Cold-rolled steel sheets and plated steel sheets, and method for manufacturing same

Abstract

The present invention relates to steel sheets suitable for a variety of uses including automobile parts, more specifically to cold-rolled steel sheets and plated steel sheets containing residual elements and having good hole expansion ratio and plating adhesiveness, and to a manufacturing method thereof.

Description

Cold rolled steel sheets, galvanized steel sheets, and their manufacturing methods

[0001] The present invention relates to a steel sheet suitable for various purposes including automobile parts, and more specifically, to a cold-rolled steel sheet, a plated steel sheet containing residual elements and having excellent hole expandability and plating adhesion, and a method for manufacturing the same.

[0002] To address the global climate crisis, automakers are demanding steelmakers supply automotive steel with reduced CO2 emissions, aiming to achieve carbon neutrality by 2050. For this reason, steelmakers are currently developing automotive steel with reduced CO2 emissions through the recycling of scrap iron, utilizing existing blast furnace-converter furnace or electric arc furnace steelmaking processes.

[0003] When using scrap iron as a raw material, it is difficult to remove residual elements (tramp elements) such as Cu and Ni contained in the scrap iron during refining, so they end up being incorporated into the steel after refining. These residual elements have the problem of lowering the physical properties of the steel or deteriorating the surface quality. Therefore, until now, high-quality thin plate products, such as automotive steel plates, have been manufactured using molten iron as the main raw material and using a general blast furnace-converter process to greatly reduce the C and N in the steel while extremely controlling the content of residual elements.

[0004] Meanwhile, a technology for manufacturing automobile steel sheets with excellent processability from electric furnace steel containing residual elements using an electric furnace steelmaking method was proposed as follows.

[0005] Patent Documents 1 and 2 present techniques for manufacturing cold-rolled steel sheets with excellent burring resistance. Specifically, the steel sheets disclosed herein exhibit excellent burring resistance despite containing a large amount of residual elements. However, these techniques do not address the objective of improving the thermal plating adhesion of the steel sheets, nor do they address the means for achieving this objective.

[0006] In this way, although a technology for manufacturing automotive steel sheets containing residual elements has been proposed, automotive steel sheets with improved pore expansion and plating adhesion despite containing residual elements have not yet been developed.

[0007] (Patent Document 1) Japanese Patent No. 6179698

[0008] (Patent Document 2) Japanese Patent Publication No. 2004-250749

[0009] One aspect of the present invention is to provide a cold-rolled steel sheet, a plated steel sheet, and a method for manufacturing the same, which contain residual elements while manufacturing automobile steel sheets by recycling iron scrap and have improved hole expandability and plating adhesion.

[0010] The objectives of the present invention are not limited to the above-described content. Those skilled in the art will have no difficulty understanding the additional objectives of the present invention from the overall description of the present invention.

[0011] One aspect of the present invention is a method for producing a metal alloy, comprising, in weight %, carbon (C): more than 0% to 0.2500%, silicon (Si): more than 0% to 0.700%, manganese (Mn): more than 0% to 1.800%, aluminum (Al): more than 0% to 0.700%, phosphorus (P): 0.080% or less, sulfur (S): 0.050% or less, nitrogen (N): 0.0300% or less, copper (Cu): 1.000% or less, nickel (Ni): 1.000% or less, chromium (Cr): 1.000% or less, magnesium (Mg): 0.050% or less, calcium (Ca): 0.050% or less, rare earth elements (REM) excluding yttrium (Y): 0.050% or less, tungsten (W): 0.50% or less, zirconium (Zr): 0.50% Hereinafter, a cold-rolled steel sheet is provided, which includes at least one selected from among antimony (Sb): 0.500% or less, tin (Sn): 0.500% or less, cobalt (Co): 0.500% or less, yttrium (Y): 0.200% or less, and hafnium (Hf): 0.200% or less, at least one selected from among titanium (Ti): 0.220% or less, niobium (Nb): 0.220% or less, vanadium (V): 0.220% or less, molybdenum (Mo): 1.000% or less, and boron (B): 0.0200% or less, the remainder being Fe and unavoidable impurities.

[0012] According to one embodiment of the present invention, when the average content (weight %) of (Cu+Cr+Ni+Sn) in the surface layer of a cold-rolled steel sheet is A and the average content (weight %) of (Cu+Cr+Ni+Sn) in the center layer is B, a cold-rolled steel sheet is provided in which A / B satisfies 0.15 to 30.00.

[0013] The cold-rolled steel sheet of the present invention has excellent hole expandability and can also have excellent plating adhesion when subjected to a subsequent plating process.

[0014] In one embodiment of the present invention, the cold rolled steel sheet may include at least one of titanium (Ti), niobium (Nb), and vanadium (V) added so that the sum of the contents (Ti+Nb+V) is 0.22% or less.

[0015] In one embodiment of the present invention, the cold rolled steel sheet can satisfy the following relational expression 1 in the relationship between tensile strength (TS) and elongation (El).

[0016] [Relationship 1]

[0017] 0.6×10 6 ≤ TS 2 ×√El ≤ 2.3×10 6

[0018] (The unit of equation 1 is (MPa) 2 % 0.5 am.)

[0019] In one embodiment of the present invention, the cold rolled steel sheet can satisfy the following relationship 2 between tensile strength (TS) and hole expandability (HER).

[0020] [Relationship 2]

[0021] 0.9×10 6 ≤ TS 2 ×√HER ≤ 3.8×10 6

[0022] (The unit of equation 2 is (MPa) 2 % 0.5 am.)

[0023] In one embodiment of the present invention, the cold rolled steel sheet may have a yield ratio of 0.50 to 0.95.

[0024] Another aspect of the present invention provides a method for manufacturing a cold-rolled steel sheet, comprising the steps of: preparing a steel slab; heating the steel slab in a temperature range of 900 to 1300°C; finish-rolling the heated steel slab in an austenite region above the Ar3 transformation point or in a ferrite region below the Ar3 transformation point to obtain a hot-rolled steel sheet; coiling the hot-rolled steel sheet in a temperature range of 330 to 750°C; cooling the coiled hot-rolled steel sheet to a temperature range of 250 to 300°C at a rate of 0.2 to 10°C / min; cold-rolling the hot-rolled steel sheet after the cooling at a cold reduction ratio of 30 to 90% to obtain a cold-rolled steel sheet; and annealing the cold-rolled steel sheet at 600°C or higher for 10 seconds or longer.

[0025] In one embodiment of the present invention, the steel slab may have the above-described alloy composition.

[0026] In one embodiment of the present invention, the annealing treatment step can be performed by heating the cold-rolled steel sheet obtained by cold rolling to the annealing temperature at a heating rate of 2 to 60°C / s.

[0027] In addition, another aspect of the present invention provides a plated steel sheet including a zinc-based plating layer formed on at least one surface of a cold-rolled steel sheet, and a method for manufacturing a plated steel sheet by plating a cold-rolled steel sheet.

[0028] In one embodiment of the present invention, the cold rolled steel sheet may be the cold rolled steel sheet described above.

[0029] In one embodiment of the present invention, the plating process can be performed by a hot dip plating or electroplating process.

[0030] In one embodiment of the present invention, the hot-dip galvanizing may include a step of performing hot-dip galvanizing treatment at a temperature range of 440 to 520°C, and optionally, a step of performing alloying heat treatment after the hot-dip galvanizing treatment may be further included.

[0031] According to the present invention, it is possible to provide an automotive steel sheet (cold rolled steel sheet, plated steel sheet) having improved plating adhesion as well as pore expandability despite containing residual elements.

[0032] The steel plate of the present invention is manufactured by recycling iron scrap, and has the advantage of excellent CO2 reduction effect when applied as a material for automobile bodies, etc.

[0033] The various advantageous and beneficial effects of the present invention are not limited to the above-described contents, and will be more easily understood in the course of explaining specific embodiments of the present invention.

[0034] The terminology used herein is for the purpose of describing specific embodiments only and is not intended to limit the invention. As used herein, the singular forms also include the plural forms, unless the context clearly dictates otherwise.

[0035] The term "comprising" as used in the specification means specifying a particular characteristic, region, integer, step, operation, element and / or component, but does not exclude the presence or addition of other particular characteristics, regions, integers, steps, operations, elements, components and / or groups.

[0036] Although not defined otherwise, all terms, including technical and scientific terms, used herein have the same meaning as commonly understood by those of ordinary skill in the technical field to which the present invention pertains. Terms defined in commonly used dictionaries are further interpreted to have meanings consistent with the relevant technical literature and the present disclosure, and are not to be construed as ideal or overly formal unless otherwise defined.

[0037] Hereinafter, a cold-rolled steel sheet according to one aspect of the present invention, particularly a cold-rolled steel sheet with excellent pore expandability and plating adhesion, will be described in detail. It should be noted that, unless otherwise specified, the content of each element in the present invention refers to weight percent. Furthermore, unless otherwise specified, the ratio of crystals or structures is based on area.

[0038] According to one aspect of the present invention, a cold rolled steel sheet comprises, in weight %, carbon (C): more than 0% to 0.2500%, silicon (Si): more than 0% to 0.700%, manganese (Mn): more than 0% to 1.800%, aluminum (Al): more than 0% to 0.700%, phosphorus (P): 0.080% or less, sulfur (S): 0.050% or less, nitrogen (N): 0.0300% or less, copper (Cu): 1.000% or less, nickel (Ni): 1.000% or less, chromium (Cr): 1.000% or less, magnesium (Mg): 0.050% or less, calcium (Ca): 0.050% or less, rare earth elements (REM) excluding yttrium (Y): 0.050% or less, tungsten (W): 0.50% or less, zirconium (Zr): It may include at least one selected from among 0.50% or less, antimony (Sb): 0.500% or less, tin (Sn): 0.500% or less, cobalt (Co): 0.500% or less, yttrium (Y): 0.200% or less, hafnium (Hf): 0.200% or less, titanium (Ti): 0.220% or less, niobium (Nb): 0.220% or less, vanadium (V): 0.220% or less, molybdenum (Mo): 1.000% or less, and boron (B): 0.0200% or less.

[0039] Below, the reason for limiting the alloy composition of the cold-rolled steel sheet provided in the present invention as described above is explained in detail.

[0040] Carbon (C): 0% to 0.2500%

[0041] Carbon (C) is an effective element for securing the strength of steel. When Ti, Nb, V, etc. are present in the steel, it combines with these elements to form precipitates, which is advantageous in providing strength to the steel sheet.

[0042] In one embodiment of the present invention, if the C content exceeds 0.2500%, it becomes difficult to secure the welding strength of the welded joint during welding. Therefore, the C content may be 0.2500% or less. In another embodiment of the present invention, the C content may be 0.2300% or less or 0.2000% or less.

[0043] Meanwhile, C is an essential element in steel manufacturing, and its content is greater than 0%. However, in one embodiment of the present invention, if the C content is less than 0.0010%, the effect of reducing C is hardly obtained, and rather, it causes an increase in steel manufacturing cost, which is not preferable. Therefore, the C may be included in an amount of 0.0010% or more. In another embodiment of the present invention, the C may be included in an amount of 0.0015% or more or 0.0020% or more.

[0044] Silicon (Si): 0% to 0.700%

[0045] Silicon (Si) is an element that enhances strength through solid solution strengthening, and is useful for strengthening ferrite and uniforming its structure, thereby improving workability. Furthermore, Si is an element necessary for deoxidation during steelmaking.

[0046] In one embodiment of the present invention, if the Si content exceeds 0.700%, there is a problem of causing plating defects such as underplating during plating and hindering the weldability of the steel sheet. Therefore, the Si content may be 0.700% or less. In another embodiment of the present invention, the Si content may be 0.600% or less.

[0047] Meanwhile, in one embodiment of the present invention, Si may be included in an amount exceeding 0%, and the content may be 0.001% or more in consideration of manufacturing costs.

[0048] Manganese (Mn): 0% to 1.800%

[0049] Manganese (Mn) is a useful element for simultaneously improving the strength and ductility of steel.

[0050] In one embodiment of the present invention, when the content of Mn exceeds 1.800%, the transformation from austenite to a low-temperature transformation phase such as martensite or bainite is promoted, thereby lowering the yield ratio of the steel sheet. Accordingly, the Mn may be 1.800% or less. In another embodiment of the present invention, the Mn may be 1.790% or less, or 1.780% or less.

[0051] Meanwhile, in one embodiment of the present invention, Mn may be included in an amount exceeding 0%, and the content may be 0.001% or more in consideration of manufacturing costs.

[0052] Aluminum (Al): 0% to 0.700%

[0053] Aluminum (Al) is an element that combines with oxygen (O) in steel and acts as a deoxidizer. Similarly to Si, it is an element that strengthens ferrite, homogenizes the structure, and improves workability.

[0054] In one embodiment of the present invention, if the content of Al exceeds 0.700%, there is a risk that plating defects such as under-plating may occur during the plating process, and the weldability of the steel sheet may deteriorate. Therefore, the content of Al may be 0.700% or less. In another embodiment of the present invention, the content of Al may be 0.600% or less.

[0055] Meanwhile, in one embodiment of the present invention, Al may be included in an amount exceeding 0%, and the content may be 0.001% or more in consideration of manufacturing cost.

[0056] Phosphorus (P): 0.080% or less

[0057] Phosphorus (P) is an element added to improve the strength of steel. In one embodiment of the present invention, if the content of P exceeds 0.080%, the impact toughness of the steel deteriorates. In another embodiment of the present invention, the P may be included in an amount of 0.070% or less.

[0058] Meanwhile, in one embodiment of the present invention, P may be included in an amount exceeding 0%, and the content may be included in an amount of 0.001% or more in consideration of manufacturing costs.

[0059] Sulfur (S): 0.050% or less

[0060] Sulfur (S) is an element that is inevitably added during the steel manufacturing process, and it combines with Mn in the steel to form MnS inclusions, thereby inhibiting the ductility of the steel. Therefore, in one embodiment of the present invention, the content of S may be limited to 0.050% or less. In another embodiment of the present invention, S may be included at 0.040% or less.

[0061] Meanwhile, since S can be inevitably contained in the steel, its content can exceed 0%. In one embodiment of the present invention, there is a problem that manufacturing costs increase significantly in order to control the S content to less than 0.001%, so the S can be contained at 0.001% or more.

[0062] Nitrogen (N): 0.0300% or less

[0063] Nitrogen (N) is an element that is inevitably added during the steel manufacturing process, and is an element that causes cracks in slabs by forming nitrides during the continuous casting process. Considering this, according to one embodiment of the present invention, N may be included at 0.0300% or less.

[0064] Meanwhile, since the manufacturing cost increases significantly in order to control the N content to less than 0.0010%, the N content can be limited to 0.0010% or more.

[0065] Copper (Cu): 1.000% or less and nickel (Ni): 1.000% or less

[0066] Copper (Cu) and nickel (Ni) are elements that stabilize austenite and inhibit corrosion. Furthermore, Cu and Ni are useful elements for suppressing hydrogen-delayed fracture by concentrating on the surface of steel plates and preventing the intrusion of hydrogen into the steel.

[0067] In one embodiment of the present invention, since excessive contents of Cu and Ni result in poor processability, the contents thereof may be limited to 1.000% or less. In another embodiment of the present invention, the contents of Cu and Ni may each be included at 0.900% or less.

[0068] Meanwhile, in one embodiment of the present invention, Cu and Ni may be included in amounts exceeding 0%, and may be included in amounts of 0.001% or more in order to sufficiently obtain the effects of these elements.

[0069] Chromium (Cr): 1.000% or less

[0070] Chromium (Cr) is an element that suppresses the decomposition of austenite and stabilizes austenite during alloying treatment of manufactured steel plates.

[0071] In one embodiment of the present invention, since excessive Cr content deteriorates processability, the Cr content may be limited to 1.000% or less in consideration of this. In another embodiment of the present invention, the Cr content may be included at 0.900% or less.

[0072] Meanwhile, in one embodiment of the present invention, Cr may be included in an amount exceeding 0%, but may be included in an amount of 0.001% or more in order to sufficiently obtain the effect of Cr.

[0073] The steel plate of the present invention may contain one or more of the following residual elements in addition to the above-described alloy composition.

[0074] First, it may include at least one selected from the following: magnesium (Mg): 0.050% or less, calcium (Ca): 0.050% or less, rare earth elements (REM) excluding yttrium (Y): 0.050% or less, tungsten (W): 0.50% or less, zirconium (Zr): 0.50% or less, antimony (Sb): 0.500% or less, tin (Sn): 0.500% or less, cobalt (Co): 0.500% or less, yttrium (Y): 0.200% or less, and hafnium (Hf): 0.200% or less.

[0075] Magnesium (Mg): 0.050% or less, Calcium (Ca): 0.050% or less, and Rare Earth Elements (REM) excluding Yttrium (Y): 0.050% or less

[0076] Rare earth elements (REMs), excluding magnesium (Mg), calcium (Ca), and yttrium (Y), are elements that improve the ductility of steel by spheroidizing sulfides in the steel. In one embodiment of the present invention, if the content of each of the above elements exceeds 0.050%, not only will the above-described effects be saturated, but also the manufacturing cost will increase. Therefore, the content of each of the above elements may be limited to 0.050% or less.

[0077] In general, rare earth elements (REM) refer to a total of 17 metallic elements, including scandium (Sc), yttrium (Y), lanthanum (La), and cerium (Ce). However, according to one embodiment of the present invention, the content of yttrium (Y) is separately limited below, so in one embodiment of the present invention, REM refers to 16 elements excluding Y.

[0078] Tungsten (W): 0.50% or less and zirconium (Zr): 0.50% or less

[0079] Tungsten (W) and zirconium (Zr) are elements that enhance the hardenability of steel, thereby increasing its strength. According to one embodiment of the present invention, if W and Zr are present in excess, not only will the aforementioned effects be saturated, but manufacturing costs will also increase. Therefore, their contents may be limited to 0.50% or less, respectively.

[0080] Antimony (Sb): 0.500% or less, tin (Sn): 0.500% or less, and cobalt (Co): 0.500% or less

[0081] Antimony (Sb), tin (Sn), and cobalt (Co) are elements that improve the plating wettability and plating adhesion of steel. In one embodiment of the present invention, if the content of each of the elements exceeds 0.500%, the brittleness of the steel increases, which causes cracks during hot working or cold working, and therefore the content of each element may be limited to 0.500% or less. According to another embodiment of the present invention, Sb, Sn, and Co may each be included at 0.400% or less. Meanwhile, in order to sufficiently obtain the desired effect by containing these elements, each of them may be included at 0.0005% or more.

[0082] Yttrium (Y): 0.200% or less and Hafnium (Hf): 0.200% or less

[0083] Yttrium (Y) and hafnium (Hf) are elements that improve the corrosion resistance of steel. In one embodiment of the present invention, if the content of each of the elements exceeds 0.200%, there is a concern that the ductility of the steel may deteriorate, so the content of each element may be limited to 0.200% or less.

[0084] In addition, the steel plate of the present invention may further include at least one selected from titanium (Ti): 0.220% or less, niobium (Nb): 0.220% or less, vanadium (V): 0.220% or less, molybdenum (Mo): 1.000% or less, and boron (B): 0.0200% or less, in addition to the above-described compositions.

[0085] Titanium (Ti): 0.220% or less, niobium (Nb): 0.220% or less, and vanadium (V): 0.220% or less

[0086] Titanium (Ti), niobium (Nb), and vanadium (V) are elements that form precipitates in steel, and the strength and impact toughness of the steel can be improved by the formation of the precipitates. In particular, the Ti, Nb, and V can prevent the deterioration of workability caused by the dissolved carbon and dissolved nitrogen in the steel by precipitating the dissolved carbon and dissolved nitrogen in the form of carbides, nitrides, etc.

[0087] In one embodiment of the present invention, the above elements may be added in amounts of 0.001% or more, thereby obtaining the aforementioned effects. However, if the content of each element exceeds 0.220%, the effect of addition becomes saturated and the manufacturing cost increases, so the upper limit of each element may be limited to 0.220%. According to another embodiment of the present invention, the above elements may be included in amounts of 0.200% or less.

[0088] Meanwhile, according to one embodiment of the present invention, when adding at least one of Ti, Nb, and V, the sum of the contents of these elements (Ti+Nb+V) may be 0.220% or less. According to another embodiment, the sum of the contents of the elements may be 0.200% or less.

[0089] Molybdenum (Mo): 1.000% or less

[0090] Molybdenum (Mo), similar to the previously mentioned Cr, is an element that suppresses the decomposition of austenite and stabilizes austenite during alloying treatment of manufactured steel plates.

[0091] In one embodiment of the present invention, since excessive Mo content reduces processability, the content may be limited to 1.000% or less in consideration of this. In another embodiment of the present invention, the Mo content may be 0.900% or less. Meanwhile, in one embodiment of the present invention, in order to obtain the effect of adding Mo, the content may be 0.001% or more, and therefore the lower limit may be limited to 0.001%.

[0092] Boron (B): 0.0200% or less

[0093] Boron (B) is an element that improves the hardenability of steel, thereby increasing its strength, and inhibits nucleation at grain boundaries.

[0094] In one embodiment of the present invention, if the content of B exceeds 0.0200%, there is a concern that the deep drawability of the steel may deteriorate. Therefore, when adding B, the content may be limited to 0.0200% or less. According to another embodiment, the B may be included in an amount of 0.0100% or less. Meanwhile, in one embodiment of the present invention, in order to obtain the effect of adding B, the content may be 0.0001% or more, and in another embodiment, the B may be included in an amount of 0.0005% or more or 0.0010% or more.

[0095] In one embodiment of the present invention, the cold-rolled steel sheet may contain iron and other unavoidable impurities in addition to the aforementioned components. However, since unintended impurities may inevitably be mixed in from raw materials or the surrounding environment during the typical manufacturing process, they cannot be completely excluded. Since these impurities are readily apparent to anyone skilled in the art, not all of them are specifically mentioned herein. Furthermore, the addition of additional effective components other than the aforementioned components is not completely excluded.

[0096] According to one embodiment of the present invention, the content of some residual elements contained at a specific point based on the thickness direction of a cold-rolled steel sheet can be controlled as follows, thereby improving the hole expandability, powdering property, etc. of the steel sheet.

[0097] Specifically, in one embodiment of the present invention, when the average content (weight %) of (Cu+Cr+Ni+Sn) in the surface layer of a cold-rolled steel sheet is A, and the average content (weight %) of (Cu+Cr+Ni+Sn) in the center of the cold-rolled steel sheet is B, A / B can satisfy 0.15 to 30.00.

[0098] In one embodiment of the present invention, A / B is significant in that it is utilized as an indicator of the pore expandability and powdering properties of the steel plate. If the value of A / B is less than 0.15 or exceeds 30.00, there is a problem in that certain residual elements contained in the steel are not uniformly distributed.

[0099] Here, the center refers to a point t / 2 in the thickness direction. In addition, the surface portion is a point where the concentration of Cu, Cr, Ni, and Sn changes (or changes rapidly) when measured in the thickness direction from the surface. As an example, when the (Cu+Cr+Ni+Sn) content of the surface is greater than the (Cu+Cr+Ni+Sn) content of the center, it may mean up to a point corresponding to 99% of the (Cu+Cr+Ni+Sn) content of the center in the concentration measurement value, and when the (Cu+Cr+Ni+Sn) content of the surface is less than the (Cu+Cr+Ni+Sn) content of the center, it may mean up to a point corresponding to 1% of the (Cu+Cr+Ni+Sn) content of the center in the concentration measurement value. As a non-limiting example, the concentrations of the aforementioned elements can be measured using FE-SEM or a glow discharge spectrometer (GDS).

[0100] In one embodiment of the present invention, the microstructure of the cold rolled steel sheet may include ferrite as the main phase, and as an example, may be composed of ferrite with an area fraction of 75 to 98% and the remainder cementite.

[0101] In one embodiment of the present invention, when the microstructure of the cold-rolled steel sheet includes a ferrite phase, if the area fraction is less than 75%, there is a concern that the hole expandability may be poor, whereas if it exceeds 98%, there is a concern that the strength may be reduced.

[0102] In one embodiment of the present invention, the ferrite may include both recrystallized ferrite and non-recrystallized ferrite, and there is no particular limitation on the fraction range thereof, and it is disclosed that it will be naturally determined by the alloy composition and manufacturing process according to one embodiment of the present invention.

[0103] Meanwhile, the cold-rolled steel sheet according to one embodiment of the present invention does not intend to exclude even trace amounts of impurity structures that are inevitably included during the manufacturing process, and these structures are naturally included within the scope of the present invention. Here, the impurity structure is not particularly limited, but may be, for example, pearlite, or a bainite or martensite phase formed at low temperatures.

[0104] A cold rolled steel sheet according to one embodiment of the present invention not only has high strength but also has excellent hole expandability.

[0105] Specifically, according to one embodiment of the present invention, the relationship between the tensile strength (TS) and the elongation (El) of the cold-rolled steel sheet can satisfy the following relational expression 1, and further, the relationship between the tensile strength (TS) and the hole expandability (HER) can satisfy the following relational expression 2.

[0106] [Relationship 1]

[0107] 0.6×10 6 ≤ TS 2 ×√El ≤ 2.3×10 6

[0108] (The unit of equation 1 is (MPa) 2 % 0.5 am.)

[0109] [Relationship 2]

[0110] 0.9×10 6 ≤ TS 2 ×√HER ≤ 3.8×10 6

[0111] (The unit of equation 2 is (MPa) 2 % 0.5 am.)

[0112] In addition, the cold rolled steel sheet according to one embodiment of the present invention may have a yield ratio in the range of 0.50 to 0.95.

[0113] Hereinafter, a plated steel sheet according to another aspect of the present invention will be described.

[0114] According to one embodiment of the present invention, the galvanized steel sheet includes a zinc-based plating layer formed on at least one surface of a cold-rolled steel sheet. In one embodiment of the present invention, the zinc-based plating layer is a plating layer containing zinc (Zn) as a main component, and a composition of a plating layer commonly applied in the relevant technical field can be applied in the same manner. In this case, the zinc-based plating layer may also include a zinc-based plating layer alloyed by alloying treatment.

[0115] That is, the galvanized steel sheet according to one embodiment of the present invention is a zinc-based galvanized steel sheet, and may be a galvanized steel sheet (GI), a galvanealed steel sheet (GA), an electrogalvanized steel sheet (EG), an electrogalvanized steel sheet, or the like.

[0116] In one embodiment of the present invention, the cold-rolled steel sheet having a zinc-based plating layer formed on at least one surface may be a cold-rolled steel sheet according to one embodiment of the present invention, and it is to be noted that the above-described description can be equally applied to the cold-rolled steel sheet.

[0117] Meanwhile, a cold-rolled steel sheet according to an embodiment of the present invention may have a concentration gradient of specific elements, for example, residual elements Cu, Cr, Ni, and Sn, in the thickness direction from the surface. When a zinc-based plating layer is formed on at least one surface of such a cold-rolled steel sheet, the residual elements may further diffuse into the plating layer due to the influence of the temperature during plating or the temperature during alloying treatment. Accordingly, the concentration gradient of residual elements in the plating steel sheet may be realized in the thickness direction of the base material from the interface between the base material and the plating layer, but may also be realized from an alloy layer formed at the interface between the base material and the plating layer.

[0118] That is, the residual elements may have a concentration gradient, previously represented by A / B, due to the difference in diffusion speed of the residual elements that diffuse toward the surface of the steel sheet during the process of manufacturing the cold-rolled steel sheet. This characteristic of the cold-rolled steel sheet also appears in the plated steel sheet.

[0119] A plated steel sheet according to one embodiment of the present invention has a characteristic of excellent powdering properties of the plated layer, and specifically, can have a characteristic of a powdering peeling width of the plated layer being less than 7 mm.

[0120] Hereinafter, a method for manufacturing a cold-rolled steel sheet and a plated steel sheet according to another aspect of the present invention will be described in detail.

[0121] First, a cold-rolled steel sheet according to an embodiment of the present invention can be obtained by going through a series of processes, for example, [steel slab heating - hot rolling - coiling - cooling - cold rolling - annealing]. Each process step is described in detail below, and it is to be noted that the following manufacturing process corresponds to one example for manufacturing a cold-rolled steel sheet and a plated steel sheet according to an embodiment of the present invention.

[0122] According to one embodiment of the present invention, steel slabs or ingots can be manufactured through an electric furnace or a new blast furnace-converter process, and the raw materials used in the electric furnace or blast furnace-converter process include pig iron together with iron scrap. Here, pig iron refers to molten iron obtained from the blast furnace-converter process, or its cold material (Corrugate) or HBI (Hot Briquette Iron).

[0123] In the case of electric furnaces, desulfurization can be performed through ladle refining after the electric furnace discharge, and desulfurization and subsequent vacuum degassing can be performed. Furthermore, steel obtained from an electric furnace can be adjusted to achieve the desired final alloy composition by adding alloying elements during degassing. Common vacuum degassing methods include the RH and DH methods, but oxygen injection into the degassing tank can also be used. One such method is the oxygen injection method using a top blowing lance.

[0124] [Heating of steel slabs]

[0125] After preparing the steel slab, it can be heated. At this time, the steel slab may be a steel ingot. In one embodiment of the present invention, the steel slab may have the alloy composition described above, and thus, the alloy composition of the steel slab is replaced with the above-described content.

[0126] In one embodiment of the present invention, the heating temperature of the prepared steel slab or ingot may be in the range of 900 to 1300°C. If the heating temperature exceeds 1300°C, the steel may reach its melting point and melt, whereas if the temperature is lower than 900°C, the rolling load may increase during subsequent hot rolling, which may lower the stability of the hot rolling. In another embodiment of the present invention, the heating may be performed at 1160°C or lower.

[0127] [Hot rolling]

[0128] The above heated steel slab or ingot can be hot rolled to obtain a hot rolled steel sheet.

[0129] In one embodiment of the present invention, the finishing temperature during hot rolling can be either an austenite temperature above the Ar3 transformation point or a ferrite temperature below the Ar3 transformation point. However, if the finishing temperature is too low, the rolling load during hot rolling increases, so the lower limit temperature can be limited to 750°C or higher.

[0130] [Winding]

[0131] The hot-rolled steel sheet obtained by the above hot rolling can be wound into a coil shape.

[0132] In one embodiment of the present invention, the coiling process can be performed at a temperature range of 330 to 750°C. If the temperature during the coiling is lower than 330°C, there is a risk of unevenness occurring on the surface of the hot-rolled coil due to the excessively low temperature. On the other hand, if the temperature exceeds 750°C, there is a risk of excessively thick scale formation on the surface of the hot-rolled coil. According to another embodiment of the present invention, the coiling process can be performed at a temperature of 350°C or higher.

[0133] [cooling]

[0134] The above-mentioned hot-rolled steel sheet can be cooled while uncoiling.

[0135] In one embodiment of the present invention, post-coiling cooling can be performed at a cooling rate of 0.2 to 10.0°C / min to a temperature range of 250 to 300°C. By performing cooling at such a relatively slow cooling rate, uniform crystal grains within the microstructure can be secured.

[0136] In one embodiment of the present invention, if the cooling rate is less than 0.2°C / min during cooling, the cooling rate must be excessively reduced, which may put a strain on the equipment and make it difficult to obtain uniform grains. On the other hand, if the cooling rate exceeds 10.0°C / min, there is a possibility that the grains may become coarse.

[0137] In one embodiment of the present invention, if the cooling end temperature is less than 250°C during cooling, there is a concern that the cooling time may be excessive and productivity may decrease, while if the cooling end temperature exceeds 300°C, there is a problem of causing a load during subsequent cold rolling.

[0138] [Cold rolling]

[0139] A cold rolled steel sheet can be obtained by cold rolling the above cooled uncoiled hot rolled steel sheet.

[0140] In one embodiment of the present invention, cold rolling can be performed at a cold reduction ratio of 30 to 90%. If the cold reduction ratio is less than 30%, it may be difficult to secure the target thickness and shape correction of the steel plate may be difficult. According to one embodiment of the present invention, there is no particular limitation on the upper limit of the cold reduction ratio during cold rolling, but if it is too excessive, cold rolling load may be induced, and therefore, taking this into consideration, it may be limited to 90% or less.

[0141] [Sodun]

[0142] The cold rolled steel sheet manufactured above can be annealed and heat treated.

[0143] In one embodiment of the present invention, the annealing heat treatment may be performed in a general continuous annealing furnace, and may be performed under the condition that the cold rolled steel sheet is heated to 600°C or higher and then heat treated for 10 seconds or longer. If the temperature is lower than 600°C or the time is shorter than 10 seconds during the annealing heat treatment, precipitates in the annealed cold rolled steel sheet may not be formed finely or may not be distributed uniformly.

[0144] According to one embodiment of the present invention, the upper limits of the temperature and time during the annealing heat treatment are not particularly limited, but considering the risk of equipment trouble due to high-temperature annealing and the inferiority of powdering properties, the upper limits may be set to 960°C and 15 minutes, respectively. That is, if the temperature during the annealing heat treatment is too high or the heat treatment is performed for a long time, there is a risk that the powdering properties of the plated steel sheet obtained by the subsequent plating process may be inferior.

[0145] Meanwhile, in raising the temperature to a temperature for annealing the cold-rolled steel sheet, according to one embodiment of the present invention, the heating rate may be 2 to 60°C / s. If the heating rate is too slow or too fast, the precipitates may not be formed finely or may not be distributed uniformly.

[0146] A cold rolled steel sheet manufactured through a series of processes according to one embodiment of the present invention can have the target strength and hole expandability characteristics.

[0147] In particular, the cold-rolled steel sheet according to one embodiment of the present invention can satisfy the following relational expression 1 for the relationship between tensile strength (TS) and elongation (El), and the following relational expression 2 for the relationship between tensile strength (TS) and hole expandability (HER).

[0148] [Relationship 1]

[0149] 0.6×10 6 ≤ TS 2 ×√El ≤ 2.3×10 6

[0150] (The unit of equation 1 is (MPa) 2 % 0.5 am.)

[0151] [Relationship 2]

[0152] 0.9×10 6 ≤ TS 2 ×√HER ≤ 3.8×10 6

[0153] (The unit of equation 2 is (MPa) 2 %0.5 am.)

[0154] Meanwhile, according to one aspect of the present invention, a plated steel sheet can be obtained by plating a cold-rolled steel sheet, and the cold-rolled steel sheet at this time may be a cold-rolled steel sheet manufactured through a series of processes according to one embodiment of the present invention. Accordingly, the plated steel sheet may have a plated layer on at least one surface of the cold-rolled steel sheet.

[0155] In one embodiment of the present invention, the plating process may be a hot dip plating process or an electroplating process, and each plating process may be performed under conditions commonly practiced in the relevant technical field.

[0156] As an example, the above-mentioned hot-dip galvanizing can be performed by immersing the cold-rolled steel sheet, which has undergone the above-mentioned annealing heat treatment, in a hot-dip galvanizing bath containing zinc as the main component. The conditions for the hot-dip galvanizing treatment can be based on typical conditions and are not specifically limited in this specification. However, as one implementation example, the GI hot-dip galvanizing can be performed under typical conditions in the temperature range of 440 to 520°C.

[0157] In addition, according to one embodiment of the present invention, an alloyed hot-dip galvanized steel sheet (GA) can be obtained by selectively performing alloying heat treatment on a galvanized steel sheet having a zinc-based plating layer formed thereon. The alloying heat treatment can also be performed under typical conditions and is not specifically limited thereto. However, as an example, the alloying heat treatment can be performed at a temperature range of 500 to 560°C.

[0158] In addition, as an example, the electroplating can be performed by placing a base steel sheet (cold rolled steel sheet) on the cathode of a vertical plating cell type electroplating simulator, and then circulating a plating solution containing zinc (Zn) to form a zinc-based plating layer on at least one surface of the base steel sheet (cold rolled steel sheet).

[0159] Hereinafter, the present invention will be described in more detail through examples. However, it should be noted that the following examples are intended solely to illustrate the present invention and are not intended to limit the scope of the invention. This is because the scope of the invention is determined by the matters set forth in the patent claims and matters reasonably inferred therefrom.

[0160] (Example)

[0161] After preparing a steel slab having the alloy composition shown in Table 1 below, a steel plate (cold rolled steel plate) was obtained by subjecting the steel slab to a series of processes according to the conditions shown in Table 2 below. At this time, cooling was performed at a temperature range of 250 to 300°C after coiling.

[0162] The above steel slab was obtained through the following process. First, iron scrap mixed with molten iron from a conventional blast furnace was introduced into an electric furnace to obtain molten steel. This molten steel was then transferred to a ladle and vacuum degassing was performed in an RH degassing furnace (0.1 torr). At the same time, alloying components were added to produce molten steel having the desired composition. Thereafter, the molten steel was manufactured into a slab by continuous casting.

[0163] The microstructure and mechanical properties of each cold-rolled steel sheet were measured and evaluated, and all results are shown in Table 3 below.

[0164] First, in order to measure the microstructure, specimens were taken from each steel plate at a thickness direction t / 4 (where t represents the thickness of the cold-rolled steel plate in mm) and polished. The cross-sections of these polished specimens were nital-etched and observed using a scanning electron microscope (SEM). At this time, the structure without irregularities on the surface of the specimens after nital-etching was determined to be ferrite, and the structure with a spherical or lamellar structure was determined to be cementite. Meanwhile, in the case of unrecrystallized ferrite containing a lot of dislocations, since a difference in crystal orientation occurs within the grains, the crystal orientation of the ferrite was measured using FESEM-EBSD, and then the unrecrystallized ferrite among the ferrite was distinguished using the Kernel Average Misorientation (KAM) method and its fraction was measured.

[0165] In addition, tensile tests and hole expansion tests were conducted to evaluate the physical properties of each cold-rolled steel sheet. The tensile test was performed on specimens collected in accordance with JIS No. 5 with respect to the 0° direction with respect to the rolling direction of each cold-rolled steel sheet as the standard, and the relationship between tensile strength (TS) and elongation (El) (corresponding to equation 1) and yield ratio (YR) were calculated. The hole expansion test was performed by pressing and expanding a 60° cone punch with a 10 mmØ punching hole (die inner diameter 10.3 mm, clearance 12.5%) at 20 mm / min in the direction in which the burr of the punching hole became the outer side. The hole expansion ratio (HER) was then calculated using the equation below.

[0166] (Formula) HER(%) = {(D-D0) / D0}×100

[0167] (D: hole diameter when the crack penetrates the plate thickness (mm), D0: initial hole diameter (mm))

[0168] Meanwhile, in order to confirm the content (wt%) of specific elements (Cu, Cr, Ni, and Sn) according to the point in the thickness direction of the cold-rolled steel sheet, the cross-section of each specimen was removed by FIB and then measured by component analysis using FE-SEM. At this time, according to the definition of the surface layer, the content within the surface layer and the point at the center (t / 2) in the thickness direction were measured, and each was repeated 30 times at random points. After removing the maximum and minimum values ​​of the analyzed values ​​for each element, the content was calculated as the average value.

[0169] In addition, to evaluate powdering properties, each cold-rolled steel sheet was plated in a hot-dip galvanizing bath at 440 to 480°C, and a 45-degree V-bend test was performed on the obtained plated steel sheet. At this time, the evaluation surface was placed on the inner side of the bend, and after bending at 60 degrees using a mold with a curvature radius of 1 mm at the tip, tape was attached to the inner side, and the tape was removed, and the powdering properties of the plating layer peeled off together with the tape were evaluated on a full score of 5. The specific evaluation criteria were set as follows, and a score of 2 or higher was evaluated as passing.

[0170] Peeling width less than 2 mm: 5 points

[0171] Peeling width 2 mm or more but less than 3 mm: 4 points

[0172] Peeling width 3 mm or more but less than 5 mm: 3 points

[0173] Peeling width 5 mm or more but less than 7 mm: 2 points

[0174] Peeling width 7mm or more: 1 point

[0175] Steel alloy composition (weight %) (Ti+Nb+V) CSiMnPSAlNCuCrNiSnTi, Nb and V or moreOther A0.0140.020.180.0030.0020.0230.00170.840.690.830.302Ti 0.031Hf 0.0040.031B0.0320.050.520.0070.0050.0280.00350.620.810.480.175Ti 0.032Nb 0.029Y 0.0050.061C0.0650.060.630.0150.0090.0350.00460.450.360.420.082Ti 0.049V 0.035W0.030.084D0.0710.080.950.0280.0120.0330.00630.370.280.350.064Ti 0.058Nb 0.034V 0.021Mg 0.0020.113E0.0830.111.160.0390.0170.0300.00810.240.230.240.043Ti 0.086Nb 0.055Mo 0.03Zr 0.020.141F0.1260.321.380.0460.0210.0340.00970.130.110.140.015Ti 0.092Nb 0.056V 0.037B 0.0023Sb 0.0020.185G0.2380.681.760.0670.0380.0320.01760.0030.0020.0030.002Ti 0.165Nb 0.051Ca 0.004REM 0.0010.216XA0.2610.061.190.0260.0290.0360.00400.170.220.190.023Ti 0.035Nb 0.031-0.066XB0.0810.731.050.0230.0240.0340.00540.250.230.200.021Ti 0.047V 0.034-0.081XC0.0790.081.820.0180.0300.0320.00610.230.200.180.019Ti 0.087-0.087XD0.0830.061.120.0170.0320.7210.00680.240.190.210.018Ti 0.064Nb 0.029-0.093XE0.0860.070.980.0220.0270.0340.03450.190.160.240.022Ti 0.332Nb 0.025V 0.004-0.361XF0.0780.121.040.0180.0250.0330.00541.150.200.220.025Ti 0.049V 0.032-0.081XG0.0820.091.120.0250.0210.0350.00470.281.090.200.021Ti 0.043Nb 0.035-0.078XH0.0800.071.170.0230.0180.0320.00420.300.231.230.026Ti 0.036Nb 0.032V 0.002-0.070XI0.0830.101.080.0210.0220.0360.00490.310.220.190.525Ti 0.044V 0.035-0.079XJ0.0790.081.100.0240.0230.0330.00530.260.180.220.017Ti 0.241Nb 0.032-0.273XK0.0810.061.120.0220.0200.0310.00510.230.210.190.012Ti 0.046V 0.236-0.282XL0.0840.091.090.0180.0210.0340.00570.280.190.230.015Ti 0.052Nb 0.025V 0.238-0.315.

[0176]

[0177] Steel grade heating temperature (℃) Finish rolling temperature (℃) Coiling temperature (℃) Cooling after coiling (℃ / min) Cold rolling reduction rate (%) Heating speed (℃ / s) Annealing temperature (℃) Annealing time (s) Classification A11608805000.67657820120 Invention example 1B11608805500.96525800120 Invention example 2B13209505500.96526800120 Comparative example 1B8806303200.26524790120 Comparative example 2B12809507709.56531790120 Comparative example 3B10508205500.92832800120 Comparative example 4B11608805500.86532580120Comparative Example 5B11608805500.96529960120Comparative Example 6B11608805500.965288005Comparative Example 7B11608805501.065278001000Comparative Example 8B11608803500.16525800120Comparative Example 9B116088075010.36526790120Comparative Example 10B11608805000.6651790120Comparative Example 11B11608805000.76562800120Comparative Example 12C10508203500.26527800120 Invention example 3D11008506003.56514800120 Invention example 4E12009007006.85510790120 Invention example 5F12509304500.5456770120 Invention example 6G11608804000.3352750120 Invention example 7XA11608805000.76521800120 Comparative example 13XB11608805000.86518800120 Comparative example 14XC11608805000.66519800120 Comparative example 15XD11608805000.66522820120Comparison Example 16XE11608805000.76525820120Comparison Example 17XF11608805000.76525800120Comparison Example 18XG11608805000.86523800120Comparison Example 19XH11608805000.86521800120Comparison Example 20XI11608805500.96520780120Comparison Example 21XJ11608805501.16520780120Comparison Example 22XK11608805501.06517800120Comparative Example 23XL11608805500.96516800120Comparative Example 24

[0178]

[0179] Classification A / B Microstructure (Area Fraction %) Mechanical Properties Ferrite Cementite YRTS 2 ×√El(MPa 2 % 0.5 )TS 2 ×√HER(MPa 2 % 0.5) Powdering invention example 10.189820.540.650.935 invention example 20.359640.660.781.245 comparative example 134.5083170.710.820.761 comparative example 20.1386140.680.770.981 comparative example 332.1081190.690.790.831 comparative example 40.499910.670.560.954 comparative example 50.279910.690.550.974 comparative example 631.4073270.972.333.821 comparative example 70.299730.640.570.943 comparative example 824.6078220.922.323.612Comparative example 90.1488120.650.680.931Comparative example 1027.5083170.690.650.873Comparative example 110.189640.710.560.923Comparative example 1221.7080200.832.353.742Invention example 30.499370.680.861.475Invention example 40.3789110.720.931.755Invention example 50.5885150.791.542.285Invention example 60.7281190.851.892.644Invention example 70.6377230.932.243.754Comparative Example 1317.2084160.720.751.032Comparative Example 1425.4081190.700.721.143Comparative Example 1523.7087130.690.810.962Comparative Example 1621.4090100.750.860.933Comparative Example 1720.5085150.730.820.973Comparative Example 1823.6087130.690.781.202Comparative Example 1926.4084160.670.811.282Comparative Example In Table 3, A / B means the value (A / B) obtained by dividing the average (Cu+Cr+Ni+Sn) content (weight%, A) in the surface layer by the average (Cu+Cr+Ni+Sn) content (weight%, B) in the center.

[0180]

[0181] As shown in Tables 1 to 3 above, invention examples 1 to 7, which satisfy both the alloy composition and manufacturing conditions according to one embodiment of the present invention, have a microstructure that includes ferrite as the main phase, but has excellent pore expandability as well as strength due to the appropriate formation of cementite. In addition, the powdering property after plating was also excellent.

[0182] On the other hand, Comparative Examples 1 to 24, which deviate from at least one of the alloy composition and manufacturing conditions according to one embodiment of the present invention, either fail to form the microstructure as intended or have at least one or more properties, such as strength, pore expandability, and powdering properties (plating adhesion), are inferior due to the non-uniform distribution of specific elements.

[0183] In this way, the present invention has technical significance in that it can achieve both excellent hole expandability and plating adhesion.

Claims

1. In weight%, carbon (C): more than 0% to 0.2500%, silicon (Si): more than 0% to 0.700%, manganese (Mn): more than 0% to 1.800%, aluminum (Al): more than 0% to 0.700%, phosphorus (P): 0.080% or less, sulfur (S): 0.050% or less, nitrogen (N): 0.0300% or less, copper (Cu): 1.000% or less, nickel (Ni): 1.000% or less, chromium (Cr): 1.000% or less, and Magnesium (Mg): 0.050% or less, Calcium (Ca): 0.050% or less, Rare earth elements (REM) excluding yttrium (Y): 0.050% or less, Tungsten (W): 0.50% or less, Zirconium (Zr): 0.50% or less, Antimony (Sb): 0.500% or less, Tin (Sn): 0.500% or less, Cobalt (Co): 0.500% or less, Yttrium (Y): 0.200% or less, Hafnium (Hf): 0.200% or less, at least one selected from among Titanium (Ti): 0.220% or less, niobium (Nb): 0.220% or less, vanadium (V): 0.220% or less, molybdenum (Mo): 1.000% or less, and boron (B): 0.0200% or less, containing at least one selected from the group consisting of the remainder Fe and unavoidable impurities. A cold rolled steel sheet that satisfies A / B of 0.15 to 30.00, where the average content (weight%) of (Cu+Cr+Ni+Sn) within the surface layer is A and the average content (weight%) of (Cu+Cr+Ni+Sn) within the center is B. (However, the center refers to a point t / 2 in the thickness direction, and the surface part refers to a point where the concentration of Cu, Cr, Ni, and Sn changes when measured in the thickness direction from the surface, and when the (Cu+Cr+Ni+Sn) content of the surface is greater than that of the center, it refers to a point corresponding to 99% of the (Cu+Cr+Ni+Sn) content of the center in the concentration measurement value, and when the (Cu+Cr+Ni+Sn) content of the surface is less than the (Cu+Cr+Ni+Sn) content of the center, it refers to a point corresponding to 1% of the (Cu+Cr+Ni+Sn) content of the center in the concentration measurement value.) 2. In paragraph 1, A cold rolled steel sheet having a total content (Ti+Nb+V) of 0.220% or less when at least one of the above titanium (Ti), niobium (Nb), and vanadium (V) is added.

3. In paragraph 1, The above cold rolled steel sheet is a cold rolled steel sheet having a microstructure comprising an area fraction of 75 to 98% of ferrite and the remainder of cementite.

4. In paragraph 1, The above cold rolled steel sheet is a cold rolled steel sheet in which the relationship between tensile strength (TS) and elongation (El) satisfies the following equation 1. [Relationship 1] 0.6×10 6 ≤ TS 2 ×√El ≤ 2.3×10 6 (The unit of equation 1 is (MPa) 2 % 0.5 am.) 5. In paragraph 1, The above cold rolled steel sheet is a cold rolled steel sheet in which the relationship between tensile strength (TS) and hole expandability (HER) satisfies the following equation 2. [Relationship 2] 0.9×10 6 ≤ TS 2 ×√HER ≤ 3.8×10 6 (The unit of equation 2 is (MPa) 2 %0.5 am.) 6. In paragraph 1, The above cold rolled steel sheet is a cold rolled steel sheet with a yield ratio of 0.50 to 0.

95.

7. In weight%, carbon (C): more than 0% to 0.2500%, silicon (Si): more than 0% to 0.700%, manganese (Mn): more than 0% to 1.800%, aluminum (Al): more than 0% to 0.700%, phosphorus (P): 0.080% or less, sulfur (S): 0.050% or less, nitrogen (N): 0.0300% or less, copper (Cu): 1.000% or less, nickel (Ni): 1.000% or less, chromium (Cr): 1.000% or less, and Magnesium (Mg): 0.050% or less, Calcium (Ca): 0.050% or less, Rare earth elements (REM) excluding yttrium (Y): 0.050% or less, Tungsten (W): 0.50% or less, Zirconium (Zr): 0.50% or less, Antimony (Sb): 0.500% or less, Tin (Sn): 0.500% or less, Cobalt (Co): 0.500% or less, Yttrium (Y): 0.200% or less, Hafnium (Hf): 0.200% or less, at least one selected from among A step for preparing a steel slab including at least one selected from titanium (Ti): 0.220% or less, niobium (Nb): 0.220% or less, vanadium (V): 0.220% or less, molybdenum (Mo): 1.000% or less, and boron (B): 0.0200% or less, the remainder being iron and unavoidable impurities; A step of heating the above steel slab in a temperature range of 900 to 1300℃; A step of obtaining a hot rolled steel sheet by finish rolling the above heated steel slab in the austenite range above the Ar3 transformation point or in the ferrite range below the Ar3 transformation point; A step of coiling the above hot-rolled steel plate at a temperature range of 330 to 750°C; A step of cooling the above-mentioned coiled hot-rolled steel sheet to a temperature range of 250 to 300°C at a rate of 0.2 to 10°C / min; A step of cold rolling the hot rolled steel sheet after the cooling at a cold reduction ratio of 30 to 90% to obtain a cold rolled steel sheet; and A method for manufacturing a cold rolled steel sheet, comprising a step of annealing the cold rolled steel sheet at 600°C or higher for 10 seconds or longer.

8. In paragraph 7, The above annealing process step is: A method for manufacturing a cold rolled steel sheet, comprising heating the cold rolled steel sheet to an annealing temperature at a heating rate of 2 to 60°C / s.

9. In paragraph 7, The above steel slab is a method for manufacturing a cold rolled steel sheet, wherein the sum of the contents (Ti+Nb+V) when adding at least one of the above titanium (Ti), niobium (Nb), and vanadium (V) is 0.220% or less.

10. A cold rolled steel sheet according to any one of claims 1 to 6 and a plated steel sheet comprising a zinc-based plating layer formed on at least one surface of the cold rolled steel sheet.

11. In paragraph 10, A plated steel sheet having a powdering peeling width of the above-mentioned plating layer of less than 7 mm.

12. A method of obtaining a plated steel sheet by plating the cold rolled steel sheet of any one of clauses 1 to 6, The above plating treatment is a method for manufacturing a plated steel sheet, which is a hot-dip plating or electroplating process.

13. In paragraph 12, The above molten galvanizing process includes a step of molten zinc plating at a temperature range of 440 to 520°C. Optionally, a method for manufacturing a plated steel sheet further comprises a step of performing alloying heat treatment after the hot-dip galvanizing treatment.