JPH0344126B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to a method for manufacturing a shaft for a golf club, which improves various properties required of a shaft for a golf club from the viewpoint of materials, particularly elasticity for improving flight distance, and lightness. Various improvements have been made to the shape and structure of golf clubs in order to improve ball flight distance and ball handling properties, but for shafts, the elasticity of the material is important in order to improve flight distance. be done. Additionally, as pipes are made thinner to reduce weight, the strength and toughness of the material are also important. For these reasons, there has been a strong desire to develop a shaft for golf clubs that exhibits high strength and toughness, and also has high elastic properties. The purpose of the present invention is to provide a shaft for a golf club that satisfies such requirements, and the purpose of the present invention is to exhibit high elasticity of 130 kg/mm ² or more at 0.03% proof stress. Of course, it is also necessary to have good weldability when forming a pipe shaft, as well as general properties required for a shaft for a golf club, such as good surface quality. The purpose is to provide shafts for For this purpose, the present inventors conducted various tests and studies on the chemical composition of steel and heat treatment conditions, and as a result, as a manufacturing method for a golf club shaft that satisfies the various requirements described above, C: 0.45 to 0.80.
%, Si; 0.80% or less, Mn; 0.50 to 1.50%, P;
Contains 0.030% or less, S: 0.020% or less, Al: 0.050% or less, Cr: 0.30 to 1.20%, and further contains 0.05 to 1.20%.
Either 0.40% V or 0.03-0.15% Nb
After manufacturing a polished steel strip containing one or two species and the remainder consisting of Fe and unavoidable impurities, this polished steel strip is welded into pipes, formed into the shape of a golf club shaft, and then quenched. We have developed a method for manufacturing golf club shafts that is characterized by tempering at a temperature of 200 to 400°C.
A lightweight golf club shaft having high elasticity of Kg/mm ² or more can be obtained. In addition to the above chemical components, 0.30~0.80%
By adding one or both of Ni or 0.10 to 0.50% Mo, strength and toughness can be further ensured, and if 0.30% or less of Cu is added, golf balls with excellent surface quality can be obtained. You can get a club shaft. Note that even if Ni is not added, it may be contained in steel as an impurity, but the amount of Ni of 0.25% or less, which is normally allowed, is considered as an impurity amount in the present invention. The method for manufacturing a shaft for a golf club of the present invention mainly involves appropriately selecting the chemical composition of steel in order to obtain high elasticity, high strength, high toughness, and further pipe-forming properties.
In addition, the present invention is characterized by specifying the heat treatment conditions, and for this reason, the chemical composition values and tempering conditions of the steel employed in the present invention will be individually explained below. C; C affects the strength and elastic limit of the steel after heat treatment. Figure 1 examines the relationship between C content and 0.03% proof stress when requirements other than C are within the range of the present invention, but as is clear from this test example, if C is less than 0.45%, 0.03% proof stress after tempering
It is difficult to set it to 130Kg/mm ² or more;
Even if the content exceeds 0.80%, the rate of increase in 0.03% yield strength will not be large. In return, 0.80%
If the content exceeds the above, the weldability during pipe making will deteriorate (sample No. 7 in Examples described later), and the toughness will also decrease. Therefore, the C content is set in the range of 0.45% to 0.80%. Si: Si is added as a deoxidizing agent during the refining of the present invention material, but if it is added in excess of 0.80%, surface decarburization will occur during the polishing process during the production of polished strip steel, and the surface properties will deteriorate. The Si content should be kept at 0.80% or less. Mn: Mn effectively works to improve the strength, toughness, and hardenability of steel, but if it is less than 0.50%, sufficient hardenability for golf club shafts cannot be obtained, and if it is contained in excess of 1.50%, In this case, the toughness of the shaft is reduced due to an increase in pearlite band structure and segregation, so the Mn content is set in the range of 0.50 to 1.50%. P: P has a significant negative effect on the low temperature tempering brittleness of steel, and if the P content exceeds 0.030%, the toughness of the shaft in the tempering temperature range according to the present invention will decrease, so P is 0.030%. The following shall apply. S: S has a harmful effect on the materials of the present invention, and if it is contained in excess of 0.020%, especially when welding pipes, cracks are likely to occur due to inclusions along the metal flow of the weld, and the weld will be damaged. S should be kept at 0.020% or less since it will harm the soundness. Al: Like Si, Al is added as a deoxidizing agent during the refining of the materials of the present invention, but if added in an amount exceeding 0.050%, the surface quality of the steel will deteriorate due to an increase in alumina-based inclusions, so it should be kept at 0.050% or less. Cr: Cr is effective in improving the heat treatability of steel during hardening and tempering, especially in ensuring strength and toughness after heat treatment, but if it is less than 0.30%, the required hardenability and strength after heat treatment cannot be achieved. Furthermore, even if the content exceeds 1.20%, the increase in strength after heat treatment will be small and problems will arise in weldability during pipe making, so the content should be within the range of 0.30 to 1.20%. let V or Nb; Both V and Nb serve to refine the austenite crystal grains during heat treatment of the material of the present invention, thereby increasing the 0.03% yield strength and toughness after tempering. Such an effect is 0.05 for V
If the amount is less than 0.03%, no effect will be obtained, and for Nb, if the amount is less than 0.03%, no effect will be obtained.
In addition, even if the content of V exceeds 0.40%,
Even if Nb is contained in an amount exceeding 0.15%, its effect is substantially saturated, so there is no need to contain more than this. Therefore, in the present invention, any one of V: 0.05 to 0.40% and Nb: 0.03 to 0.15% is contained, and when two types are contained, the total amount is preferably 0.40% or less. Ni or Mo: When Ni or Mo is contained in an appropriate amount in the material of the present invention, the strength and toughness after heat treatment can be improved in either case. To obtain this effect, 0.30-0.80% for Ni and 0.30% to 0.80% for Mo must be
The content is preferably in the range of 0.10 to 0.15%.
Mo content within this range also results in a tempering temperature of 200~
It also provides the effect of increasing yield strength by 0.03% under 400℃ tempering conditions. Cu: Including an appropriate amount of Cu can improve the surface properties of polished steel strip products (reducing surface flaws due to scale flaws during rolling, etc.). This surface quality improving effect does not show any difference even if the content exceeds 0.30%, so a content of 0.30% or less is sufficient. The golf club shaft of the present invention has its alloy composition and component content determined as described above, but in order to obtain a shaft with the target properties, it is necessary to manufacture a polished strip of this alloy steel. Then, this plate is welded into a tube by, for example, TIG welding or electric resistance welding, and this tube is formed into the shape of a shaft for a golf club by, for example, drawing processing, and then subjected to suitable conditions. Hardening and tempering treatment is performed below. FIG. 2 shows the results of investigating the relationship between tempering temperature and 0.03% yield strength by varying the tempering temperature after hardening sample No. 2 of the example described later. As is clear from this figure 2, even if the tempering temperature is less than 200℃, and even if the tempering temperature exceeds 400℃, the
Proof strength does not reach 130Kg/ ^mm2 . Therefore, to obtain a golf club shaft with high modulus, 200 to 400
It is necessary to temper in the temperature range of ℃. Note that this second
As mentioned above, the figure shows the results for sample No. 2 of Example, that is, the sample with a C content of 0.45%, the lower limit specified by the present invention. The value of becomes even higher as shown in FIG. In this case, at a tempering temperature of 200 to 400℃
It is clear that the 0.03% yield strength is 130Kg/mm ² or more. The present invention will be further explained below with reference to Examples. Example 1 A hot-rolled steel plate having the chemical composition values shown in Table 1 was pickled, then annealed and cold rolled repeatedly to produce a 0.5 mm thick steel strip. In Table 1, sample No. 2
No. 5 and No. 5 had no Ni added, but the analysis showed that they contained 0.12% and 0.07% Ni. This is unavoidably mixed in during the manufacturing of steel, and the amount is still within an acceptable level as an impurity. Therefore, samples No. 2 and No. 5 should be regarded as polished steel strips that do not contain Ni, and these correspond to the polished steel strips used in the methods of claims 1 and 3. JIS No. 5 tensile test pieces were prepared from each polished strip steel, and each test piece was quenched and tempered under the conditions shown in Table 2. The mechanical properties (0.03% proof stress, tensile strength, elongation) of the obtained treated products are shown in Table 2. In addition, each polished strip steel was formed into a 19 mmφ electric resistance welded steel pipe, and the pipe formability was evaluated, and the results are also listed in Table 2. In Table 2, Comparative Material No. 1 has a C content lower than the range of the present invention, so the 0.03% proof stress cannot satisfy the target of the present invention of 130 Kg/mm ² or more.
In addition, in comparison material No. 7, the C content was too high, so
Although it has good strength, there is a problem in that the toughness of the welded part during pipe making decreases and cracks occur, making it impossible to obtain a normal steel pipe. On the other hand, materials Nos. 2 to 6 according to the present invention can obtain a 0.03% yield strength of 130 Kg/mm ² or more, and have no problems in pipe formability.
Also, when comparing samples No. 5 and No. 6, Ni and Mo
It can be seen that sample No. 6, which contained Ni, had high ductility despite having higher strength, and had the effect of toughening. In addition, sample No. 2, 4, which either does not contain Cu or contains Cu only in an amount equivalent to the amount of unavoidably mixed impurities.
In No. 6, scale flaws occurred in the hot-rolled sheet, whereas samples No. 1, 3, 5, and
In No. 7, a polished strip steel with no scale defects and excellent surface quality was obtained, and the surface quality improving effect of Cu was recognized.

【table】

[Table] Example 2 A hot-rolled steel plate having the chemical composition values shown in Table 3 was pickled, then annealed and cold rolled repeatedly to produce a polished steel strip with a thickness of 0.5 mm. JIS No. 5 tensile test pieces were prepared from each polished strip steel, and each test piece was quenched and tempered under the conditions shown in Table 4. The austenite grain size (austenite grain size number) and 0.03% proof stress of the obtained heat-treated product are also listed in Table 4. In Table 4, comparative materials of Samples No. 8 and 9 are V or V which has austenite grain refining effect.
Because it does not contain Nb or contains only a small amount of Nb, the austenite crystal grains are large and the target 0.03%
Durability has not been achieved. On the other hand, samples No. 10 and No. 12 according to the method of the present invention have fine austenite crystal grains and exhibit the target high elasticity. Note that when comparing No. 10 and No. 12, No. 12 containing Ni and Mo exhibits higher elasticity, indicating that the addition of these alloying elements is effective in further improving elasticity. In addition, samples No. 11 and No. 13, which are comparative materials, contained V or Nb in an amount exceeding the range specified in the present invention.
As is clear from the comparison with Samples No. 10 and No. 12, no significant improvement in elasticity was observed considering the content, and it was found that V and Nb, which are expensive additive elements, were added beyond the scope of the present invention. It turns out that it is not economical.

【table】

[Table] Example 3 Steel having the chemical composition shown in Table 5 was melted in a converter and then cast into a steel ingot weighing approximately 7 tons. Thereafter, a polished steel strip with a thickness of 0.52 mm was produced using the usual hot rolling and polished strip steel manufacturing process (pickling, annealing, and cold rolling). Using this polished strip steel, we made a pipe by TIG welding and made a 19φ
A raw tube of ×0.52tmm was obtained. By drawing this raw tube, the small diameter side is 10φ x 0.43tmm,
It was molded into the shape of a golf club shaft with a length of 970 mm and a tapered step of 15φ x 0.30 tmm on the large diameter side. These pipes were heat treated under the heat treatment conditions shown in Table 6 and subjected to bending tests and impact tests to evaluate their elasticity and toughness as shafts for golf clubs. The bending test conducted here was performed using a so-called cantilever beam, in which the small diameter side of the pipe was fixed horizontally at 50 mm using a jig, and a load was applied at a position 500 mm from the jig. It was measured as For the impact test, a pipe-shaped test piece was cut out from the small diameter side of the pipe, and the pipe-shaped test piece was conducted at room temperature using an Izot impact tester. The measurement results of yield load and impact value are shown in Table 6. Note that the surface properties of the polished strip steel are also listed in Table 6. Compared to test No. 14, which is a comparative material, according to the method of the present invention
The yield loads of No. 15 and No. 16 are clearly large. It also has sufficient toughness. Comparative material sample No. 17
(low V) has a higher C content than No. 14 and No. 15, so the yield load is the same, but the impact value is low and the toughness is poor. Note that the Cu content of No. 15 is 0.03%, and it is not produced by adding Cu. Therefore, compared to No. 16 with Cu added, the influence of scale flaws in the hot rolled sheet (hot coil) remained on the polished strip steel, and scale encroachment and scale patterns appeared in some parts, so these parts were removed. This resulted in a decrease in yield.

【table】

【table】 [Brief explanation of drawings]

Figure 1 is a diagram showing the relationship between 0.03% proof stress as an elastic index and C content in the shaft material, and Figure 2 is a diagram showing the relationship between tempering temperature and 0.03% proof stress for sample No. 2 of the example. .

Claims (1)

[Claims] 1 C; 0.45 to 0.80%, Si; 0.80% or less, Mn;
Contains 0.50 to 1.50%, P; 0.030% or less, S; 0.020% or less, Al; 0.050% or less, Cr; 0.30 to 1.20%, and further contains 0.05 to 0.40% V or 0.03 to 0.15%.
A polished steel strip containing one or two types of Nb with the remainder consisting of Fe and unavoidable impurities is produced, and this polished steel strip is welded into pipes and then formed into the shape of a golf club shaft. A method for manufacturing a shaft for a golf club having high elasticity of 130 Kg/mm ² or more with a 0.03% yield strength, which comprises quenching and then tempering at a temperature of 200 to 400°C. 2 C; 0.45-0.80%, Si; 0.80% or less, Mn;
Contains 0.50 to 1.50%, P; 0.030% or less, S; 0.020% or less, Al; 0.050% or less, Cr; 0.30 to 1.20%, and further contains 0.05 to 0.40% V or 0.03 to 0.15%.
any one or two types of Nb, and 0.30~
A polished steel strip containing one or two of 0.80% Ni or 0.10 to 0.50% Mo, with the balance consisting of Fe and unavoidable impurities is produced, and this polished steel strip is welded into pipes and used for golf purposes. A method for manufacturing a golf club shaft having high elasticity of 130 Kg/mm ² or more with a 0.03% proof stress, which comprises forming into the shape of a club shaft, then quenching, and then tempering at a temperature of 200 to 400°C. . 3C; 0.45-0.80%, Si; 0.80% or less, Mn;
0.50-1.50%, P; 0.030% or less, S; 0.020% or less, Al; 0.050% or less, Cr; 0.30-1.20%, Cu;
A polished steel strip containing 0.30% or less and further containing one or both of 0.05 to 0.40% of V or 0.03 to 0.15% of Nb, with the balance consisting of Fe and unavoidable impurities is manufactured. Polished band steel is welded into pipes, formed into the shape of a golf club shaft, and then quenched at 200 to 400℃.
with 0.03% yield strength consisting of tempering treatment at a temperature of
A method for manufacturing a golf club shaft having high elasticity of 130Kg/mm ² or more. 4 C; 0.45-0.80%, Si; 0.80% or less, Mn;
0.50-1.50%, P; 0.030% or less, S; 0.020% or less, Al; 0.050% or less, Cr; 0.30-1.20%, Cu;
Contains 0.30% or less, and further contains either 0.05 to 0.40% of V or 0.03 to 0.15% of Nb or two.
seeds, and 0.30-0.80% Ni or 0.10-0.50%
A polished strip steel containing one or two types of Mo with the remainder consisting of Fe and unavoidable impurities is produced, and this polished strip steel is welded into pipes and then formed into the shape of a golf club shaft. A method for manufacturing a shaft for a golf club having high elasticity of 130 Kg/mm ² or more with a 0.03% yield strength, which comprises quenching and then tempering at a temperature of 200 to 400°C.