 to 0.2 wt%, preferably 0.05 to 0.17 wt%.

[0040] Ti is an element that may preferentially combine with interstitial elements such as C and N to form precipitates. When the amount of titanium (Ti) is less than 0.05 wt%, it may be difficult to form Ti-based inclusions during manufacturing. When the titanium content is excessive, the Ti component reacts with oxygen, causing surface defects such as discoloring to yellow.

[0041] The remainder of the ferritic stainless steel according to the present invention is iron (Fe). However, unintended impurities from raw materials or the surrounding environment may inevitably be introduced during typical manufacturing process, and thus cannot be excluded. Since such impurities may be well known to those skilled in the typical manufacturing process, details thereof are not specifically described in this specification.

[0042] In addition, the ferritic stainless steel according to an embodiment may satisfy Expression (1) below. 2 * Ti / N ≤ 2.3

[0043] In Expression (1), [Ti] and [N] represent the content (wt%) of each element.

[0044] In order to improve the ridging resistance of stainless steel, the present invention is provided to form TiN precipitates by adjusting the contents of Ti and N to obtain a fine cast structure. When the value of 2*[Ti] / [N] in Expression (1) calculated based on the alloy composition exceeds 2.3, the amount of N available to combine with Ti becomes insufficient, thereby preventing refinement of the cast structure.

[0045] The value of 2*[Ti] / [N] in Expression (1) may be specifically 0.5 to 2.3, more specifically 1.0 to 2.3, and more specifically 1.7 to 2.3. Within the range, the ferritic stainless steel according to an embodiment of the present invention may have a further improved effect of controlling the microstructure, thereby having better workability and ridge resistance.

[0046] The ferritic stainless steel according to an embodiment may have a measured ridging height of 10 µm or less measured after being tensioned by 15% in a direction perpendicular to the rolling direction. In addition, the ferritic stainless steel according to an embodiment may have an elongation of 32% or more, and preferably, a cold-rolled annealed steel sheet having a thickness of about 0.4 to 0.6 mm may have an elongation of 32% or more. A higher elongation may contribute to an improved workability.

[0047] In order to have the workability of cold-rolled stainless steel products used for home appliances, both the ridging characteristics and elongation need to be satisfied. Since the steel sheet need to have good elongation during forming, it is preferable to satisfy an elongation of 32% or more while the ridging height is limited to about 10 µm or less, preferably 8.5 µm or less, in order to minimize streaks after processing and achieve a desired gloss.

[0048] The ferritic stainless steel according to an embodiment may satisfy a grain size of 20 to 25 µm, preferably 20 to 23 µm.

[0049] When the average grain size of the stainless steel is limited to 20 to 25 µm, a desired elongation and a desired ridging height may be satisfied simultaneously due to the refinement of the casting structure.

[0050] Next, a method of manufacturing a ferritic stainless steel with improved ridging resistance according to another aspect of the present invention will be described.

[0051] A method of manufacturing a ferritic stainless steel with improved workability and ridging resistance according to an aspect of the present invention includes: preparing a slab including, in percent by weight (wt%), 0.0005 to 0.02% of carbon (C), 0.01 to 0.2% of nitrogen (N), 0.01 to 1.0% of silicon (Si), 0.01 to 1.0% of manganese (Mn), 0.001 to 0.05% of phosphorus (P), 13.0 to 20.0% of chromium (Cr), 0.05 to 0.2% of titanium (Ti), and the balance being iron (Fe) and inevitable impurities, and satisfying Expression (1) below; reheating the slab; hot-rolling the reheated slab, followed by hot-rolled annealing; and cold-rolling the hot-rolled steel sheet, followed by cold-rolled annealing. 2 * Ti / N ≤ 2.3

[0052] In Expression (1), [Ti] and [N] represent the content (wt%) of each element.

[0053] The reasons for numerically limiting the component range of each alloy composition and the value of Expression (1) are as described above, and the following provides details of manufacturing operations.

[0054] First, after manufacturing a slab satisfying the above alloy composition, a series of processes including reheating, hot rolling, hot-rolled annealing, cold rolling, and cold-rolled annealing may be performed.

[0055] First, the slab may be heated at a temperature of 1,000 to 1,300 °C in a hot rolling furnace, and then hot rolled to produce a hot rolled steel sheet.

[0056] When the heating temperature is low, it may be difficult to re-decompose coarse precipitates generated during slab manufacturing. Considering this, the heating temperature may be 1,000 °C or higher. However, when the heating temperature is excessively high, the internal grains may become overly coarse, and severe surface oxidation may occur, causing surface defects. Considering this, the upper limit of the heating temperature may be limited to 1,300°C.

[0057] In the hot rolling, the finish rolling may be performed at 700 to 900°C.

[0058] When the finish rolling temperature is less than 700°C, sticking bonds may occur on the sheet surface of the slab during hot rolling. However, when the finish rolling temperature exceeds 900°C, coarse ferrite grains may be formed, resulting in poor ridging resistance.

[0059] The hot-rolled steel sheet is subjected to hot-rolled annealing to recrystallize the cast structure. In this case, the hot-rolled annealing may be performed at a temperature of 700 to 900°C.

[0060] When the hot-rolled annealing temperature is low, the stress generated during hot rolling may not be sufficiently removed, resulting in poor workability. However, when the hot-rolled annealing temperature is excessively high, grain coarsening may occur, leading to lowered strength and degraded ridging resistance.

[0061] The hot-rolled steel sheet, which has been subjected to the hot-rolled annealing, may be cold-rolled and then subjected to cold-rolled annealing to produce a cold-rolled steel sheet. In this case, the cold-rolled annealing may be performed at a temperature of 800 to 850°C.

[0062] By satisfying the cold-rolled annealing temperature, the grain size may be controlled to 20 to 25 µm. When the cold-rolled annealing temperature exceeds 850°C, the grain size becomes coarser, and structures having a {001} / / ND crystal orientation, which reduce the ridging resistance, grows. The growth of structures having a {001 } / / ND crystal orientation not only increases plastic anisotropy with respect to the matrix, thereby reducing the ridging resistance, but also degrades the surface roughness. However, when the cold-rolled annealing temperature is less than 800°C, recrystallization may not occur, leading to degradation in the elongation and the ridging resistance.

[0063] As described above, by optimizing the alloy composition and the composition relationship as well as the reheating, hot-rolled annealing, and cold-rolled annealing processes, grain refinement in the casting structure may be realized, thereby ensuring ridging resistance and elongation of the ferritic stainless steel.

[0064] The stainless steel manufactured according to an embodiment may satisfy a grain size range of 20 to 25 µm. By satisfying the grain size range, a stainless steel with excellent workability with targeted workability and ridging resistance may be obtained.

[0065] The stainless steel manufactured according to an embodiment may have a measured ridging height of 10 µm or less after being tensioned by 15% in a direction perpendicular to the rolling direction. By satisfying the ridging height range, a stainless steel having a minimum stripe formation after processing and a desired gloss may be obtained.

[0066] The stainless steel manufactured according to an embodiment may have an elongation of 32% or more. By satisfying the elongation range, a stainless steel with excellent formability due to high elongation of steel material during forming may be obtained.

[0067] Hereinafter, the present invention will be described in more detail through examples. However, the following examples are intended to further illustrate the present invention, and the scope of the present invention is not limited by the following examples.[Examples]

[0068] For the various alloy composition ranges shown in Table 1 below, slabs were prepared in a vacuum induction melting furnace. The prepared slabs were reheated in a heating furnace at 1,100 °C, hot-rolled to produce hot-rolled steel sheets, and then air-cooled. The air-cooled, hot-rolled steel sheets were subjected to hot-rolled annealing at 850°C, and then cold-rolled to a thickness of 0.5 mm, and then subjected to cold-rolling annealing at a temperature shown in Table 2 below to produce cold-rolled steel sheet specimens.

[0069] In addition, Expression (1) below is calculated and the values of Expression (1) are show in Table 1 below. 2 * Ti / N

[0070] In Expression (1), [Ti] and [N] represent the content (wt%) of each element. [Table 1]Alloy composition (wt %)Class.CSiMnPCrTiNExpr.(1)RemarksSteel 10.0200.110.500.00114.00.200.0626.45 Comparative ExampleSteel 20.0100.200.280.00116.80.190.0665.76 Steel 30.0200.240.810.00616.20.170.1961.73Inventive ExampleSteel 40.0150.150.880.00715.80.30 0.0807.50 Comparative ExampleSteel 50.0200.200.640.00114.90.140.1461.92Inventive ExampleSteel 60.0180.280.700.00316.50.160.1502.13Steel 70.0080.090.940.00813.90.180.1492.42 Comparative ExampleSteel 80.0140.170.730.01017.20.180.1382.61 Steel 90.0200.550.900.01516.00.050.0452.23Inventive Example

[0071] Table 2 below shows the average grain size in the cast structure, the ridging height measured after 15% tension, and the elongation of the steel having the alloy composition of Table 1, according to the cold-rolled annealing temperature. In addition, FIG. 1 shows the correlation between the ridging height and the elongation of the steel having the alloy composition of Steel 3 according to the cold rolled annealing temperature. The grain size was measured by photographing the cast structure with an optical microscopy (OM). FIGS. 2A to 2E are photographs of the grain sizes of stainless steels having the alloy composition of Steel 3, which were treated at cold rolled annealing temperatures of 750°C, 800°C, 850°C, 900°C, and 950°C, respectively. The ridging height was measured using a surface roughness tester after the specimen was tensioned by 15% in a direction perpendicular to the rolling direction of the specimen.

[0072] The elongation was calculated by dividing the amount of extension by the initial length during uniaxial tension of a cold-rolled stainless steel product at a time of fracture. [Table 2]Compositi onCold-Rolled Annealing Temperature (°C)Grain Size (µm)Ridging Height (µm)Elongation (%)RemarksSteel 180028.4 16.8 29.0 Comparative Example82033.3 22.3 29.5 85041.9 29.2 32.6Steel 280030.6 15.3 30.3 Comparative Example82038.4 18.2 32.6 85045.5 18.9 33.5 Steel 3750 Unrecrystallized 12.5 16.9 Comparative Example80020.88.432.0Inventive Example82021.38.232.285022.17.932.6880 28.5 10.1 33.4Comparative Example900 31.2 10.3 34.2920 40.4 12.3 34.3950 44.8 12.8 34.5960 49.2 13.9 35.0Steel 480031.2 18.2 28.6 Comparative Example82039.8 19.6 33.185048.7 20.3 34.0Steel 580020.98.632.3Inventive Example82021.58.933.585023.49.333.9Steel 680021.39.032.0Inventive Example82021.99.232.585022.59.633.0Steel 780029.0 19.2 30.0 Comparative Example82031.5 19.5 30.9 85036.0 22.8 32.4Steel 880032.6 18.4 31.1 Comparative82038.8 19.9 31.3 Example85044.1 22.6 32.5Steel 980022.69.232.3Inventive Example82023.99.532.585024.09.733.0

[0073] Referring to Tables 1 and 2 above, Steels 3, 5, 6, and 9 satisfied the alloy composition, component range, and Expression (1) proposed in the present invention, and furthermore, when the cold rolled annealing temperature was satisfied, the grain size in the cast structure was refined to 20 to 25 µm (see FIGS. 2B and 2C), and the ridging height was 10 µm or less while the elongation was 32% or more. That is, it can be seen that the invention examples satisfying all of the alloy composition, component range, Expression (1), and cold rolled annealing temperature have excellent workability and ridging resistance. However, in the case of the comparative examples that do not satisfy the cold rolled annealing temperature even while satisfying the alloy composition, component range, and Expression (1) proposed in the present invention, one or more of the properties among the grain size, ridging height, or elongation were not satisfied.

[0074] Specifically, referring to FIGS. 1 and 2A, when the cold rolled annealing temperature was less than 800°C, recrystallization did not occur, resulting in a ridging height exceeding 10 µm and a significant decrease in elongation.

[0075] On the other hand, referring to FIGS. 1, 2D and 2E, when the cold rolled annealing temperature exceeded 850°C, the elongation was improved, but the grains in the cast structure coarsened, resulting in a ridging height exceeding 10 µm. That is, it can be seen that as the cold rolled annealing temperature increases, elongation is improved, but the cast structure coarsens, leading to an increase in ridging height.

[0076] In addition, Steels 1, 2, 4, 7 and 8 have values of Expression (1) exceeding 2.3. Accordingly, even when the cold rolled annealing temperature falls within the range of 800 to 850°C, the content of N to be combined with Ti was low, and thus equiaxed grain refinement was not realized. Accordingly, it can be seen that the ridging resistance was also inferior.

[0077] While exemplary embodiments of the present disclosure have been described above with reference to the accompanying drawings, it will be understood by those of ordinary skill in the art that various modifications and changes can be made without departing from the spirit and scope of the present disclosure as defined by the appended claims.[Industrial applicability]

[0078] According to the present invention, a ferritic stainless steel with improved workability and ridging characteristics by optimizing the steel composition and the manufacturing process to control the grain size of the final cold-rolled annealed material such that the workability of a cold-rolled product is improved, and a method of manufacturing the same can be provided, and thus the present invention is considered to have the industrial applicability.

Claims

1. A ferritic stainless steel with improved workability and ridging resistance, comprising, in percent by weight (wt%), 0.0005 to 0.02% of carbon (C); 0.01 to 0.2% of nitrogen (N); 0.01 to 1.0% of silicon (Si); 0.01 to 1.0% of manganese (Mn); 0.001 to 0.05% of phosphorus (P); 13.0 to 20.0% of chromium (Cr); 0.05 to 0.2% of titanium (Ti); and the balance being iron (Fe) and inevitable impurities, and satisfying Expression (1) below, and satisfying a grain size in a range of 20 to 25 µm: 2 * Ti / N ≤ 2.3 In Expression (1), [Ti] and [N] represent the content (wt%) of each element.

2. The ferritic stainless steel with improved workability and ridging resistance of claim 1, having a ridging height of 10 µm or less measured after 15% tension.

3. The ferritic stainless steel with improved workability and ridging resistance of claim 1, having an elongation of 32% or more.

4. A method of manufacturing a ferritic stainless steel with improved workability and ridging resistance, the method comprising preparing a slab comprising, in percent by weight (wt%), 0.0005 to 0.02% of carbon (C), 0.01 to 0.2% of nitrogen (N), 0.01 to 1.0% of silicon (Si), 0.01 to 1.0% of manganese (Mn), 0.001 to 0.05% of phosphorus (P), 13.0 to 20.0% of chromium (Cr), 0.05 to 0.2% of titanium (Ti), and the balance being iron (Fe) and inevitable impurities, and satisfying Expression (1) below; reheating the slab; hot-rolling the reheated slab, followed by hot-rolled annealing; and cold-rolling the hot-rolled steel sheet, followed by cold-rolled annealing at 800 to 850°C, 2 * Ti / N ≤ 2.3 In Expression (1), [Ti] and [N] represent the content (wt%) of each element.

5. The method of claim 4, wherein the reheating is performed at 1,000 to 1,300°C.

6. The method of claim 4, wherein the stainless steel has a grain size satisfying a range of 20 to 25 µm.

7. The method of claim 4, wherein the stainless steel has a ridging height of 10 µm or less measured after 15% tension.

8. The method of claim 4, wherein the stainless steel has an elongation of 32% or more.

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