KR102321270B1 - Wear resistant steel sheet and manufacturing method thereof - Google Patents

Abstract

Abrasion-resistant steel sheet according to an aspect of the present invention, by weight, C: 0.18 to 0.28%, Si: 0.05% or more, less than 0.1%, Mn: 0.8 to 1.4%, Mo: 0.08 to 0.18%, Ti: 0.01 ~0.03%, B: 0.001 ~ 0.003%, including the remaining Fe and unavoidable impurities, limiting Cr contained in the impurities to less than 0.02% (including 0%), Di defined by the following relation 1 is 1.0 ~ 2.0 range can be satisfied.
[Relational Expression 1]
Di (wt%) = 3 * {(0.54*[C]) * (1 + 2.07*[Mn]) * (1 + 0.7*[Si]) * (1 + 0.37*[Ni]) * (1 + 2.16*[Cr]) * (1 + 3.0*[Mo]) * (1 + 0.37*[Cu]) * (1 + 1.73*[V]) * (1 + 2.5*[Zr])}
In the above relation 1, [C], [Mn], [Si], [Ni], [Cr], [Mo], [Cu], [V] and [Zr] the content (% by weight) of each component means, and 0 is substituted if the corresponding component is not added.

Description

Wear resistant steel sheet and manufacturing method thereof

The present invention relates to a wear-resistant steel sheet used as a component material for industrial machines and the like and a method for manufacturing the same.

Steel is a material used in various fields due to its excellent strength, formability and economic feasibility, but it is not free from loss due to wear, which is a representative mechanism of material loss. Therefore, in the related industry, various studies have been made on steel materials with improved wear resistance properties.

In general, since hardness and abrasion resistance of steel are in a proportional relationship, a method of increasing hardness of steel may be used as a method to secure wear resistance of steel. A representative method for increasing the strength of steel is a method of using solid solution strengthening by the addition of carbon (C). When a large amount of carbon (C) is added, while securing the hardness of the material is advantageous, the possibility of distortion of the material increases in the cooling step after hot rolling due to the increased hardenability.

In particular, in the case of thin materials with a thickness of 6 mm or less, hot rolling using a hot-rolled coil is more economically advantageous than a plate-unit thick plate process, but the hot-rolled coil process is not actively applied to the production of the steel. situation. When the steel material is manufactured using a hot-rolled coil, serious shape distortion occurs at the front and rear ends, and the front and rear ends of the hot-rolled coil must be removed and discarded, so there is a problem in that the real rate is significantly lowered.

Patent Document 1 discloses a method of manufacturing a steel material using a soft continuous rolling mode. When the continuous rolling mode is applied, it is possible to effectively prevent the decrease in the real rate of the hot-rolled coil, but there is no realistic plan for securing the bondability of the material with high hardness and reducing the difference in the physical properties in the thickness direction of the material. .

Republic of Korea Patent Publication No. 10-2019-0006115 (2019.01.17, published)

According to one aspect of the present invention, an abrasion-resistant steel sheet and a method for manufacturing the same may be provided

The subject of the present invention is not limited to the above. A person of ordinary skill in the art will have no difficulty in understanding the further problems of the present invention from the overall content of the present specification.

The wear-resistant steel sheet according to an aspect of the present invention, by weight, C: 0.18 to 0.28%, Si: 0.05% or more, less than 0.1%, Mn: 0.8 to 1.4%, Mo: 0.08 to 0.18%, Ti: 0.01 ~0.03%, B: 0.001 ~ 0.003%, including the remaining Fe and unavoidable impurities, limiting Cr contained in the impurities to less than 0.02% (including 0%), Di defined by the following relation 1 is 1.0 ~ 2.0 range can be satisfied.

[Relational Expression 1]

Di (wt%) = 3 * {(0.54*[C]) * (1 + 2.07*[Mn]) * (1 + 0.7*[Si]) * (1 + 0.37*[Ni]) * (1 + 2.16*[Cr]) * (1 + 3.0*[Mo]) * (1 + 0.37*[Cu]) * (1 + 1.73*[V]) * (1 + 2.5*[Zr])}

In Relation 1, [C], [Mn], [Si], [Ni], [Cr], [Mo], [Cu], [V] and [Zr] is the content (% by weight) of each component. means, and 0 is substituted if the corresponding component is not added.

The microstructure of the thickness center of the steel sheet may be 80 area% or more of martensite and the remainder of bainite.

The surface Brinell hardness (HBW) of the steel sheet may be 420 to 480, and the Brinell hardness (HBW) at the center of the thickness of the steel sheet may be 400 to 480.

_{The steel sheet may have an R H} of 15% or less, which is defined by the following Relational Equation 2 below.

[Relational Expression 2]

R _H (%) = (R _S - R _C ) * 100 / R _S

In Relation 2, Rs is the Brinell hardness (HBW) of the surface of the steel sheet, and R _C is the Brinell hardness (HBW) of the center of the thickness of the steel sheet.

The thickness of the steel plate may be 1.5 ~ 6mm.

The maximum wave height of the steel sheet may be 10 mm or less.

The method of manufacturing a wear-resistant steel sheet according to an aspect of the present invention, by weight, C: 0.18 to 0.28%, Si: 0.05% or more, less than 0.1%, Mn: 0.8 to 1.4%, Mo: 0.08 to 0.18%, Ti: 0.01 to 0.03%, B: 0.001 to 0.003%, including the remaining Fe and unavoidable impurities, limiting Cr contained in the impurities to less than 0.02% (including 0%), Di defined by the following relation 1 Reheating the slab satisfying the range of 1.0 ~ 2.0; providing a hot-rolled steel sheet by hot rolling the reheated slab in a soft continuous rolling mode, but hot rolling in a temperature range of 850 to 1200°C; cooling the hot-rolled hot-rolled steel sheet to a cooling stop temperature of 250° C. or less at a cooling rate of 30 to 100° C./s; and winding the cooled hot-rolled steel sheet at the cooling stop temperature.

[Relational Expression 1]

Di (wt%) = 3 * {(0.54*[C]) * (1 + 2.07*[Mn]) * (1 + 0.7*[Si]) * (1 + 0.37*[Ni]) * (1 + 2.16*[Cr]) * (1 + 3.0*[Mo]) * (1 + 0.37*[Cu]) * (1 + 1.73*[V]) * (1 + 2.5*[Zr])}

In Relation 1, [C], [Mn], [Si], [Ni], [Cr], [Mo], [Cu], [V] and [Zr] is the content (% by weight) of each component. means, and 0 is substituted if the corresponding component is not added.

The method may further include correcting the shape by applying an external force to the wound hot-rolled steel sheet.

The slab reheating temperature is 1200 ~ 1300 ℃, the rolling end temperature of the hot rolling may be 850 ~ 950 ℃.

The thickness of the hot-rolled steel sheet may be 1.5 ~ 6mm.

According to one aspect of the present invention, it is possible to provide a steel sheet having excellent wear resistance and a method for manufacturing the same.

According to one aspect of the present invention, it is possible to provide a steel sheet having an excellent shape and a method for manufacturing the same by suppressing material deviation between the surface layer portion and the center portion, as well as a high real rate because the continuous rolling mode can be applied.

The effects of the present invention are not limited to the above, and may be interpreted as including technical effects that those skilled in the art can derive from the following description.

1 is a microstructure observation photograph of the center of specimen A.

The present invention relates to a wear-resistant steel sheet and a method for manufacturing the same, and preferred embodiments of the present invention will be described below. Embodiments of the present invention may be modified in various forms, and the scope of the present invention should not be construed as being limited to the embodiments described below. The present embodiments are provided in order to further detail the present invention to those of ordinary skill in the art to which the present invention pertains.

Hereinafter, the wear-resistant steel sheet according to an aspect of the present invention will be described in more detail.

The wear-resistant steel sheet according to an aspect of the present invention, by weight, C: 0.18 to 0.28%, Si: 0.05% or more, less than 0.1%, Mn: 0.8 to 1.4%, Mo: 0.08 to 0.18%, Ti: 0.01 ~0.03%, B: 0.001 ~ 0.003%, including the remaining Fe and unavoidable impurities, limiting Cr contained as the impurity to less than 0.02% (including 0%), Di defined by the following relation 1 is 1.0 ~ 2.0 range can be satisfied.

[Relational Expression 1]

Di (wt%) = 3 * {(0.54*[C]) * (1 + 2.07*[Mn]) * (1 + 0.7*[Si]) * (1 + 0.37*[Ni]) * (1 + 2.16*[Cr]) * (1 + 3.0*[Mo]) * (1 + 0.37*[Cu]) * (1 + 1.73*[V]) * (1 + 2.5*[Zr])}

In Relation 1, [C], [Mn], [Si], [Ni], [Cr], [Mo], [Cu], [V] and [Zr] is the content (% by weight) of each component. means, and 0 is substituted if the corresponding component is not added.

Hereinafter, the alloy composition of the present invention will be described in more detail. Hereinafter, unless otherwise specified, % and ppm related to the content of the alloy composition are based on weight.

The wear-resistant steel sheet according to an aspect of the present invention, by weight, C: 0.18 to 0.28%, Si: 0.05% or more, less than 0.1%, Mn: 0.8 to 1.4%, Mo: 0.08 to 0.18%, Ti: 0.01 ~0.03%, B: 0.001~0.003%, the remainder may contain Fe and unavoidable impurities.

Carbon (C): 0.18 to 0.28%

Carbon (C) is an element that effectively contributes to the improvement of the strength of steel through solid solution strengthening. Therefore, the present invention may contain 0.18% or more of carbon (C) to secure the desired hardness. A preferable carbon (C) content may be 0.19% or more, and a more preferable carbon (C) content may be 0.20% or more. On the other hand, when carbon (C) is excessively added, ductility and workability may become inferior, and bondability in continuous rolling may become inferior. The present invention limits the upper limit of the carbon (C) content to 0.28% can do. A preferable carbon (c) content may be 0.27% or less, and a more preferable carbon (C) content may be 0.25% or less.

Silicon (Si): 0.05% or more, less than 0.1%

Silicon (Si) is an element which improves the cleanliness of steel by the deoxidation effect. For this effect, the present invention may contain 0.05% or more of silicon (Si). A preferable silicon (Si) content may be 0.06% or more, and a more preferable silicon (Si) content may be 0.07%. However, when silicon (Si) is added excessively, it may cause surface defects in the final product by making it difficult to remove the surface scale, and may reduce the bondability between the preceding material and the succeeding material during continuous rolling. The silicon (Si) content may be limited to less than 0.1%. A preferable silicon (Si) content may be 0.09% or less, and a more preferable silicon (Si) content may be 0.08% or less.

Manganese (Mn): 0.8~1.4%

Manganese (Mn) is a hardenability improving element that effectively contributes to the formation of martensite up to the center of the material, and is an element that effectively contributes to the improvement of the strength of the material by solid solution strengthening. In addition, manganese (Mn) combines with sulfur (S) in steel to form MnS, so it is an element that effectively contributes to the reduction of cracks caused by impurities. Therefore, the present invention may contain 0.8% or more of manganese (Mn) for such an effect. A preferable manganese (Mn) content may be 0.9% or more, and a more preferable manganese (Mn) content may be 0.9% or more. On the other hand, manganese (Mn) is a representative segregation element, and when the manganese (Mn) content is excessive, a non-uniform band structure may be formed inside the material, resulting in poor material uniformity. In addition, when manganese (Mn) is added in excess of a certain amount, there may be a problem in that weldability is deteriorated. Accordingly, the present invention may limit the upper limit of the manganese (Mn) content to 1.4%. A preferable manganese (Mn) content may be 1.3% or less, and a more preferable manganese (Mn) content may be 1.2% or less.

Molybdenum (Mo): 0.08 to 0.18%

Since molybdenum (Mo) is an element that effectively contributes to the improvement of hardenability, the present invention may contain 0.08% or more of molybdenum (Mo) in order to secure the hardness of the center of the material. A preferable molybdenum (Mo) content may be 0.10% or more, and a more preferable molybdenum (Mo) content may be 0.12% or more. On the other hand, when the content of molybdenum (Mo) is excessive, it is not preferable in terms of weldability, and molybdenum (Mo) is an expensive element, and adding a large amount is not preferable in terms of economy. Therefore, the present invention may limit the upper limit of the molybdenum (Mo) content to 0.18%. A preferable molybdenum (Mo) content may be 0.17% or less, and a more preferable molybdenum (Mo) content may be 0.16% or less.

Titanium (Ti): 0.01~0.03%

Since titanium (Ti) is combined with nitrogen (N) in steel to form TiN, boron (B) added in steel is prevented from being lost to BN, and is an element that effectively contributes to securing effective B. Therefore, the present invention may contain 0.01% or more of titanium (Ti) for this effect. A preferable titanium (Ti) content may be 0.012% or more, and a more preferable titanium (Ti) content may be 0.015% or more. However, when titanium (Ti) is excessively added, there is a concern about deterioration of physical properties due to the formation of coarse precipitates, and the present invention may limit the upper limit of the titanium (Ti) content to 0.03%. A preferable upper limit of the titanium (Ti) content may be 0.028%, and a more preferable upper limit of the titanium (Ti) content may be 0.025%.

boron (B): 0.001 to 0.003%;

Boron (B) is an element capable of increasing hardenability with only a small amount of addition, and is also an element capable of delaying the transformation of ferrite by lowering the grain boundary energy of austenite. Therefore, the present invention may contain 0.001% or more of boron (B) for such an effect. A preferable content of boron (B) may be 0.0012% or more, and a more preferable content of boron (B) may be 0.0015% or more. On the other hand, when boron (B) is excessively added _{, it is precipitated in the form of Fe 23} (C, B) _{6 at} the austenite grain boundary and acts as a nucleus of ferrite transformation, which can rather reduce hardenability. Therefore, the present invention may limit the upper limit of the boron (B) content to 0.003%. A preferred content of boron (B) may be 0.0028% or less, and a more preferred content of boron (b) may be 0.0025% or less.

The wear-resistant steel sheet according to an aspect of the present invention may include the remainder Fe and other unavoidable impurities in addition to the above-described components. However, since unintended impurities from raw materials or the surrounding environment may inevitably be mixed in the normal manufacturing process, it cannot be completely excluded. Since these impurities are known to those of ordinary skill in the art, all contents thereof are not specifically mentioned in the present specification. In addition, addition of effective ingredients other than the above composition is not excluded.

In addition, the wear-resistant steel sheet according to an aspect of the present invention may limit the content of Cr contained in impurities to less than 0.02% (including 0%).

Chromium (Cr) is an element that contributes to the improvement of hardenability, but it is an element that can not only deteriorate the weldability of the material, but also significantly reduce the bondability of the preceding material and the succeeding material during continuous rolling. Therefore, the present invention does not artificially add chromium (Cr), and actively suppresses its content to less than 0.02% even if it is unavoidably added. A preferred chromium (Cr) content may be 0.01% or less.

In the abrasion-resistant steel sheet according to an aspect of the present invention, Di defined by the following relation 1 may satisfy the range of 1.0 to 2.0.

[Relational Expression 1]

Di (wt%) = 3 * {(0.54*[C]) * (1 + 2.07*[Mn]) * (1 + 0.7*[Si]) * (1 + 0.37*[Ni]) * (1 + 2.16*[Cr]) * (1 + 3.0*[Mo]) * (1 + 0.37*[Cu]) * (1 + 1.73*[V]) * (1 + 2.5*[Zr])}

In Relation 1, [C], [Mn], [Si], [Ni], [Cr], [Mo], [Cu], [V] and [Zr] is the content (% by weight) of each component. means, and 0 is substituted if the corresponding component is not added.

The inventor of the present invention performed an in-depth study on a component system that can secure hardness up to the center of the steel sheet while applying the soft continuous rolling mode. As a result, it was found that strict control of hardenability in the mutual relationship of each element as well as absolute content control of individual elements is an important factor, and Relation 1 defining the relative content relationship of individual elements was derived.

When Di specified in Relational Expression 1 is less than 1.0, the desired thickness center hardness cannot be secured. That is, the present invention intends to provide a steel sheet having a thickness of 1.5 to 6.0 mm, but when Di defined in Relation 1 is less than 1.0, sufficient hardenability cannot be secured, so even by applying a quenching condition, the desired core hardness can be secured. There are impossible problems. A preferred lower limit of Di may be 1.1, and a more preferred lower limit of Di may be 1.2. On the other hand, when Di defined in Relation 1 exceeds 2.0, the desired thickness center hardness of the present invention can be secured, but weldability is poor, and the jointability between the preceding material and the succeeding material during continuous rolling is significantly inferior. There is a problem with cancellation. That is, when Di defined in Relation 1 exceeds 2.0, since the continuous rolling mode cannot be applied, there is a problem in that productivity and real rate are lowered. A more preferable upper limit of Di may be 1.95.

In the wear-resistant steel sheet according to an aspect of the present invention, the microstructure at the center of the thickness of the steel sheet may be composed of 80 area% or more of martensite and the remainder ferrite. That is, since the present invention has martensite of 80 area% or more in the center of the thickness of the steel sheet, it is possible to effectively secure the hardness of the center of the thickness of the steel sheet. Here, the center of the thickness of the steel sheet may mean a region including a point 1/2 of the thickness of the steel sheet or an area from a point 1/4 to 3/4 of the thickness of the steel sheet.

The wear-resistant steel sheet according to one aspect of the present invention may have a surface Brinell hardness (HBW) of 420 to 480, and a thickness central Brinell hardness (HBW) of 400 to 480. Further, wear resistant steel sheet according to an aspect of the invention may be in the R _H is 15% or less defined by the relational expression (2) below. Brinell hardness (HBW) of the present invention means a hardness value measured using a tungsten carbide indenter (indenter).

[Relational Expression 2]

R _H (%) = (R _S - R _C ) * 100 / R _S

In Relation 2, Rs is the Brinell hardness (HBW) of the surface of the steel sheet, and R _C is the Brinell hardness (HBW) of the center of the thickness of the steel sheet.

Since the wear-resistant steel sheet according to an aspect of the present invention suppresses the occurrence of material deviation in the thickness direction of the steel sheet, it is possible to control the hardness deviation between the center of the steel sheet and the surface of the steel sheet to a certain level or less, and the maximum generated along the length direction of the steel sheet. The wave height may be limited to 10 mm or less. Accordingly, the wear-resistant steel sheet according to an aspect of the present invention may have excellent wear resistance as well as an excellent shape.

The wear-resistant steel sheet according to an aspect of the present invention may have a thickness of 1.5 to 6 mm.

Hereinafter, a method for manufacturing a wear-resistant steel sheet according to an aspect of the present invention will be described in more detail.

The method of manufacturing a wear-resistant steel sheet according to an aspect of the present invention, by weight, C: 0.18 to 0.28%, Si: 0.05% or more, less than 0.1%, Mn: 0.8 to 1.4%, Mo: 0.08 to 0.18%, Ti: 0.01 to 0.03%, B: 0.001 to 0.003%, including the remaining Fe and unavoidable impurities, limiting Cr contained in the impurities to less than 0.02% (including 0%), Di defined by the following relation 1 Reheating the slab satisfying the range of 1.0 ~ 2.0; providing a hot-rolled steel sheet by hot rolling the reheated slab in a soft continuous rolling mode, but hot rolling in a temperature range of 850 to 1200°C; cooling the hot-rolled hot-rolled steel sheet to a cooling stop temperature of 250° C. or less at a cooling rate of 30 to 100° C./s; and winding the cooled hot-rolled steel sheet at the cooling stop temperature.

[Relational Expression 1]

Di (wt%) = 3 * {(0.54*[C]) * (1 + 2.07*[Mn]) * (1 + 0.7*[Si]) * (1 + 0.37*[Ni]) * (1 + 2.16*[Cr]) * (1 + 3.0*[Mo]) * (1 + 0.37*[Cu]) * (1 + 1.73*[V]) * (1 + 2.5*[Zr])}

In Relation 1, [C], [Mn], [Si], [Ni], [Cr], [Mo], [Cu], [V] and [Zr] is the content (% by weight) of each component. means, and 0 is substituted if the corresponding component is not added.

In addition, the method of manufacturing a wear-resistant steel sheet according to an aspect of the present invention may further include the step of correcting the shape by applying an external force to the wound hot-rolled steel sheet.

slab reheat

After preparing a slab provided with a predetermined alloy composition, the temperature may be raised to a certain temperature range and reheated. Since the slab alloy composition content range and Relation 1 of the present invention correspond to the description of the alloy composition content range and Relation 1 of the above-described steel sheet, the description of the slab alloy composition content range and Relation 1 of the present invention is the alloy of the above-described steel sheet It is replaced with the description of the composition content range and Relational Equation 1. In addition, the slab reheating and hot rolling of the present invention may be carried out in a direct connection process, that is, in a continuous rolling mode.

The reheating of the slab of the present invention may be carried out in a normal temperature range, and any reheating conditions for destroying the non-uniform cast structure and securing a hot rolling temperature range to be described later may be sufficient. As a non-limiting example, the reheating of the slab of the present invention may be carried out in a temperature range of 1200 to 1300 °C.

hot rolled

Hot rolling can be performed on the reheated slab. Since the hot rolling of the present invention is performed by applying the continuous rolling mode, it is possible to continuously perform hot rolling after joining the rear end of the preceding material and the leading end of the succeeding material. In general, 2 to 10 slabs may be continuously hot-rolled.

The hot rolling temperature of the present invention may be in the range of 850 ~ 1200 ℃, in particular, in order to secure the desired central microstructure, the hot rolling end temperature may be limited to 850 ~ 950 ℃. A hot-rolled steel sheet having a thickness of 1.5 to 6 mm may be provided by hot rolling.

cooling and winding

In consideration of the fact that the cooling rate of the central portion of the steel sheet is generally slower than that of the surface portion of the steel sheet, in the present invention, cooling may be performed under rapid cooling conditions after hot rolling. Considering the desired central microstructure and equipment conditions, the preferred cooling rate may be 30-100° C./s. After cooling the hot-rolled steel sheet to a cooling stop temperature of 250°C or less, it can be wound and provided as a hot-rolled coil.

When the coiling temperature is too high, since there is concern about a decrease in hardness due to the tempering effect, in the present invention, the winding can be carried out after the cooling is finished at a cooling stop temperature of 250° C. or less. In addition, when the coiling temperature is too low, the shape defect of the steel sheet occurs due to material deviation, so there is a problem that an additional step such as shape fixing must be performed. Therefore, the preferred cooling stop temperature may be 150 ℃ or more, it is possible to carry out the winding in the temperature range.

shape correction

After winding, if necessary, the step of correcting the shape by applying an external force to the hot-rolled steel sheet may be performed. The shape correction method of the present invention is not limited to a specific method, and may be interpreted as a concept including all processes performed for shape correction of a steel sheet in general. As a non-limiting example, one or more of a skin pass mill, a tension leveler, a flattener, or a roll leveler may be used.

The steel sheet manufactured by the above-described manufacturing method, the microstructure of the center thickness of the steel sheet may be composed of more than 80 area% martensite and the remainder ferrite, the surface Brinell hardness (HBW) is 420 ~ 480, the thickness center Brinell hardness ( HBW) may be 400-480. In addition, in the steel sheet manufactured by the above-described manufacturing method, R _H defined by Relation 2 may be 15% or less, and the maximum wave height occurring along the length direction of the steel sheet may be 10 mm or less.

[Relational Expression 2]

R _H (%) = (R _S - R _C ) * 100 / R _S

In Relation 2, Rs is the Brinell hardness (HBW) of the surface of the steel sheet, and R _C is the Brinell hardness (HBW) of the center of the thickness of the steel sheet.

Hereinafter, the present invention will be described in more detail through examples. However, it is necessary to note that the examples described below are for illustrative purposes only and not for limiting the scope of the present invention.

(Example)

After preparing a slab having the alloy composition of Table 1, reheating of the slab was performed at 1250 °C. Thereafter, the reheated slab was hot-rolled to a thickness of 5 mm by applying the soft continuous rolling mode, and hot rolling was performed by applying the hot-rolling end temperature described in Table 2. After measuring the surface temperature, cooling the steel sheet by water cooling was performed. Thereafter, shape correction was performed using a skin pass mill and a tension leveler.

steel grade Alloy composition (wt%) [Relational Expression 1]
Di C Si Mn Cr Mo Ti B One 0.2 0.07 1.2 0.01 0.15 0.02 0.002 1.76 2 0.23 0.07 1.1 0.01 0.13 0.02 0.0015 1.83 3 0.17 0.08 One 0.01 0.15 0.02 0.002 1.33 4 0.3 0.06 0.9 0.01 0.1 0.02 0.002 1.93 5 0.22 0.07 1.1 0.2 0.01 0.03 0.0018 1.81 6 0.2 0.05 0.8 0.01 0.01 0.03 0.0013 0.94 7 0.23 0.15 1.1 0.01 0.13 0.02 0.0015 1.92 8 0.23 0.07 1.3 0.1 0.2 0.02 0.0015 2.81

Psalter
No. steel grade Rolling end temperature (℃) cooling rate
(℃/s) winding temperature
(℃) A One 902 80 170 B 881 52 221 C 2 910 84 165 D 877 45 231 E 730 85 211 F 850 15 210 G 910 115 20 H 3 900 80 210 I 4 905 75 185 J 5 911 82 205 K 6 908 69 211 L 7 911 65 215 M 8 897 60 223

For each specimen, microstructure and mechanical properties were measured, and the results are shown in Table 3. The microstructure was observed using an optical microscope and an electron scanning microscope after each specimen was cut and a mirror surface was prepared, corroded using a nital etching solution of 2 vol%. After repeatedly measuring the Vickers hardness (HV) with a load of 1 kgf, the average value was calculated, and it was converted into Brinell hardness (HBW) according to the following relational equation (3).

[Relational Expression 3]

Brinell hardness (HBW) = Vickers hardness (HV) * 0.9209 + 9.6861

Whether continuous continuity in Table 3 is possible means that when hot rolling in the soft continuous bonding mode is applied, bonding is not smoothly performed between the preceding material and the succeeding material. That is, when the preceding material and the succeeding material are not joined, it means a case in which cracks and cracks occur in the joint. The maximum wave height was measured by placing the specimen on a surface plate and measuring the difference in the maximum height between the valley and the crest formed in the specimen.

Psalter
NO. surface hardness
(HBW) central hardness
(HBW) [Relational Expression 2]
R _H center
martensite
fraction
(area %) maximum digging
(mm) consecutive
right or wrong A 432 410 5 100 8 O B 431 408 5 92 6 O C 471 444 6 100 9 O D 462 422 9 95 5 O E 395 384 3 75 2 O F 460 245 47 61 3 O G 460 430 7 100 21 O H 385 370 4 95 5 O I 540 510 6 94 3 X J 460 451 2 100 7 X K 432 388 10 62 4 O L 442 411 11 85 9 X M 464 451 3 91 7 X

In the case of specimens A to D satisfying the alloy composition and process conditions limited by the present invention, it can be confirmed that the hardness characteristics and shape characteristics are excellent, and the continuous rolling characteristics are excellent. 1 is a photograph of observation of the central microstructure of specimen A, and it can be confirmed that the central microstructure of the present invention is realized.

Specimens H to M satisfy the process conditions limited by the present invention, but do not satisfy the alloy composition limited by the present invention. It can be seen that it is difficult to simultaneously implement hardness characteristics, shape characteristics, and continuous rolling characteristics. .

Although the present invention has been described in detail through examples above, other types of embodiments are also possible. Therefore, the spirit and scope of the claims set forth below are not limited to the embodiments.

Claims (10)

By weight%, C: 0.18 to 0.28%, Si: 0.05% or more, less than 0.1%, Mn: 0.8 to 1.4%, Mo: 0.08 to 0.18%, Ti: 0.01 to 0.03%, B: 0.001 to 0.003%, remainder Fe and unavoidable impurities,
Limiting Cr contained in the impurities to less than 0.02% (including 0%),
A wear-resistant steel sheet, wherein Di defined by the following relational formula (1) satisfies the range of 1.2 to 2.0.
[Relational Expression 1]
Di (wt%) = 3 * {(0.54*[C]) * (1 + 2.07*[Mn]) * (1 + 0.7*[Si]) * (1 + 0.37*[Ni]) * (1 + 2.16*[Cr]) * (1 + 3.0*[Mo]) * (1 + 0.37*[Cu]) * (1 + 1.73*[V]) * (1 + 2.5*[Zr])}
In the above relation 1, [C], [Mn], [Si], [Ni], [Cr], [Mo], [Cu], [V] and [Zr] the content (% by weight) of each component means, and 0 is substituted if the corresponding component is not added.
According to claim 1,
The thickness center microstructure of the steel sheet is,
Abrasion-resistant steel sheet with more than 80 area% martensite and the balance bainite.
According to claim 1,
The surface Brinell hardness (HBW) of the steel sheet is 420 to 480,
Brinell hardness (HBW) at the center of the thickness of the steel sheet is 400 to 480, wear-resistant steel sheet.
4. The method of claim 3,
The steel sheet is an abrasion-resistant steel sheet, _{wherein R H} defined by the following relation 2 is 15% or less.
[Relational Expression 2]
R _H (%) = (R _S - R _C ) * 100 / R _S
In Relation 2, Rs is the Brinell hardness (HBW) of the surface of the steel sheet, and R _C is the Brinell hardness (HBW) of the center of the thickness of the steel sheet.
According to claim 1,
The thickness of the steel sheet is 1.5 ~ 6mm, wear-resistant steel sheet.
According to claim 1,
The maximum wave height of the steel plate is 10 mm or less, a wear-resistant steel plate.
By weight%, C: 0.18 to 0.28%, Si: 0.05% or more, less than 0.1%, Mn: 0.8 to 1.4%, Mo: 0.08 to 0.18%, Ti: 0.01 to 0.03%, B: 0.001 to 0.003%, remainder Reheating the slab including Fe and unavoidable impurities, but limiting Cr contained in the impurities to less than 0.02% (including 0%), and Di defined by the following Relational Expression 1 satisfies the range of 1.2 to 2.0;
providing a hot-rolled steel sheet by hot rolling the reheated slab in a soft continuous rolling mode, but hot rolling in a temperature range of 850 to 1200°C;
cooling the hot-rolled hot-rolled steel sheet to a cooling stop temperature of 250° C. or less at a cooling rate of 30 to 100° C./s; and
Including the step of winding the cooled hot-rolled steel sheet at the cooling stop temperature, a method of manufacturing a wear-resistant steel sheet.
[Relational Expression 1]
Di (wt%) = 3 * {(0.54*[C]) * (1 + 2.07*[Mn]) * (1 + 0.7*[Si]) * (1 + 0.37*[Ni]) * (1 + 2.16*[Cr]) * (1 + 3.0*[Mo]) * (1 + 0.37*[Cu]) * (1 + 1.73*[V]) * (1 + 2.5*[Zr])}
In the above relation 1, [C], [Mn], [Si], [Ni], [Cr], [Mo], [Cu], [V] and [Zr] the content (% by weight) of each component means, and 0 is substituted if the corresponding component is not added.
8. The method of claim 7,
The method of manufacturing a wear-resistant steel sheet further comprising the step of correcting the shape by applying an external force to the wound hot-rolled steel sheet.
8. The method of claim 7,
The slab reheating temperature is 1200 ~ 1300 ℃,
The rolling end temperature of the hot rolling is 850 ~ 950 ℃, a method of manufacturing a wear-resistant steel sheet.
8. The method of claim 7,
The thickness of the hot-rolled steel sheet is 1.5 ~ 6mm, a method of manufacturing a wear-resistant steel sheet.

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