JP2017203198A - Original pipe for aluminum alloy bat, bat and manufacturing method thereof - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an original pipe for an aluminum alloy bat intended for obtaining an aluminum alloy bat excellent in appearance quality while simultaneously realizing a high repulsive force and durability and also to provide an aluminum alloy bat excellent in appearance quality while simultaneously realizing a high repulsive force and durability, and an efficient manufacturing method thereof.SOLUTION: An aluminum alloy bat includes 9.0-11.0 wt% Zn, 1.3-1.8 wt% Mg, 2.0-2.6 wt% Cu, 0.02-0.30 wt% Cr, 0.05-0.20 wt% Zr, 0.01-0.15 wt% Ti, 0.001-0.05 wt% B, and a balance Al with inevitable impurities. Zn content (wt%)/Mg content (wt%) is at least 5, and a sum of Cu content (wt%) and Mg content (wt%) is 3.4-4.2 wt%.SELECTED DRAWING: Figure 3

Description

  The present invention relates to an aluminum alloy bat used for baseball, softball, and the like, and an efficient manufacturing method thereof.

  The main body of an aluminum alloy bat used for baseball, softball, etc. is formed by subjecting a raw tube made of a tubular extruded material or a drawn material to plastic processing such as thickness adjustment processing or swaging processing. The Then, the aluminum alloy bat which is the final product can be obtained through surface treatment and assembly of the grip end and the head portion on the main body portion.

  Here, as an element tube for an aluminum alloy bat, a 6000 series (Al-Mg-Si series) aluminum alloy excellent in workability, or a 7000 series (Al-Mg-Zn) that easily obtains a repulsive force with high strength. Series) aluminum alloys have been used.

  For example, in Patent Document 1 (Japanese Patent Application Laid-Open No. 2004-2983), a bat made of a heat treatment type 7000 series aluminum alloy extruded material has a tensile strength of 540 MPa or more and elongation of 10% or more after artificial aging treatment. , Having a proof stress of 540 MPa or more, compressive property of longitudinal modulus of 70000 MPa or more, corrosion resistance of SCC stress of 180 MPa or more, exfoliation corrosion resistance EB or more, and loss factor of 0.017 or less in the first mode. In addition, aluminum alloy bats having a tertiary mode of 0.010 or more have been proposed.

  The aluminum alloy bat disclosed in Patent Document 1 is excellent in corrosion resistance, has tensile properties and compression properties necessary for the bat, and can obtain an excellent hit feeling.

JP 2004-2983 A

  However, in recent years, in addition to the increasing demand for flying the ball further away, there is a demand for an aluminum alloy bat that is excellent in durability and appearance quality. The bat cannot fully satisfy these requirements.

  SUMMARY OF THE INVENTION In view of the above-described problems in the prior art, the object of the present invention is to provide an aluminum alloy bat blank for obtaining an aluminum alloy bat that has both high repulsive force and durability and is excellent in appearance quality. It is another object of the present invention to provide an aluminum alloy bat that has both high repulsive force and durability and is excellent in appearance quality, and an efficient manufacturing method thereof. Here, in order to improve the repulsive force of the bat, it is effective to reduce the thickness of the striking portion, but even if it is reduced to 2% flat proof strength of 7500 N or more (SG standard CPSA 0024 of non-wood bat) It is necessary to satisfy.

  In order to achieve the above object, the present inventors have conducted extensive research on an aluminum alloy bat base tube, an aluminum alloy bat, and a method for producing the same, and as a result, optimized the composition of the aluminum alloy used and the aluminum alloy. The inventors have found that it is extremely effective to appropriately control the metal structure of the bat base tube and the metal structure of the bat, and have reached the present invention.

That is, the present invention
Zn: 9.0 to 11.0 wt%, Mg: 1.3 to 1.8 wt%, Cu: 2.0 to 2.6 wt% and Cr: 0.02 to 0.30 wt%, Zr: 0.05 to 0.20 wt%, Ti: 0.01-0.15 wt%, B: 0.001-0.05 wt%,
The balance consists of Al and inevitable impurities,
Zn content (wt%) / Mg content (wt%) is 5 or more,
The total of the Cu content (wt%) and the Mg content (wt%) is 3.4 to 4.2 wt%;
An aluminum alloy vat tube is provided.

  The composition of the aluminum alloy bat base tube of the present invention is 7055 standard (main alloy element, Zn: 7.6 to 8.4 wt%, Mg: 1. 8 to 2.3 wt%, Cu: 2.0 to 2.6 wt%, Cr: <0.04 wt%, Zr: 0.08 to 0.25 wt%) Thus, the Mg content is reduced.

  More specifically, increasing the Zn content increases the precipitation density in the final tempered aluminum alloy and contributes to the strength, thereby achieving high strength.

  Cu and Mg are also added for the purpose of strengthening the aluminum alloy by precipitation strengthening. However, if the amount of addition is increased more than necessary, the crystallization becomes larger, the ductility is reduced, and the anodized film property is increased. In order to reduce the Zn content (wt%) / Mg content (wt%) ratio is 5 or more, and the total of Cu content (wt%) and Mg content (wt%) is 3.4 or more. By making it 4.2 or less, both high strength and high ductility are realized.

  The aluminum alloy used in the aluminum alloy vat base tube of the present invention is Cr: 0.02 to 0.30 wt%, Zr: 0.05 to 0.20 wt%, Ti: 0.01 to 0.15 wt%. , B: 0.001 to 0.05 wt%. By adding a small amount of Cr and Zr, recrystallization during or after extrusion or drawing can be suppressed due to the pinning effect. Moreover, the cast structure can be refined by adding a small amount of Ti and B.

  Furthermore, the entire surface of the aluminum alloy bat blank for use in the present invention has a fibrous structure (fiber structure), and has high formability during thickness adjustment processing. In addition, in the bat which is a product, high strength is realized by leaving the fiber structure which is the processed structure in the hitting part where the ball is hit, but when the surface is a fiber structure, the streaks along the fiber structure are realized. Will appear and the appearance will be damaged. On the other hand, since the aluminum alloy bat manufactured using the aluminum alloy bat blank according to the present invention has a recrystallized structure layer having a thickness of 50 to 500 μm in the outer layer portion, a streak is formed on the surface. It is possible to prevent the pattern from being formed and to achieve both high strength.

  Here, by setting the thickness of the recrystallized structure layer to 50 μm or more, it is possible to sufficiently prevent the streak pattern resulting from the fiber structure from appearing on the surface. By setting the thickness to 500 μm or less, aluminum In addition to being able to suppress the decrease in tensile strength and repulsion of the alloy bat, corrosion resistance can be enhanced.

The present invention also provides:
It comprises the above-described aluminum alloy vat base tube of the present invention,
Having at least one of an anodized film, a paint layer or a plating layer on the outer peripheral surface;
In the metal structure of the striking part, the outer layer part has a recrystallized structure layer having a thickness of 50 to 500 μm, and the fibrous structure inside the plate thickness,
The tensile strength of the striking part is 630 MPa or more, the 0.2% proof stress value is 605 MPa or more, and the elongation is 14% or more,
An aluminum alloy bat is also provided.

  The aluminum alloy bat according to the present invention is manufactured using the aluminum alloy bat blank according to the present invention (that is, formed or constituted by the aluminum alloy bat blank according to the present invention). The main body portion has the same composition as that of the above-described aluminum alloy vat base tube. Further, the metal structure of the striking part of the aluminum alloy bat has a fiber structure inside and a recrystallized structure in the outer layer part, and is sufficiently precipitation strengthened by an appropriate aging treatment. As a result, the tensile strength of the tensile test piece cut out from the striking part is 630 MPa or more, the 0.2% proof stress value is 605 MPa or more, and the elongation is 14% or more, which has both high strength and high ductility. Therefore, the aluminum alloy bat has high repulsive force and durability.

  Since the flight distance of the ball becomes longer due to the improvement of the repulsive force, it is preferable to increase the repulsive force in the aluminum alloy bat. Here, in order to improve the resilience, it is effective to increase the resilience coefficient, that is, to reduce the thickness of the hitting portion. However, in conventional aluminum alloy bats, if the striking part is thin, the 2% flatness proof strength is less than 7500N, which satisfies the SG standard (CPSA0024) for non-wood bats established by the Japan Product Safety Association. I couldn't. On the other hand, the aluminum alloy bat of the present invention can satisfy the 2% flat proof stress even with a wall thickness thinner than that of the conventional material due to the high proof stress, and can improve the repulsive force.

  In addition, since the aluminum alloy bat of the present invention can reduce the thickness of the hitting portion, the degree of freedom of balance and MOI (moment of inertia) increases even with the bat of the same weight. That is, even if the weight is the same, the bat having a low MOI and easy to swing can be realized by distributing a large weight to the grip side. Similarly, if the weight is distributed to the tip cap side, the bat preferred by the power hitter can be obtained. Here, balance and MOI can be evaluated by the measurement method of ASTM F2398-11. In the aluminum alloy bat of the present invention, when the outer diameter of the hitting part is 66.7 mm, the thickness of the hitting part is 2.91 to 3.3 mm, and the outer diameter of the hitting part is 63.5 mm. In this case, it is preferable that the thickness of the hitting portion is 2.80 to 3.3 mm, and the 2% flat proof stress of the hitting portion is 7500 N or more.

  In addition, due to the high yield strength, the 2% flat yield strength can clear the SG standard (CPSA0024) even when the thickness is thinner than that of the conventional material, so that the thickness of the bat can be reduced and the weight can be reduced. As a result, an aluminum alloy bat that is lightweight and easy to swing can be realized. Furthermore, the thinning increases the coefficient of restitution, increases the repulsive force, increases the flight distance, and provides a favorable bat.

  In addition, the aluminum alloy bat of the present invention has at least one of an anodized film, a coating layer, and a plating layer on the outer peripheral surface, but a recrystallized structure layer having a thickness of 50 to 500 μm on the outer layer portion. Therefore, a streak pattern or the like does not appear on the surface, and the appearance is extremely good.

Furthermore, the present invention provides
Thickness adjustment and swaging processing are performed on the aluminum alloy vat base tube of the present invention, and the aluminum alloy vat base tube is plastically processed into a bat shape. A second step in which a solution treatment is carried out at a low temperature, followed by a quenching treatment; a third step in which an aging treatment is carried out at a holding temperature of 100 to 140 ° C. and a holding time of 10 to 48 hours; and anodization Having a fourth step of performing at least one of a film treatment, a coating treatment or a plating treatment,
Also provided is a method of manufacturing an aluminum alloy bat characterized by:

  In the method for producing an aluminum alloy bat of the present invention, it is preferable to perform an aging treatment at a holding temperature of 140 to 180 ° C. and a holding time of 1 to 12 hours after the third step, if necessary.

  By applying an appropriate aging treatment to the aluminum alloy vat base tube of the present invention that has been plastically processed into the shape of the bat, it is cut out from the striking portion while maintaining the structural characteristics of the aluminum alloy vat base tube. In addition, an aluminum alloy bat having a tensile strength of 630 MPa or more, a 0.2% proof stress value of 605 MPa or more, and an elongation of 14% or more can be efficiently obtained. Due to these mechanical characteristics, when the outer diameter of the hitting part is 66.7 mm, the hitting part has excellent durability and crack resistance even when the thickness of the hitting part is reduced to 2.91 mm. 2% flat proof stress: 7500 N or more can be satisfied. Further, when the outer diameter of the hitting portion is 63.5 mm, even if the hitting portion is thinned to 2.80 mm, it has excellent durability and crack resistance, and is 2% flat which is SG standard. Yield strength: 7500N or more can be satisfied.

  In addition, since the outer layer portion of the raw tube plastically processed into the shape of the bat has a recrystallized structure, a smooth surface having a good appearance can be obtained by anodizing film treatment, painting treatment or plating treatment (fourth step). Can be obtained.

  By carrying out the solution treatment, coarse compounds (Zn—Mg, Mg—Si, Al—Cu, etc.) that do not contribute to the improvement of the strength crystallized when an aluminum alloy is cast are Al base. It is dissolved in the phase. Solid elements such as Zn, Mg, and Cu are maintained in a supersaturated solid state in the Al matrix by quenching, and fine precipitates are formed by subsequent aging treatment. An improvement can be achieved.

  According to the present invention, it is possible to provide an aluminum alloy bat base tube for obtaining an aluminum alloy bat which has both high repulsive force and durability and is excellent in appearance quality, and further has high repulsive force and durability. It is possible to provide an aluminum alloy bat excellent in appearance quality while also having the properties and an efficient manufacturing method thereof.

It is a cross-sectional schematic diagram of the aluminum alloy bat blank for the present invention. It is sectional drawing which shows schematic structure of the aluminum alloy bat | bat of this invention. It is a cross-sectional schematic diagram of the aluminum alloy bat of the present invention. It is process drawing regarding the manufacturing method of the aluminum alloy bat of the present invention. It is a graph which shows the relationship between 2% flat proof stress of the aluminum alloy bat of this invention, and a hit | damage part thickness.

  Hereinafter, typical embodiments of an aluminum alloy bat blank and a bat and a manufacturing method thereof according to the present invention will be described in detail with reference to the drawings. However, the present invention is not limited to these. In the following description, the same or corresponding parts are denoted by the same reference numerals, and redundant description may be omitted. Further, since the drawings are for conceptually explaining the present invention, the dimensions and ratios of the components shown may be different from the actual ones.

1. Aluminum alloy bat blank (1) composition The aluminum alloy used in the aluminum alloy bat blank of the present invention is:
Zn: 9.0 to 11.0 wt%, Mg: 1.3 to 1.8 wt%, Cu: 2.0 to 2.6 wt% and Cr: 0.02 to 0.30 wt%, Zr: 0.05 to 0.20 wt%, Ti: 0.01-0.15 wt%, B: 0.001-0.05 wt%,
The balance consists of Al and inevitable impurities,
Zn content (wt%) / Mg content (wt%) is 5 or more,
The total of Cu content (wt%) and Mg content (wt%) is 3.4 to 4.2 wt%,
The aluminum alloy vat base tube of the present invention has a full-face fiber structure.
Hereinafter, each component element will be described.

Zn: 9.0 to 11.0 wt% (preferably 9.2 to 10.5 wt%)
When Zn is subjected to an aging treatment, Zn is precipitated as a Zn—Mg-based or Al—Zn—Mg—Cu-based compound, and the mechanical strength of the aluminum alloy is improved. By setting the content to 9.0 wt% or more, the precipitation strengthening can be sufficiently expressed, and by setting the content to 11.0 wt% or less, a decrease in ductility due to the coarsening of the compound can be suppressed.

Mg: 1.3 to 1.8 wt% (preferably less than 1.3 to 1.6 wt%)
Mg has an effect of improving strength by solid solution strengthening, and when subjected to an aging treatment, Mg precipitates as an Al—Zn—Mg compound and improves mechanical strength. By setting the content to 1.3 wt% or more, solid solution strengthening and precipitation strengthening can be sufficiently expressed, and by setting the content to 1.8 wt% or less, ductility is reduced due to the coarsening of the Zn-Mg compound. Can be suppressed. Further, by setting the Zn content (wt%) / Mg content (wt%) to 5 or more, both strength and ductility can be achieved, and corrosion resistance can be improved.

Cu: 2.0 to 2.6 wt% (preferably 2.0 to 2.5 wt%)
Cu has the effect of improving the strength by solid solution strengthening, and when it is subjected to an aging treatment, it precipitates as an Al—Cu-based compound and improves the mechanical strength. By setting the content to 2.0 wt% or more, solid solution strengthening and precipitation strengthening can be sufficiently expressed, and 2.6 wt% or less, and further Cu content (wt%) and Mg content (wt%) By making the total of 3.4 or more and 4.2 or less, it is possible to suppress a decrease in ductility and a decrease in anodized film property due to the coarsening of the Al—Cu-based compound.

Cr: 0.02-0.30 wt%
Cr has the effect of suppressing recrystallized structure due to the pinning effect of the compound, and can stabilize the fiber structure as a processed structure. By setting the content to 0.02 wt% or more, the effect can be sufficiently expressed, and by setting the content to 0.30 wt% or less, it is possible to suppress a decrease in ductility due to the coarsening of the compound.

Zr: 0.05-0.20 wt%
Zr has the effect of suppressing recrystallized structure due to the pinning effect of the compound, and can stabilize the fiber structure that is the processed structure. By setting the content to 0.05 wt% or more, the effect can be sufficiently expressed, and by setting the content to 0.20 wt% or less, it is possible to suppress a decrease in ductility associated with the coarsening of the compound.

Ti: 0.01-0.15 wt%
The cast structure can be refined by adding Ti. The refinement effect can be sufficiently expressed by setting the Ti content to 0.01 wt% or more, and by suppressing the Ti content to 0.15 wt% or less, the reduction in ductility due to the formation of the coarse compound is suppressed. Can do. In order to obtain a refined effect of the cast structure, it is preferable to add Ti to the molten alloy immediately before casting.

B: 0.001 to 0.05 wt%
By adding B, the cast structure can be refined. The refinement effect can be sufficiently expressed when the B content is 0.001 wt% or more, and by suppressing the content of B to 0.05 wt% or less, the reduction in ductility due to the formation of a coarse compound is suppressed. Can do. In order to obtain a refined effect of the cast structure, B is preferably added to the molten alloy immediately before casting.

Content ratio of Zn and Mg (Zn content (wt%) / Mg content (wt%) ≧ 5)
Zn and Mg are added mainly for the purpose of strengthening the aluminum alloy by precipitation strengthening. In order to obtain sufficient precipitation strengthening, a solution treatment is performed before the aging treatment, so that a compound that does not contribute to improvement in strength that is crystallized or precipitated during casting is dissolved in the Al matrix. Is done. When the content of Mg increases, the compound does not dissolve sufficiently even when solution treatment is performed. As a result, the precipitation amount of the compound that contributes to improvement in strength during aging treatment decreases, and mechanical properties are improved. Becomes smaller. Therefore, the Mg content is regulated in the aluminum alloy used in the aluminum alloy vat base tube of the present invention.

  Furthermore, strength is increased by precipitation strengthening by containing Cu. On the other hand, if it is added more than necessary, the crystallized product becomes coarse and the ductility decreases. In order to obtain high strength and suppress the decrease in elongation, the total of Cu content (wt%) and Mg content (wt%) is set to 3.4 to 4.2 wt%. High ductility is achieved at the same time, and more specifically, tensile properties of a tensile strength of 630 MPa or more, a 0.2% proof stress of 605 MPa or more and an elongation of 14% or more can be realized after appropriate aging treatment.

Other component elements As long as the effects of the present invention are not impaired, it is allowed to contain other elements. Specifically, it can contain 0.2 wt% or less of Si, 0.2 wt% or less of Fe, and 0.4 wt% or less of Mn, and other elements are preferably limited to 0.05 wt% or less. . Further, inevitable impurities other than the elements described above are allowed to be contained within a range that does not affect the characteristics of the aluminum alloy used in the present invention. Specifically, it is acceptable if the total of these inevitable impurities is 0.05 wt% or less.

(2) Structure FIG. 1 shows a schematic cross-sectional view of an aluminum alloy bat blank for the present invention. The aluminum alloy bat base tube 1 has a full-face fiber structure. If there is a recrystallized structure in the outer layer of the blank tube, recrystallized structure is likely to occur in the manufacturing process of the bat, and it becomes difficult to suppress the thickness of the recrystallized structure in the striking part of the bat to 500 μm or less.

  An aluminum alloy extruded tube or drawn tube is used to manufacture the aluminum alloy bat base tube 1. Thickness adjustment processing is performed with O tempering, but in order to improve workability, it is preferable that the uneven thickness ratio of the pipe material is 10% or less. Also, when using a drawn tube, if the cold work degree is greater than 30%, the recrystallized structure layer tends to be excessively thick during the solution treatment, and the formability when adjusting the thickness is improved. Is preferably regulated to 30% or less.

2. Aluminum alloy bat The aluminum alloy bat of the present invention is manufactured using the aluminum alloy bat base tube of the present invention.

  FIG. 2 is a sectional view showing a schematic configuration of the aluminum alloy bat of the present invention. The aluminum alloy bat 2 is used by a batter for hitting (striking) a ball in ball games such as baseball, softball, cricket, and the like. The bat body 4, the head cap 6, the grip end 8, A grip tape 10 is provided. In the following description, “base end” means the base end or one end in the length direction of the aluminum alloy bat 2, and “tip” means the tip end or the other end in the length direction of the metal bat.

  The bat main body 4 is configured by integrally connecting a striking portion 12 on the distal end side, a grip portion 14 on the proximal end side, and a transition portion 16 that connects between the striking portion 12 and the grip portion 14. The hitting part 12 is provided at the tip of the bat main body part 4 as a part for hitting a ball. The striking portion 12 is formed in a cylindrical shape extending in the length direction of the aluminum alloy bat 2, and is formed so that the outer diameter decreases toward the proximal end side.

  In this embodiment, the outer diameter D that is the maximum diameter of the striking portion 12 is set to 66.7 to 63.5 mm. The inner diameter d of the striking portion 12 is substantially constant as a whole. Moreover, the length L1 of the striking part 12 is set to 20 to 30 cm. The outer diameter D, inner diameter d, wall thickness T, and length L1 of the striking portion 12 can be appropriately changed according to characteristics required for the aluminum alloy bat 2.

  On the inner peripheral surface of the striking portion 12, a groove portion for attaching the head cap 6 is provided in a circular shape on the distal end side, and an enlarged diameter portion is provided on the proximal end side with respect to the groove portion. Further, an outer design surface 18 is formed on the outer peripheral surface of the striking portion 12 by an anodic oxide coating or painting of aluminum.

  The grip portion 14 is provided at the proximal end portion of the bat main body portion 4 as a portion that the batter grips. The grip portion 14 is formed in a cylindrical shape having an outer diameter smaller than that of the striking portion 12 and extends in the length direction of the aluminum alloy bat 2. The inner diameter of the grip portion 14 is also smaller than the striking portion 12. The inner and outer diameters of the grip portion 14 of this embodiment are substantially constant as a whole. However, the inner and outer diameters of the grip portion 14 do not need to be constant. For example, according to the required characteristics, the outer diameter is relatively set at the intermediate portion in the length direction of the grip portion 14 such as a so-called flare type. It is possible to make it smaller.

  An internal thread portion for fixing the grip end 8 is formed on the inner periphery of the grip portion 14 at the base end portion. On the outer peripheral surface of the grip portion 14, an outer design surface 18 continuous from the striking portion 12 is formed from the front end side to the intermediate portion.

  The transition portion 16 is a portion that smoothly transitions between the striking portion 12 and the grip portion 14, and the inner and outer diameters gradually decrease from the striking portion 12 on the distal end side toward the grip portion 14 on the proximal end as a whole. Tapered shape. In the transition portion 16 of the present embodiment, the outer peripheral surface transitions in a curved shape without an edge between the striking portion 12 and the grip portion 14. An outer design surface 18 extending from the striking portion 12 is also formed on the outer peripheral surface of the transition portion 16.

  The inner peripheral surface of the transition portion 16 is continuous with the grip portion 14 so as to have an obtuse edge portion, and is transitioned between the striking portion 12 without an edge due to an enlarged diameter portion described later. The head cap 6, the grip end 8, and the grip tape 10 are attached to the bat main body 4 having such a configuration to form the aluminum alloy bat 2.

  The head cap 6 is formed of resin or the like and closes the tip opening of the striking portion 12 of the bat main body portion 4. The head cap 6 has a cylindrical end portion inserted from the tip opening of the striking portion 12, and a protrusion on the outer edge of the head cap 6 is engaged with the groove portion of the striking portion 12. Further, the other end of the head cap 6 is abutted against the tip surface of the striking portion 12 and bulges from the tip of the striking portion 12 into a dome shape. The shape and the like of the head cap 6 can be changed according to the characteristics of the aluminum alloy bat 2.

  The grip end 8 is formed of a metal such as an aluminum alloy like the bat main body 4 and closes the proximal end opening of the grip portion 14 of the bat main body 4. The grip end 8 has one end portion formed of a male screw portion screwed into the inner screw portion of the grip portion 14, and the other end portion having a disc shape is abutted against the base end surface of the grip portion 14. Thereby, the grip end 8 is fastened and fixed to the base end of the grip part 14. The outer edge of the other end protrudes in the radial direction with respect to the grip portion 14. In addition, the shape of the other end can be appropriately changed according to the characteristics of the aluminum alloy bat 2.

  The grip tape 10 is made of resin or the like, and is provided for preventing slipping when hitting a ball. The grip tape 10 is wound from the distal end portion to the proximal end portion of the outer peripheral surface of the grip portion 14, and covers the grip portion 14 including a part of the outer design surface 18.

  FIG. 3 is a schematic sectional view of the aluminum alloy bat of the present invention. Here, an embodiment in which an anodized film is formed on the surface will be described. The aluminum alloy bat 2 is formed by plastic processing into a bat shape, T6 treatment, an anodic oxide film or the like is formed on the surface, and the head cap 6 and the grip portion 14 are attached.

  The striking portion 12 of the aluminum alloy bat 2 has a fiber structure in which the plate thickness center portion 20 is an extruded structure, and high strength is obtained by the fiber structure.

  By having the recrystallized structure layer 22 of 50 to 500 μm in the outer layer portion, the aluminum alloy bat of the present invention suppresses the surface pattern after the anodized film and enhances the film property. A similar recrystallized structure layer 22 'is also formed on the inner surface layer part. However, in the head part, the tensile strength is 630 MPa or more by setting the thickness of the fiber structure inside the plate thickness to 75% or more of the wall thickness. , 0.2% proof stress value of 605 MPa or more and elongation of 14% or more can be obtained.

  The aluminum alloy bat 2 has an outer design surface 18 made of an anodized film or the like on the outer peripheral surface, but has a recrystallized structure layer 22 with a thickness of 50 to 500 μm. No pattern or the like appears, and the appearance is extremely good.

3. 4. Manufacturing method of aluminum alloy bat FIG. 4 shows a process chart relating to the manufacturing method of the aluminum alloy bat of the present invention. The method for producing an aluminum alloy bat according to the present invention includes the first step of subjecting the aluminum alloy bat blank 1 to thickness adjustment and swaging, and plastic processing the aluminum alloy bat blank 1 into the shape of the bat. (S01), a second step (S02) in which a quenching treatment is performed after a solution treatment for holding at a temperature 5 to 25 ° C. lower than the solidus temperature, a holding temperature: 100 to 140 ° C., a holding time: Third step (S03) for aging treatment for 6 to 48 hours, further aging treatment for holding temperature: 140 to 180 ° C., holding time: 1 to 12 hours (S03 ′) as necessary, and anodization And a fourth step (S04) for performing at least one of a film treatment, a coating treatment, and a plating treatment. Hereinafter, each step will be described.

(1) Casting In order to obtain an aluminum alloy vat base tube 1 made of aluminum alloy, after preparing a molten aluminum alloy having the above composition, conventionally known degassing treatment and filtration treatment (filtering with ceramic foam filter or porous tube filter) The filtration method used, etc.). The effect of the degassing treatment can be measured by a known hydrogen determination method such as the Lansley method or the LECO method, and the effect of removing inclusions by the filtration treatment can be measured, for example, by a fracture surface observation method or the like. .

  Then, if necessary, a rod hardener (Al—Ti—B alloy) for the purpose of refining the structure is added before the mold, and a cylindrical ingot (hereinafter referred to as “billet”) is obtained by a DC continuous casting method or the like. Get. Here, the DC continuous casting method refers to pouring the molten metal introduced into the rapid casting mold whose inner wall surface is water-cooled, and rapidly solidifying the molten metal on the inner wall surface of the rapid mold, and the billet immediately after solidification is directed downward or laterally. This is a casting method in which the billet is sequentially drawn and then cooled by spraying cooling water onto the billet, and is known as a casting method of an aluminum alloy having excellent productivity.

  Here, since the aluminum alloy bat base tube 1 contains a large amount of Zn and is likely to cause hot cracking during casting, it is preferably cast while applying low-frequency vibration or ultrasonic vibration to the molten metal. A billet before plastic working can be obtained by performing a homogenization process on the cast billet under conventionally known conditions.

(2) Extrusion process An extruded material (element tube) can be obtained by heating the billet obtained in (1) to 350 to 450 ° C to perform extrusion. By setting the heating temperature to 350 ° C. or higher, recovery of processing strain can be promoted, and generation of a recrystallized structure layer can be prevented. Moreover, the deterioration of surface property can be suppressed by making heating temperature into 450 degrees C or less.

  Here, since the recrystallized texture can be suppressed by forcibly cooling the extruded material (element tube) immediately after coming out of the die, it can be cooled at a cooling rate of 1 ° C./s or more using air and nitrogen. preferable.

  Further, when the extrusion ratio is large, the processing strain increases, and recrystallization texture is likely to progress during the solution treatment. In order to prevent the recrystallized structure layer 22 from becoming thicker than 500 μm in the product bat, the extrusion ratio is preferably 100 or less.

  In addition, in order to improve the dimensional accuracy of the obtained extruded material (element tube), cold drawing may be performed. However, if the degree of drawing is high, the recrystallized structure is likely to be coarsened when the solution treatment is performed, and therefore, the degree of cold work is preferably 30% or less.

(3) Plastic working (first step: S01)
In the first step (S01), the aluminum alloy bat blank 1 obtained in (1) and (2) is subjected to thickness adjustment and swaging, and the aluminum alloy bat blank 1 is formed into a bat shape. This is a step of plastic working.

  As long as the effect of the present invention is not impaired, the shape and thickness of the bat are not particularly limited, and various conventional shapes and thicknesses can be used. However, when the outer diameter of the hitting portion is 66.7 mm When the thickness of the hitting portion is 2.91 to 3.3 mm and the outer diameter of the hitting portion is 63.5 mm, the thickness of the hitting portion is preferably 2.80 to 3.3 mm.

(4) Solution treatment and quenching (second step: S02)
In the method for producing an aluminum alloy bat according to the present invention, the solution that is maintained at a temperature 5 to 25 ° C. lower than the solidus temperature with respect to the aluminum alloy bat blank 1 plastically processed in the first step (S01). It has the 2nd process (S02) which performs a hardening process after performing a chemical conversion process.

  By applying a solution treatment, a coarse compound (Zn-Mg-based, Al-Zn-Mg-Cu-based, Mg-Si-based, Al-Cu-based, which does not contribute to the improvement in strength crystallized when an aluminum alloy is cast) Compound) is dissolved in the Al matrix. Solid elements such as Zn, Mg, and Cu are maintained in a supersaturated solid state in the Al matrix by quenching, and fine precipitates are formed by subsequent aging treatment. An improvement can be achieved.

  Here, by setting the solution treatment temperature to a temperature lower by 25 ° C. than the solidus temperature, the compound can be sufficiently dissolved. In addition, by lowering the solution treatment temperature by 5 ° C. or less from the solidus temperature, it is possible to suppress a decrease in mechanical strength due to local melting (burning), and to coarsen the recrystallized structure Can be suppressed.

  The solution treatment and quenching may be performed after the extrusion process, but it is preferably performed after the molding process because the forming process into a bat shape becomes difficult.

(5) Aging treatment (third step: S03)
The third step (S03) is a step of performing the first stage aging treatment on the aluminum alloy bat that has been plastic-worked into a bat shape. High strength can be obtained by performing the first-stage aging treatment under the conditions of holding temperature: 100 to 140 ° C. and holding time: 6 to 48 hours. Further, the mechanical properties can be adjusted by the second-stage aging treatment, and the improvement in strength or ductility can be exhibited to the maximum extent.

(6) Aging process (S03 ')
The aging treatment (S03 ′) is a step of performing the second-stage aging treatment in a temperature range higher than the first-stage aging treatment temperature. Specifically, the aging treatment is performed under the conditions of holding temperature: 140 to 180 ° C. and holding time: 1 to 12 hours.

  The precipitation distribution of the compound that is the strengthening phase is greatly influenced by the GP zone of the precursor structure. In the aluminum alloy bat of the present invention, precipitates can be finely dispersed at a high density by growing the GP zone. High strength is obtained by the first-stage aging treatment, and the precipitate structure is further controlled by the second-stage aging treatment, thereby contributing to strength or ductility.

  Good strength, ductility and corrosion resistance can be obtained by sufficiently growing the precipitate at a holding temperature of 140 ° C. or higher. Moreover, by setting it as 180 degrees C or less, the excessive growth of a precipitation phase can be suppressed and a strength reduction can be suppressed.

  In the tensile test piece cut out from the striking part of the aluminum alloy bat 2 by the above-described one-stage or two-stage aging, the tensile strength is 630 MPa or more, the 0.2% proof stress value is 605 MPa or more, and the elongation is 14% or more. Tensile properties can be obtained. In addition, the 2% flat proof stress of the striking portion of the aluminum alloy bat 2 can be 7500 N or more.

(7) Anodized film treatment, etc. (fourth step: S04)
In this step, the aluminum alloy bat 2 is subjected to at least one of an anodized film treatment, a coating treatment, and a plating treatment. For example, by forming the outer design surface 18 made of an anodized film or the like on the surface of the aluminum alloy bat 2, corrosion resistance, appearance quality, and the like can be improved.

  As long as the effects of the present invention are not impaired, a method such as anodized film treatment is not particularly limited, and various conventionally known methods can be used. Here, since the surface on which the anodic oxide film treatment or the like is performed has a recrystallized structure, a smooth anodic oxide film or the like having a good appearance can be obtained.

  As mentioned above, although typical embodiment of this invention was described, this invention is not limited only to these, Various design changes are possible and these design changes are all contained in the technical scope of this invention. It is.

<< Example >>
After performing degassing treatment and filtration treatment on the molten aluminum alloy (Examples 1 to 8) having the composition (wt%) shown in Table 1, billets were obtained by DC continuous casting. Next, the billet was heated to 380 ° C. and subjected to extrusion to obtain an aluminum alloy vat base tube (outer diameter 75 mm, wall thickness 3.3 mm). Here, the aluminum alloy that came out of the die The cooling rate of the vat base tube is 1 ° C./s, and the extrusion ratio is 68.

  Next, the obtained aluminum alloy bat blank was subjected to wall thickness adjustment and swaging, and the aluminum alloy bat blank was plastic processed into a bat shape with a striking portion having a wall thickness of 3 mm. First step: S01).

After that, holding temperature: 460 ° C. ± 10 ° C., holding time: solution treatment was performed for 30 minutes or more after reaching the holding temperature, and quenching was performed with water cooling (second step: S02). If necessary, the distortion due to the treatment was corrected by cold working, and then an aging treatment (third step: S03 and S03 ′) was performed under the conditions (A to E) shown in Table 1. Here, the conditions of the aging treatments A to E are as follows.
A: 120 ° C. 24 hours + 155 ° C. 2 hours B: 120 ° C. 24 hours + 165 ° C. 2 hours C: 120 ° C. 24 hours + 175 ° C. 2 hours D: 120 ° C. 12 hours + 155 ° C. 2 hours E: 120 ° C. 12 hours

  Next, an anodic oxide film treatment (fourth step: S04) was performed under the condition of a film thickness of 15 μm and attached to the head part and the grip part to obtain the aluminum alloy bat of the present invention.

≪Comparative example≫
For aluminum alloys (Comparative Examples 1 to 4) having the composition (wt%) shown in Table 1, aluminum alloy bats were obtained in the same manner as in the examples. In Comparative Example 3, 45% drawing was used instead of extrusion.

[Evaluation]
(1) Tensile test Tensile test pieces (14B test piece of JISZ2201) in the longitudinal direction of the bat were collected from the striking part of the obtained aluminum alloy bat, and tensile properties were evaluated according to the tensile test method of JISZ2241. The obtained results are shown in Table 2. The number of test repetitions was 3, and the average value was calculated.

(2) Flat test (SG standard for non-wood bat (CPSA 0024))
A specimen having a length of 50 mm was taken from the striking part of the aluminum alloy bat obtained in Examples 1 to 5, 8 and Comparative Examples 1, 2, and 4, and the residual deformation amount of the specimen was “aluminum alloy bat. Load (2% flat load) and maximum load (maximum load until breakage) were measured. In any of the examples and comparative examples, no fracture was observed when the amount of deformation reached 20% of the diameter. Note that the 2% flatness proof stress value was measured load value / (measured thickness / 3 mm). The obtained results are shown in Table 2. If the tensile strength is 630 MPa or more, the 0.2% proof stress is 605 MPa or more, the elongation is 14% or more, and the 2% flat proof stress is 7500 N or more, ○, if one is not satisfied The evaluation results are shown in Table 2. Here, according to the standard values for hard baseball and general use in the SG standard, the 2% flat proof stress is 7500 N or more, and even when a deformation of the maximum outer diameter of the aluminum alloy bat × 0.2 or more is applied, it does not break. And that the test piece does not break at a load of 10,000 N.

  Evaluation of Example 1-Example 8 of this invention becomes all (circle), and it turns out that it has the outstanding tensile characteristic, 2% flat proof stress, and the maximum load. On the other hand, Comparative Example 1 and Comparative Example 2 have less than 14% elongation, and the maximum load is lower than that of the example, so that the durability (crack resistance, etc.) is inferior to that of the example. In Comparative Example 3, the 0.2% proof stress value does not reach 605 MPa, and the 2% flat proof stress does not reach 7500N. In Comparative Example 1, since the Mg content exceeds the specified range of the present invention, the ratio of the Zn content to the Mg content and the total of the Cu content and the Mg content are outside the specified range of the present invention. . In Comparative Example 2, the Mg content and the Cu content exceed the specified range of the present invention, and the ratio of the Zn content and the Mg content is outside the specified range of the present invention. Further, in Comparative Example 3, the content of each component is within the specified range of the present invention, but the degree of cold work until bat molding is high, the structure is recrystallized, and the residual ratio of the fiber structure reaches the specified value. Not described later. Since Comparative Example 4 has a low Zn content, the 0.2% yield strength is low.

  Except that the outer diameter of the striking part was 66.7 mm or 63.5 mm, and the thickness of the striking part was 2.94 to 2.98 mm or 2.82 to 2.90 mm, respectively, An aluminum alloy bat of the present invention was obtained. FIG. 5 shows the relationship between the 2% flat strength of these aluminum alloy bats and the striking thickness.

  The 2% flattening strength increases with the increase of the hitting portion thickness. In the alloy of Example 5 of the present invention, when the hitting portion has an outer diameter of 66.7 mm, the hitting portion thickness is 2.91 mm. With the above, the 2% flattening strength can be 7500 N or more, and when the outer diameter of the hitting part is 63.5 mm, the 2% flattening strength is 7500 N or more by setting the hitting part thickness to 2.80 mm or more. It can be.

(3) Microstructure observation A sample for microstructural observation was taken from the striking part of the obtained aluminum alloy bat, and the LT-L surface was polished, and then anodized under conditions of 15 V and 2 minutes in a Barker test solution. The crystal structure was observed using a polarizing filter with an optical microscope. The thickness of the recrystallized structure layer in the outer layer part and the residual ratio of the fiber structure were measured, and the results obtained are shown in Table 3.

  In Example 1 to Example 8 of the present invention, the thickness of the recrystallized structure layer in the outer layer portion is in the range of 50 to 500 μm, and the fiber structure ratio is 75% or more. On the other hand, in Comparative Example 3, the entire surface has a fiber structure.

(4) Restitution coefficient test With the same composition and manufacturing method as in Example 8 and Comparative Example 3, a bat having a different thickness at the hitting portion was manufactured and a 2% flattening strength test was conducted. The 2% flat proof stress of the hitting part thickness (2.95 mm) and the bat equivalent to the comparative example 3 (striking part thickness 3.00 mm) was both about 7650 N. Therefore, when the coefficient of restitution was measured based on the test method of ASTM F2219-11, the coefficient of restitution of the bat corresponding to Example 8 was 0.581, which was 0.017 higher than 0.564 of the bat corresponding to Comparative Example 3. In general, it is said that when the restitution coefficient changes by 0.01, the flight distance increases by 1 m. Therefore, an increase in the restitution coefficient of 0.017 corresponds to an increase in the flight distance of 1.7 m.

1 ... Aluminum alloy bat base tube,
2 ... Aluminum alloy bat,
4 ... Bat body,
6 ... Head cap,
8 ... Grip end,
10: Grip tape,
12 ... striking part,
14 ... grip part,
16 ... transition part,
18 ... outside design surface,
20 ... thickness center part,
22 (22 ') ... recrystallized structure layer.

Claims (5)

Zn: 9.0 to 11.0 wt%, Mg: 1.3 to 1.8 wt%, Cu: 2.0 to 2.6 wt% and Cr: 0.02 to 0.30 wt%, Zr: 0.05 to 0.20 wt%, Ti: 0.01-0.15 wt%, B: 0.001-0.05 wt%,
The balance consists of Al and inevitable impurities,
Zn content (wt%) / Mg content (wt%) is 5 or more,
The total of the Cu content (wt%) and the Mg content (wt%) is 3.4 to 4.2 wt%;
An aluminum alloy bat tube made of The aluminum alloy vat base tube according to claim 1,
Having at least one of an anodized film, a paint layer or a plating layer on the outer peripheral surface;
In the metal structure of the striking part, the outer layer part has a recrystallized structure layer having a thickness of 50 to 500 μm, and the fibrous structure inside the plate thickness,
The tensile strength of the striking part is 630 MPa or more, the 0.2% proof stress value is 605 MPa or more, and the elongation is 14% or more,
An aluminum alloy bat characterized by The wall thickness of the striking part is 2.8 to 3.3 mm,
The 2% flat strength of the striking part is 7500 N or more,
The aluminum alloy bat according to claim 2. A first step of performing wall thickness adjustment and swaging on the aluminum alloy bat blank according to claim 1, and plastically processing the aluminum alloy bat blank into a bat shape;
A second step of performing a quenching treatment after a solution treatment that is maintained at a temperature 5 to 25 ° C. lower than the solidus temperature;
A third step of performing an aging treatment of holding temperature: 100 to 140 ° C., holding time: 10 to 48 hours;
A fourth step of applying at least one of an anodized film treatment, a coating treatment or a plating treatment,
A method for producing an aluminum alloy bat characterized by the above. After the third step, an aging treatment of holding temperature: 140 to 180 ° C., holding time: 1 to 12 hours,
The method for producing an aluminum alloy bat according to claim 4.