Ferrite-based stainless steel with improved anti-wrinkling properties and method for manufacturing the same

Abstract

The present specification discloses ferrite-based stainless steel with improved anti-wrinkling property. According to one disclosed embodiment, the ferrite-based stainless steel with improved anti-wrinkling property comprises, in weight %, 0.001 to 0.3% of C; 0.01 to 1.0% of Si; 0.1 to 3.0% of Mn; 10 to 15% of Cr; 0.001 to 0.3% of N; 0.03% or less of P; 1.0% or less of Ni; 1.0% or less of Cu; 1.0% or less of Al; 0.003% or less of Mo; 1.0% or less of Ti; balance of Fe; and unavoidable other impurities, and γ S satisfies 6 or more. Formula (1): γS = 900C - 30Si + 12Mn + 23Ni - 17Cr - 12Mo + 12Cu - 49Ti - 52Al + 950N + 178 (where C, Si, Mn, Ni, Cr, Mo, Cu, Ti, Al, and N represent the content of the corresponding element (wt%)).

Description

TECHNICAL FIELD

[0001] The present invention relates to a ferritic stainless steel and a method for manufacturing the same, and more particularly, to a ferritic stainless steel having improved anti-wrinkling property and a method for manufacturing the same. BACKGROUND

[0002] Generally, stainless steels are classified according to their chemical composition or metal organization. According to the metal organization, the stainless steels are classified into austenitic type (300 series), ferritic type (400 series), martensitic type, and ideal type.

[0003] Among them, the ferritic stainless steel becomes a steel material having high price competitiveness compared to the austenitic stainless steel due to the addition of a small amount of expensive alloy elements. The ferritic stainless steel has good surface gloss, drawability, and oxidation resistance, and is widely used for kitchen utensils, building exterior materials, home appliances, and electronic parts. In particular, the ferritic stainless steel is a type of steel that requires high-quality surface gloss when used for exterior purposes.

[0004] However, the ferritic stainless steel has a problem that a strip-shaped wrinkling defect occurs in parallel with the rolling direction during a forming process such as deep drawing. Such a wrinkling defect deteriorates the appearance of the product, and when a serious wrinkling defect occurs, causes an increase in manufacturing cost due to the addition of a polishing process after forming.

[0005] The cause of the wrinkling has not been determined, but it is known as follows. Columnar grains generated during slab casting mainly have a {001} / / ND texture which does not recrystallize well even after hot rolling, leaving a band texture or a clustered texture.

[0006] In particular, most of the ferritic stainless steels do not have a phase transition from casting to cold rolling annealing, making it more difficult to remove the {001} / / ND texture. Therefore, even after the final cold rolling, the {001} / / ND texture remains as a long clustered texture in the rolling direction. The remaining clustered texture exhibits a relatively low plasticity (R value) compared to the texture having other surrounding textures. This plastic anisotropy difference causes a plasticity imbalance between the two textures during forming, resulting in a wrinkling defect of the ferritic stainless steel.

[0007] In order to solve the wrinkling defect, conventionally, various manufacturing methods such as hot rolling at an extremely low temperature, double-speed rolling, and cold rolling re-pressing have been proposed. However, the conventionally proposed manufacturing methods have a problem in that it is difficult to apply to the field and increases the manufacturing cost, thereby reducing the productivity of the product. SUMMARY

[0008] TECHNICAL PROBLEM

[0009] The present invention relates to a ferritic stainless steel and a method for manufacturing the same and provides a ferritic stainless steel having improved wrinkle resistance and a method for manufacturing the same.

[0010] Technical Solution

[0011] The ferritic stainless steel having improved wrinkle resistance includes, in weight percent (wt.%): 0.001 to 0.3% of C, 0.01 to 1.0% of Si, 0.1 to 3.0% of Mn, 10 to 15% of Cr, 0.001 to 0.3% of N, 0.03% or less of P, 1.0% or less of Ni, 1.0% or less of Cu, 1.0% or less of Al, 0.003% or less of Mo, 1.0% or less of Ti, a remainder of Fe, and other inevitable impurities,

[0012] wherein γ represented by the following formula (1) is 6 or more. S

[0013] Formula (1): γ S = 900C - 30Si + 12Mn + 23Ni - 17Cr - 12Mo + 12Cu - 49Ti - 52Al + 950N + 178

[0014] (wherein, C, Si, Mn, Ni, Cr, Mo, Cu, Ti, Al, and N represent contents (wt.%) of each element).

[0015] Further, according to one embodiment of the present invention, the ferritic stainless steel can satisfy a ferrite grain size of 15 µm or less.

[0016] Further, according to one embodiment of the present invention, the ferritic stainless steel can satisfy a wrinkle height (Wt) of 10 µm or less measured after 15% of tensile at a thickness of 1.0 mm or less.

[0017] According to another embodiment of the present invention, a method of manufacturing a ferritic stainless steel having improved wrinkle resistance includes: reheating a slab including, in weight percent (wt.%): 0.001 to 0.3% of C, 0.01 to 1.0% of Si, 0.1 to 3.0% of Mn, 10 to 15% of Cr, 0.001 to 0.3% of N, 0.03% or less of P, 1.0% or less of Ni, 1.0% or less of Cu, 1.0% or less of Al, 0.003% or less of Mo, 1.0% or less of Ti, a remainder of Fe, and other inevitable impurities, at a temperature of 1050 to 1250°C, wherein γ represented by the following formula (1) is 6 or more. S ​is 6 or more; the reheated slab is hot-rolled; and the hot-rolled material is cold-rolled and cold-rolled annealed; wherein, in the reheating step, γ Wt (T) is controlled to satisfy the following equation (2).

[0018] Equation (1): γ S = 900C - 30Si + 12Mn + 23Ni - 17Cr - 12Mo + 12Cu - 49Ti - 52Al + 950N + 178

[0019] (wherein C, Si, Mn, Ni, Cr, Mo, Cu, Ti, Al, and N indicate the content (wt%) of each element).

[0020] Equation (2): γ Wt (1200°C) ≥ 19%

[0021] Further, according to one embodiment of the present application, in the reheating step, the following equation (3) can be satisfied.

[0022] Equation (3): γ S * γ Wt (1200°C) ≥ 114

[0023] Further, according to one embodiment of the present application, the hot-rolling can include a step of finish rolling at a temperature of 700°C to 950°C.

[0024] Further, according to one embodiment of the present application, after the hot-rolling, a step of hot-rolling annealing at 600°C to 900°C can be further included.

[0025] Advantageous Effects

[0026] The present application can provide a ferritic stainless steel having improved wrinkle resistance with uniform surface quality and a method of manufacturing the same by optimizing the alloy composition and composition relationship and reheating and hot-rolling conditions. BRIEF DESCRIPTION OF DRAWINGS

[0027] Figure 1a is a state diagram of γ Wt (1200°C) using JMatPro including Example 3.

[0028] Figure 1b is a state diagram of γ Wt (1200°C) using JMatPro including Example 10.

[0029] Figure 1c is a state diagram of γ Wt (1200°C) using JMatPro including Comparative Example 1.

[0030] Figure 1d The γ phase of Comparative Example 6 for investigation using JMatPro. Wt The state diagram of Comparative Example 1 at 1200 °C.

[0031] Figure 2a The hot rolled microstructure of Example 3 for investigation using IQ (Image Quality) map.

[0032] Figure 2b The hot rolled microstructure of Example 10 for investigation using IQ (Image Quality) map.

[0033] Figure 2c The hot rolled microstructure of Comparative Example 1 for investigation using IQ (Image Quality) map.

[0034] Figure 2d The hot rolled microstructure of Comparative Example 6 for investigation using IQ (Image Quality) map.

[0035] Figure 3a The hot rolled microstructure of Example 3 for investigation using IPF (Inverse Pole Figure) map.

[0036] Figure 3b The hot rolled microstructure of Example 10 for investigation using IPF (Inverse Pole Figure) map.

[0037] Figure 3c The hot rolled microstructure of Comparative Example 1 for investigation using IPF (Inverse Pole Figure) map.

[0038] Figure 3d The hot rolled microstructure of Comparative Example 6 for investigation using IPF (Inverse Pole Figure) map.

[0039] Figure 4a The photograph showing the surface microstructure of Example 3 after cold rolling and annealing.

[0040] Figure 4b The photograph showing the surface microstructure of Example 10 after cold rolling and annealing.

[0041] Figure 4c The photograph showing the surface microstructure of Comparative Example 1 after cold rolling and annealing.

[0042] Figure 4d The photograph showing the surface microstructure of Comparative Example 6 after cold rolling and annealing. DETAILED DESCRIPTION

[0043] The ferritic stainless steel having improved anti-wrinkling properties according to one embodiment of the present application contains, in weight (wt%), 0.001 to 0.3% of C, 0.01 to 1.0% of Si, 0.1 to 3.0% of Mn, 10 to 15% of Cr, 0.001 to 0.3% of N, 0.03% or less of P, 1.0% or less of Ni, 1.0% or less of Cu, 1.0% or less of Al, 0.003% or less of Mo, 1.0% or less of Ti, the remainder of Fe, and other inevitable impurities,

[0044] where γ represented by the following formula (1) is 6 or more. S

[0045] Formula (1): γ S = 900C - 30Si + 12Mn + 23Ni - 17Cr - 12Mo + 12Cu - 49Ti - 52Al + 950N + 178

[0046] (where, C, Si, Mn, Ni, Cr, Mo, Cu, Ti, Al, and N represent the content (wt%) of each element).

[0047] Embodiment of Invention

[0048] Preferred embodiments of the present application are described below. However, embodiments of the present application can be changed in many different forms, and the technical idea of the present application is not limited to the embodiments described below. In addition, the embodiments of the present application are provided to more completely explain the present application to those skilled in the art.

[0049] The terms used in the present application are used only to describe particular examples. Thus, for example, the expression of a singular number includes the expression of a plural number unless the context clearly dictates otherwise. In addition, the term "comprise / comprising" or "have / having" used in the present application is used to explicitly indicate the presence of features, steps, functions, components, or combinations thereof described in the specification. It should be noted that it is not intended to initially exclude the presence of any step, function, component, or combination thereof.

[0050] Meanwhile, all terms used in the present application should be considered to have the same meaning as commonly understood by those having ordinary knowledge in the art to which the present application belongs unless otherwise defined in the present application. Therefore, certain terms should not be interpreted in an excessively subjective or formal sense unless explicitly defined herein. For example, in the present specification, a singular expression includes a plural expression unless there is a clear exception according to the context.

[0051] ​Furthermore, "about", "substantially" and the like in the present specification are used in the sense of values or close to values inherent to manufacturing and materials at the time of presenting the representation and are precise to help understanding of the present invention. Or absolute numbers are used to prevent an unscrupulous infringer from unfairly utilizing the disclosure.

[0052] The ferritic stainless steel having improved anti-wrinkling properties according to the present invention comprises, in weight (wt%), 0.001 to 0.3% of C, 0.01 to 1.0% of Si, 0.1 to 3.0% of Mn, 10 to 15% of Cr, 0.001 to 0.3% of N, 0.03% or less of P, 1.0% or less of Ni, 1.0% or less of Cu, 1.0% or less of Al, 0.003% or less of Mo, 1.0% or less of Ti, the remainder of Fe and other inevitable impurities.

[0053] Hereinafter, the reason for limiting the composition range of each alloying element will be described as follows.

[0054] Carbon (C) is contained in an amount of 0.001 to 0.3%.

[0055] C is an interstitial solid solution strengthening element that improves the strength of the ferritic stainless steel. When the content of C is less than 0.001%, sufficient strength cannot be obtained due to a decrease in the amount of carbide generated. However, if the content of C is excessive, the ductility, toughness and corrosion resistance of the steel decrease, and thus the upper limit is limited to 0.3%.

[0056] Silicon (Si) is contained in an amount of 0.01 to 1.0%.

[0057] Si is an alloying element added mainly to deoxidize molten steel during steelmaking, improves strength and corrosion resistance, and can be added in an amount of 0.01% or more as an element that stabilizes the ferrite phase in the present invention. However, when the content is excessive, there is a problem of a decrease in ductility and formability, and thus the upper limit is limited to 1.0%.

[0058] Manganese (Mn) is contained in an amount of 0.1 to 3.0%.

[0059] Mn is an austenite phase stabilizing element and can induce nucleation of austenite during hot rolling to promote grain refinement. However, when the content is excessive, the corrosion resistance decreases, manganese-based smoke is generated during welding, and the elongation decreases due to causing MnS phase precipitation. Thus, in the present invention, the content of Mn is controlled to 0.1 to 3.0%.

[0060] Chromium (Cr) is contained in an amount of 10 to 15%.

[0061] Cr is added in an amount of 10% or more as an element to improve corrosion resistance by forming a passivation film in a chemical environment. However, when the content of Cr is excessive, there are problems that sticking defects occur due to the formation of a dense oxide scale during hot rolling, and the manufacturing cost increases. Therefore, in the present invention, it is intended to limit the upper limit of the Cr content to 15%.

[0062] Nitrogen (N) is contained in an amount of 0.001 to 0.3%.

[0063] N is, like carbon, an interstitial solid solution strengthening element that not only improves the strength of ferritic stainless steel, but also promotes recrystallization by precipitating an austenite phase during hot rolling. However, when the content is excessive, there is a problem that the ductility of the steel decreases. Therefore, in the present invention, the N content is controlled to 0.001% to 0.3%.

[0064] Phosphorus (P) is contained in an amount of 0.03% or less.

[0065] P is an impurity that is inevitably contained in steel, and since it is an element that causes intergranular corrosion during pickling or inhibits hot workability, it is preferable to control the content thereof as low as possible. Therefore, in the present invention, the content of P is controlled to 0.03% or less.

[0066] Nickel (Ni) is contained in an amount of 1.0% or less.

[0067] Although Ni has the effect of improving corrosion resistance, when a large amount is added, there is a problem that the elongation decreases due to the increase of impurities in the material. In addition, Ni is a typical austenite stabilizing element or an expensive element, which increases the manufacturing cost. Therefore, in the present invention, the content of Ni is controlled to 1.0% or less.

[0068] Copper (Cu) is contained in an amount of 1.0% or less.

[0069] Cu is an element effective in improving corrosion resistance, workability, and wrinkling characteristics. However, when a large amount is added, there is a problem that the workability decreases. Therefore, in the present invention, the content of Cu is controlled to 1.0% or less.

[0070] Aluminum (Al) is contained in an amount of 1.0% or less.

[0071] Al is a ferrite phase stabilizing element and acts as a strong deoxidizing agent to reduce the oxygen content in molten steel. However, when the content is excessive, the room temperature ductility decreases, and cracking defects of cold-rolled stripes occur due to the increase of non-metallic inclusions, and at the same time, there is a problem that the weldability is deteriorated. Therefore, in the present invention, the Al content is controlled to 1.0% or less.

[0072] Molybdenum (Mo) is contained in an amount of 0.003% or less.

[0073] Mo is an element effective in improving corrosion resistance of stainless steel. However, Mo is an expensive element that causes an increase in raw material cost and deteriorates workability when added in a large amount. Therefore, in the present application, the content of Mo is controlled to be 0.003% or less.

[0074] Titanium (Ti) is contained in an amount of 1.0% or less.

[0075] Ti is an element effective in reducing the amount of solid solution C and solid solution N in steel and ensuring corrosion resistance of steel by preferentially combining with interstitial elements such as carbon (C) and nitrogen (N) to form precipitates (carbonitrides). However, when the content is excessive, austenite stability decreases, making it difficult to obtain fine grains, thereby reducing toughness and increasing titanium-based inclusions, leading to surface defects. Therefore, in the present application, the content of titanium is controlled to be 1.0% or less.

[0076] The remaining portion of the components of the present application is iron (Fe). However, since unintended impurities from raw materials or the surrounding environment can inevitably be mixed in the normal manufacturing process, it cannot be excluded. Since these impurities are known to the skilled person in the ordinary manufacturing process, all of them are not specifically mentioned in the present specification.

[0077] Further, the ferritic stainless steel according to one embodiment of the present application has a γ s of 6 or more.

[0078] Formula (1): γ S = 900C - 30Si + 12Mn + 23Ni - 17Cr - 12Mo + 12Cu - 49Ti - 52Al + 950N + 178

[0079] (wherein C, Si, Mn, Ni, Cr, Mo, Cu, Ti, Al, and N represent the content (wt%) of each element).

[0080] (Austenite (gamma phase) stability) is an index of the stability of the austenite phase corresponding to the maximum amount of austenite at high temperatures. In the present application, in order to induce austenite phase transformation during hot rolling by ensuring the stability of the austenite phase, it is intended to limit the value of γ s to 6 or more. Further, when the value of γ s When the value of γ

[0081] By optimizing the alloy components of the ferritic stainless steel, an austenite phase transformation is induced in hot rolling. Thus, the ferritic stainless steel according to one embodiment of the present application can ensure fine grains of a single phase of ferrite without band structure or aggregated structure. The size of the ferrite single phase grains can be 15 μm or less.

[0082] Next, a method for manufacturing a ferritic stainless steel having improved wrinkle resistance according to another embodiment of the present application will be described.

[0083] According to one embodiment of the present application, the method for manufacturing a ferritic stainless steel having improved wrinkle resistance includes: reheating a slab including, in weight percent (wt%), 0.001 to 0.3% of C, 0.01 to 1.0% of Si, 0.1 to 3.0% of Mn, 10 to 15% of Cr, 0.001 to 0.3% of N, 0.03% or less of P, 1.0% or less of Ni, 1.0% or less of Cu, 1.0% or less of Al, 0.003% or less of Mo, 1.0% or less of Ti, a remainder of Fe, and other inevitable impurities at a temperature of 1050 to 1250°C; hot rolling the reheated slab; and cold rolling and cold rolling annealing the hot rolled material; wherein γ S is 6 or more; hot rolling the reheated slab; and cold rolling and cold rolling annealing the hot rolled material; wherein, in the reheating step, γ Wt (T) is controlled to satisfy the following equation (2).

[0084] Equation (1): γ S = 900C - 30Si + 12Mn + 23Ni - 17Cr - 12Mo + 12Cu - 49Ti - 52Al + 950N + 178

[0085] (wherein C, Si, Mn, Ni, Cr, Mo, Cu, Ti, Al, and N represent the content of each element (wt%)).

[0086] Equation (2): γ Wt (1200°C) ≥ 19%

[0087] The reason for limiting the composition range of each alloying element is as described above.

[0088] γ Wt (T) (the weight of austenite (γ phase) at temperature T) is the weight percent of austenite at temperature T in the reheated phase. Even if γ S satisfies 6 or more, the stability of the austenite phase decreases when the reheating temperature is high. When the stability of the austenite phase decreases, the austenite phase transformation does not occur sufficiently during hot rolling, and hot band structure remains on the surface of the ferritic stainless steel.

[0089] As a result of examining various control conditions using JmatPro, when the austenite weight % is controlled to be 19% or more at a reheating temperature of 1200°C, fine ferrite grains on the surface of the ferritic stainless steel after hot rolling can be ensured.

[0090] Further, according to one embodiment of the present application, in the reheating step, the following formula (3) can be satisfied.

[0091] Formula (3): γ S *γ Wt (1200°C) ≥ 114

[0092] When formula (1) and formula (2) are satisfied while the value of formula (3) representing the product of formula (1) and formula (2) is 114 or more, the wrinkle height can be suppressed to 10 μm or less as desired in the present application.

[0093] Next, in order to ensure a desired final thickness during hot rolling, finish rolling (finish rolling) can be performed at 700°C to 950°C.

[0094] If the temperature of the finish rolling is kept below 700°C, a sticking defect occurs on the slab surface of the slab during hot rolling. Further, in order to roll the slab to an appropriate thickness, the hot rolling should be performed at 700°C or more.

[0095] On the other hand, when the temperature of the finish rolling exceeds 900°C, relatively large ferrite grains are formed. Therefore, in the present application, the temperature of the finish rolling is controlled to 900°C or less so that fine ferrite grains can be made after hot rolling.

[0096] The hot rolled product is subjected to a surface pickling treatment for cold rolling. At this time, hot rolling annealing can be omitted. However, when excessively fine ferrite grains are formed or there is a decrease in elongation due to residual dislocations, the hot rolled material can be subjected to hot rolling and annealing.

[0097] Therefore, according to one embodiment of the present application, after hot rolling, a step of hot rolling annealing can also be included. The hot rolling annealing is preferably performed at 600°C to 900°C to remove stress formed during hot rolling without generating an austenite phase.

[0098] In this way, by optimizing the reheating and hot rolling processes as well as the alloy components and component relationships, the surface properties of the ferritic stainless steel can be ensured by obtaining fine grains of a single phase of ferrite.

[0099] Hereinafter, the present application will be described in more detail by examples. However, it should be noted that the following examples are only for illustrating the present application in more detail, and are not intended to limit the scope of the present application. This is because the scope of the present application is determined by matters described in the claims and matters reasonably inferred therefrom.

[0100] {Examples}

[0101] For the various alloy composition ranges shown in Table 1 below, slabs were prepared by continuous casting and reheating at 1,050 to 1,200°C. Next, the reheated slabs were finish-rolled at a temperature of 700 to 950°C.

[0102] [Table 1]

[0103]

[0104] The hot-rolled material was pickled and cold-rolled to a thickness of 1.0 t or less so that the austenite phase was no longer generated. This was cold-rolled annealed at 700 to 900°C. Thereafter, the cold-rolled annealed material was stretched by 15% in the rolling direction, and the height of the wrinkle arc was measured with a surface roughness instrument. Table 2 below shows the values of γ S , γ Wt (1200°C), γ S *γ Wt (1200°C), and the wrinkle height (μm) of the examples and comparative examples.

[0105] [Table 2]

[0106]

[0107] Referring to Table 2, Examples 1 to 10 satisfy γ S of 6 or more, γ Wt (1200°C) of 19% or more, and γ S *γ Wt (1200°C) of 114 or more. Thus, in Examples 1 to 10, the wrinkle height is 10 μm or less, and the surface quality is good.

[0108] On the other hand, in Comparative Example 1, γ S is -22.1 and less than 6, γ Wt (1200°C) is 0% and less than 19%, and γ S *γ Wt (1200°C) is 0 and less than 114. Thus, in Comparative Example 1, a wrinkle defect having a height of 22.9 μm occurs.

[0109] In Comparative Examples 2 to 5, γ S is less than 6, γ S*γ Wt (1200°C) is less than 19%, and γ S *γ Wt (1200°C) is less than 114. Thus, Comparative Examples 2 to 5 all have a wrinkle defect of more than 10 μm.

[0110] In Comparative Example 6, γ S is 15.6, which satisfies 6 or more proposed in the present invention, and γ S *γ Wt (1200°C) has a value of 280.8, which is 114 or more. However, in Comparative Example 6, γ Wt (1200°C) is 18% and less than 19%, resulting in a wrinkle defect of 13.8 μm, which is more than 10 μm.

[0111] In Comparative Example 7, γ Wt (1200°C) is 24%, which is 19% or more. However, in Comparative Example 7, γ S is -7.2, which is less than 6, and γ S *γ Wt (1200°C) is -172.8, which is less than 114. Thus, in Comparative Example 7, a wrinkle defect of 12.4 μm, which is more than 10 μm, occurs.

[0112] Through the disclosed examples and comparative examples, it is found that when the ranges of γ S , γ Wt (1200°C) and γ S *γ Wt (1200°C) proposed in the present invention are satisfied, a wrinkle defect of 10 μm or less occurs.

[0113] Table 3 below shows the strip texture observed after hot rolling and the strip texture observed after cold rolling annealing and the measured values of ferrite grain size for Example 3, Example 10, Comparative Example 1 and Comparative Example 6.

[0114] [Table 3]

[0115]

[0116] Referring to Table 3 and Figures 2a to 2d , in Examples 3 and 10, no strip texture is observed, and fine ferrite grains are uniformly distributed. On the other hand, in Comparative Example 1 and Comparative Example 6, a remaining portion of the strip texture after hot rolling is observed.

[0117] Referring to Table 3 and Figures 4a to 4dThe ferrite grain size of Example 3 was 10.8 μm, and the ferrite grain size of Example 10 was 11.2 μm. On the other hand, the ferrite grain size of Comparative Example 1 was 35.1 μm, and the ferrite grain size of Comparative Example 6 was 18.9 μm.

[0118] No band structure was observed on the surface of Examples 3 and 10 and Comparative Examples 1 and 6 after cold annealing. However, in the case of Comparative Example 1 and Comparative Example 6, it was determined that the size of the ferrite grains was greater than 15 μm and coarser than the size of the ferrite grains of the Examples.

[0119] According to the disclosed embodiments, by optimizing not only the alloy composition and composition relationship but also the reheating and hot rolling conditions, no band structure and aggregated structure are exhibited on the surface, and the wrinkle height is suppressed to 10 μm or less, so that the ferritic stainless steel is uniform. The surface quality can be ensured.

[0120] In the foregoing, exemplary embodiments of the present application have been described, but the present application is not limited thereto, and those skilled in the art will understand that many changes and modifications are possible within the scope of the concepts and the range described in the appended claims, without departing from the described.

[0121] Industrial applicability

[0122] According to the embodiments of the present application, a ferritic stainless steel having improved resistance to wrinkling with uniform surface quality can be provided by optimizing the alloy composition and composition relationship and the reheating and hot rolling conditions. Therefore, the ferritic stainless steel can be used in different industrial fields.

Claims

1. A ferritic stainless steel with improved wrinkle resistance, comprising, by weight percentage: 0.001% to 0.011% C, 0.01% to 1.0% Si, 0.1% to 3.0% Mn, 10% to 15% Cr, 0.001% to 0.3% N, 0.03% or less P, 1.0% or less Ni, 1.0% or less Cu, 1.0% or less Al, 0.003% or less Mo, 1.0% or less Ti, the remainder Fe and other unavoidable impurities, wherein γ is represented by the following formula (1). S 6 or greater Equation (1): in, C, Si, Mn, Ni, Cr, Mo, Cu, Ti, Al, and N represent the content of each element in weight percent.

2. The ferritic stainless steel with improved wrinkle resistance according to claim 1, wherein the ferrite grain size is 15 μm or smaller.

3. The ferritic stainless steel with improved wrinkling resistance according to claim 1, wherein the wrinkling height (Wt) measured after 15% stretching at a thickness of 1.0 mm or less is 10 μm or less.

4. A method for manufacturing a ferritic stainless steel with improved wrinkle resistance, comprising: The slab is reheated at a temperature of 1050°C to 1250°C, the slab comprising, by weight percentage: 0.001% to 0.011% C, 0.01% to 1.0% Si, 0.1% to 3.0% Mn, 10% to 15% Cr, 0.001% to 0.3% N, 0.03% or less P, 1.0% or less Ni, 1.0% or less Cu, 1.0% or less Al, 0.003% or less Mo, 1.0% or less Ti, the remainder Fe and other unavoidable impurities, wherein γ is represented by the following formula (1). S 6 or greater; Hot rolling of reheated slabs; and The hot-rolled material is then subjected to cold rolling and cold rolling annealing; In the reheating step, γ, defined as austenite weight % at temperature T, is... Wt (T) is controlled to satisfy the following formula (2). Equation (1): Wherein, C, Si, Mn, Ni, Cr, Mo, Cu, Ti, Al, and N represent the content of each element in weight percent. Equation (2): .

5. The method for manufacturing ferritic stainless steel with improved wrinkle resistance according to claim 4, wherein the reheating step satisfies the following formula (3). Equation (3): .

6. The method for manufacturing ferritic stainless steel with improved wrinkle resistance according to claim 4, wherein the hot rolling step includes finishing rolling at a temperature of 700°C to 950°C.

7. The method for manufacturing ferritic stainless steel with improved wrinkle resistance according to claim 4, wherein the hot rolling step further includes hot rolling annealing at a temperature of 600°C to 900°C after the hot rolling step.

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