Classifications

• • A—HUMAN NECESSITIES
  • A63—SPORTS; GAMES; AMUSEMENTS
  • A63B—APPARATUS FOR PHYSICAL TRAINING, GYMNASTICS, SWIMMING, CLIMBING, OR FENCING; BALL GAMES; TRAINING EQUIPMENT
  • A63B53/00—Golf clubs
  • A63B53/04—Heads
• • A—HUMAN NECESSITIES
  • A63—SPORTS; GAMES; AMUSEMENTS
  • A63B—APPARATUS FOR PHYSICAL TRAINING, GYMNASTICS, SWIMMING, CLIMBING, OR FENCING; BALL GAMES; TRAINING EQUIPMENT
  • A63B60/00—Details or accessories of golf clubs, bats, rackets or the like
• • C—CHEMISTRY; METALLURGY
  • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
  • C22C—ALLOYS
  • C22C14/00—Alloys based on titanium
• • A—HUMAN NECESSITIES
  • A63—SPORTS; GAMES; AMUSEMENTS
  • A63B—APPARATUS FOR PHYSICAL TRAINING, GYMNASTICS, SWIMMING, CLIMBING, OR FENCING; BALL GAMES; TRAINING EQUIPMENT
  • A63B2209/00—Characteristics of used materials

Definitions

• the present invention relates to a low density titanium alloy, a golf club head, and a process for producing a low density titanium alloy part, more specifically, to a low density titanium alloy having high specific strength and excellent in hot workability, a golf club head using the low density titanium alloy, and a process for producing a low density titanium alloy part using the low density titanium alloy.
• the ⁇ + ⁇ type alloy is a well-balanced material as being excellent in strength, specific strength, heat processability, workability, corrosion resistance, and the like, and therefore it has heretofore been used mainly as an aerospace material. Furthermore, the ⁇ + ⁇ type alloy has heretofore been used as an automobile material, a mechanical structure part material, a general civilian goods material, and the like. Particularly, a Ti-6Al-4V alloy among the ⁇ + ⁇ type alloys has widely been used as a general purpose high tensile titanium alloy, and about 80% of whole the Ti alloy consumption is occupied with the Ti-6Al-4V alloy consumption.
• the Ti-6Al-4V alloy entails a high cost since it contains V which is expensive. Further, although the Ti alloys are generally high in specific strength, further reduction in cost and further improvement in specific strength has been in demand for certain applications such as application in golf club head.
• Patent Reference 1 discloses an ⁇ + ⁇ type Ti alloy containing, in terms of mass %, 5.5% to 7.0% of Al, 0.5% to 4.0% of Fe, 0.5% or less of O, and a remainder being Ti and inevitable impurities.
• Patent Reference 1 discloses that:
• Patent Reference 2 discloses that:
• Patent Reference 3 discloses a high strength Ti alloy contaihing, in terms of mass %, 5.50% to 7.00% of Al, 0.50% to 4.00% of Fe, 0.02% to 0.10% of N, 0.05% to 0.40% of O, and a remainder being Ti and inevitable impurities.
• Patent Reference 3 discloses that:
• Patent Reference 1 Japanese Patent No. 3306878
• Patent Reference 2 JP-A-2001-115221
• Patent Reference 3 JP-A-2004-10963
• Ti-6Al-1Fe alloy is being used as a low density titanium alloy for golf club heads.
• the effect of the Ti-6Al-1Fe alloy for the achievement of low density is weaker than that of a Ti-6Al-4V alloy that is the representative titanium alloy.
• An object of the invention is to provide a low density titanium alloy having higher specific strength as compared to the Ti-6Al-4V alloy, excellent in hot workability, and reduced in cost; a golf club head using the low density titanium alloy; and a low density titanium alloy part using the low density titanium alloy.
• the present invention relates to the following items 1 to 32.
• a low density titanium alloy comprising:
• the low density titanium alloy according to item 1 which has a specific strength of 205 or more.
• the low density titanium alloy according to item 2 which has a specific strength of 205 or more.
• the low density titanium alloy according to item 3 which has a specific strength of 205 or more.
• the low density titanium alloy according to item 4 which has a specific strength of 205 or more.
• the low density titanium alloy according to item 6 which has a specific strength of 205 or more.
• the low density titanium alloy according to item 7 which has a specific strength of 205 or more.
• the low density titanium alloy according to item 8 which has a specific strength of 205 or more.
• the low density titanium alloy according to item 1 which has a reduction of area at 1000° C. of 40% or more and a flow stress at 1000° C. of 200 MPa or less.
• the low density titanium alloy according to item 2 which has a reduction of area at 1000° C. of 40% or more and a flow stress at 1000° C. of 200 MPa or less.
• the low density titanium alloy according to item 3 which has a reduction of area at 1000° C. of 40% or more and a flow stress at 1000° C. of 200 MPa or less.
• the low density titanium alloy according to item 4 which has a reduction of area at 1000° C. of 40% or more and a flow stress at 1000° C. of 200 MPa or less.
• the low density titanium alloy according to item 5 which has a reduction of area at 1000° C. of 40% or more and a flow stress at 1000° C. of 200 MPa or less.
• the low density titanium alloy according to item 6 which has a reduction of area at 1000° C. of 40% or more and a flow stress at 1000° C. of 200 MPa or less.
• the low density titanium alloy according to item 7 which has a reduction of area at 1000° C. of 40% or more and a flow stress at 1000° C. of 200 MPa or less.
• the low density titanium alloy according to item 8 which has a reduction of area at 1000° C. of 40% or more and a flow stress at 1000° C. of 200 MPa or less.
• the low density titanium alloy according to item 9 which has a reduction of area at 1000° C. of 40% or more and a flow stress at 1000° C. of 200 MPa or less.
• the low density titanium alloy according to item 10 which has a reduction of area at 1000° C. of 40% or more and a flow stress at 1000° C. of 200 MPa or less.
• the low density titanium alloy according to item 11 which has a reduction of area at 1000° C. of 40% or more and a flow stress at 1000° C. of 200 MPa or less.
• the low density titanium alloy according to item 12 which has a reduction of area at 1000° C. of 40% or more and a flow stress at 1000° C. of 200 MPa or less.
• the low density titanium alloy according to item 13 which has a reduction of area at 1000° C. of 40% or more and a flow stress at 1000° C. of 200 MPa or less.
• the low density titanium alloy according to item 14 which has a reduction of area at 1000° C. of 40% or more and a flow stress at 1000° C. of 200 MPa or less.
• the low density titanium alloy according to item 15 which has a reduction of area at 1000° C. of 40% or more and a flow stress at 1000° C. of 200 MPa or less.
• the low density titanium alloy according to item 16 which has a reduction of area at 1000° C. of 40% or more and a flow stress at 1000° C. of 200 MPa or less.
• the present invention also relates to a golf club head containing the above-mentioned low density titanium alloy.
• the present invention also relates to a process for producing a low density titanium alloy part, the process including: blending raw materials so as to obtain the above-mentioned low density titanium alloy, followed by melting and casting the raw materials to thereby obtain an ingot; and heating the ingot to a temperature which is ⁇ transus temperature or higher and is 1200° C. or lower, followed by forging or rolling the ingot to thereby complete a rough processing step.
• the increase in Al content generally entails deterioration of hot workability.
• Fe is contained in the alloy as a principal addition element, it is possible to reduce a cost by using the inexpensive raw materials and reducing the amount of expensive V.
• the low density titanium alloy according to the invention is usable for various structure parts, parts for anti-corrosion, and the like that are used for golf club heads, chemical industrial apparatuses, electric appliances, aerospace appliances, airplanes, boats and ships, wheeled vehicles, medical equipments, condensers, heat exchangers, desalination apparatuses, and the like.
• a low density titanium alloy according to the invention contains following elements with a remainder being Ti and inevitable impurities.
• Types of addition elements, component ratios thereof, and reasons for limitation are as follows.
• Al is the element that achieves solution hardening of an ⁇ -phase of the alloy. Further, since Al is lighter than Ti, Al acts for reducing density of the alloy (i.e. for achieving high specific strength). In order to attain such effects, an Al content may preferably be 7.1 mass % or more.
• the Al content when the Al content is excessive, an intermetallic compound Ti 3 Al is precipitated to cause embrittlement of the alloy. Therefore, the Al content may preferable by 10.0 mass % or less.
• a Fe content may preferably be 0.1 mass % or more.
• the Fe content may preferably be 3.0 mass % or less.
• an O content may preferably be 0.01 mass % or more.
• the O content when the O content is excessive, rigidity is increased to deteriorate ductibility. Therefore, the O content may preferably be 0.3 mass % or less.
• N has an effect of strengthening the ⁇ -phase as being dissolved into the ⁇ -phase.
• the N content may preferably be 0.5 mass % or less.
• C has an effect of strengthening the ⁇ -phase as being dissolved into the ⁇ -phase.
• the C content may preferably be 0.5 mass % or less.
• the low density titanium alloy according to the invention may further contain one or more of elements described below.
• V has an effect of stabilizing a ⁇ -phase.
• a V content may preferably be 0.01 mass % or more.
• the V content when the V content is excessive, a specific gravity is increased. Therefore, the V content may preferably be 2.0 mass % or less.
• a pure metal or a Ti-6Al-4V alloy scrap may be used as a V source in the production of the alloy.
• Each of Cr, Ni and Mo has an effect of stabilizing the ⁇ -phase.
• a content of these elements is excessive, a specific gravity is increased. Therefore, a sole or total amount of at least one element selected from the group consisting of Cr, Ni and Mo may preferably be 2.0 mass % or less.
• each of B and Si has an effect of fining grains.
• each of a B content and a Si content may preferably be 0.01 mass % or more.
• each of the B content and the Si content may preferably be 0.3 mass % or less.
• B and Si may be added solely or both of them may be added simultaneously.
• the increase in Al content generally entails deterioration of hot workability.
• the low density titanium alloy according to the invention contains Fe as the principal addition element, it is possible to use, as a raw material, an inexpensive sponge titanium containing Fe as impurity. Further, by adding Fe, it is possible to reduce the amount of expensive V to be used. Therefore, it is possible to reduce a cost of the low density titanium alloy.
• the low density titanium alloy according to the invention has high specific strength and is excellent in hot workability, it is possible to obtain, for example, a golf club head, that is inexpensive, light-weight, and high in repulsion by using the low density titanium alloy.
• a process for producing a low density titanium alloy part according to the invention includes a melting/casting step, a rough processing step, a finish processing step, and an annealing step.
• the melting/casting step is a step of blending raw materials so as to obtain the low density titanium alloy of the invention, followed by melting and casting the raw materials.
• the low density titanium alloy according to the invention contains Fe as the essential element, it is possible to use, as a Ti source, not only a high purity sponge titanium but also a low purity sponge titanium containing 0.1 to 2.0 mass % of Fe or a Ti-6Al-4V alloy scrap. Therefore, it is possible to reduce a cost for the titanium alloy part.
• the melting/casting of the blended materials is not particularly limited, and it is possible to employ a conventional method.
• the rough processing step is a step of heating an ingot, which is obtained by blending the raw materials so as to obtain the low density titanium alloy according to the invention followed by melting and casting the raw materials, to a temperature which is ⁇ transus temperature ( ⁇ transforming point) or higher and is 1200° C. or lower, followed by forging or rolling the ingot.
• the processing temperature in the rough processing may preferably be the ⁇ transus temperature or higher at which only the ⁇ -phase remains.
• the processing temperature in the rough processing may preferably be 1200° C. or less.
• the finish processing step is a step of performing a finish-forging or finish-rolling of the low density titanium alloy forged or rolled in the rough processing step after heating the alloy to a temperature which is 600° C. or higher and is less than the ⁇ transus temperature.
• the finish processing step is performed according to the necessity.
• the processing temperature in the finish processing step may preferably be 600° C. or more.
• the processing temperature in the finish processing step may preferably be less than ⁇ transus temperature.
• the annealing step is a step of annealing the low density titanium alloy forged or rolled in the finish processing step.
• the annealing step is performed according to the necessity.
• the annealing is performed for the purpose of eliminating a strain after the finish processing step.
• Annealing conditions are not particularly limited, and optimum conditions may be selected depending on the alloy composition.
• Raw materials were weighed so as to achieve predetermined compositions, and titanium alloy ingots each having a mass of 6 kg and a diameter of 100 mm were produced through melting using a plasma skull furnace. Shown in Table 1 are chemical compositions of the thus-obtained ingots.
• each of the ingots was heated to 1000° C., and a round bar having a diameter of 20 mm was obtained by hot forging. Further, a heat treatment at 750° C. for 2 h under an air cooling (AC) was performed. From the round bar after the heat treatment, a No. 3 tensile test piece (diameter: 6.35 mm, evaluation distance: 25 mm) defined in ASTM E8 was prepared.
• a high-temperature high-speed tensile test was performed at 1000° C. to measure flow stress and reduction of area at 1000° C.
• a tensile test was performed using an insutoron type tensile test at a crosshead speed of 5 ⁇ 10 ⁇ 5 m/s machine to measure tensile strength.
• a specific gravity of each of the tensile test pieces was measured by employing a water-impregnation method. Specific strength was calculated from the detected specific gravity and tensile strength.
• Manufacturability was evaluated in terms of reduction of area at 1000° C. Those having reduction of area at 1000° C. of 40% or more is evaluated as “good”, and those having reduction of area at 1000° C. of less than 40% is evaluated as “poor”.
• Comparative Examples 1 to 3 are remarkably poor in manufacturability due to the high content of Al. Particularly, it was impossible to measure the flow stress and reduction of area of Comparative Examples 2 and 3 having the Al content exceeding 11 mass %. Comparative Example 4 having the Fe content exceeding 3.0 mass % has poor manufacturability though it has high tensile strength and specific strength. Comparative Example 5 (Ti-4Al-6V alloy) has good manufacturability, but it has low tensile strength and specific strength.
• each of Examples 1 to 40 has high tensile strength and specific strength due to the appropriate content of Al. Furthermore, each of Examples 1 to 40 also has good hot workability due to the adjustment of the Fe content and the O content and the optional addition of the small amount of V, as well as the relatively increased Al content.

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• 2008
  • 2008-09-10 JP JP2008231619A patent/JP5287062B2/ja active Active
  • 2008-09-12 CN CNA2008101488074A patent/CN101386932A/zh active Pending
  • 2008-09-12 US US12/232,198 patent/US20090074606A1/en not_active Abandoned

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