JP2004323874A - Slitter blade and its manufacturing method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a slitter blade which is composed of tool steel having high toughness and high wear resistance and is practically free from edge chipping over a long period of time even if used for cutting steel sheets, and to provide a method for manufacturing the slitter blade. <P>SOLUTION: The slitter blade is composed of matrix high speed steel having a composition containing, by mass, Fe as a principal component, 0.7 to 0.9% C, 0.15 to 0.35% Si, ≤2% Mn, 5 to 6% Cr, 2.5 to 3.5% Mo and 1.8 to 2.3% V. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

【００２９】
【表２】

【００３０】
上記実施鋼１〜５及び比較鋼１１〜１６の試験品に対し、以下の特性評価を行った。
・硬さ評価
前記試験品の外周面のロックウェルＣスケール硬さＨＲＣを、ＪＩＳ：Ｚ２２４５に規定された方法により測定した。
・靭性評価
シャルピー衝撃試験により実施した。試験片は、前記試験品の長手方向から切り出した１０Ｒ・Ｃ型ノッチ試験片（ノッチ深さ２ｍｍ、Ｒ径１０ｍｍ）とし、ＪＩＳ：Ｚ２２４２に規定された方法によりシャルピー衝撃試験を行って、シャルピー衝撃値を測定した。
・耐磨耗性評価
焼なまし材で製造したφ３０、幅３ｍｍのスリッタ刃のリング円周面を、リング外周の回転速度を１ｍ／ｓｅｃとして、平板試験片（ＳＣＭ４２５鋼）に荷重１００ｋｇｆで２００ｍこすりつけ、摩耗幅から算定した摩耗体積により耐摩耗性を評価した。
以上の評価結果を表３に示す。
【００３１】
また、上記実施鋼１〜５及び比較鋼１１〜１６からなるスリッタ刃に対して、以下の条件の寿命試験を行った。厚さ０．５ｍｍのＳＰＣＣ鋼を、スリッタ刃により一定のバリが発生するまで切断し、その切断長さを測定した。条件は、加圧１ｔ、回転数１００ｒｐｍである。なお、各々の測定値は比較鋼１１の切断長さを１００としたときの、比で表している。
以上の試験結果を表３に示す。
【００３２】
さらに、上記実施鋼１〜５及び比較鋼１１〜１６の試験品に対し、硝酸アルコールにより表面のエッチングを行い、ＳＥＭ−ＥＤＸ装置（元素分析機器付き走査型電子顕微鏡）を用いて表面における炭化物組織の形態観察を行った。具体的には、観察視野において以下のパラメータを測定した。
・Ｍ_６Ｃ炭化物が占める面積をＡ、ＭＣ炭化物が占める面積をＢとしたときの面積比Ａ／（Ａ＋Ｂ）。
・ＭＣ炭化物の外形線に接する最大幅平行線の間隔をＣ、最小幅平行線の間隔をＤとしたときの最小最大幅比Ｄ／Ｃ。
・最大幅平行線の間隔Ｃが５μｍ以上４０μｍ以下のＭＣ炭化物の個数（視野面積０．０１ｍｍ^２当たり）
表４に観察結果を示す。
【００３３】
【表３】

【００３４】
【表４】

【００３５】
表３の評価結果によると、ロックウェルＣスケール硬さにおいて、実施鋼１〜５の平均がＨＲＣ５９、比較鋼１１〜１６の平均がＨＲＣ５７、と実施鋼の方が若干の高硬度を有する。靭性を表すシャルピー衝撃値では、実施鋼の方が、比較鋼１１〜１５よりも大きく、高靭性を有することがわかる。耐磨耗性を表す摩耗体積では、実施鋼の方が、比較鋼１１、１２、１４〜１６よりも小さく、高耐磨耗性を有することがわかる。これによると、実施鋼では高靭性及び高耐磨耗性が両立しており、本発明のスリッタ刃に好適に用いることができると予想される。なお、比較鋼について、靭性が優れている比較鋼１６は耐磨耗性に劣り、また耐磨耗性が優れている比較鋼１３は靭性に劣るという結果になっており、靭性と耐磨耗性の両立がなされていない。また、スリッタ刃の寿命試験は、実施鋼からなるスリッタ刃の方が比較鋼のものよりも、２．０５〜１３．３３倍程度大きく、長寿命であることがわかる。つまり、上記実施鋼の高靭性及び高耐磨耗性を証明する結果となっている。
【００３６】
また、実施鋼４及び５と比較鋼１４の高温ソーキングを施した鋼材は、高温ソーキングを施してないものと比べて、更に靭性、耐磨耗性、及びスリッタ刃の寿命が向上していることがわかる。これによって、高温ソーキングが鋼の靭性及び耐磨耗性の向上に寄与していると考えられる。
【００３７】
表４の炭化物の形態観察結果によると、面積比Ａ／（Ａ＋Ｂ）は、実施鋼では全て０．２５以下となっており、比較鋼１４〜１６と比べて、Ｍ_６Ｃ炭化物が少なく、ＭＣ炭化物が多く生成している。また、最小最大幅比Ｄ／Ｃは、実施例では全て０．４５以上となっており、全ての比較例と比べて、より球状に近い形態となっている。さらに、高温ソーキングを施した発明鋼４、５は、施していない発明鋼１〜３と比べてもＤ／Ｃが大きく、より球状に近い形態となっている。また、視野面積０．０１ｍｍ^２当たりにおける最大幅平行線の間隔Ｃが５μｍ以上４０μｍ以下のＭＣ炭化物の個数は、実施例では全て２０個を超えており、比較鋼１１、１２、１４〜１６と比べて多くなっている。さらに、高温ソーキングを施した発明鋼４、５は、施していない発明鋼１〜３と比べても個数が多い。
【００３８】
以上の結果から、高温ソーキングにより、ＭＣ炭化物の形状がより球状化し、また靭性に影響を及ぼさない程度の大きさのＭＣ炭化物が適度に分散することがわかる。これらは、オストワルド成長によるものと推測される。これにより、高温ソーキングはＭＣ炭化物を球状化且つ径大化させるため、鋼の靭性及び耐磨耗性を向上させることがわかる。
【図面の簡単な説明】
【図１】スリッタ刃の主面を表す模式図
【図２】スリッタ刃の断面を表す模式図
【図３】スリッタ刃を用いた裁断を表す模式図
【図４】図３における２つのスリッタ刃の近接した部分を拡大した図
【符号の説明】
１ スリッタ刃
２ 外周縁
２１ 鋭角部（刃先）
３ 挿通孔
３１ 凹部
４ａ、４ｂ 回転軸部
５ 裁断される鋼板
６ 裁断領域[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a slitter blade and a method of manufacturing the same, and more particularly, to a slitter blade that has a small number of chip edges for a long time even after cutting a steel plate, and a method of manufacturing the slitter blade.
[0002]
[Prior art]
In recent years, a slitter blade, particularly a slitter blade for cutting a steel plate or the like, is particularly required among tools, and is required to have a hard cutting edge and a long life. Therefore, tool steel used as a material for the slitter blade is required to have high toughness and high wear resistance in addition to high hardness required for cutting.
[0003]
In general, selection according to the use of tool steel is performed by selecting a desired toughness among carbon steel, high Cr steel, and high-speed tool steel (so-called high-speed steel) having Rockwell C scale hardness of, for example, high hardness of about HRC60. And those having abrasion resistance. Of these, steels that actively utilize crystallized carbides formed in a solidified state are used in applications that require abrasion resistance, and typical examples thereof include M ₇ C ₃ carbides. high C high Cr-based cold die steel utilizing (JIS: SKD11 other), high-speed tool steel utilizing _{M 6} C and MC carbides (JIS: SKH51 other) can be mentioned. On the other hand, for applications requiring particularly toughness, a matrix type steel (hereinafter, referred to as a matrix high-speed steel) having a base composition of a high-speed tool steel as a main component is used.
[0004]
[Problems to be solved by the invention]
However, in applications where high toughness and high wear resistance are required at the same time, such as slitter blades, there is no tool steel suitable for that purpose. Attempts have been made to bring the contents of elements such as Mo and W, which are forming elements, closer to the composition of high-speed tool steel (so-called high-speed steel) to enhance hardness and wear resistance. The original toughness was impaired, and a material that could withstand practical use could not be obtained.
[0005]
Further, in order to improve abrasion resistance, a hardness commensurate with the abrasion resistance is required. Therefore, it is essential to increase the hardness. However, today's quenching and tempering treatments are generally performed in a vacuum heat treatment furnace, and the amount of Cr is increased in order to improve the hardenability corresponding to vacuum quenching and increase the hardness. There has been a problem that the -W-based crystallized carbides are coarsened and the toughness is also reduced.
As described above, it is difficult to achieve both high toughness and high wear resistance in tool steel, and at present, there is no tool steel suitable as a material for the slit blade.
[0006]
Therefore, an object of the present invention is to provide a slitter blade made of tool steel having high toughness and high abrasion resistance and having a small chipping of the cutting edge for a long time even when cutting a steel plate, and a method of manufacturing the slitter blade. That is.
[0007]
Means for Solving the Problems and Functions / Effects of the Invention
In order to solve the above-mentioned problems, the present inventors have conducted intensive studies on tool steel that can be suitably used for a slitter blade, and as a result, it has been found that a matrix high-speed steel (hereinafter, referred to as SKH51) having a base composition of a high-speed tool steel as a main component. SKH51-based matrix high-speed steel), it is possible to reduce the crystallization of M ₆ C carbides and increase the crystallization of MC carbides, and to increase the crystallinity of Cr for increasing the hardness. A composition of a matrix high-speed steel capable of preventing coarsening of carbides has been found.
[0008]
That is, the slitter blade of the present invention
Fe as a main component,
0.7% by mass or more and 0.9% by mass or less of C;
0.15% by mass or more and 0.35% by mass or less of Si;
Mn of 2% by mass or less;
5% by mass or more and 6% by mass or less of Cr;
2.5% by mass or more and 3.5% by mass or less of Mo;
V of 1.8% by mass or more and 2.3% by mass or less;
And a matrix high-speed steel containing
[0009]
In the above matrix high-speed steel, MC carbide and M ₆ C carbide exist as primary carbides that are directly crystallized from a molten state. Since MC carbide has higher hardness than M ₆ C carbide, in the matrix high-speed steel having high toughness, the proportion of M ₆ C carbide among the primary carbides to be crystallized should be smaller and the proportion of MC carbide should be larger. Thus, the hardness and wear resistance of the steel can be reinforced, whereby a matrix high-speed steel having high hardness, high toughness and high wear resistance, which can be suitably used for a slitter blade can be obtained. . Further, among MC carbides, those containing V (so-called VC carbides) have particularly high hardness, so that the hardness and wear resistance of steel can be further reinforced by positively increasing VC carbides. It becomes.
[0010]
Specifically, in the matrix high-speed steel, the MC carbide and the M ₆ C carbide present in the steel indicate that the area occupied by the M ₆ C carbide is A and the area occupied by the MC carbide is B on the observed sectional structure. , The area ratio A / (A + B) is 0.25 or less.
[0011]
As means for observing the cross-sectional structure, for example, a publicly known SEM-EDX apparatus, that is, an SEM (Scanning Electron Microscope: scanning electron microscope) and an EDX (Energy-Dispersive X-ray Spectroscopy: energy-dispersive X-ray analyzer) Can be performed by using a device in which is combined. This enables two-dimensional mapping of the composition on the surface, so that it is possible to distinguish between MC carbides and M ₆ C carbides, and to know the morphology of these carbides.
[0012]
Further, the present inventors have found that the above-mentioned crystallized MC carbide can improve the wear resistance of steel when the stress concentration is close to a spherical shape with little stress concentration when a load is applied. To obtain such a shape, it has been found that it is effective to subject steel to high-temperature soaking.
[0013]
Specifically, in the above matrix high-speed steel, the MC carbide present in the steel was defined as C, the interval between the maximum width parallel lines in contact with the outline observed on the cross-sectional structure, and D, the interval between the minimum width parallel lines. Sometimes, the minimum / maximum width ratio D / C is 0.4 or more. As described above, when the shape of the MC carbide approaches the sphere, the stress concentration when a load is applied can be reduced. Further, it is more preferable that the minimum / maximum width ratio D / C is 0.6 or more.
[0014]
Also, if the crystallized carbide is too large, it causes a decrease in the toughness of the steel. However, in the matrix high-speed steel, MC carbide having a size that does not affect the toughness (for example, the maximum width parallelism) Line spacing C is defined as 40 μm or less, and larger ones (for example, the maximum width parallel line spacing C is defined as 5 μm or more) are more spherical in shape than smaller ones. It turned out that. Further, since the MC carbide having a size in such a range (a shape capable of further reducing stress concentration) is appropriately dispersed in the steel, the wear resistance of the steel can be further improved. Specifically, in the matrix high-speed steel, among the MC carbides present in the steel, those having an interval C between the maximum width parallel lines of 5 μm or more and 40 μm or less have a visual field area of 0.01 mm ² on a cross-sectional structure of 20 mm per 0.01 mm ^2. When there is more than one, the wear resistance is further improved. Further, the number is more preferably 50 or more.
[0015]
In addition, high-temperature soaking is required to form the MC carbide into the above-described form. Specifically, a cast or forged steel containing the above-mentioned components is subjected to a temperature of 1150 ° C or more and 1280 ° C or less. For 10 hours or more and 100 hours or less. By performing such a heat treatment, the MC carbides in the steel undergo Ostwald ripening (small particles of the precipitate particles disappear and large particles grow). It is conceivable that the minimum / maximum width ratio D / C increased and became closer to a sphere, and the number of particles having a relatively large particle size (the interval C between the parallel lines of the maximum width was 5 μm or more and 40 μm or less) increased and was appropriately dispersed. More preferably, heat treatment is performed at a temperature of 1180 ° C. to 1240 ° C. for 20 hours to 50 hours.
[0016]
Hereinafter, the reasons for limiting each numerical range in the present invention will be described.
The reasons for limiting the composition of the matrix high-speed steel used for the slitter blade of the present invention are as follows.
Fe (iron): main component The matrix high-speed steel is based on exhibiting a function as a slitter blade, and Fe is an essential component for constituting steel, and is therefore contained as a main component.
[0017]
C (carbon): 0.7% by mass or more and 0.9% by mass or less C is necessary for improving the hardenability of steel by solid solution in the matrix and increasing the hardness of martensite at the time of quenching. Element. It is also necessary to combine with the carbide forming elements of Cr, Mo and V added simultaneously to crystallize primary carbides, and to precipitate fine secondary carbides in the matrix by tempering to strengthen the precipitation. Element. To obtain these effects, the content must be 0.7% by mass or more. However, if the content exceeds 0.9% by mass, the toughness is reduced. Mainly on the above effects, the matrix high-speed steel has high hardness (for example, about HRC60 or more).
[0018]
Si (silicon): 0.15% by mass or more and 0.35% by mass or less Si is added as a deoxidizing element at the time of melting the alloy, and contributes to improving the high temperature tempering hardness by forming a solid solution in the matrix. There is. In order to obtain these effects, the content of 0.15% by mass or more is necessary. However, if the content exceeds 0.35% by mass, high toughness cannot be obtained.
[0019]
Mn (manganese): 2% by mass or less Mn is added as a deoxidizing element at the time of melting the alloy, and also has the effect of increasing hardenability and improving hardness. However, if the content exceeds 2% by mass, sintering cracks occur during heat treatment or a large amount of retained austenite is generated to embrittle the steel.
[0020]
Cr (chromium): 5% by mass or more and 6% by mass or less Cr is an element contained in the matrix to improve the hardenability by forming a solid solution in the matrix during quenching and to form a Cr carbide to improve wear resistance. is there. Further, it has an effect of precipitating fine secondary carbides during tempering and increasing the hardness. To obtain these effects, the content of 5 mass% or more is necessary. However, if the content exceeds 6 mass%, the formation amount of coarse carbides increases due to an increase in the solid-liquid coexistence temperature range. Since the toughness of steel is reduced, the content is set as described above. Further, a more preferable content is 4.5% by mass or more and 6% by mass or less.
[0021]
Mo (Molybdenum): Mo is not less than 2.5% by mass and not more than 3.5% by mass. Mo is an element contained in the matrix at the time of quenching to form a carbide and improve hardness and wear resistance. It also has the effect of increasing the softening resistance in quenching and tempering. In order to obtain these effects, the content of 2.5 mass% or more is necessary. However, if the content exceeds 3.5 mass%, the formation amount of coarse carbides increases, and the toughness of steel decreases. Therefore, the content is set as described above. Further, the more preferable content is 2.7% by mass or more and 3.2% by mass or less.
[0022]
V (Vanadium): 1.8 mass% or more and 2.3 mass% or less V forms high hardness MC carbide (so-called VC carbide) and improves the hardness and wear resistance of steel. It is an element that is positively contained. It also has the effect of preventing the austenite crystal grains of the matrix from becoming coarse. In order to obtain these effects, the content of 1.8 mass% or more is necessary. However, if the content exceeds 2.3 mass%, coarse MC carbides increase and the toughness of steel decreases. And the above content. Further, a more preferable content is 1.9% by mass or more and 2.2% by mass or less.
[0023]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, embodiments of the slitter blade of the present invention will be described with reference to the drawings.
FIG. 1 is a schematic diagram showing a main surface of the slitter blade 1, and FIG. 2 is a schematic diagram showing a cross section of the slitter blade 1. The slitter blade 1 is formed in a disk shape. The outer peripheral edge 2 is tapered and has an acute angle portion 21 and an obtuse angle portion 22. The acute angle portion 21 is a cutting edge. At the center of the slitter blade 1, there is formed an insertion hole 3 through which a rotary shaft (not shown) for rotating the slitter blade 1 in a direction along the outer peripheral edge 2 (the direction of the arrow in the figure) is inserted. . Further, the insertion hole 3 is formed with a concave portion 31 which engages with a convex portion provided on the rotating shaft portion and fixes the slitter blade 1 to the rotating shaft portion in the rotation direction.
[0024]
The slitter blade 1 has, for example, a diameter W1 of 75 mm, a diameter W2 of the insertion hole 3 of 30 mm, and a thickness D of 7 mm. In addition, the acute angle portion 21 serving as the cutting edge has an angle θ of, for example, 45 °.
[0025]
At the time of cutting, as shown in FIG. 3, two slitter blades 1 each having the rotary shaft portions 4a and 4b inserted through the insertion holes 3 are arranged in parallel with each other and with the acute angle portions 21 close to each other. . A region where the acute angle portion 21 is close is defined as a cutting region 6. Then, for example, as shown by arrows in the figure, the rotating shaft 4a and the rotating shaft 4b are rotated counterclockwise with respect to the rotating shafts 4a and 4b. By applying the rotation, the two slitter blades 1 are rotated in opposite directions, and the steel plate 5 or the like is cut in the cutting area 6. As described above, since the slitter blade 1 of the present invention has high hardness, and also has high toughness and high wear resistance, it can be suitably used for cutting high-hardness members such as steel plates.
[0026]
As shown in FIG. 4, the arrangement of the two slitter blades 1 is such that a part of the main surface on the acute angle portion 21 side of the slitter blade 1 overlaps with each other in a direction along the main surface. Be placed. The radial length OR of the overlapping area is, for example, 5 mm. In the thickness direction, the two slitter blades 1 do not contact each other, and the interval S is, for example, 5 to 10% of the thickness of the material to be cut.
[0027]
【Example】
Hereinafter, the results of experiments performed to confirm the effects of the present invention will be described.
In order to obtain a slitter blade of the above-described embodiment of the present invention and a test piece of a steel material constituting the slitter blade, a 150 kg ingot having a component composition shown in Table 1 is melted in a vacuum furnace to have a diameter of φ80. After hot forging and annealing and annealing, a slitter having a shape of φ75 × φ30 × 8 L and various test pieces were respectively manufactured, and were subjected to finish grinding after heat treatment under the conditions shown in Table 2. Further, the working steels 4 and 5 and the comparative steel 14 were subjected to high-temperature soaking under the conditions shown in Table 2. In addition, among the contained elements of the comparative steels 11 to 16, those that deviate from the composition described in claim 1 are marked.
[0028]
[Table 1]

[0029]
[Table 2]

[0030]
The following characteristic evaluation was performed with respect to the test samples of the above-described Examples 1 to 5 and Comparative Steels 11 to 16.
Hardness evaluation The Rockwell C scale hardness HRC of the outer peripheral surface of the test sample was measured by the method specified in JIS: Z2245.
-Toughness evaluation It was carried out by a Charpy impact test. The test piece was a 10R · C-type notch test piece (notch depth 2 mm, R diameter 10 mm) cut out from the longitudinal direction of the test piece, and a Charpy impact test was performed by the method specified in JIS: Z2242. The value was measured.
・ Evaluation of abrasion resistance The ring circumferential surface of a slitter blade with a diameter of 30 mm and a width of 3 mm manufactured from an annealed material was 200 m on a flat plate test piece (SCM425 steel) at a load of 100 kgf with a rotation speed of the ring outer circumference of 1 m / sec. The wear resistance was evaluated by the rubbing and the wear volume calculated from the wear width.
Table 3 shows the above evaluation results.
[0031]
In addition, a life test under the following conditions was performed on slitter blades made of the above-described working steels 1 to 5 and comparative steels 11 to 16. A 0.5 mm-thick SPCC steel was cut by a slitter blade until certain burrs were generated, and the cut length was measured. The conditions are 1 t of pressure and 100 rpm. In addition, each measured value is represented by the ratio when the cutting length of the comparative steel 11 is set to 100.
Table 3 shows the above test results.
[0032]
Furthermore, the test specimens of the above-described Examples 1 to 5 and Comparative Steels 11 to 16 were etched on the surface with nitric acid alcohol, and the carbide structure on the surface was measured using a SEM-EDX apparatus (scanning electron microscope with an elemental analyzer). Was observed. Specifically, the following parameters were measured in the observation visual field.
The area ratio A / (A + B), where A is the area occupied by M ₆ C carbides and B is the area occupied by MC carbides.
A minimum / maximum width ratio D / C, where C is the distance between the maximum width parallel lines in contact with the outline of the MC carbide, and D is the distance between the minimum width parallel lines.
-The number of MC carbides whose distance C between the parallel lines with the maximum width is 5 μm or more and 40 μm or less (per 0.01 mm ^{2 of} visual field area)
Table 4 shows the observation results.
[0033]
[Table 3]

[0034]
[Table 4]

[0035]
According to the evaluation results in Table 3, in the Rockwell C scale hardness, the average of the execution steels 1 to 5 is HRC59, the average of the comparison steels 11 to 16 is HRC57, and the execution steel has slightly higher hardness. In the Charpy impact value indicating toughness, the working steel is larger than the comparative steels 11 to 15, and it is understood that the working steel has high toughness. With respect to the wear volume representing the wear resistance, the working steel is smaller than the comparative steels 11, 12, 14 to 16, indicating that the steel has high wear resistance. According to this, high toughness and high abrasion resistance are compatible in the practical steel, and it is expected that the steel can be suitably used for the slitter blade of the present invention. As for the comparative steel, the comparative steel 16 having excellent toughness is inferior in abrasion resistance, and the comparative steel 13 having excellent abrasion resistance is inferior in toughness. Gender compatibility has not been achieved. In addition, in the life test of the slitter blade, it is found that the slitter blade made of the working steel is about 2.05 to 13.33 times larger than that of the comparative steel, and has a longer life. In other words, the results prove the high toughness and high wear resistance of the above-described steel.
[0036]
Further, the steel material subjected to high-temperature soaking of Example Steels 4 and 5 and Comparative Steel 14 has further improved toughness, abrasion resistance, and the life of the slitter blade as compared with those not subjected to high-temperature soaking. I understand. Thereby, it is considered that the high-temperature soaking contributes to the improvement of the toughness and the wear resistance of the steel.
[0037]
According to the morphological observation results of the carbides in Table 4, the area ratio A / (A + B) was 0.25 or less in all of the working steels, the amount of M ₆ C carbide was smaller than that of the comparative steels 14 to 16, and MC Many carbides are generated. In addition, the minimum / maximum width ratio D / C is 0.45 or more in all of the examples, and has a more spherical shape than all the comparative examples. Further, the inventive steels 4 and 5 subjected to the high-temperature soaking have a larger D / C than those of the inventive steels 1 to 3 not subjected to the high-temperature soaking, and have a more spherical shape. Also, the number of MC carbides having a maximum width parallel line interval C of 5 μm or more and 40 μm or less per 0.01 mm ^{2 of} the visual field area is more than 20 in all examples, and the comparative steels 11, 12, 14 to 16 More than in comparison. Furthermore, the number of the inventive steels 4 and 5 subjected to the high-temperature soaking are larger than those of the inventive steels 1 to 3 not subjected to the high-temperature soaking.
[0038]
From the above results, it is understood that the MC carbide becomes more spherical by the high-temperature soaking, and the MC carbide having a size that does not affect the toughness is appropriately dispersed. These are presumed to be due to Ostwald ripening. This shows that high-temperature soaking increases the toughness and abrasion resistance of the steel because MC carbides are spheroidized and have a large diameter.
[Brief description of the drawings]
FIG. 1 is a schematic diagram showing a main surface of a slitter blade. FIG. 2 is a schematic diagram showing a cross section of a slitter blade. FIG. 3 is a schematic diagram showing cutting using a slitter blade. FIG. 4 is a diagram showing two slitter blades in FIG. Enlarged view of the close part of [Description of symbols]
DESCRIPTION OF SYMBOLS 1 Slitter blade 2 Outer peripheral edge 21 Sharp corner (blade edge)
3 Insertion hole 31 Recesses 4a, 4b Rotation shaft 5 Steel plate 6 to be cut 6 Cutting area

Claims (5)

Fe as a main component,
0.7% by mass or more and 0.9% by mass or less of C;
0.15% by mass or more and 0.35% by mass or less of Si;
Mn of 2% by mass or less;
5% by mass or more and 6% by mass or less of Cr;
2.5% by mass or more and 3.5% by mass or less of Mo;
V of 1.8% by mass or more and 2.3% by mass or less;
A slitter blade comprising a matrix high-speed steel containing In the matrix high-speed steel, MC carbides and M ₆ C carbides present in the steel were defined as A, the area occupied by the M ₆ C carbides on the observed cross-sectional structure, and B, the area occupied by the MC carbides. The slitter blade according to claim 1, wherein the area ratio A / (A + B) is 0.25 or less. In the matrix high-speed steel, the MC carbide present in the steel has a minimum distance C when the interval between the maximum width parallel lines in contact with the outline observed on the cross-sectional structure and D when the minimum width parallel line is D. The slitter blade according to claim 1 or 2, wherein the maximum width ratio D / C is 0.4 or more. Present in the matrix high-speed steel, of the MC carbides present in the steel, the ones spacing C of the maximum width parallel lines following 40μm or 5μm is field area 0.01 mm ² per 20 or more on the cross section structure The slitter blade according to any one of claims 1 to 3, wherein the slitter blade is formed. The method for producing a slitter blade according to claim 3 or 4, wherein the cast or forged steel containing the component according to claim 1 is at a temperature of 1150 ° C to 1280 ° C for 10 hours to 100 hours. A method for producing a slitter blade, comprising a step of performing a heat treatment for holding for the following time to obtain the matrix high-speed steel.

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