steel plate

Abstract

To provide a steel plate with excellent resistance to corrosion and wear.SOLUTION: A steel plate comprises, in mass%, C: 0.24% or more and less than 0.32%, Si: 0.05% or more and 1.00% or less, Mn: 0.10% or more and 2.00% or less, P: 0.030% or less (excluding 0%), S: 0.0300% or less (excluding 0%), 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 460 or more and 590 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 components that require wear resistance in industrial machinery, transport equipment, etc., and in particular to a steel plate that has 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, ore, coal, and other materials. For this reason, thick steel plates with excellent wear resistance are used to extend the life of these components. The actual operating environments of industrial machinery and transport equipment vary, from dry to wet, and when used in wet conditions, they often contain corrosive substances. Corrosive wear in such environments is known to be extremely severe. In particular, in coal mining environments, the leachate from the coal can be acidic, further exacerbating corrosive wear. Therefore, there has been a demand for steel plates with excellent corrosion 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, by mass%, 0.18-0.25% C, 0.05-1.00% Si, 0.10-2.00% Mn, 0.020% or less P, 0.0050% or less S, 0.005-0.100% Al, 0.05-2.00% Cr, 0.005-0.100% Nb, 0.005-0.100% Ti, 0.05-1.00% W, and optionally one or more of Mo, Cu, Ni, V, B, REM, Ca, and Mg, with an appropriate amount of W. Patent Document 1 also discloses a steel having excellent wear resistance in a corrosive environment, which is evaluated using an aqueous NaCl solution as the corrosive environment.

[0004] Furthermore, Patent Document 2 discloses a steel sheet containing, in mass%, C: 0.20 to 0.35%, Si: 0.02% to 1.00%, Mn: 0.1 to 2.0%, P: 0.020% or less, S: 0.005% or less, Al: 0.005 to 0.100%, Sb: 0.005 to 0.20%, B: 0.0003 to 0.0030%, and further containing one or more selected from Cr: 0.05 to 2.0% and Mo: 0.05 to 1.0%, and 0.05≦(Crsol+2.5Mosol)≦0.2 (where Crsol: amount of Cr dissolved in steel (mass %), Mosol: amount of Mo dissolved in steel (mass %)), and the amounts of solute Cr and Mo are kept within appropriate ranges to create a component system that can suppress corrosive wear to some extent, and further Sb and B are essentially contained in combination, thereby providing a wear-resistant steel plate with excellent corrosive wear resistance. In Patent Document 2, 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 to 0.25%, Si: 0.01 to 0.50%, Mn: 0.1 to 2.0%, P: 0.035% or less, S: 0.035% or less, Al: 0.003 to 0.10%, Cu: 0.05 to 0.35%, Ni: 0.02 to 0.40%, Sb: 0.01 to 0.2%, W: 0.005 to 0.5%, Nb: 0.003 to 0.025%, Cr: 0.1% or less, N: 0.0010 to 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 specific environments.

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

[0007] Patent Document 5 also 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 in particular containing Cr, which is an alloy element that contributes to improving the hardenability of the steel and improving its hardness, and satisfying the following formula (Ceq(%)=[C]+[Mn] / 6+[Si] / 24+[Ni] / 40+[Cr] / 5+[Mo] / The steel plate disclosed has a carbon equivalent Ceq (%) of 0.20% or more, calculated by the formula (4+[V] / 4) (wherein [X] represents the content of element X in mass %), an area ratio of lath-shaped structures in the surface layer of 90% or more, a metal structure in which the major axis / minor axis ratio of cementite present in the lath-shaped structures is 2.00 or more, and a surface layer hardness of 200 or more in HV5, and therefore has excellent corrosion resistance and wear resistance, making it suitable for the holds of dedicated coal carriers or combined coal and mine carriers. [Prior art documents] [Patent documents]

[0008] [Patent Document 1] Japanese Patent Application Laid-Open No. 2015-193873 [Patent Document 2] Japanese Patent Application Laid-Open No. 2016-222969 [Patent Document 3] Japanese Patent Application Laid-Open No. 2017-128762 [Patent Document 4] Japanese Patent Application Publication No. 2020-007589 [Patent Document 5] Japanese Patent Application Publication No. 2020-132994 Summary of the Invention [Problem to be solved by the invention]

[0009] However, Patent Documents 1, 2, and 4 have the problem that the corrosive environments targeted for improving corrosion resistance are NaCl aqueous solutions and artificial seawater, and therefore do not improve corrosion and wear resistance in acidic environments such as coal mining environments. Patent Documents 3 and 5 also have the problem that the hardness of the steel materials is low, at 365 or less in Vickers hardness, making them unsuitable for industrial machinery, transport equipment, etc. Industrial machinery, transport equipment, etc., also require appropriate toughness due to the harsh environments 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 corrosion 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 acidic environments such as coal mining environments can be improved by simultaneously satisfying the following (1) and (2) in order to simultaneously improve the wear resistance and corrosion resistance of steel materials. To improve wear resistance, (1) Increases hardness. To improve corrosion resistance in acidic environments, (2) In an acidic corrosive environment, Cr is added because it dissolves as an ion through an anodic reaction and suppresses corrosion through its inhibitor effect, thereby improving corrosion and wear resistance. That is, it was found that in order to solve the above problems, it is necessary to add Cr while increasing hardness so as to simultaneously improve wear resistance and corrosion resistance. The gist of the present invention that solves the problems is as follows. [1] In mass %, C: 0.24% or more and less than 0.32% Si: 0.05% or more and 1.00% or less, Mn: 0.10% or more and 2.00% or less, P: 0.030% or less (excluding 0%) S: 0.0100% or less (excluding 0%) Al: 0.005% or more and 0.100% or less, Cr: 3.00% or more and 11.50% or less; The balance has a composition consisting of Fe and unavoidable impurities, Surface hardness is Brinell hardness HBW10 / 3000, 460 to 590. A steel plate characterized by: [2] Furthermore, in mass %, Mo: 1.000% 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: 1.000% 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. [Effects of the Invention]

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

[0013] The present invention will be described in detail below. Note that "%" regarding the component composition means "% by mass" unless otherwise specified.

[0014] C: 0.24% or more and less than 0.32% C is an element that increases the hardness of steel. To ensure the desired hardness, it must be contained in an amount of 0.24% or more. On the other hand, if the C content is 0.32% or more, the hardness becomes too high and the target hardness cannot be ensured. Therefore, the C content is set to 0.24% or more and less than 0.32%. Preferably, it is 0.25% or more and 0.30% or less. More preferably, it is 0.26% or more and 0.29% or less.

[0015] Si: 0.05% or more and 1.00% or less Si 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%, ductility decreases and the number of inclusions increases, which then become the starting point for a decrease in toughness. Therefore, the Si content is set to 0.05% or more and 1.00% or less. Preferably, it is 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 in an amount of 0.10% or more to ensure a specified 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. Preferably, it is set to 0.15% or more and 1.80% or less. More preferably, it is set to 0.20% or more and 1.80% or less.

[0017] P: 0.030% or less (excluding 0%) If a large amount of P is contained in steel, it deteriorates weldability. Therefore, the upper limit is set to 0.030%. It is desirable to reduce it as much as possible, preferably to 0.015% or less. To ensure the properties, it is desirable to reduce it as much as possible, but excessive reduction leads to an increase in refining costs, so 0.001% or more is preferable.

[0018] S: 0.0300% or less (excluding 0%) If S is contained in steel in large amounts, it precipitates as MnS, which deteriorates gas cuttability, so it is desirable to reduce it as much as possible, to 0.0300% or less. However, since excessive reduction leads to increased refining costs, it is preferable to keep the S content at 0.0001% or more.

[0019] Al: 0.005% or more and 0.100% or less Al is an element necessary for deoxidation during steelmaking, and forms nitrides to reduce the austenite grain size and improve toughness. To achieve these effects, 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 and wear resistance, particularly in acidic, corrosive environments such as coal mining environments. Cr is an element that improves hardenability and increases hardness. Furthermore, in acidic, corrosive environments such as coal mining environments, Cr dissolves as Cr oxide ions through an anodic reaction, suppressing corrosion through its inhibitor effect and thereby improving corrosion and wear resistance. To achieve this effect, a Cr content of 3.00% or more is required. However, a Cr content exceeding 11.50% reduces weldability and increases manufacturing costs, so the Cr content is limited to a range of 3.00% to 11.50%. The upper limit of the Cr content is preferably 11.00% or less, and more preferably 10.00% or less.

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

[0022] Mo: 1.000% or less Mo is an element effective for improving hardenability and has the effect of increasing hardness. To achieve this effect, it is necessary to include 0.001% or more. On the other hand, if it exceeds 1.000%, the Mo consumption increases, resulting in an increase in costs. Therefore, if Mo is included, the upper limit of the Mo content is set to 1.000% or less, and preferably 0.800% or less. Furthermore, if Mo is included, the lower limit of the Mo content is preferably set to 0.100% or more.

[0023] Nb: 0.100% or less Nb is an element effective in increasing strength. To fully obtain this effect, it is necessary to include 0.001% or more. On the other hand, if it exceeds 0.100%, the effect saturates. Therefore, if Nb is included, the upper limit of the Nb content is set to 0.100% or less. Furthermore, if it is included, the lower limit of the Nb content is preferably set to 0.001%.

[0024] Ti:0.100% or less Ti is an element necessary for increasing strength. To fully obtain this effect, it is necessary to include 0.001% or more. On the other hand, if it exceeds 0.100%, the effect saturates. Therefore, if Ti is included, the upper limit of the Ti content is set to 0.100% or less. Furthermore, if Ti is included, the lower limit of the Ti content is preferably set to 0.001%.

[0025] V:0.200% or less V is an element effective for increasing strength. To fully obtain this effect, it is necessary to include 0.001% or more. On the other hand, if it exceeds 0.200%, the effect saturates. Therefore, if V is included, the upper limit of the V content is set to 0.200% or less. Furthermore, if V is included, the lower limit of the V content is preferably set to 0.001%.

[0026] Zr: 0.100% or less Zr is an element effective in increasing strength. To fully obtain this effect, it is necessary to include 0.001% or more. On the other hand, if it exceeds 0.100%, the effect saturates. Therefore, if Zr is included, the upper limit of the Zr content is set to 0.100% or less. Furthermore, if Zr is included, the lower limit of the Zr content is preferably set to 0.001%.

[0027] Sn: 0.200% or less Sn is an element that is effective in improving the weather resistance of steel materials in acidic, corrosive environments such as coal mining environments by suppressing the anodic reaction of steel materials and the hydrogen evolution reaction, which is a cathodic reaction. To fully achieve this effect, a content of 0.001% or more is required. However, if an excessive amount of Sn is contained, the effect saturates. Therefore, if Sn is contained, the upper limit of the Sn content is set to 0.200% or less. Furthermore, if Sn is contained, the lower limit of the Sn content is preferably set to 0.001%.

[0028] Sb: 0.200% or less Sb is an element that is effective in improving the weather resistance of steel materials in acidic, corrosive environments such as coal mining environments by suppressing the anodic reaction of steel materials and the hydrogen evolution reaction, which is a cathodic reaction. To fully achieve this effect, a content of 0.001% or more is required. However, even if an excessive amount of Sb is contained, the effect saturates. Therefore, when Sb is contained, the upper limit of the Sb content is set to 0.200% or less. Furthermore, when Sb is contained, the lower limit of the Sb content is preferably set to 0.001%.

[0029] Cu:2.00% or less Cu densifies corrosion products and inhibits the penetration of corrosion-accelerating 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 achieve this effect, a Cu content of 0.01% or more is preferable. On the other hand, if Cu exceeds 2.00%, hot workability deteriorates and manufacturing costs increase. Therefore, if Cu is contained, the upper limit of the Cu content is 2.00% or less, preferably 1.50% or less, and even more preferably 1.20% or less. If Cu is contained, the lower limit of the Cu content is preferably 0.01% or more, more preferably 0.10% or more, and even more preferably 0.60% or more.

[0030] Ni: 2.00% or less Ni is an element effective in improving hardenability. To achieve this effect, a content of 0.01% or more is required. On the other hand, a content of more than 2.00% increases manufacturing costs, so if Ni is contained, the upper limit of the Ni content is limited to 2.00%, preferably 1.50%, and more preferably 0.60%. If Ni is contained, the lower limit of the Ni content is preferably 0.01%, more preferably 0.10%, and even more preferably 0.30%.

[0031] Co:2.00% or less Co is an element effective in improving hardenability. To achieve this effect, a content of 0.01% or more is required. On the other hand, a content of more than 2.00% increases manufacturing costs, so if Co is contained, the upper limit of the Co content is limited to 2.00% or less. Furthermore, if Co is contained, the lower limit of the Co content is preferably 0.01% or more.

[0032] W: 1.000% or less W is an element effective in improving hardenability and has the effect of increasing hardness. To achieve this effect, it must be contained in an amount of 0.001% or more. On the other hand, if it exceeds 1.00%, the cost increases due to the increased W consumption. Therefore, if W is contained, the upper limit of the W content is set to 1.000% or less, preferably 0.800% or less. Furthermore, if W is contained, the lower limit of the W content is preferably set to 0.050% or more, more preferably 0.100% or more.

[0033] B: 0.0030% or less B is an element effective in improving hardenability. To obtain this effect, it is necessary to include 0.0001% or more of B. On the other hand, if the content exceeds 0.0030%, the effect saturates. Therefore, if B is included, the upper limit of the B content is set to 0.0030% or less. Furthermore, if B is included, the lower limit of the B content is preferably set to 0.0001% or more.

[0034] REM: 0.0100% or less REM is effective in fixing S and suppressing the formation of MnS, which causes cracking. To achieve this effect, a content of 0.0005% or more is required. On the other hand, if the content exceeds 0.0100%, the amount of inclusions in the steel increases, leading to cracking. Therefore, if REM is contained, the upper limit of the REM content is limited to 0.0100% or less, and preferably 0.0020% or less. Furthermore, if REM is contained, the lower limit of the REM content is preferably 0.0005% or more.

[0035] Ca:0.0100% or less Ca is an element that fixes S in steel and is effective in improving the toughness of the weld heat-affected zone. To fully obtain this effect, a content of 0.0001% or more is required. On the other hand, if the content exceeds 0.0100%, the amount of inclusions in the steel increases, which can cause cracking. Therefore, if Ca is contained, the upper limit of the Ca content is set to 0.0100% or less. Furthermore, if Ca is contained, the lower limit of the Ca content is preferably set to 0.0001% or more.

[0036] Mg: 0.0100% or less Mg is an element that fixes S in steel and is effective in improving the toughness of the weld heat-affected zone. To fully obtain this effect, a content of 0.0001% or more is required. On the other hand, if the content exceeds 0.0100%, the amount of inclusions in the steel increases, which can cause cracking. Therefore, if Mg is contained, the upper limit of the Mg content is set to 0.0100% or less. Furthermore, if Mg is contained, the lower limit of the Mg content is preferably set to 0.0001% or more.

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

[0038] The steel plate of the present invention has a surface hardness of 460 or more and 590 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 plate thickness direction.

[0039] Surface hardness: Brinell hardness HBW10 / 3000: 460 to 590 If the surface hardness is less than 460 in HBW10 / 3000, the surface hardness is low, and therefore the desired wear life cannot be ensured when higher corrosion wear resistance is required in a severe wear environment. For this reason, the surface hardness of the steel plate of the present invention is limited to a Brinell hardness of 460 or more in HBW10 / 3000. On the other hand, if the surface hardness exceeds 590 in HBW10 / 3000, bending workability deteriorates. For this reason, the surface hardness is limited to a Brinell hardness of 590 or less in HBW10 / 3000.

[0040] [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. It goes without saying that degassing and other treatments may be added. In order to maintain this, the heating temperature of the steel material, the finishing temperature during hot rolling, and the cooling rate are set appropriately. That is, from the viewpoint of ensuring the hot finish rolling end temperature, the steel material is preferably heated to a temperature of 1000 to 1250°C and then hot rolled into a desired size and shape, or, if the temperature of the steel material is high enough to be hot rolled, it is preferable to hot roll the steel material into a steel material of the desired size and shape without heating or by merely soaking it.

[0041] In hot rolling, in order to ensure strength, it is preferable to optimize the finish temperature of hot finish rolling and the cooling rate after completion of hot rolling. It is preferable to complete hot rolling at a temperature of 770°C or higher, air-cooling, and then reheating to 850 to 1000°C, and then immediately thereafter, or after a short standing time, cooling (e.g., 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 to finish cooling at a cooling stop temperature of 200°C or lower. Alternatively, immediately after completion of hot rolling, or after a short standing time, accelerated cooling (e.g., water cooling) from a cooling start temperature of 750°C or higher (in the case of water cooling, this is the water cooling start temperature) at a cooling rate of 0.5°C / s to 100°C / s may be performed, and the accelerated cooling may be finished at a cooling stop temperature of 200°C or lower. [Example]

[0042] Steels having the chemical compositions shown in Table 1 (the balance being Fe and unavoidable impurities) were melted in a vacuum melting furnace and cast into molds to produce 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.

[0043] (1) Surface hardness test Test pieces for surface hardness measurement were taken from the obtained steel sheets so that the measurement surface was 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 under a load of 3000 kgf. Measurements were taken at three points 0.5 mm from the surface, and the arithmetic average of the obtained measurements was calculated, and this average value was used as the surface hardness of the steel sheet.

[0044] (2) Corrosion and wear test Abrasion test specimens (size: 10 mmφ×75 mm length) were taken from the 1 / 4t portion (t indicates the plate thickness) of the obtained steel plate in the plate thickness direction. The test specimens were attached to an abrasion tester, and an abrasion test was carried out. Three abrasion test pieces were attached parallel to the rotation axis of the test machine rotor, at a 120-degree angle, 150 mm from the axis, 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 a weight ratio of silica sand to dilute sulfuric acid of 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. Furthermore, 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 as the ratio of the weight loss of each test piece to the weight loss of SS400, and if this ratio was 0.70 or less, it was evaluated as good.

[0045] (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 21.0 J or more at -40°C.

[0046] The evaluation results of (1) and (2) and (3) the toughness values measured by the Charpy test are shown in Table 2.

[0047] As shown in Table 2, all of the inventive examples have both surface hardness and corrosion wear resistance. In contrast, comparative steels 18 to 22 do not exhibit sufficient properties in terms of at least one of surface hardness and corrosion wear resistance, and comparative steels 23 and 24 do not exhibit sufficient properties in terms of toughness.

[0048] [Table 1]

[0049] [Table 2] [Industrial Applicability]

[0050] As described above, according to the present invention, it is possible to provide a thick steel plate used for components that require wear resistance in industrial machinery, transport equipment, etc., which has excellent corrosion resistance and wear resistance, particularly in acidic corrosive environments such as coal mining environments.

Claims

1. In mass%, C: 0.24% or more and less than 0.32%; Si: 0.05% or more and 0.40% or less, Mn: 0.10% or more and 2.00% or less, P: 0.030% or less (excluding 0%), S: 0.0300% or less (excluding 0%), Al: 0.010% or more and 0.070% or less, Cr: 3.00% or more and 11.50% or less; The balance has a composition consisting of Fe and unavoidable impurities, Surface hardness is Brinell hardness HBW10 / 3000, 460 to 590 A steel plate characterized by:

2. Furthermore, in mass%, Mo: 1.000% 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: 1.000% 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 one or more selected from the group consisting of:

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