JP2019504192A - High hardness wear resistant steel with excellent toughness and cut crack resistance, and method for producing the same - Google Patents

Abstract

The present invention relates to high hardness wear resistance excellent in toughness and cut cracking resistance and a method for producing the same.
The high-hardness wear-resistant steel according to one aspect of the present invention is, by weight ratio, Mn: 2.1 to 4.0%, C: 0.15 to 0.2%, Si: 0.02 to 0.5 %, Cr: 0.2 to 0.7%, balance Fe, and other inevitable impurities are included, the prior austenite grain size is 25 μm or less, and the microstructure is martensite as the main structure. , Ac3-Ac1 satisfies the condition that it is 100 ° C. or lower.
[Selection] Figure 1

Description

  The present invention relates to a high hardness wear resistant steel excellent in toughness and cut cracking resistance, and a method for producing the same. The present invention uses Korean Patent Application No. 10-2015-0179009 as a basis for claiming priority, and incorporates the entire contents thereof into the present invention as a reference.

  In the field of manufacturing industrial equipment such as mining dump trucks, heavy equipment for construction, and earthen equipment, there is a high demand for wear-resistant steel having a high hardness of Brinell hardness of 450 or more, although not necessarily limited thereto.

  Wear resistant steels must basically have high surface hardness, but martensitic high hardness steels not only have high hardness but also high yield strength and tensile strength, so structural materials and transportation / construction Widely used for applications such as machinery.

  By the way, in general, in order to manufacture martensitic high-hardness steel, it has a high carbon content in order to ensure so-called quenchability, and has a component system containing a large amount of alloy elements, and in the manufacturing process. A quenching process is essential.

  However, since conventional martensitic steel contains a large amount of carbon and alloy elements as components, it not only adversely affects weldability and low-temperature toughness, but also occurs when cutting steel to a desired size. There exists a problem that the tolerance with respect to the crack of a cut part, ie, a cut cracking resistance, worsens.

  One aspect of the present invention is wear-resistant steel, which is a high-hardness wear-resistant steel having high toughness and cut cracking resistance while relatively reducing the amount of addition of an alloying element such as C that adversely affects toughness. Is to provide.

  Moreover, the other side surface of this invention is providing the manufacturing method which can manufacture the above-mentioned high-hardness wear-resistant steel efficiently.

  The subject of this invention is not limited to the above-mentioned content. Anyone having ordinary knowledge in the technical field to which the present invention pertains has no difficulty in understanding further problems of the present invention from the overall contents of the present specification.

  The high-hardness wear-resistant steel according to one aspect of the present invention is, by weight ratio, Mn: 2.1-4.0%, C: 0.15-0.2%, Si: 0.02-0.5%, Cr: 0.2 to 0.7%, balance Fe, and other inevitable impurities, a prior austenite grain size of 25 μm or less, martensite is the main structure, Ac3 -Ac1 satisfies the condition that 100C or less.

  According to another aspect of the present invention, the method for producing a high hardness wear resistant steel is Mn: 2.1-4.0%, C: 0.15-0.2%, Si: 0.02-0 in weight ratio. 0.5%, Cr: 0.2 to 0.7%, the balance Fe, and the stage which hot-rolls the slab which has a composition which consists of other inevitable impurities, and obtains a steel plate, and the said steel plate is 3 degrees C / sec or more. A step of quenching to a temperature of 200 ° C. or less at a cooling rate, a step of reheating the rapidly cooled steel plate to an austenite temperature region, and a temperature of 200 ° C. or less at a cooling rate of 3 ° C./second or more. Secondary quenching.

  As described above, the present invention increases the Mn content instead of optimizing the C content in the steel, and by making the crystal grains ultrafine, while maintaining the hardness of the steel at 450 HB class, high toughness And the steel material which has cut | disconnection cracking resistance can be provided.

  The effects of the present invention are not limited to the contents described above, and further effects of the present invention can be fully understood from the further contents of the specification.

It is the figure which showed the result of having performed EBSD (Electron Back Scatter Diffraction) analysis with respect to the heat affected zone formed at the time of gas cutting. 2 is a photomicrograph of an observed structure of Invention Example 1, Comparative Example 1, and Comparative Example 2 obtained from Example 1. FIG.

  Hereinafter, the present invention will be described in detail.

  In the present invention, in order to ensure the low temperature toughness of the wear-resistant steel, the C content of the steel material is adjusted to an appropriate range, and a large amount of Mn is added to ensure hardenability. In addition, the alloy components are appropriately controlled to ensure cut cracking resistance. Hereinafter, the composition of the present invention will be described.

  The wear-resistant steel of the present invention is, by weight ratio, Mn: 2.1 to 4.0%, C: 0.15 to 0.2%, Si: 0.02 to 0.5%, Cr: 0.2 It can have a composition containing ~ 0.7%, the balance Fe, and other inevitable impurities. In the present invention, it should be noted that the content of each component is displayed on the basis of weight unless otherwise indicated.

Mn: 2.1-4.0%
Mn (manganese) is an element added to stabilize martensite and to obtain high surface hardness. In this invention, in order to acquire this effect, 2.1% or more of Mn is added. When the Mn content is insufficient, ferrite or bainite is likely to be generated, and it becomes difficult to obtain high hardness of the surface layer portion. However, when the content exceeds 4.0%, not only the weldability and cut cracking resistance are remarkably lowered, but also the problem that the manufacturing cost of the steel material is lowered may occur. Therefore, in the present invention, the Mn content is added in the range of 2.1 to 4.0%.

C: 0.15-0.2%
C (carbon) is an element necessary for securing the hardness of the surface layer portion of the steel material together with Mn. However, if the amount is excessive, there is a problem that the toughness and weldability are deteriorated, so it is necessary to control within an appropriate range. In the present invention, C is added in an amount of 0.15% or more in order to sufficiently secure the hardness of the surface layer portion. However, if added excessively, the toughness, weldability and the like deteriorate, so the upper limit of the content is 0. Limit to 20%.

Si: 0.02 to 0.5%
Si (silicon) plays a role as a deoxidizer and acts as an element for improving strength by solid solution strengthening. In addition, since the content cannot be reduced to a very small amount in the manufacturing process, the lower limit of the Si content is set to 0.02%. However, if the content is too high, the toughness of the base metal as well as the welded portion is reduced, so the Si content is limited to 0.5% or less.

Cr: 0.2-0.7%
When contained in steel, Cr (chromium) is an element that plays a role of increasing the hardenability of the steel, and facilitates securing martensite during quenching. In addition, the wear resistant steel of the present invention improves the low temperature impact toughness as the content increases, and plays a role of increasing the resistance to cutting cracks by narrowing the interval between Ac1 and Ac3 which are phase transformation temperatures. In order to obtain the advantageous effect of Cr, the content is advantageously 0.2% or more. However, if the amount is excessive, the weldability may be lowered and the manufacturing cost may be increased, so the upper limit of the Cr content can be set to 0.7%.

  Moreover, the wear-resistant steel of the present invention may further contain Nb: 0.1% or less, B: 0.02% or less, and Ti: 0.1% or less in addition to the alloy elements described above.

Nb: 0.1% or less Nb (niobium) is an element that increases the strength of steel by solid solution and precipitation hardening effect, and refines crystal grains to improve impact toughness, and is added as necessary. Can do. However, when the content is excessive, coarse precipitates are formed and the hardness and impact toughness are rather deteriorated. Therefore, the content can be limited to 1.0% or less.

B: 0.02% or less B (boron) is an element that effectively enhances the hardenability of the material even when added in a small amount, and is necessary because it has the effect of suppressing grain boundary destruction by strengthening the grain boundaries. It can be added and used accordingly. However, when the content is excessive, the toughness and weldability are lowered due to the formation of coarse precipitates, and therefore the content is preferably limited to 0.02% or less.

Ti: 0.1% or less Although N (nitrogen) is mentioned as an impurity element inevitably contained in the steel material, N combines with B to adversely affect the effect of B. Ti (titanium) is an element having an effect of maximizing the effect of addition of B by suppressing the decrease in the effect of B by such N. That is, Ti acts to suppress the formation of BN by reacting with N present in the steel to form TiN. In addition, TiN also has an effect of suppressing a coarsening of crystal grains by pinning austenite crystal grains. Therefore, in this invention, Ti can be added in steel as needed. However, when the addition amount of Ti is excessive, coarse precipitates may be formed and the toughness and weldability may be reduced, so the content can be limited to 0.1% or less.

  The remaining component of the present invention is Fe (iron). However, in an ordinary steel manufacturing process, unintended impurities may be inevitably mixed in from the raw material or the surrounding environment, so this is not particularly excluded in the wear resistant steel of the present invention. Since these types can be understood by any ordinary engineer, the type and content thereof are not particularly limited in the present invention.

The wear-resistant steel of the present invention can limit the value of Ac3-Ac1 to 100 ° C. or less in addition to the above-described component system in order to improve the cut cracking resistance.
According to the results of research conducted by the inventors of the present invention, the cutting crack generated during gas cutting is a kind of hydrogen-induced cracking, and the residual stress generated in the heat affected zone (particularly, Inter Critical Heat Affected Zone: ICHAZ) The larger the size, the more often it occurs. That is, reducing the residual stress in the heat-affected zone is one means for improving the cut cracking resistance. Therefore, in the present invention, it is proposed to adjust the value of Ac3-Ac1.
Ac3 means a temperature at which pro-eutectoid ferrite begins to be generated in austenite during cooling, and Ac1 means a temperature at which the structure completely transforms into ferrite. According to the research results of the present inventors, when the value of Ac3-Ac1 is adjusted, the residual stress of ICHAZ can be remarkably reduced, and the occurrence of cracks in this portion can be reduced. The reason is that the large Ac3-Ac1 value means that the temperature range in the region where the two structures of austenite and ferrite coexist is wide, and therefore, when cooling after cutting, two of austenite and martensite are used. This is because the ICHAZ in which the tissue exists becomes large, and thus a large stress remains inside due to the difference in volume change between the two tissues.
FIG. 1 shows the result of EBSD (Electron Back Scatter Diffraction) analysis performed on the heat-affected zone formed during gas cutting. In the upper part of the drawing, the Kernel average misation map in which the structure of the weld heat affected zone is observed is shown, and in the lower part, the region where the residual stress is concentrated is shown. As can be seen from the drawing, the present inventors have found that ICHAZ is displayed darkest, and it has been found that the residual stress is concentrated on ICHAZ. That is, when the Ac3-Ac1 value, which has the effect of reducing the size of ICHAZ, is controlled to 100 ° C. or less, excellent cut crack resistance can be obtained.

  Therefore, in one implementation example of the present invention, the value of Ac3-Ac1 can be limited to 100 ° C. or less.

  The wear-resistant steel according to another aspect of the present invention has an internal structure in which the prior austenite grain size of the surface is 25 μm or less and martensite is included as a main structure. In the present invention, the “main structure” means a structure having the highest occupation ratio by area fraction. According to one implementation, the wear resistant steel of the present invention can include 95% or more of martensite in area fraction. That is, martensite having a fine particle size has an effect of improving low temperature toughness. In order to have high hardness and excellent wear resistance, the martensite fraction is preferably 95% or more. In the present invention, the prior austenite grain size can be a value obtained by observing a structure corroded with a picric acid corrosive solution with an optical microscope (for example, having a magnification of 200 times) in accordance with the provisions of JIS G0551.

  In particular, the wear-resistant steel of the present invention has a fine grain size and excellent toughness, and it is not necessary to perform an additional tempering step to ensure toughness. That is, the martensite of the wear resistant steel of the present invention is substantially free of carbide precipitates formed as a result of tempering. Therefore, it should be noted that the fact that martensite does not contain carbide-based precipitates in the present invention means that it does not contain "substantially".

  In one example of realization of the present invention, the thickness of the steel sheet can be in the range of 80 mm or less that can ensure the hardness of the central part up to 400 HB. The lower the thickness, the easier the cooling and the more advantageous for ensuring the hardness. However, according to an embodiment of the present invention, the thickness of the wear resistant steel can be set to 3 mm or more in consideration of the fact that the wear resistant steel is manufactured by hot rolling.

  The wear resistant steel of the present invention that satisfies such conditions can have a value of 420 to 480 on the basis of Brinell hardness, and can have excellent toughness with a Charpy impact energy at −40 ° C. of 35 J or more. According to another embodiment of the present invention, the wear-resistant steel of the present invention is a steel plate manufactured to a thickness of, for example, 11 mm, and is cut at 400 mm or more under the condition of not preheating at the time of gas cutting and the cutting speed of 500 mm / min. Then, after one week or more has passed, it can have cut cracking resistance such that cut cracks do not occur. In particular, the wear-resistant steel of the present invention can only have high wear resistance without substantially adding alloy elements such as Mo and Ni that are usually added to the wear-resistant steel in order to increase wear resistance. In addition, it has the effect of being excellent in toughness and cut cracking resistance.

  Although not necessarily limited thereto, one advantageous method for producing the wear resistant steel of the present invention is proposed as follows. That is, in the method for producing wear-resistant steel according to the present invention, after hot rolling a steel material, quenching is immediately performed to obtain martensite, and then this is heated to the austenite temperature range and then quenched again. It can be manufactured by the process. Each process will be described in detail as follows.

Hot rolling process The hot rolling process can be performed by a usual method. However, the hot rolling end temperature can be set in a range of Ar3 to 900 ° C. based on the surface portion so as to be compatible with the subsequent quenching process. That is, when hot rolling is performed to a temperature lower than Ar3, excessive ferrite is formed inside the steel material, and the problem that the intended structure cannot be obtained in the subsequent quenching process may occur. The rolling end temperature can be Ar3 or higher. In one implementation example of the present invention, the hot rolling end temperature may be set to 800 ° C. or higher. In addition, when the hot rolling end temperature is too high, the austenite crystal grain size before quenching becomes coarse, and the resulting martensite packet size is difficult to be sufficiently refined. Can be set to 900 ° C. or lower.

Hardening immediately after hot rolling (Direct quenching)
In the present invention, the steel material is immediately quenched immediately after hot rolling. Here, “immediately” means that quenching is started in a state where the surface temperature of the steel material does not fall below the austenite region. When quenching immediately after hot rolling as in the present invention, the martensite transformation occurs in a state where crystal grains are refined by hot rolling, so that the obtained martensite can be refined. There is. In the present invention, the quenching immediately after the hot rolling is performed at a cooling rate of 3 ° C./second or more until the center temperature of the steel material is 200 ° C. or less (according to one realization example, from room temperature to 200 ° C.) Can be The higher the cooling rate, the more advantageous. Therefore, it is not necessary to set the upper limit of the cooling rate in particular. However, considering the normal quenching process, the cooling rate can be set to a range of 50 ° C./second or less. The steel material hot-rolled by the above process has its structure transformed from austenite to martensite.

Reheating The steel material that has been hot-rolled and quenched is then subjected to a reheating process. When a steel material containing martensite is heated to the austenite temperature region, the boundaries of the already formed martensite internal packets all act as austenite nucleation sites, and austenite nucleation occurs at many positions. Therefore, the resulting austenite crystal grains can be very fine in size.

  For that purpose, it is necessary to heat the quenched steel material to a temperature of Ac3 or higher with reference to the center. However, if the heating temperature is too high, the austenite grain size may increase again, so the upper limit of the heating temperature can be set to 960 ° C.

  According to an embodiment of the present invention, it is preferable to maintain a heat treatment time (also referred to as a maturing heat time) of 120 minutes or less after the central portion of the steel sheet reaches the Ac3 temperature. Considering a sufficient heat treatment effect, a time of 20 minutes or more may be required. However, the said time can also be changed little by little according to the thickness of a steel plate, and when the thickness of a steel plate is thick, it can also be maintained for a longer time.

Secondary quenching The steel material austenitized by the above-described process is cooled to a temperature of 200 ° C. or less (according to one realization example, any temperature from room temperature to 200 ° C.) at the central portion again at a cooling rate of 3 ° C./second or more. The Through such a process, martensite having a fine grain size is formed in the wear resistant steel of the present invention at an area fraction of 95% or more. In an embodiment of the present invention, the austenite immediately before the secondary quenching may have a crystal grain size of 25 μm or less. By making the austenite structure just before the secondary quenching fine, the packet size of the final martensite obtained can be controlled very finely. In the present invention, the size of austenite immediately before secondary quenching can be confirmed by measuring the crystal grain size of prior austenite of the steel material finally obtained.

  The upper limit of the cooling rate in the secondary quenching process is not particularly limited, but can be limited to 50 ° C./second or less in one implementation example of the present invention.

  According to the above process, it is possible to provide a wear resistant steel having excellent toughness having a value of 420 to 480 on the basis of Brinell hardness and a Charpy impact energy at −40 ° C. of 35 J or more. Further, according to another embodiment of the present invention, the wear-resistant steel manufactured by the manufacturing method of the present invention is, for example, a steel plate manufactured to a thickness of 11.8 mm under conditions that do not preheat at the time of gas cutting and 500 mm / After cutting for 400 mm or more under the condition of min cutting speed, it can have a cutting crack resistance such that no cracking occurs even after one week or more.

  Hereinafter, the present invention will be described more specifically through examples. However, it should be noted that the examples described below are merely intended to illustrate and embody the present invention and are not intended to limit the scope of the present invention. The scope of the right of the present invention is defined by the claims and cases reasonably inferred therefrom.

[Example 1]
(Invention Example 1)
In order to confirm the effect of the production method of the present invention, by weight ratio, C: 0.19%, Mn: 2.6%, Si: 0.2%, Cr: 0.4%, Nb: 0.04 %, Ti: 0.01%, B: 0.002%, and a slab having a thickness of 70 mm with Ac3-Ac1 of 91 ° C. is rolled at 800 ° C., which is equal to or higher than the Ar3 temperature, and thick. After obtaining a 11.8 mm steel plate, it was immediately quenched to 200 ° C. with high-pressure water. The cooling rate at this time was 20 ° C./second, and 96% martensite was formed on the steel sheet in an area ratio.

  Thereafter, the steel sheet is heated to a temperature of 910 ° C. with respect to the central portion, and after maintaining for 60 minutes after the central portion reaches Ac3, the steel plate is heated at a cooling rate of 20 ° C./second with respect to the central portion. The final product was obtained by second quenching to 0 ° C.

[Comparative Example 1]
The process up to the process of quenching after hot rolling was carried out in the same manner as in Invention Example 1, and the final product was obtained by omitting additional reheating and secondary quenching.

[Comparative Example 2]
A final product was obtained in the same manner as in Invention Example 1 except that it was air-cooled to room temperature without being rapidly cooled after hot rolling.

  The results of observation of the structures of Invention Example 1, Comparative Example 1, and Comparative Example 2 with a microscope are shown in FIG. In FIG. 2, (a) shows Invention Example 1, (b) shows Comparative Example 1, and (c) shows Comparative Example 2. As can be seen from the drawings, 95% or more of martensite is formed in each of Invention Example 1, Comparative Example 1, and Comparative Example 2 (specifically, Invention Example 1 is 96 based on area). %, Comparative Examples 1 and 2 have 100% martensite formed), and the prior austenite crystal grain size (grain size of the region divided by the solid line in the drawing) is 20 μm in the case of Invention Example 1, However, Comparative Example 1 and Comparative Example 2 confirmed that the prior austenite grain size was 31 μm and 28 μm, respectively, which were outside the conditions defined in the present invention.

  As a result, the Brinell hardness of Invention Example 1, Comparative Example 1, and Comparative Example 2 were 460, 462, and 455, respectively, indicating sufficient hardness values. Moreover, as a result of testing the cut cracking resistance according to one embodiment of the present invention, all showed good results. However, Invention Example 1 shows high low temperature toughness with Charpy impact energy at −40 ° C. of 42 J, while Comparative Example 1 and Comparative Example 2 have Charpy impact energy at −40 ° C. of only 20 J and 22 J, respectively. It was confirmed that the toughness level defined in the present invention was not satisfied. Thereby, the effect of the manufacturing method by one implementation example of this invention has been confirmed.

[Example 2]
A slab having the composition described in Table 1 below was produced under the same conditions as in Invention Example 1 of Example 1 to obtain wear-resistant steel, and the analysis results for the obtained wear-resistant steel are shown in Table 2. . Comparative Example 7 in Table 2 shows the analysis results when a slab having the same composition as Invention Example 7 was produced by the same method as Comparative Example 2 of Example 1 above. In particular, cutting cracks tend to occur as the cutting speed increases and the thickness of the steel sheet increases under conditions of no residual heat (no preheating) during gas cutting. This is because the residual stress formed in the portion increases under the above conditions. Such cut cracks are characterized by hydrogen delayed cracks that occur after a period of up to about a week after cutting. Therefore, in order to evaluate the cutting cracking resistance, when cutting a steel plate manufactured to a thickness of 11.8 mm without preheating, after cutting at 400 mm or more under the condition of a cutting speed of 500 mm / min, one week It was determined whether or not a cut crack occurred even after the lapse of the above, and "-" was displayed when the cut crack occurred and "O" was displayed when it did not occur. In Table 2, impact toughness means Charpy impact energy measured at −40 ° C.

  For the analysis in Table 2, specimens of the appropriate form for testing were prepared. The microstructure was analyzed using an optical microscope and a scanning electron microscope (SEM), and the hardness of the surface layer portion was measured using a Brinell hardness meter after grinding to a depth of about 2 mm from the surface.

  First, considering from the viewpoint of wear resistance and low temperature toughness, Comparative Example 3 in which the contents of C and Mn are lower than the values specified in the present invention has a Brinell hardness of only 410, which is required in the present invention. It was judged not to have wear resistance. Comparative Example 4 is not only advantageous for ensuring toughness, but also is an example in which no Cr was added to reduce the space between Ac1 and Ac3 and increase the resistance to cut cracking. As a result, the impact toughness was 67J, which was very low. Comparative Example 5 was an example in which C was added excessively, and the hardness was sufficient, but the Charpy impact energy was only 22 J, and the low-temperature toughness was very poor. In Comparative Example 6, the C content was only 0.14%, the Brinell hardness was only 408, and the level required by the present invention was not satisfied. In Comparative Example 7, although the composition of the steel material satisfies the conditions of the present invention, it is a case where air cooling is performed after hot rolling, and coarse crystal grains are formed with a prior austenite grain size of 38 μm, resulting in a decrease in low temperature toughness. Results were obtained.

  Further, from the viewpoint of cutting crack resistance, Comparative Example 4 and Comparative Example 6 are cases where the value of Ac3-Ac1 exceeds 100 ° C. and does not satisfy the conditions of the present invention. After cutting under the given conditions, a result that a crack occurred after one week passed was obtained. In the case of the comparative example 5, although the temperature interval of Ac3-Ac1 was narrow, the cutting crack occurred, but the reason is that the Brinell hardness is too high, and the cutting conditions used in this measurement method are compared with the hardness. This is because it was a severe condition.

  Therefore, it was confirmed that not satisfying the conditions of the steel material defined in the present invention, not only the low temperature toughness and the wear resistance but also the cutting crack resistance could not be satisfied.

Claims (10)

By weight, Mn: 2.1% to 4.0%, C: 0.15% to 0.2%, Si: 0.02% to 0.5%, Cr: 0.2% to 0.7% %, The balance Fe, and other inevitable impurities,
The prior austenite grain size is 25 μm or less, and has a microstructure in which martensite is the main structure,
A high-hardness wear-resistant steel excellent in toughness and cut cracking resistance, characterized in that Ac3-Ac1 satisfies a condition of 100 ° C. or less.   The toughness and cut crack resistance according to claim 1, further comprising Nb: 0.1% or less, B: 0.02% or less, and Ti: 0.1% or less by weight ratio. High hardness wear resistant steel.   The wear-resistant steel excellent in toughness and cut crack resistance according to claim 1 or 2, wherein the martensite is contained in an area fraction of 95% or more.   The high hardness wear resistant steel excellent in toughness and cut crack resistance according to claim 1 or 2, wherein the Brinell hardness is 420 to 480, and the Charpy impact energy at -40 ° C is 35 J or more.   3. The high-hardness wear-resistant steel having excellent toughness and cut cracking resistance according to claim 1, wherein the martensite contains no carbides inside. 3. By weight, Mn: 2.1% to 4.0%, C: 0.15% to 0.2%, Si: 0.02% to 0.5%, Cr: 0.2% to 0.7% %, The balance Fe, and the stage which hot-rolls the slab which has a composition which consists of other inevitable impurities, and obtaining a steel plate,
Quenching the steel sheet to a temperature of 200 ° C. or less at a cooling rate of 3 ° C./second or more;
Reheating the quenched steel sheet to an austenite temperature range;
Secondary quenching the reheated steel sheet at a cooling rate of 3 ° C./second or more to a temperature of 200 ° C. or less;
A method for producing a high-hardness wear-resistant steel excellent in toughness and cut cracking resistance, characterized by comprising:   The toughness and cut crack resistance according to claim 6, further comprising Nb: 0.1% or less, B: 0.02% or less, and Ti: 0.1% or less by weight ratio. A method for producing high hardness wear resistant steel.   The method for producing wear-resistant steel having excellent toughness and cut crack resistance according to claim 6 or 7, wherein the hot rolling end temperature is Ar3 or higher.   The method for producing wear-resistant steel with excellent toughness and cut crack resistance according to claim 6 or 7, wherein a heating temperature in the reheating step is Ar3 to 960 ° C.   The method for producing a wear-resistant steel excellent in toughness and cut crack resistance according to claim 6 or 7, wherein the austenite grain size of the steel sheet to be secondarily quenched is 25 µm or less.

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