JP4650013B2 - Abrasion resistant steel plate with excellent low temperature toughness and method for producing the same - Google Patents

Description

  The present invention relates to a wear-resistant steel plate used for industrial machines, transportation equipment, and the like and a method for manufacturing the same.

  Industrial machinery, parts, transportation equipment, etc. used in the fields of construction, civil engineering, mining, etc. (for example, excavators, bulldozers, hoppers, buckets, etc.) have excellent wear resistance to ensure their life Steel is used. In order to improve the wear resistance, it is necessary to increase the surface hardness by making the steel surface into a quenched structure. In general, the quenching hardness of steel can be ensured by increasing the amount of C. On the other hand, when the hardness increases, the material becomes brittle and the low temperature toughness deteriorates. Considering work in a low temperature range of 0 ° C. or lower, if the wear resistance is good but the low temperature toughness is low, brittle fracture occurs and the work is seriously hindered. For this reason, there is a demand for wear-resistant steel that has wear resistance and excellent low-temperature toughness.

  Several methods have been examined for such a requirement. For example, Patent Document 1, Patent Document 2, Patent Document 3, and the like disclose a technique for improving the toughness of a wear-resistant steel sheet by adding a large amount of an alloy element such as Cr or Mo. In these techniques, Cr is added for the purpose of improving hardenability, and Mo is added for the purpose of improving hardenability and at the same time improving the grain boundary strength. In Patent Documents 1 and 2, low temperature toughness is improved by performing tempering heat treatment.

  On the other hand, there is a technique disclosed in Patent Document 4 as a technique that devised a manufacturing process, and it is disclosed to improve toughness by expanding old γ grains by using ausfoam in a hot rolling process. .

  However, when the toughness is improved by strengthening the grain boundary strength by adding a large amount of alloying elements as in the techniques described in Patent Documents 1 to 3, there is a problem that the alloying element addition cost increases. Furthermore, in patent document 1 and patent document 2, the hardness most important as wear-resistant steel is reduced by performing tempering heat treatment, and wear resistance is deteriorated. Moreover, when using an ausfoam in a hot rolling process like the technique described in patent document 4, it is necessary to make the finishing temperature of hot rolling low, productivity is bad, and also for stable manufacture. A device such as strict temperature control is required, and it is not always an easy process in actual production.

As described above, it is difficult for the conventional technology to provide a wear-resistant steel sheet that is inexpensive and easy to make and has excellent low-temperature toughness. In particular, in a thick wear-resistant steel plate, the toughness of the wear-resistant steel deteriorates as the plate thickness increases, and therefore it is difficult to produce a wear-resistant steel plate with excellent low-temperature toughness.
JP-A-8-41535 JP-A-2-179842 JP-A 61-166554 JP 2002-20837 A

  This invention is made | formed in view of this situation, Comprising: It aims at providing the abrasion-resistant steel plate which can obtain the outstanding low temperature toughness without the difficulty of a process, and its manufacturing method.

  As a result of repeated studies to solve the above-mentioned problems, the inventors have made the steel composition a specific composition to which Nb has been added, and most of the steel composition has a martensitic structure that is finely quenched, so that the plate thickness can be compared. Even if it is thick, especially in the range of 25 to 100 mm, it is possible to obtain a steel sheet having both excellent low-temperature toughness and wear resistance. It has been found that by controlling the speed above a certain level, when the plate thickness is 25 to 100 mm, water cooling to 700 ° C. or less can be achieved by preventing precipitation of Nb compounds during the cooling process. It was.

The present invention has been completed based on such findings, and in terms of mass%, C: 0.10 to 0.35%, Si: 0.05 to 1.0%, Mn: 0.1 to 2 0.0%, P: 0.020% or less, S: 0.005% or less, Nb: 0.005 to 0.03%, Cu: 0.03 to 2.0%, Ni: 0.0. Contains one or more of 03-2.0%, Cr: 0.03-2.0%, Mo: 0.03-1.0%, V: 0.005-0.1% The formula (1) shown below is 4.5 or more, and consists of the balance Fe and inevitable impurities , and has excellent low temperature toughness characterized by having 90% or more of as-quenched martensite having a particle size of 25 μm or less. Provide wear-resistant steel sheets.
100 × (Cu + Ni + 4Cr + 6Mo + 4V) / t (1)
However,
Cu, Ni, Cr, Mo, V: Content of each element (mass%)

Moreover, this invention is mass%, C: 0.10-0.35%, Si: 0.05-1.0%, Mn: 0.1-2.0%, P: 0.020% or less S: 0.005% or less, Nb: 0.005-0.03%, Ti: 0.005-0.1%, Al : 0.035-0.1%, B: 0.0003-0. 002%, further Cu: 0.03-2.0%, Ni: 0.03-2.0%, Cr: 0.03-2.0%, Mo: 0.03-1.0% V: One or two or more of 0.005 to 0.1% is contained, the following formula (1) is 3.1 or more, the balance is Fe and inevitable impurities, and the particle size is 25 μm. Provided is a wear-resistant steel sheet having excellent low-temperature toughness, characterized by having 90% or more of the following as-quenched martensite.
100 × (Cu + Ni + 4Cr + 6Mo + 4V) / t (1)
However,
Cu, Ni, Cr, Mo, V: Content of each element (mass%)
t: Plate thickness (mm)

Furthermore, the present invention is mass%, C: 0.24 to 0.35%, Si: 0.05 to 1.0%, Mn: 0.1 to 2.0%, P: 0.020% or less. S: 0.005% or less, Nb: 0.005 to 0.03%, Cu: 0.03 to 2.0%, Ni: 0.03 to 2.0%, Cr: 0.005%. 3 to 2.0%, Mo: 0.03 to 1.0%, V: 0.005 to 0.1%, or one or more of them are contained, and the following formula (1) is 4. 5 or more, balance Fe and inevitable impurities , 90% or more of as-quenched martensite having a particle size of 25 μm or less, a plate thickness of 25 to 100 mm, a surface hardness of 450 HB or more in Brinell hardness Provided is a wear-resistant steel sheet having excellent low-temperature toughness characterized by being.
100 × (Cu + Ni + 4Cr + 6Mo + 4V) / t (1)
However,
Cu, Ni, Cr, Mo, V: Content of each element (mass%)
t: Plate thickness (mm)

Furthermore, the present invention is mass%, C: 0.24-0.35%, Si: 0.05-1.0%, Mn: 0.1-2.0%, P: 0.020%. Hereinafter, S: 0.005% or less, Nb: 0.005-0.03%, Ti: 0.005-0.1%, Al : 0.035-0.1%, B: 0.0003-0 0.002%, Cu: 0.03-2.0%, Ni: 0.03-2.0%, Cr: 0.03-2.0%, Mo: 0.03-1.0 %, V: One or more of 0.005 to 0.1%, the following formula (1) is 3.1 or more, the balance Fe and unavoidable impurities, 90% or more of as-quenched martensite of 25 μm or less, a plate thickness of 25 to 100 mm, and a surface hardness of 450 HB or more in terms of Brinell hardness It provides excellent abrasion steel sheet temperature toughness that.
100 × (Cu + Ni + 4Cr + 6Mo + 4V) / t (1)
However,
Cu, Ni, Cr, Mo, V: Content of each element (mass%)
t: Plate thickness (mm)

Furthermore, the present invention is mass%, C: 0.10 to 0.35%, Si: 0.05 to 1.0%, Mn: 0.1 to 2.0%, P: 0.020% Hereinafter, S: 0.005% or less, Nb: 0.005 to 0.03%, Cu: 0.03-2.0%, Ni: 0.03-2.0%, Cr: 0 0.03 to 2.0%, Mo: 0.03 to 1.0%, and V: 0.005 to 0.1%, containing one or more, and the following formula (1) is 4 .5 or more, and the steel slab comprising the balance Fe and inevitable impurities is heated to 1050 to 1250 ° C. and then hot-rolled, and the cooling rate after hot rolling is controlled to 0.5 ° C./s or more. There is provided a method for producing a wear-resistant steel sheet having excellent low-temperature toughness, which is cooled to 700 ° C. or lower and then reheated to 850 to 950 ° C. and quenched.
100 × (Cu + Ni + 4Cr + 6Mo + 4V) / t (1)
However,
Cu, Ni, Cr, Mo, V: Content of each element (mass%)
t: Plate thickness (mm)

Furthermore, the present invention is mass%, C: 0.10 to 0.35%, Si: 0.05 to 1.0%, Mn: 0.1 to 2.0%, P: 0.020% Hereinafter, S: 0.005% or less, Nb: 0.005-0.03%, Ti: 0.005-0.1% and / or Al: 0.035-0.1%, B: 0.0003 ~ 0.002%, Cu: 0.03-2.0%, Ni: 0.03-2.0%, Cr: 0.03-2.0%, Mo: 0.03-1 0.0%, V: steel containing one or more of 0.005 to 0.1%, the following formula (1) is 3.1 or more, and the balance is Fe and inevitable impurities The piece was heated to 1050 to 1250 ° C., hot-rolled, cooled to 700 ° C. or lower while controlling the cooling rate after hot rolling to 0.5 ° C./s or higher, and then 850 Provided is a method for producing a wear-resistant steel sheet having excellent low-temperature toughness, which is reheated to ˜950 ° C. and quenched.
100 × (Cu + Ni + 4Cr + 6Mo + 4V) / t (1)
However,
Cu, Ni, Cr, Mo, V: Content of each element (mass%)
t: Plate thickness (mm)

Furthermore, the present invention is mass%, C: 0.24-0.35%, Si: 0.05-1.0%, Mn: 0.1-2.0%, P: 0.020%. Hereinafter, S: 0.005% or less, Nb: 0.005 to 0.03%, Cu: 0.03-2.0%, Ni: 0.03-2.0%, Cr: 0 0.03 to 2.0%, Mo: 0.03 to 1.0%, and V: 0.005 to 0.1%, containing one or more, and the following formula (1) is 4 .5 or more, and the steel slab comprising the balance Fe and inevitable impurities is heated to 1050 to 1250 ° C., then hot-rolled to a thickness of 25 to 100 mm, and immediately cooled to 700 ° C. or less immediately after hot rolling, Then, the present invention provides a method for producing a wear-resistant steel sheet having excellent low-temperature toughness, which is reheated to 850 to 950 ° C. and quenched.
100 × (Cu + Ni + 4Cr + 6Mo + 4V) / t (1)
However,
Cu, Ni, Cr, Mo, V: Content of each element (mass%)
t: Plate thickness (mm)

Furthermore, the present invention is mass%, C: 0.24-0.35%, Si: 0.05-1.0%, Mn: 0.1-2.0%, P: 0.020%. Hereinafter, S: 0.005% or less, Nb: 0.005-0.03%, Ti: 0.005-0.1% and / or Al: 0.035-0.1%, B: 0.0003 ~ 0.002%, Cu: 0.03-2.0%, Ni: 0.03-2.0%, Cr: 0.03-2.0%, Mo: 0.03-1 0.0%, V: steel containing one or more of 0.005 to 0.1%, the following formula (1) is 3.1 or more, and the balance is Fe and inevitable impurities The piece was heated to 1050 to 1250 ° C., then hot-rolled to a thickness of 25 to 100 mm, immediately cooled to 700 ° C. or less immediately after hot rolling, and then 850 to 950 ° C. A method for producing a wear-resistant steel sheet excellent in low-temperature toughness, characterized by being reheated and quenched.
100 × (Cu + Ni + 4Cr + 6Mo + 4V) / t (1)
However,
Cu, Ni, Cr, Mo, V: Content of each element (mass%)
t: Plate thickness (mm)

  ADVANTAGE OF THE INVENTION According to this invention, the abrasion-resistant steel plate which can obtain the low-temperature toughness which is not accompanied by the difficulty of a process and is comparatively thick and can obtain the low temperature toughness and its manufacturing method can be obtained.

  Hereinafter, the present invention will be specifically described by dividing it into chemical components, structures, plate thicknesses, hardnesses, and manufacturing conditions.

[Chemical composition]
C: 0.10 to 0.35%
The wear-resistant steel sheet needs to have a predetermined hardness or more in order to exhibit the desired wear resistance, and the required hardness (wear resistance) varies depending on the use environment. C is an important element capable of ensuring a predetermined hardness and adjusting the hardness of the steel depending on its content. However, 0.10% or more is necessary to ensure the necessary hardness for wear-resistant steel. On the other hand, when C is added in a large amount exceeding 0.35%, weldability, toughness, and workability are improved. Deteriorate. Therefore, the C content is set to 0.10 to 0.35%. Further, in order to secure the surface hardness of 450 HB or more in terms of Brinell hardness, it is preferable to contain 0.24% or more of C.

Si: 0.05-1.0%
Si is an effective element as a deoxidizing element, and therefore, addition of 0.05% or more is necessary. Moreover, although it is an element effective also for solid solution strengthening, when the addition amount exceeds 1.0%, there are problems such as a decrease in ductility and an increase in inclusions. Therefore, the Si content is set to 0.05 to 1.0%.

Mn: 0.1 to 2.0%
Mn is an effective element from the viewpoint of ensuring hardenability, and therefore, addition of 0.1% or more is necessary. On the other hand, when it exceeds 2.0%, weldability deteriorates. For this reason, Mn content shall be 0.1-2.0%.

P: 0.020% or less Since P causes toughness deterioration when contained in a large amount, its content is set to 0.020% or less.

S: 0.005% or less Since S precipitates as MnS in steel and becomes a fracture starting point of high-strength steel as inclusions, leading to deterioration of toughness. Therefore, the content is made 0.005% or less.

Nb: 0.005 to 0.03%
Nb is an element that exists as a precipitate during reheating and quenching, and has an effect of refining the grain size. However, if it is less than 0.005%, this effect cannot be exhibited. Since the properties deteriorate, the content is made 0.005 to 0.03%.

Cu: 0.03-2.0%, Ni: 0.03-2.0%, Cr: 0.03-2.0%, Mo: 0.03-1.0%, V: 0.005- One or more of 0.1% or more Cu is an element that enhances hardenability, but if it is less than 0.03%, this effect cannot be exhibited, and if it exceeds 2.0%, hot workability In addition, when the Cu is added, the content is made 0.03 to 2.0%.

  Ni is an element that enhances hardenability and improves low-temperature toughness. However, if it is less than 0.03%, this effect cannot be exhibited, and if it exceeds 2.0%, the cost increases. When adding, let the content be the range of 0.03 to 2.0%.

  Cr is an element that enhances hardenability, but if it is less than 0.03%, this effect cannot be achieved. If it exceeds 2.0%, weldability deteriorates and costs increase, so Cr is added. When it does, the content shall be 0.03 to 2.0% of range.

  Mo is an element that enhances hardenability, but if it is less than 0.03%, this effect cannot be exhibited. If it exceeds 1.0%, weldability deteriorates and costs increase, so Mo is added. When it does, the content shall be 0.03-1.0% of range.

  V is an element that enhances hardenability. However, if less than 0.005%, this effect cannot be exhibited, and if it exceeds 0.1%, weldability deteriorates. The content is in the range of 0.005 to 0.1%.

Ti: 0.005-0.1% and / or Al: 0.035-0.1%
These have the effect of securing solid solution B effective in improving hardenability while improving toughness by fixing solid solution N harmful to toughness as TiN or AlN. Can be added. However, if Ti is less than 0.005% and Al is less than 0.035%, this effect cannot be exhibited, and if both exceed 0.1%, toughness deteriorates. Therefore, when these are added, the Ti content is 0.005 to 0.1%, the Al content is 0.035 to 0.1%, and at least one of them is added.

B: 0.0003 to 0.002%
It is an element that enhances hardenability by adding a small amount, and can be added as necessary. However, if the content is less than 0.0003%, this effect cannot be exhibited. If the content exceeds 0.002%, the toughness deteriorates. Therefore, when B is added, the content is 0.0003 to 0.002. % Range.

Formula (1): 4.5 or more, or 3.1 or more The following formula (1) is related to the microstructure of the steel sheet, and the microstructure of the steel sheet is related to toughness.
100 × (Cu + Ni + 4Cr + 6Mo + 4V) / t (1)
However,
Cu, Ni, Cr, Mo, V: Content of each element (mass%)
t: Plate thickness (mm)

  FIG. 1 shows the relationship between the value of formula (1), the martensite fraction, and toughness. Here, steels having various chemical composition were heated to 1150 ° C., rolled to 50 mm thickness, immediately cooled to 600 ° C., air cooled to room temperature, and then reheated to 900 ° C. and quenched. In the case of B-free steel, by setting the formula (1) ≧ 4.5, the martensite fraction of the microstructure of the steel sheet becomes 90% or more, and the toughness is improved. Further, in the case of B-added steel, by setting the formula (1) ≧ 3.1, the martensite fraction of the steel sheet becomes 90% or more and the toughness is improved. Therefore, in the case of B-free steel, the formula (1) ≧ 4.5, and in the case of B-added steel, the formula (1) ≧ 3.1. In addition, B addition steel here is steel which combined Ti and / or Al and B.

[Organization]
The steel sheet of the present invention has 90% or more of as-quenched martensite having a particle size of 25 μm or less. Thereby, the steel plate which has the outstanding low temperature toughness and abrasion resistance is obtained. If the grain size of the martensite as-quenched exceeds 25 μm, the desired low temperature toughness cannot be obtained, and if the martensite as-quenched is less than 90%, the desired wear resistance cannot be obtained. Such fine crystals are achieved by the precipitation of Nb-based compounds during reheating and quenching by adding Nb.

[Thickness]
In the present invention, the thickness of the steel sheet is not particularly limited, but is preferably in the range of 5 to 100 mm, and is particularly effective in the case of a relatively thick steel sheet of 25 to 100 mm, which has conventionally been difficult to obtain desired low temperature toughness. . On the other hand, if the plate thickness exceeds 100 mm, it is necessary to add a large amount of alloying elements in order to bring the value of the above formula (1) into the above range, leading to an increase in cost. Of course, when the cost is neglected and the plate thickness exceeds 100 mm, the effect of improving toughness can be obtained in the same manner.

[hardness]
The wear resistance increases as the hardness of the steel sheet surface increases. Usually, if the surface hardness is 300 B or more in Brinell hardness, it is preferable as wear-resistant steel. In a more severe environment (for example, in an environment where a hard ore is mined in a mine), the surface hardness is more preferably 450 HB or more in terms of Brinell hardness.

[Production conditions]
In the present invention, the steel slab having the above composition is heated to 1050 to 1250 ° C., then hot-rolled, and cooled to 700 ° C. or lower while controlling the cooling rate after hot rolling to 0.5 ° C./s or higher. Then, reheat to 850 to 950 ° C. and quench. In the case of a plate thickness of 25 to 100 mm, the steel slab having the above composition is heated to 1050 to 1250 ° C., then hot-rolled to a plate thickness of 25 to 100 mm, and immediately cooled to 700 ° C. or less immediately after hot rolling. Then, reheat to 850 to 950 ° C. and quench.

Heating temperature of steel slab: 1050-1250 ° C
When the heating temperature of the steel slab is less than 1050 ° C., the hot rolling finishing temperature is lowered, the deformation resistance is increased and the productivity is deteriorated, and when it exceeds 1250 ° C., surface flaws are generated on the steel sheet. Therefore, the heating temperature of the steel slab is in the range of 1050 to 1250 ° C.

Cooling rate after hot rolling: 0.5 ° C./s (or water cooling)
The cooling rate after rolling correlates with the particle size after reheating and quenching. FIG. 2 shows 0.21% C-0.38% Si-1.32% Mn-0.01% P-0.003% S-0.15% Cr-0.20% Mo-0.018% Nb. The result of investigating the relationship between the cooling rate after rolling and the particle size and toughness after reheating and quenching using -0.012Ti-0.0012% B steel is shown. The controlled cooling stop temperature at this time was room temperature. As shown in this figure, when the cooling rate is less than 0.5 ° C./s, the particle size after reheating and quenching becomes extremely coarse, and the toughness deteriorates. This is considered to be because when the cooling rate is less than 0.5 ° C./s, the Nb compound precipitates in the cooling process after rolling and does not precipitate during reheating and quenching. For this reason, the cooling rate after rolling shall be 0.5 degrees C / s or more. Such a cooling rate can be obtained even with normal air cooling equipment if the plate thickness is less than 25 mm, but if the plate thickness is 25 to 100 mm, the above cooling rate of 0.5 ° C./s or more is ensured after hot rolling. In order to prevent the precipitation of the Nb compound during the cooling process, water cooling is essential. In such a case, it is preferable to use a water cooling device capable of controlling the cooling rate. In addition, when the C content is high, there is a possibility that delayed fracture may occur under a remarkably fast cooling rate, so it is desirable to control to 0.5 to 15 ° C./s.

Cooling stop temperature (water cooling stop temperature): 700 ° C. or less The cooling stop temperature correlates with the particle size after reheating and quenching. FIG. 3 shows 0.21% C-0.38% Si-1.32% Mn-0.01% P-0.003% S-0.15% Cr-0.20% Mo-0.018% Nb. The result of having investigated the relationship between the controlled cooling stop temperature after rolling, a particle size, and toughness using -0.012Ti-0.0012% B steel is shown. As shown in FIG. 3, when the controlled cooling stop temperature exceeds 700 ° C., the particle size is remarkably coarsened and the toughness is deteriorated. Therefore, the cooling stop temperature is set to 700 ° C. or lower. In addition, when C content is high, since it may cause a delayed fracture if it cools to near room temperature under a high cooling rate, it is desirable to stop cooling at 700-500 degreeC.

Reheating quenching temperature: 850-950 ° C
When the reheating quenching temperature is less than 850 ° C., the transformation is not completed completely, and even if quenched as it is, an incompletely quenched structure is obtained. Moreover, when it exceeds 950 ° C., the austenite grain size during reheating becomes coarse, and as a result, the structure of the as-quenched martensitic steel becomes coarse, resulting in deterioration of toughness. Therefore, the reheating quenching temperature is set to a range of 850 to 950 ° C.

  In addition, conditions other than the conditions specified here, for example, hot rolling conditions, etc. are not particularly limited, and may be conditions normally employed.

Example 1
A steel piece having a thickness of 200 mm having chemical composition A to H shown in Table 1 was subjected to hot rolling-controlled cooling to a plate thickness of 12 to 100 mm under the production conditions shown in Table 2, and then reheated and quenched. No. 1 to 40 steel plates were obtained.

  No. 1, 2, 3, 5, 7, 9, 11, 12, 13, 15, 17, 19, 21, 22, 23, 25, 27, 29, 31, 32, 33, 35, 37, 39 For example, No. 4, 6, 8, 10, 14, 16, 18, 20, 24, 26, 28, 30, 34, 36, 38, 40 are comparative examples. About the obtained steel plate, structure | tissue observation was implemented and the martensite fraction and the particle size were measured. Further, surface hardness and low temperature toughness were measured as characteristic values.

  The hardness was based on JIS Z2243, and an average value of 5 points randomly selected on the steel sheet surface was used. The low temperature toughness was measured in accordance with JIS Z2242, and the fracture surface transition temperature was measured. The obtained hardness (HB) and low temperature toughness (vTs: [° C.]) are also shown in Table 2.

  As shown in Table 2, the present invention has high hardness effective as a wear-resistant steel and has 90% or more of as-quenched martensite having a particle size of 25 μm or less, and therefore has a fracture surface transition temperature in the Charpy impact test. It was low and it was confirmed that it has good toughness in a low temperature range. On the other hand, although the comparative example has a high surface hardness, the fracture surface transition temperature is high and the toughness is deteriorated because the grain size of as-quenched martensite exceeds 25 μm. confirmed.

(Example 2)
A steel piece having a thickness of 200 mm having chemical composition compositions I to Q shown in Table 3 was subjected to hot rolling and water cooling to a plate thickness of 25 to 100 mm under the manufacturing conditions shown in Table 4, and then reheated and quenched. . Steel plates 41 to 73 were obtained.

  No. Nos. 41, 44, 45, 46, 47, 53, 55, 57, 59, 62, 63 and 64 are examples of the present invention. 42, 43, 48, 49, 50, 51, 52, 54, 56, 58, 60, 61, 65 to 73 are comparative examples. About the obtained steel plate, structure | tissue observation was implemented and the martensite fraction and the particle size were measured. Further, as characteristic values, surface hardness and low temperature toughness were measured in the same manner as in Example 1. The obtained hardness (HB) and low temperature toughness (vTs: [° C.]) are also shown in Table 4.

  As shown in Table 4, the present invention example has a high hardness effective as a wear-resistant steel, the value of the formula (1) is appropriate, and it has 90% or more of as-quenched martensite having a particle size of 25 μm or less. It was confirmed that the fracture surface transition temperature in the Charpy impact test was low and that the steel had good toughness in the low temperature range. In contrast, No. of the comparative example. 42, 43, 49, 50, 51, 52, 60, 61, 65 to 73 have a low martensite fraction because the value of the formula (1) is low. 48, 50, 52, 54, 56, and 58 are not cooled immediately after rolling, or the cooling stop temperature is as high as over 700 ° C., so that the grain size is coarse and the toughness is low. Was confirmed.

  INDUSTRIAL APPLICABILITY The present invention can obtain a wear-resistant steel plate having excellent low-temperature toughness while ensuring stable wear resistance, and is effective in the fields of industrial machines, parts, transporting equipment, etc. used in cold regions. The utility value is high.

The figure which shows the relationship between the value of Formula (1), the particle size after reheating quenching, and toughness. The figure which shows the relationship between the cooling rate after rolling, and the particle size and toughness after reheating quenching. The figure which shows the relationship between the water cooling stop temperature after rolling, a particle size, and toughness.

Claims (8)

In mass%, C: 0.10 to 0.35%, Si: 0.05 to 1.0%, Mn: 0.1 to 2.0%, P: 0.020% or less, S: 0.005 %, Nb: 0.005 to 0.03%, Cu: 0.03 to 2.0%, Ni: 0.03 to 2.0%, Cr: 0.03 to 2.0% , Mo: 0.03 to 1.0%, V: One or more of 0.005 to 0.1% is contained, and the following formula (1) is 4.5 or more, and the balance A wear-resistant steel sheet excellent in low-temperature toughness, characterized by comprising 90% or more of as-quenched martensite having a grain size of 25 μm or less, comprising Fe and inevitable impurities.
100 × (Cu + Ni + 4Cr + 6Mo + 4V) / t (1)
However,
Cu, Ni, Cr, Mo, V: Content of each element (mass%)
t: Plate thickness (mm) In mass%, C: 0.10 to 0.35%, Si: 0.05 to 1.0%, Mn: 0.1 to 2.0%, P: 0.020% or less, S: 0.005 %: Nb: 0.005-0.03 %, Ti 0.005-0.1 %, Al : 0.035-0.1%, B: 0.0003-0.002%, and Cu : 0.03-2.0%, Ni: 0.03-2.0%, Cr: 0.03-2.0%, Mo: 0.03-1.0%, V: 0.005-0 .1% or more of 1%, the following formula (1) is 3.1 or more, the balance is Fe and inevitable impurities, and the as-quenched martensite having a particle size of 25 μm or less A wear-resistant steel sheet having excellent low-temperature toughness, characterized by having 90% or more.
100 × (Cu + Ni + 4Cr + 6Mo + 4V) / t (1)
However,
Cu, Ni, Cr, Mo, V: Content of each element (mass%)
t: Plate thickness (mm) In mass%, C: 0.24 to 0.35%, Si: 0.05 to 1.0%, Mn: 0.1 to 2.0%, P: 0.020% or less, S: 0.005 %, Nb: 0.005 to 0.03%, Cu: 0.03 to 2.0%, Ni: 0.03 to 2.0%, Cr: 0.03 to 2.0% , Mo: 0.03 to 1.0%, V: One or more of 0.005 to 0.1% is contained, and the following formula (1) is 4.5 or more, and the balance It is composed of Fe and inevitable impurities, has 90% or more of as-quenched martensite with a particle size of 25 μm or less, a plate thickness of 25 to 100 mm, and a surface hardness of 450 HB or more in Brinell hardness. Wear-resistant steel sheet with excellent low-temperature toughness.
100 × (Cu + Ni + 4Cr + 6Mo + 4V) / t (1)
However,
Cu, Ni, Cr, Mo, V: Content of each element (mass%)
t: Plate thickness (mm) In mass%, C: 0.24 to 0.35%, Si: 0.05 to 1.0%, Mn: 0.1 to 2.0%, P: 0.020% or less, S: 0.005 %: Nb: 0.005-0.03%, Ti: 0.005-0.1%, Al : 0.035-0.1%, B: 0.0003-0.002%, Furthermore, Cu: 0.03-2.0%, Ni: 0.03-2.0%, Cr: 0.03-2.0%, Mo: 0.03-1.0%, V: 0.005 -0.1% of one or two or more, the following formula (1) is 3.1 or more, the balance is made of Fe and inevitable impurities, and the as-quenched marten having a particle size of 25 μm or less Excellent resistance to low temperature toughness, characterized by having 90% or more sites, a plate thickness of 25 to 100 mm, and a surface hardness of 450 HB or more in Brinell hardness.耗鋼 plate.
100 × (Cu + Ni + 4Cr + 6Mo + 4V) / t (1)
However,
Cu, Ni, Cr, Mo, V: Content of each element (mass%)
t: Plate thickness (mm) In mass%, C: 0.10 to 0.35%, Si: 0.05 to 1.0%, Mn: 0.1 to 2.0%, P: 0.020% or less, S: 0.005 %, Nb: 0.005 to 0.03%, Cu: 0.03 to 2.0%, Ni: 0.03 to 2.0%, Cr: 0.03 to 2.0% , Mo: 0.03 to 1.0%, V: One or more of 0.005 to 0.1% is contained, and the following formula (1) is 4.5 or more, and the balance A steel slab composed of Fe and inevitable impurities is heated to 1050 to 1250 ° C. and then hot-rolled, and cooled to 700 ° C. or lower while controlling the cooling rate after hot rolling to 0.5 ° C./s or higher. Then, a method for producing a wear-resistant steel sheet having excellent low-temperature toughness, characterized by reheating to 850 to 950 ° C. and quenching.
100 × (Cu + Ni + 4Cr + 6Mo + 4V) / t (1)
However,
Cu, Ni, Cr, Mo, V: Content of each element (mass%)
t: Plate thickness (mm) In mass%, C: 0.10 to 0.35%, Si: 0.05 to 1.0%, Mn: 0.1 to 2.0%, P: 0.020% or less, S: 0.005 %: Nb: 0.005-0.03%, Ti: 0.005-0.1% and / or Al: 0.035-0.1%, B: 0.0003-0.002% Cu: 0.03-2.0%, Ni: 0.03-2.0%, Cr: 0.03-2.0%, Mo: 0.03-1.0%, V: 0 A steel slab containing one or more of 0.005 to 0.1%, the following formula (1) is 3.1 or more, and the balance is Fe and unavoidable impurities is 1050 to 1250 ° C. , Then hot rolled, cooled to 700 ° C. or lower while controlling the cooling rate after hot rolling to 0.5 ° C./s or higher, and then reheated to 850-950 ° C., A method for producing a wear-resistant steel sheet having excellent low-temperature toughness, characterized by quenching.
100 × (Cu + Ni + 4Cr + 6Mo + 4V) / t (1)
However,
Cu, Ni, Cr, Mo, V: Content of each element (mass%)
t: Plate thickness (mm) In mass%, C: 0.24 to 0.35%, Si: 0.05 to 1.0%, Mn: 0.1 to 2.0%, P: 0.020% or less, S: 0.005 %, Nb: 0.005 to 0.03%, Cu: 0.03 to 2.0%, Ni: 0.03 to 2.0%, Cr: 0.03 to 2.0% , Mo: 0.03 to 1.0%, V: One or more of 0.005 to 0.1% is contained, and the following formula (1) is 4.5 or more, and the balance A steel slab composed of Fe and inevitable impurities is heated to 1050 to 1250 ° C., then hot-rolled to a thickness of 25 to 100 mm, immediately cooled to 700 ° C. or less immediately after hot rolling, and then reheated to 850 to 950 ° C. A method for producing a wear-resistant steel sheet having excellent low-temperature toughness, characterized by heating and quenching.
100 × (Cu + Ni + 4Cr + 6Mo + 4V) / t (1)
However,
Cu, Ni, Cr, Mo, V: Content of each element (mass%)
t: Plate thickness (mm) In mass%, C: 0.24 to 0.35%, Si: 0.05 to 1.0%, Mn: 0.1 to 2.0%, P: 0.020% or less, S: 0.005 %: Nb: 0.005-0.03%, Ti: 0.005-0.1% and / or Al: 0.035-0.1%, B: 0.0003-0.002% Cu: 0.03-2.0%, Ni: 0.03-2.0%, Cr: 0.03-2.0%, Mo: 0.03-1.0%, V: 0 A steel slab containing one or more of 0.005 to 0.1%, the following formula (1) is 3.1 or more, and the balance is Fe and unavoidable impurities is 1050 to 1250 ° C. And then hot-rolled to a thickness of 25 to 100 mm, immediately water-cooled to 700 ° C. or less immediately after hot rolling, and then reheated to 850 to 950 ° C. and quenched. A method for producing a wear-resistant steel sheet having excellent low-temperature toughness.
100 × (Cu + Ni + 4Cr + 6Mo + 4V) / t (1)
However,
Cu, Ni, Cr, Mo, V: Content of each element (mass%)
t: Plate thickness (mm)

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