JP6180984B2 - Steel plates for chainsaw parts and chainsaw parts - Google Patents

Description

  The present invention relates to a steel plate for a chainsaw component and a chainsaw component that is used as a material for a chain saw component and has excellent durability.

  For example, chainsaw parts such as chainsaw blades, drive links, ruble links, and chainsaw guide bars are required to have wear resistance and fatigue characteristics. Therefore, steel plates that have undergone tempering treatment such as austempering, martempering, or quenching and tempering are used. It is used.

  The chain saw is configured by combining a chain saw blade, a drive link, and a ruble link with a pin, and rotates at a peripheral speed of several tens of m / s to cut wood with the chain saw blade.

  This chainsaw blade is a blade with a cutting edge angle of several tens of degrees with a grinder after punching and bending, and in order to prevent breakage at the time of impact between the wood and the cutting edge, the strength level is reduced to reduce wear resistance and fatigue. At the present time, durability such as characteristics is sacrificed.

  The chain saw blade worn with use is sharpened with a tool such as a Luther (registered trademark) or a file to regenerate the sharpness of the blade.

  Therefore, the chain saw blade is required to have a long-lasting property that maintains the sharpness in consideration of maintenance such as sharpening.

  In addition, although the amount of wear is smaller than that of a chain saw blade, other chain saw parts such as a drive link, a ruble link, and a chain saw guide bar are also worn due to rubbing with wood or the like with use.

  Regarding the durability of the chainsaw component, Patent Document 1 discloses a steel composition in which low-temperature toughness is improved by making the Ni content within an appropriate range and a method for producing the same. And since low temperature toughness is favorable, it can be applied to heat treatment or punching in a cold region of 0 ° F. or less.

  Patent Documents 2 to 4 disclose techniques related to chipping suppression and toughness improvement that are assumed when using woodworking tools used for veneer lace knives, shear blades, saw blades, and canna blades. Has been.

  Furthermore, Patent Document 5 specifies wear resistance and impact resistance by prescribing the balance of components for impact resistant tool steel used for veneer lace knives, and suppresses polishing cracks on the blade surface during grinding. Technology to do is shown.

Japanese Patent Laid-Open No. 8-31604 JP 58-174555 A JP-A-62-164853 JP-A-4-83824 JP-A-5-9654

  However, in the above-mentioned Patent Document 1, only durability such as low-temperature toughness when manufacturing a chain saw component is examined, and durability when using a chain saw such as wear resistance and impact resistance is examined. It has not been.

  In Patent Documents 2 to 4, although suppression of chipping and improvement of toughness when using a woodworking tool are studied, durability such as wear resistance and impact resistance is not studied.

  Here, because the wear form of the chainsaw parts is a complex mechanism, the cause of wear of the worn parts has not been clarified, so it is not possible to secure sufficient wear resistance at present, and the actual usage environment In the actual machine, the material life was evaluated while using the steel plate used for the chain saw parts. For this reason, not only does it take a long time to select a material, but also it is difficult to select an appropriate material.

  Further, since the blade portion of the chainsaw blade is bent at an angle of about 90 degrees after punching, the material used for the chainsaw blade is required to have an appropriate workability.

  And in patent document 5, although it considers improvement of abrasion resistance and impact resistance on the premise of using for a veneer lace knife, and suppression of the abrasion crack of the blade surface in the case of grinding, it improves grindability. Therefore, since Si is added by 0.8% or more, it is difficult to soften by annealing. Therefore, when the technique of Patent Document 5 is applied to a chain saw part, there is a possibility that a crack may occur in the bending process described above. In Patent Document 5, fatigue characteristics are not examined.

  Therefore, there has been a demand for a material steel plate for a chainsaw component that has excellent workability of the material, wear resistance after tempering, impact resistance, and fatigue characteristics and excellent durability.

  This invention is made | formed in view of such a point, and it aims at providing the raw material steel plate and chain saw components for chain saw components with favorable durability.

Chainsaw component material steel sheet described in 請 Motomeko 1, by mass%, C: 0.50% to 0.90% or less, Si: 0.70% or less, Mn: 0.30% or more 1.20 %: P: 0.02% or less, S: 0.02% or less, Cr: 1.00% or less, Nb: 0.10% or more and 0.50% or less, with the balance being Fe and inevitable impurities A matrix having a density of 3000 / mm ² or more and 9000 / mm ² or less hard carbides containing Nb and having a particle diameter of 0.5 μm or more on an arbitrary cross-section wet-polished by a method for observing a normal metal structure It exists in the inside.

The material steel plate for chainsaw parts described in claim 2 is in mass%, C: 0.50% or more and 0.90% or less, Si: 0.70% or less, Mn: 0.30% or more and 1.20%. Hereinafter, P: 0.02% or less, S: 0.02% or less, Cr: 1.00% or less, Nb: 0.10% or more and 0.50% or less, Ti: 0.01% or more and 0.50% Ni: 0.2% or more and 2.0% or less, B: 0% (including no addition) or more and 0.005% or less, Mo: 0% (including no addition) or more and 0.50% or less V: 0% (including no addition) or more and 0.50% or less, the balance being Fe and unavoidable impurities , Nb on any cross-section wet-polished by a method of observing the normal metal structure 3,000 / mm ² or more of hard carbides containing at least one of Ti and Ti having a particle diameter of 0.5 μm or more Those present in the matrix at a density of 9000 pieces / mm ² or less.

A chain saw component according to a third aspect is manufactured from the material steel plate for a chain saw component according to the first or second aspect .

According to the present invention, since the hard carbide having a particle diameter of 0.5 μm or more exists in the matrix at a density of 3000 / mm ² or more and 9000 / mm ² or less , the durability is good.

It is a schematic diagram which shows the method of a bending test. (A) is a side view which shows the shape of the test piece used for an abrasion test, (b) is a schematic diagram which shows the method of an abrasion test, (c) is a schematic diagram which shows the tip retraction amount of a blade part. It is a side view which shows the shape of the test piece used for a tensile fatigue test. It is a side view which shows the shape of the test piece used for an impact test.

  Hereinafter, the configuration of an embodiment of the present invention will be described in detail. The content of each element is mass% unless otherwise specified.

  The material steel for chainsaw parts is 0.50% or more and 0.90% or less of C (carbon), 0.70% or less of Si (silicon), 0.30% or more and 1.20% or less of Mn (manganese), Contains 0.02% or less P (phosphorus), 0.02% or less S (sulfur), 1.00% or less Cr (chromium), 0.10% or more and 0.50% or less Nb (niobium) The balance consists of Fe (iron) and inevitable impurities.

  In addition, 0.01% to 0.50% Ti (titanium), 0.2% to 2.0% Ni (nickel), 0% to 0.005% B (optional) Boron), 0% to 0.50% Mo (molybdenum), and 0% to 0.50% V (vanadium) are preferably contained.

  C is an element necessary for improving the strength of the steel sheet, and the content must be 0.50% or more in order to obtain the strength and wear resistance required for the chain saw component. However, when the C content exceeds 0.90%, coarse undissolved carbides increase, which causes deterioration of toughness. Therefore, the content of C is set to 0.50% or more and 0.90% or less.

  Si is added as a deoxidizer in the steelmaking stage, but no deoxidation failure occurs even if it is not added. On the other hand, if the Si content exceeds 0.70%, the toughness after tempering and the workability with the material deteriorate, which is not preferable. Therefore, the Si content is 0.70% or less (including no addition), and preferably 0.50% or less.

  Mn is an element effective for improving hardenability, and if the content is less than 0.30%, hardenability cannot be sufficiently improved. However, if the content of Mn exceeds 1.20%, it becomes hard and causes a deterioration in manufacturability and toughness. Therefore, the Mn content is set to be 0.30% or more and 1.20% or less.

  Since both P and S adversely affect toughness and fatigue properties, it is preferable that the content is as small as possible. Accordingly, the P content and the S content are both 0.02% or less (including no addition).

  Cr is an element having both an effect of improving the hardenability of steel and an effect of improving the strength of the steel plate. However, if Cr is contained in a large amount exceeding 1.00%, it may have an adverse effect of preventing solution of cementite in the heating and holding of the quenching process, and the amount of undissolved cementite during the quenching process may be reduced. It can be a factor to increase. Therefore, the Cr content is set to 1.00% or less.

  Nb forms an Nb-containing carbide which is a very hard carbide in the steel in the cooling process after casting, and contributes to improvement of wear resistance, particularly abrasive wear resistance. Further, Nb contributes to improvement of toughness by refining crystal grains during quenching. In order to exhibit these actions by Nb, the Nb content needs to be 0.10% or more. However, when Nb is contained in a large amount exceeding 0.50%, Nb-containing carbide is excessively generated, and this Nb-containing carbide becomes a starting point of fracture and a crack propagation path, and there is an adverse effect on toughness deterioration and fatigue characteristics. Concerned. Therefore, the Nb content is set to 0.10% or more and 0.50% or less.

  Ti, like Nb, forms Ti-containing carbides that are very hard carbides in the steel after casting, and contributes to wear resistance. In addition, TiC that is re-dissolved during hot rolling or the like and precipitated during hot rolling or cooling contributes to improving toughness by refining crystal grains during quenching. Further, since the bonding force between Ti and N is strong, when B is added, the formation of BN is prevented, and it is effective in extracting the effect of improving the hardenability of B. Therefore, it is preferable to add Ti as necessary. In order to achieve the above-described effects of Ti, it is effective that the Ti content is 0.01% or more. However, if the Ti content exceeds 0.50%, a large amount of Ti-containing carbide is present in the steel sheet, which tends to cause toughness deterioration. Therefore, when Ti is contained, the Ti content is preferably 0.01% or more and 0.50% or less.

  Ni is an element effective for improving hardenability and low temperature toughness, and is preferably added as necessary. In order to achieve the effect of improving the hardenability and the low temperature toughness by Ni, it is effective to make the Ni content 0.2% or more. However, since excessive addition of Ni becomes a factor which impairs economical efficiency, considering the economical efficiency, the content is preferably set to 2.0% or less. Therefore, when Ni is contained, the Ni content is preferably 0.2% or more and 2.0% or less.

  B is an element effective for improving hardenability, and is preferably added as necessary. In order to sufficiently exhibit the effect of improving hardenability by B, it is effective to make the B content 0.0003% or more. In addition, the hardenability improvement effect by B is saturated when the B content is 0.005%. Therefore, when B is contained, the B content is preferably 0.0003% or more and 0.005% or less.

Mo and V are both effective elements for improving toughness, and it is preferable to add them as necessary. It is effective to make the Mo content 0.10% or more in order to achieve the toughness improving action by Mo, and it is effective to make the V content 0.10% or more to show the toughness improving action by V. is there. However, Mo and V are relatively expensive elements, and excessive addition causes an increase in cost. Therefore, when at least one of Mo and V is contained, the content of Mo and the content of V are reduced. Each is preferably 0.5% or less. Therefore, when Mo is contained, the Mo content is preferably 0.10% or more and 0.50% or less. When V is contained, the V content is 0.10% or more and 0 or less. It is preferable to set it to 50 % or less .

  Here, the wear resistance is the most important factor in the durability of the material steel for chainsaw parts. However, the wear is a very complicated mechanism, and it is necessary to grasp the wear form in accordance with the environment in which it is used, such as the material of the wear counterpart material, lubrication, speed, and load load.

  For example, in horticultural machinery blades such as grass cutting blades and lawn cutting blades, contact with grass is not the main cause of wear, and so-called gouging wear occurs in which steel is sharply cut by contact with soil during high-speed rotation. Yes. In addition, the wear of power shovel and bulldozer construction vehicles used in the construction of industrial machinery and transport machinery, civil engineering and mining is also caused by contact with earth and sand.

  The wear of the chainsaw part is wear due to contact with wood, and the wear form is greatly different from the wear of the garden machine blade or the attachment of the construction vehicle.

  Since the wear forms of the chain saw parts are complicated, the cause of wear of the worn parts is not clarified, so that sufficient wear resistance cannot be ensured at present.

  Considering the structure of the chain saw parts, the gaps between the parts, and the movement of the parts, we observed a number of wear-damaged parts and wear-tested objects and investigated them from a microscopic viewpoint.

As a result, a linear wear mark such as ground having a width of 1 μm or less and a depth of 0.2 μm or less was observed in the worn part, and impurities (mainly SiO 2) in the wood as a counterpart material. It was found that the abrasive wear due to rubbing with ₂ ) was the main factor.

In order to improve wear resistance and suppress abrasive wear due to SiO ₂ in the steel sheet for chainsaw component having the above composition, hard carbide in the steel material is effective.

  The hard carbide is a hard carbide containing Nb or a hard carbide containing at least one of Nb and Ti. The hard carbide containing Nb has NbC or the like as a main component, for example, and the hard carbide containing Ti has TiC or the like as a main component.

In order to ensure toughness, the particle size and number of hard carbides are also important. Specifically, a material steel plate for a chainsaw part, which is a final steel plate that can be formed into a part shape after temper rolling, has a particle size of 0 on any cross-section wet-polished by a method for observing a normal metal structure. When the hard carbide having a thickness of 0.5 μm or more has a metal structure dispersed in the matrix at a density of 3000 / mm ² or more and 9000 / mm ² or less, the wear resistance is improved and the adverse effect of impairing the toughness can be avoided.

  Whether or not the precipitated particles contained in the steel correspond to hard carbide can be confirmed by microscopic analysis using EDX or the like. Moreover, about the hard carbide confirmed in this way, each area is measured, the diameter of the perfect circle which has the same area is calculated, and this diameter is made into the particle diameter of a hard carbide.

Hard carbide in steel with a particle diameter of 0.5 μm or more is less than 3000 pieces / mm ² , and the effect of improving the wear resistance by the hard carbide is insufficient, and the wear resistance sufficient as a material steel plate for chainsaw parts May not be secured. On the other hand, if the number of hard carbide particles having a particle size of 0.5 μm or more is more than 9000 / mm ² , these hard carbides become the starting point of fracture and crack propagation path, leading to deterioration of toughness. Therefore, in the material steel plate for chainsaw parts, hard carbide having a particle diameter of 0.5 μm or more is present in the matrix at a density of 3000 / mm ² or more and 9000 / mm ² or less.

  The material steel plate for chain saw parts is manufactured through a casting process, hot rolling, and a tempering heat treatment process.

  In the casting process, hard carbides are precipitated in the steel during the cooling process. Therefore, the particle size and density of the hard carbide are adjusted by adjusting the contents of C, Nb and Ti and the cooling rate.

  A conventional general method is applied to the hot rolling process. For example, the hot rolling can be performed under conditions of a heating extraction temperature of 1200 ° C. or higher and 1300 ° C. or lower, a finish rolling temperature of 800 ° C. or higher and 900 ° C. or lower, and a winding temperature of 550 ° C. or higher and 630 ° C. or lower.

For the annealing of the hot-rolled sheet, the conditions of heating and holding in a temperature range of 600 ° C. or higher and lower than Ac ₁ point (equilibrium temperature which is the lower limit of austenite), for example, for 10 hours to 50 hours can be applied.

Furthermore, if necessary, it is preferably cold-rolled and subjected to finish annealing that is heated and held in a temperature range of 600 ° C. or higher and less than ₁ Ac for 10 hours to 50 hours.

  In this way, a steel sheet for use in quenching and tempering or tempering heat treatment such as martemper or austemper is obtained.

  In addition, the matrix in the annealed structure of the material steel plate for chainsaw parts is a ferrite phase. The matrix of the part after the tempering heat treatment is a martensite phase when subjected to quenching / tempering and martemper, and is a bainite phase when subjected to austempering.

  Next, effects of the above embodiment will be described.

  According to the above-mentioned steel sheet for chainsaw parts, C of 0.50% or more and 0.90% or less, Si of 0.70% or less, Mn of 0.30% or more and 1.20% or less, 0.02% or less P, 0.02% or less of S, 1.00% or less of Cr, 0.10% or more and 0.50% or less of Nb, with the balance being Fe and inevitable impurities, so durability is good is there.

In particular, the presence of hard carbides containing Nb particles with a particle size of 0.5 μm or more in the matrix at a density of 3000 / mm ² or more and 9000 / mm ² or less ensures the effect of improving the wear resistance by the hard carbides. It is possible to prevent deterioration of toughness due to excessive formation of hard carbides and improve fatigue characteristics. Therefore, it is excellent in workability of the material, wear resistance after tempering, impact resistance and fatigue characteristics, and durability for a chain saw part is good.

Moreover, the material steel plate for chainsaw parts contains 0.01% or more and 0.50% or less of Ti as required, and 3000 hard carbides having a particle diameter of 0.5 μm or more containing Ti in the matrix / By being present at a density of mm ² or more and 9000 pieces / mm ² or less, wear resistance can be improved and sufficient toughness as a chain saw part can be secured.

  Furthermore, the material steel plate for chainsaw parts can improve hardenability by containing B as needed. In addition, when B is contained, the formation of BN due to the combination of B and N can be prevented by Ti, and the effect of improving the hardenability by B can be easily achieved.

  Moreover, the raw material steel plate for chainsaw parts can improve toughness, hardenability, and low temperature toughness by containing at least one of Mo, V and Ni as required.

And since the chain saw parts manufactured with the above-mentioned steel plates for chain saw parts have good wear resistance, not only are abrasive wear due to SiO ₂ which is a cause of wear in the chain saw parts, but also toughness is good. In addition, since the impact resistance and fatigue characteristics are good, the durability of the chainsaw formed by assembling the respective chain saw parts is good.

  Examples of the present invention and comparative examples will be described below.

  Table 1 shows the chemical components of the steel sheet that is the base material of the chain saw part.

  A 30 kg steel ingot (120 mm square, 310 mm length) having the chemical composition shown in Table 1 was melted. The obtained slab was subjected to heating at 1250 ° C. for 1 hour, hot forged to a thickness of 30 mm, and this forged material was used as a wear test piece.

  For other test pieces, the forging was subjected to heating at 1250 ° C. × 1 hour, hot-rolled under conditions of a finish rolling temperature of 850 ° C. and a winding temperature of 590 ° C., and a plate thickness of 3.0 mm. A rolled steel sheet was obtained.

  Next, the hot-rolled steel sheet was subjected to soft annealing at 710 ° C. for 18 hours, and a raw steel sheet having a thickness of 1.5 mm was obtained by cold rolling. Furthermore, softening annealing was performed at 690 ° C. for 15 hours, and the hardness was adjusted to 200 to 240 HV.

  The obtained steel sheet was subjected to a bending test, and the particle size of the hard carbide was measured.

  In addition, a wear test, a tensile fatigue test, and an impact test were performed on each sample material after tempering the raw steel plate. The test method of each test is as follows.

  The bending test relates to the bending workability of the material. Using a test piece having a width of 30 mm and a length of 180 mm in a direction perpendicular to the rolling direction, it conforms to the provisions of JIS Z 2248, and as shown in FIG. A block bending test was performed. The test piece was bent into a specified shape, the tip bending radius was measured, and the surface of the test piece after the bending test was visually observed. Further, in each test piece of the present example after the bending test, the critical bending radius at the tip where no cracks occurred at the number n of 3 was obtained.

  And the bending workability evaluated that a crack did not generate | occur | produce after a bending test and the limit bending radius was 1 mm or less as a pass.

The particle size of the hard carbide was measured on the raw steel plate before being subjected to the quenching treatment. The steel plate before quenching is mirror-polished on the L section parallel to the rolling direction and thickness direction, and then the surface etched with Murakami reagent (alkaline solution of red blood salt) is observed with a confocal laser microscope. did. Moreover, the image obtained by observation was processed, the number of carbides containing Nb and Ti present in the visual field area was measured, and the existence density (pieces / mm ² ) was calculated. Note that the hard carbide was counted as particles having a particle diameter of 0.5 μm or more existing in 20 fields of view with an observation area of 90 μm × 60 μm as one field of view, and converted to the number per 1 mm ² based on the counted number. The particle diameter is a value corresponding to the equivalent circle diameter of the particle area, and particles having a particle diameter of 0.5 μm or more were picked up by image processing.

  In the tempering heat treatment, the material steel plate was subjected to austempering or martempering using a salt bath furnace. Except for steel type O, which is a comparison, all tempered materials corresponding to tempered hardness of 55HRC were obtained. The hardness of each tempered material was within a range of ± 0.5 HRC with a Rockwell hardness meter. The heat treatment was performed under the conditions of heating at 850 ° C. for 10 minutes, heating at T ° C. for 60 minutes, and then air cooling.

  For the wear test, a small woodworking lathe was used. A strip-shaped test piece having a thickness of 8 mm, a width of 10 mm, and a length of 55 mm was cut out from the forged material of each test material, and a blade having a tip angle of 45 ° at the tip in the longitudinal direction as shown in FIG. A cutting tool 11 provided with a portion 12 was produced. The wear test conditions are as follows. The direction indicated by the arrow in FIG. 2B is the moving direction of the cutting bit 11, the rotation speed of the wood 13 is 500 rpm, the cutting depth is 0.2 mm, and the moving speed of the cutting bit 11 is The cutting frequency was 600 mm / min, and the number of cuttings was 10,000. Thereafter, the tip retraction amount of the blade portion 12 was measured at the site shown in FIG.

The abrasion resistance was evaluated as acceptable when the tip retraction amount of the blade portion 12 was less than 10 μm. In addition, in the wear when the work material is wood, it is generally said that the higher the silica content of the work material, the easier it is to wear. Therefore, in this wear test, the work material has an air-dry specific gravity of 1.0 or less, a moisture content of 12% or more and 16% or less, and a silica (SiO ₂ ) content of 0.50% ± 0.1%. Mangashinoro (from Southeast Asia) having a high silica content was used.

In the tensile fatigue test, fatigue test pieces having a shape shown in FIG. 3 (plate thickness of 1.5 mm, the longitudinal direction coincided with the rolling direction) were prepared from each test material, and a hydraulic servo fatigue tester was used. Further, the stress ratio is σmin / σmax = 0.1, frequency was fatigue tested at 50 N / mm ² pitches from applying stress 400 N / mm ² at 23Hz to 900 N / mm ^2. In the vicinity of the fatigue limit, 10 test pieces are used at each stress stage, and the maximum applied stress at which the number of test pieces that do not break up to 10 ⁷ times is 6 or more is the fatigue limit of the specimen. did. The tensile fatigue test environment was 26 ° C. ± 5 ° C. and a relative humidity of 50% or less. In addition, since the damage of the chainsaw leads to a serious disaster to the human body, it is necessary to ensure fatigue characteristics at a predetermined stress, so the fatigue limit was measured.

  And the fatigue characteristic evaluated that a fatigue limit is 600 Mpa or more as a pass.

  In the impact test, as shown in FIG. 4, steel was collected so that the longitudinal direction was perpendicular to the rolling direction, and the length in the longitudinal direction was 55 mm, the width was 10 mm, and the plate thickness was 1.5 mm. 21 was used. The test piece 21 was provided with a 2 mm U-notch 22 at the center in the longitudinal direction. For such a test piece 21, a Charpy impact test was performed at room temperature, and an impact value according to an impact direction indicated by an arrow was obtained. The ductility-toughness transition temperature (DBTT) was also determined.

And impact resistance evaluated that a shock value is 50 J / cm < ² > or more as a pass.

  Table 2 shows the results of the above tests for each steel plate.

Steel types A to F, which are examples of the present invention, each have an edge retraction amount of less than 10 μm in the wear resistance after 55HRC tempering. In addition, the fatigue limit in the fatigue characteristics is 600 MPa or more, the impact value is maintained at 50 J / cm ² or more, and the ductility-toughness transition temperature is -50 ° C. or less. Is possible. Furthermore, the limit bending radius in the 90 ° V block bending test of the material was 1 mm or less, and the workability as a chain saw part was sufficiently secured.

  On the other hand, in the steel types G, I, J, L, M, N, and P, which are comparative examples, cracks occurred when the tip bending radius of the tip was 1 mm or less in the bending of the material.

  Steel types G, H, I, J, K, N, and P, which are comparative examples, have a large tip retraction amount of 10 μm or more, and wear of the blade edge is remarkable.

Steel types G, H, I, J, K, L, M, N, and P, which are comparative examples, have a fatigue limit of 500 to 550 MPa in fatigue characteristics, an impact value of 40 J / cm ² or less, and ductility-toughness. Since the transition temperature is room temperature or higher, there is a concern about durability and safety as a chain saw part.

  Steel types H, K, and O, which are comparative examples, ensure bending workability with the raw material, but are inferior in wear resistance, fatigue characteristics, and toughness after tempering as compared with the present example.

  Note that steel type O, which is a comparative example, has a low C content of 0.42% and a small amount of Si, Mn, and Cr. Therefore, the hardness after tempering could not be ensured to 55 HRC by a desired heat treatment. Although the bending workability of the material was good, it could not be used for wear tests, impact tests and fatigue tests.

Claims (3)

In mass%, C: 0.50% or more and 0.90% or less, Si: 0.70% or less, Mn: 0.30% or more and 1.20% or less, P: 0.02% or less, S: 0.00. 02% or less, Cr: 1.00% or less, Nb: 0.10% or more and 0.50% or less, with the balance being Fe and inevitable impurities,
Hard carbide with a particle diameter of 0.5 μm or more containing Nb is present in the matrix at a density of 3000 / mm ² or more and 9000 / mm ² or less on an arbitrary cross-section wet-polished by a normal metal structure observation method features and be Ruchi Enso parts for the steel sheet to be. In mass%, C: 0.50% or more and 0.90% or less, Si: 0.70% or less, Mn: 0.30% or more and 1.20% or less, P: 0.02% or less, S: 0.00. 02% or less, Cr: 1.00% or less, Nb: 0.10% or more and 0.50% or less, Ti: 0.01% or more and 0.50% or less, Ni: 0.2% or more and 2.0% or less , B: 0% (including no addition) to 0.005% or less, Mo: 0% (including no addition) to 0.50% or less, V: 0% (including no addition) or more, 0 .50% or less, with the balance being Fe and inevitable impurities,
Density of 3000 / mm ² or more and 9000 / mm ² or less hard carbides having a particle diameter of 0.5 μm or more containing at least one of Nb and Ti on an arbitrary cross section wet-polished by a method of performing normal metal structure observation in characteristics and to Ruchi Enso component base steel sheet to be present in the matrix. A chain saw component manufactured by the steel plate for a chain saw component according to claim 1 or 2 .

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