steel plate

Abstract

To provide a steel plate with excellent resistance to corrosion and wear.SOLUTION: A steel plate comprises, in mass%, C: 0.32% or more and 0.37% or less, Si: 0.05% or more and 1.00% or less, Mn: 0.10% or more and 2.00% or less, P: 0.001% or more and 0.030% or less, S: 0.0001% or more and 0.0300% or less, Al: 0.005% or more and 0.100% or less, Cr: 3.00% or more and 11.50% or less, with the balance being Fe and inevitable impurities, where its surface hardness is 560 or more and 640 or less, measured by Brinell hardness HBW10 / 3000.SELECTED DRAWING: None

Description

[Technical field]

[0001] The present invention relates to a steel plate used for members requiring wear resistance in industrial machinery, transport equipment, etc., and more particularly to a steel plate having excellent corrosion and wear resistance in acidic corrosive environments such as coal mining environments. [Background technology]

[0002] Components of industrial machinery and transport equipment, such as power shovels, bulldozers, hoppers, buckets, dump trucks, and conveyors, are subject to wear due to contact with soil, ores, coal, and the like. For this reason, steel plates with excellent wear resistance are used to extend the lifespan of components. The actual use environments of industrial machinery and transport equipment include various conditions, such as dry and wet conditions, and when used in wet conditions, they often contain corrosive substances. It is known that corrosive wear in such environments is very severe. In particular, in coal mining environments, the leachate from the coal may be acidic, and in such cases, the corrosive wear becomes even more severe. For this reason, there has been a demand for steel plates with excellent corrosive wear resistance.

[0003] In response to such demands, for example, Patent Document 1 discloses a steel having excellent wear resistance in a corrosive environment, which has a composition containing, in mass%, C: 0.18-0.25%, Si: 0.05-1.00%, Mn: 0.10-2.00%, P: 0.020% or less, S: 0.0050% or less, Al: 0.005-0.100%, Cr: 0.05-2.00%, Nb: 0.005-0.100%, Ti: 0.005-0.100%, W: 0.05-1.00%, and, as necessary, one or more of Mo, Cu, Ni, V, B, REM, Ca, and Mg. W suppresses the corrosion reaction, thereby improving the wear resistance in the corrosive environment. In Patent Document 1, the wear resistance is evaluated using an aqueous NaCl solution as the corrosive environment.

[0004] Patent Document 2 discloses a wear-resistant steel plate having excellent corrosion and wear resistance, which contains, in mass%, C: 0.20-0.35%, Si: 0.02%-1.00%, Mn: 0.1-2.0%, P: 0.020% or less, S: 0.005% or less, Al: 0.005-0.100%, Sb: 0.005-0.20%, B: 0.0003-0.0030%, and further contains one or more selected from Cr: 0.05-2.0% and Mo: 0.05-1.0%, and satisfies 0.05≦(Crsol+2.5Mosol)≦0.2 (where Crsol: amount of Cr dissolved in steel (mass%), Mosol: amount of Mo dissolved in steel (mass%)). The dissolved Cr and dissolved Mo suppress the corrosion reaction, thereby improving the corrosion and wear resistance. In addition, in Patent Document 2, the wear resistance is evaluated using an NaCl aqueous solution as the corrosive environment.

[0005] Patent Document 3 discloses a corrosion-resistant steel that contains C: 0.01-0.25%, Si: 0.01-0.50%, Mn: 0.1-2.0%, P: 0.035 or less, S: 0.035% or less, Al: 0.003-0.10%, Cu: 0.05-0.35%, Ni: 0.02-0.40%, Sb: 0.01-0.2%, W: 0.005-0.5%, Nb: 0.003-0.025%, Cr: 0.1% or less, N: 0.0010-0.0080%, with the balance being Fe and unavoidable impurities, and that has a Vickers hardness of 140 or more at a position 2 mm deep from the surface, thereby exhibiting excellent corrosion resistance, wear resistance, and high toughness under a specific environment.

[0006] Patent Document 4 describes a steel containing, by mass%, C: 0.10-0.35%, Si: more than 1.00% and not more than 2.00%, Mn: 0.10-2.00%, P: 0.0200% or less, S: 0.0100% or less, Cr: more than 0.05% and not more than 2.00%, Al: 0.010-0.100%, N: 0.0020-0.0100%, B: 0.0003-0.0030%, and the remainder being Fe and impurities, and H≧235+706[C](1-0.3[C] 2) (wherein H represents the surface layer hardness (HV) of the corrosion-resistant and wear-resistant steel plate, and [C] represents the C content (mass%)), thereby providing a corrosion-resistant and wear-resistant steel plate that is excellent in toughness and also has both corrosion resistance and wear resistance. In Patent Document 4, the wear resistance is evaluated using artificial seawater as the corrosive environment.

[0007] Patent Document 5 describes a steel containing, by mass%, C: 0.01 to 0.15%, Si: 0.05 to 1.00%, Mn: 0.10 to 2.00%, Cr: more than 0.05% but not more than 3.00%, Al: 0.01 to 0.10%, and B: 0.0003 to 0.0020%, and the Ceq(%) is expressed by the following formula (Ceq(%)=[C]+[Mn] / 6+[Si] / 24+[Ni] / 40+[Cr] / 5+[Mo] / 4+[V] / 4) (wherein [X] is an element). The steel plate has a carbon equivalent Ceq (%) of 0.20% or more, determined by a carbon equivalent calculation (representing the content by mass of element X) and a metal structure in which the area ratio of lath-shaped structures in the surface layer is 90% or more, the major axis / minor axis ratio of cementite present in the lath-shaped structures is 2.00 or more, and the surface layer hardness is 200HV5 or more, and therefore has excellent corrosion resistance and wear resistance and is suitable for the holds of dedicated coal carriers or combined coal and mine carriers. [Prior art documents] [Patent documents]

[0008] [Patent Document 1] JP 2015-193873 A [Patent Document 2] JP 2016-222969 A [Patent Document 3] JP 2017-128762 A [Patent Document 4] JP 2020-007589 A [Patent Document 5] JP 2020-132994 A Summary of the Invention [Problem to be solved by the invention]

[0009] However, in Patent Documents 1, 2, and 4, the corrosive environments targeted for improving corrosion resistance are NaCl aqueous solutions and artificial seawater, and therefore there is a problem in that corrosion wear resistance in acidic environments such as coal mining environments cannot be improved. In addition, Patent Documents 3 and 5 have a problem in that the hardness of the steel material is low, at 365 or less in Vickers hardness, and is not suitable for industrial machinery, transport equipment, etc. In addition, industrial machinery, transport equipment, etc. need to have appropriate toughness due to the harsh environment in which they are used.

[0010] In view of the above circumstances, an object of the present invention is to provide a steel plate having excellent corrosive wear resistance and toughness. [Means for solving the problem]

[0011] In order to solve the above problems, the influence of various factors from the viewpoint of corrosion wear resistance was thoroughly investigated. As a result, it was discovered that the corrosion wear resistance in an acidic environment such as a coal mining environment can be improved by simultaneously satisfying the following (1) and (2) in order to simultaneously improve the wear resistance and corrosion resistance of a steel material. To improve wear resistance, (1) Increases hardness. To improve corrosion resistance in acidic environments, (2) In an acidic corrosive environment, Cr is added, which is effective in improving corrosion and wear resistance by dissolving as an ion through an anodic reaction and suppressing corrosion through its inhibitor effect. That is, it was found that in order to solve the above problems, it is necessary to add Cr while increasing the hardness so as to simultaneously improve the wear resistance and corrosion resistance. [1] In weight percent: C: 0.32% or more and 0.37% or less, Si: 0.05% or more and 1.00% or less, Mn: 0.10% or more and 2.00% or less, P: 0.001% or more and 0.030% or less, S: 0.0001% or more and 0.0300% or less, Al: 0.005% or more and 0.100% or less, Cr: 3.00% or more and 11.50% or less; The balance is Fe and unavoidable impurities. Surface hardness is 560 to 640 on the Brinell hardness scale HBW10 / 3000. A steel plate characterized by: [2] Furthermore, in mass percent: Mo: 1.00% or less Nb: 0.100% or less, Ti: 0.100% or less, V: 0.200% or less, Zr: 0.100% or less, Sn: 0.200% or less, Sb: 0.200% or less, Cu: 2.00% or less, Ni: 2.00% or less, Co: 2.00% or less, W: 1.00% or less, B: 0.0030% or less, REM: 0.0100% or less, Ca: 0.0100% or less, Mg: 0.0100% or less, The steel sheet according to [1], characterized in that it contains one or more selected from the following: Effect of the Invention

[0012] According to the present invention, a steel plate having excellent corrosion wear resistance can be obtained. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0013] The present invention will be described in detail below. In the following, "%" regarding the composition of a component means "% by mass" unless otherwise specified.

[0014] C: 0.32% or more and 0.37% or less C is an element that increases the hardness of steel. To ensure the desired hardness, it must be contained at 0.32% or more. On the other hand, if it exceeds 0.37%, gas cuttability is significantly deteriorated and cracks occur. Therefore, the C content is set to 0.32% or more and 0.37% or less. It is preferably 0.33% or more and 0.36% or less. It is more preferably 0.34% or more and 0.35% or less.

[0015] Si: 0.05% or more and 1.00% or less Silicon is an effective element that acts as a deoxidizer for molten steel. To ensure this effect, a content of 0.05% or more is required. On the other hand, if the content exceeds 1.00%, the ductility decreases and the amount of inclusions increases. Therefore, the silicon content is set to 0.05% or more and 1.00% or less. The silicon content is preferably set to 0.10% or more and 0.40% or less.

[0016] Mn: 0.10% or more and 2.00% or less Mn is an element that improves hardenability, and must be contained at 0.10% or more to ensure a certain level of hardenability. On the other hand, excessive Mn content exceeding 2.00% deteriorates weldability. Therefore, the Mn content is set to 0.10% or more and 2.00% or less. It is preferably set to 0.15% or more and 1.80% or less, and more preferably set to 0.20% or more and 1.80% or less.

[0017] P: 0.001% or more and 0.030% or less If a large amount of P is contained in steel, it deteriorates weldability. Therefore, the upper limit is set at 0.030%. It is desirable to reduce it as much as possible, but since excessive reduction leads to high refining costs, it is set at 0.001% or more. Therefore, the P content is set at 0.001% or more and 0.030% or less. It is preferably 0.015% or less.

[0018] S: 0.0001% or more and 0.0300% or less If a large amount of S is contained in the steel, it precipitates as MnS, which deteriorates the gas cutting ability, so it must be 0.0300% or less. However, since excessive reduction leads to an increase in refining costs, the S content is set to 0.0001% or more. Therefore, the S content is set to 0.0001% or more and 0.0300% or less. It is preferably 0.0005% or more and 0.0030% or less, and more preferably 0.0030% or less.

[0019] Al: 0.005% or more and 0.100% or less Al is an element necessary for deoxidation during steelmaking, and has the effect of forming nitrides to reduce the austenite grain size and improve toughness. To obtain such an effect, the Al content must be 0.005% or more. On the other hand, if it exceeds 0.100%, the cleanliness of the steel material or steel plate decreases, resulting in a decrease in toughness. Therefore, the Al content is set to 0.005% or more and 0.100% or less. It is preferably 0.070% or less, and more preferably 0.050% or less. It is preferably 0.010% or more.

[0020] Cr:3.00% or more and 11.50% or less Cr is an important element in the present invention, and has the effect of significantly improving corrosion wear resistance, especially in an acidic corrosive environment such as a coal mining environment. Cr is an element that improves hardenability and has the effect of increasing hardness. In addition, in an acidic corrosive environment such as a coal mining environment, Cr is dissolved as a Cr oxide ion by an anodic reaction, and has the effect of suppressing corrosion by an inhibitor effect, thereby improving corrosion wear resistance. In order to obtain such an effect, it is necessary to contain 3.00% or more. On the other hand, if it is contained in excess of 11.50%, the weldability decreases and the manufacturing cost increases, so it is limited to a range of 3.00% or more and 11.50% or less. The upper limit of the Cr content is preferably 11.00% or less, more preferably 10.00% or less.

[0021] The steel of the present invention can obtain the desired properties with the above essential elements, but in addition to the above essential elements, one or more elements selected from the following elements can be added as necessary.

[0022] Mo: 1.00% or less Mo is an element that improves hardenability and has the effect of increasing hardness. To obtain such an effect, it is preferable to contain 0.01% or more. On the other hand, if it exceeds 1.00%, the Mo consumption increases, resulting in an increase in costs. Therefore, if Mo is contained, the Mo content is set to 1.00% or less, preferably 0.80% or less. It is preferably 0.01% or more, and more preferably 0.10% or more.

[0023] Nb: 0.100% or less Nb is an element necessary for increasing strength. In order to fully obtain this effect, it is preferable to contain 0.001% or more. On the other hand, if it exceeds 0.100%, the effect saturates. Therefore, if Nb is contained, the Nb content is 0.100% or less. Preferably, it is 0.001% or more.

[0024] Ti:0.100% or less Ti is an element necessary for increasing strength. To obtain this effect sufficiently, it is preferable to contain 0.001% or more. On the other hand, if it exceeds 0.100%, the effect is saturated. Therefore, if Ti is contained, the Ti content is 0.100% or less, and preferably 0.001% or more.

[0025] V:0.200% or less V is an element necessary for increasing strength. To obtain this effect sufficiently, it is preferable to contain 0.001% or more. On the other hand, if it exceeds 0.200%, the effect is saturated. Therefore, if V is contained, the V content is 0.200% or less. Preferably, it is 0.001% or more.

[0026] Zr: 0.100% or less Zr is an element necessary for increasing strength. To obtain this effect sufficiently, it is preferable to contain 0.001% or more. On the other hand, if it exceeds 0.100%, the effect is saturated. Therefore, if Zr is contained, the Zr content is 0.100% or less. It is preferably 0.001% or more.

[0027] Sn: 0.200% or less Sn is an element that inhibits the anodic reaction of steel materials in acidic corrosive environments such as coal mining environments, and inhibits the hydrogen generation reaction, which is a cathodic reaction, thereby improving the weather resistance of steel materials. In order to fully obtain such effects, it is preferable to contain 0.001% or more. On the other hand, even if the content exceeds 0.200%, the effect is saturated. Therefore, when Sn is contained, the content is set to 0.200% or less, and preferably 0.001% or more.

[0028] Sb: 0.200% or less Sb is an element that inhibits the anodic reaction of steel materials in acidic corrosive environments such as coal mining environments, and inhibits the hydrogen generation reaction, which is a cathodic reaction, thereby improving the weather resistance of steel materials. In order to fully obtain such effects, it is preferable to contain 0.001% or more. On the other hand, even if the Sb content exceeds 0.200%, the effect is saturated. Therefore, when Sb is contained, the content is set to 0.200% or less, and preferably 0.001% or more.

[0029] Cu:2.00% or less Cu densifies corrosion products and inhibits the penetration of corrosion-promoting factors such as water, oxygen, sulfate ions, and chloride ions into the base steel, thereby inhibiting corrosion reactions. This effect improves corrosion wear resistance. To obtain this effect, the content is preferably 0.01% or more. On the other hand, if it exceeds 2.00%, hot workability decreases and manufacturing costs increase. Therefore, if Cu is contained, the Cu content is set to 2.00% or less. It is preferably 1.50% or less, and more preferably 1.20% or less. It is preferably 0.01% or more, more preferably 0.1% or more, and even more preferably 0.60% or more.

[0030] Ni: 2.00% or less Ni is an element that improves hardenability. To obtain such an effect, it is preferable to contain 0.01% or more. On the other hand, a content exceeding 2.00% increases the manufacturing cost, so when Ni is contained, it is limited to 2.00% or less. It is preferably 1.50% or less, and more preferably 0.60% or less. It is preferably 0.01% or more, more preferably 0.1% or more, and even more preferably 0.30% or more.

[0031] Co:2.00% or less Co is an element that improves hardenability. To obtain this effect, it is preferable to contain 0.01% or more. On the other hand, a content exceeding 2.00% increases the manufacturing cost, so if Co is contained, it is limited to 2.00% or less. The content is preferably 0.01% or more.

[0032] W: 1.00% or less W is an element that improves hardenability and has the effect of increasing hardness. To obtain such an effect, it is preferable to contain 0.01% or more. On the other hand, if it exceeds 1.00%, the cost increases due to the increase in W consumption. Therefore, if W is contained, the W content is 1.00% or less, preferably 0.80% or less. It is preferably 0.01% or more, and more preferably 0.10% or more.

[0033] B: 0.0030% or less B is an element that improves hardenability. To obtain this effect, it is preferable to contain 0.0001% or more. On the other hand, if it exceeds 0.0030%, the effect saturates. Therefore, if B is contained, the B content is set to 0.0030% or less. It is preferably 0.0020% or less. It is preferably 0.0001% or more, and more preferably 0.0005% or more.

[0034] REM: 0.0100% or less REM fixes S and suppresses the generation of MnS, which causes cracking. In order to obtain such an effect, it is preferable to contain 0.0001% or more. On the other hand, if it is contained in excess of 0.0100%, the amount of inclusions in the steel increases, which causes cracking, so if it is contained, it is limited to a range of 0.0100% or less. It is preferably 0.0050% or less. It is preferably 0.0001% or more, and more preferably 0.0005% or more.

[0035] Ca:0.0100% or less Ca fixes S in steel and suppresses the formation of MnS, which causes cracking. To fully obtain this effect, it is preferable to contain 0.0001% or more. On the other hand, if it is contained in excess of 0.0100%, the amount of inclusions in the steel increases, which can cause cracking, so if it is contained, it is set to 0.0100% or less. It is preferably 0.0050% or less. It is preferably 0.0001% or more, and more preferably 0.0005% or more.

[0036] Mg: 0.0100% or less Mg fixes S and suppresses the generation of MnS, which causes cracking. In order to obtain such an effect, it is preferable to contain 0.0001% or more. On the other hand, if it is contained in excess of 0.0100%, the amount of inclusions in the steel increases, which causes cracking, so if it is contained, it is limited to a range of 0.0100% or less. It is preferably 0.0050% or less. It is preferably 0.0001% or more, and more preferably 0.0005% or more.

[0037] The balance is Fe and unavoidable impurities. As for the unavoidable impurities, N and O can be allowed to be up to 0.0100% and O can be allowed to be up to 0.0100%.

[0038] The steel sheet of the present invention has a surface hardness of 560 or more and 640 or less in terms of Brinell hardness HBW10 / 3000. The term "surface hardness" as used herein refers to a value (Brinell hardness) measured in accordance with the provisions of JIS Z 2243 (2008) at a position 0.5 mm from the surface in the sheet thickness direction.

[0039] Surface hardness: Brinell hardness HBW10 / 3000: 560 to 640 If the surface hardness is less than 560 in HBW10 / 3000, the surface hardness is low, and therefore the desired wear life cannot be ensured in the case where a severe wear environment requires higher corrosion wear resistance. For this reason, the surface hardness of the steel plate of the present invention is limited to 560 or more in Brinell hardness HBW10 / 3000. On the other hand, if the surface hardness exceeds 640 in HBW10 / 3000, bending workability deteriorates. For this reason, the surface hardness is limited to 640 or less in Brinell hardness HBW10 / 3000.

[0040] The thickness of the steel plate in the present invention is not particularly limited and may be any value, but is preferably 6 mm or more and 100 mm or less.

[0041] [Steel plate manufacturing method] The molten steel having the above-mentioned composition is melted by a known method such as a converter or an electric furnace, and then cast by continuous casting or ingot casting. The molten steel is processed into steel materials such as slabs and billets by known methods such as ladle refining and vacuum refining. Needless to say, degassing and other treatments may be added. In order to maintain the quality of the steel, the heating temperature of the steel material, the finishing temperature during hot rolling, and the cooling rate must be appropriately set. That is, from the viewpoint of ensuring the end temperature of hot finish rolling, it is preferable to heat the steel material to a temperature of 1000 to 1250°C and then hot roll it into a desired size and shape, or, when the temperature of the steel material is high enough to be hot rolled, it is preferable to immediately hot roll it into a steel material of the desired size and shape without heating or after soaking.

[0042] In hot rolling, in order to ensure strength, it is preferable to optimize the hot finish rolling end temperature and the cooling rate after the end of hot rolling, and it is preferable to end hot rolling at a temperature of 770 ° C. or higher, air-cool, reheat to 850 ° C. to 1000 ° C., and then immediately or after a short period of time, perform cooling (for example, water cooling) from a cooling start temperature of 750 ° C. or higher at a cooling rate of 0.5 ° C. / s to 100 ° C. / s, and end cooling at a cooling stop temperature of 200 ° C. or lower. Also, immediately or after a short period of time after the end of hot rolling, accelerated cooling (for example, water cooling) may be performed from a cooling start temperature of 750 ° C. or higher (in the case of water cooling, the water cooling start temperature) at a cooling rate of 0.5 ° C. / s to 100 ° C. / s, and end accelerated cooling at a cooling stop temperature of 200 ° C. or lower. EXAMPLES

[0043] Steels having the composition shown in Table 1 (the balance being Fe and unavoidable impurities) were melted in a vacuum melting furnace and cast into molds to obtain steel materials. These steel materials were then hot-rolled and immediately air-cooled after hot-rolling. After air-cooling, they were further reheated and then water-cooled. Test pieces were taken from the obtained steel plates and subjected to a surface hardness test and a corrosion wear test.

[0044] (1) Surface hardness test A test piece for measuring surface hardness was taken from the surface of the obtained steel plate at a position 0.5 mm from the surface, and the surface hardness HBW10 / 3000 was measured in accordance with the provisions of JIS Z 2243 (2008). The hardness measurement was performed using a 10 mm tungsten hard ball and a load of 3000 kgf. Measurements were performed at 5 or more points at a position 0.5 mm from the surface, and the arithmetic average of the obtained measured values ​​was calculated, and the average value was determined as the surface hardness of the steel plate.

[0045] (2) Corrosion wear test Abrasion test pieces (size: 10 mmφ×75 mm length) were taken from the 1 / 4t portion (t indicates the plate thickness) in the plate thickness direction of the obtained steel plate. The test pieces were attached to an abrasion tester, and an abrasion test was carried out. Three abrasion test pieces were attached at a 120 degree angle, 150 mm from the axis of the rotor of the test machine, parallel to the axis of rotation, and then the test pieces were placed in the test tank and an abrasive material was introduced inside. The abrasive material was a mixture of silica sand with an average particle size of 0.7 mm and dilute sulfuric acid with a pH of 2, with the weight ratio of silica sand to dilute sulfuric acid being 5:3. The test conditions were a rotation speed of 500 rpm and a number of revolutions of 60,000. After the test, the weight of each test piece was measured. The difference between the post-test weight and the initial weight (= weight loss) was calculated. In addition, a similar abrasion test was carried out on a test piece taken from a general structural rolled steel material SS400 (JIS G3101) as a conventional example, and the weight loss of the test piece was calculated. The corrosion wear resistance was evaluated based on the ratio of the weight loss of each test piece to the weight loss of SS400, and if this ratio was 0.65 or less, it was evaluated as good.

[0046] (3) Charpy test The toughness according to the Charpy test (JIS Z 2242 (2018)) was evaluated as good if the average absorbed energy for one set (n=3) was 15.0 J or more at -40°C.

[0047] The evaluation results for (1), (2), and (3) are shown in Table 2.

[0048] As shown in Table 2, all of the examples of the invention combine surface hardness and corrosive wear resistance. In contrast, in the comparative examples, sufficient properties are not obtained with respect to at least one of the surface hardness and the corrosive wear resistance.

[0049] [Table 1]

[0050] [Table 2] [Industrial Applicability]

[0051] As described above, according to the present invention, it is possible to provide a steel plate used for components requiring abrasion resistance in industrial machinery, transport equipment, and the like, and in particular a steel plate having excellent corrosion resistance and abrasion resistance in acidic corrosive environments such as coal mining environments.

Claims

1. In mass percent, C: 0.32% or more and 0.37% or less, Si: 0.05% or more and 1.00% or less, Mn: 0.10% or more and 2.00% or less, P: 0.001% or more and 0.030% or less, S: 0.0001% or more and 0.0300% or less, Al: 0.005% or more and 0.100% or less, Cr: 3.00% or more and 11.50% or less; The balance is Fe and unavoidable impurities, Surface hardness is 560 to 640 on the Brinell hardness scale HBW10 / 3000. A steel plate characterized by:

2. Further, in mass%, Mo: 1.00% or less, Nb: 0.100% or less, Ti: 0.100% or less, V: 0.200% or less, Zr: 0.100% or less, Sn: 0.200% or less, Sb: 0.200% or less, Cu: 2.00% or less, Ni: 2.00% or less, Co: 2.00% or less, W: 1.00% or less, B: 0.0030% or less, REM: 0.0100% or less, Ca: 0.0100% or less, Mg: 0.0100% or less, The steel sheet according to claim 1, further comprising at least one selected from the following:

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