WO2017179652A1 - チタン合金、時計外装部品用素材の製造方法 - Google Patents
チタン合金、時計外装部品用素材の製造方法 Download PDFInfo
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- WO2017179652A1 WO2017179652A1 PCT/JP2017/015114 JP2017015114W WO2017179652A1 WO 2017179652 A1 WO2017179652 A1 WO 2017179652A1 JP 2017015114 W JP2017015114 W JP 2017015114W WO 2017179652 A1 WO2017179652 A1 WO 2017179652A1
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- 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
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- C—CHEMISTRY; METALLURGY
- C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
- C22F—CHANGING THE PHYSICAL STRUCTURE OF NON-FERROUS METALS AND NON-FERROUS ALLOYS
- C22F1/00—Changing the physical structure of non-ferrous metals or alloys by heat treatment or by hot or cold working
- C22F1/16—Changing the physical structure of non-ferrous metals or alloys by heat treatment or by hot or cold working of other metals or alloys based thereon
- C22F1/18—High-melting or refractory metals or alloys based thereon
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- C—CHEMISTRY; METALLURGY
- C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
- C22F—CHANGING THE PHYSICAL STRUCTURE OF NON-FERROUS METALS AND NON-FERROUS ALLOYS
- C22F1/00—Changing the physical structure of non-ferrous metals or alloys by heat treatment or by hot or cold working
- C22F1/16—Changing the physical structure of non-ferrous metals or alloys by heat treatment or by hot or cold working of other metals or alloys based thereon
- C22F1/18—High-melting or refractory metals or alloys based thereon
- C22F1/183—High-melting or refractory metals or alloys based thereon of titanium or alloys based thereon
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- C—CHEMISTRY; METALLURGY
- C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
- C22F—CHANGING THE PHYSICAL STRUCTURE OF NON-FERROUS METALS AND NON-FERROUS ALLOYS
- C22F1/00—Changing the physical structure of non-ferrous metals or alloys by heat treatment or by hot or cold working
Definitions
- the present invention relates to a titanium alloy and a method for producing a watch exterior component material made of a titanium alloy having high hardness, excellent toughness and hot forgeability, and extremely low occurrence of skin allergies.
- Ti-based alloys are often used as materials for watch exterior parts. Ti-based alloys are significantly lighter than conventionally used stainless steel and have extremely good corrosion resistance against seawater and the like. In addition, elements that may cause skin allergies such as Hg, Ni, Cr, and Co are known, but Ti-based alloys can be configured by removing these elements and may cause skin allergies. It is excellent in that it can be configured to be significantly lowered.
- the uniformity of the microstructure of the material is necessary to prevent unevenness in color tone and light intensity. For this reason, it is not appropriate to use a cast material having a non-uniform microstructure, and it is necessary to use a forging material having a uniform microstructure.
- a forging material having a uniform microstructure.
- casting defects may exist in the cast material, it is necessary to use the forged material also from this viewpoint. In order to use a forging material based on these needs, an excellent forging workability is required for the alloy to be used.
- Patent Document 1 discloses a decorative titanium alloy containing 0.5% or more of iron by weight, but the maximum value of the Vickers hardness of the disclosed titanium alloy is about HV400 to prevent scratches. However, it is insufficient from the viewpoint of improving the mirror polishability.
- Patent Document 2 proposes a Ti alloy containing 4.5% Al (wt%, hereinafter the same), 3% V, 2% Fe, 2% Mo, 0.1% O, This Ti alloy has a Vickers hardness of HV440, which is insufficient from the viewpoint of preventing scratches and improving mirror polishing.
- Patent Document 3 4.0 to 5.0% aluminum by weight, 2.5 to 3.5% vanadium, 1.5 to 2.5% molybdenum, and 1.5 to 2.5% iron. And the remainder is titanium and an inevitable component titanium alloy is disclosed. Although the Vickers hardness of this titanium alloy is not explicitly described in the specification, its composition is not much different from the composition of the titanium alloy of Patent Document 2, so that the hardness is about HV440 as well. Conceivable.
- Nb is contained in mass% in a proportion of more than 20% and not more than 40%
- Ge is contained in a proportion of 0.2% to 4.0%
- Ta, W, V, Cr, Ni, Mn A germanium-containing high-strength titanium alloy containing one or more of Co, Fe, Cu, and Si in a proportion of 15% or less in total, the balance being made of Ti and inevitable impurities, and excellent in cold workability is disclosed.
- this alloy is a ⁇ -type titanium alloy. It is hard to think that it is remarkably hard in comparison.
- JP-A-7-62466 Japanese Patent Laid-Open No. 7-150274 JP-A-9-145855 JP 2008-127667 A
- the present invention has been made in view of the above circumstances, and the material itself is so hard that surface curing treatment is unnecessary. Specifically, the Vickers hardness is about HV600 or more, and the hot forgeability is excellent. An object is to provide a Ti-based alloy that is not extremely brittle.
- the hardness, strength, and ductility of metal materials are closely related. As the hardness increases, the strength increases and the ductility decreases. That is, the hard material targeted by the present invention has high strength but low ductility. If the ductility is small, the hot forgeability is naturally low, and problems such as cracking of the material during the forging operation occur. That is, it is usually a difficult technical problem to achieve both hardness and hot forgeability.
- the present inventors should develop a Ti-based alloy that is extremely hard at room temperature but softens rapidly at high temperatures. Thought. In order to realize this, the inventors have come to the idea that it is effective to use the ⁇ phase present in the Ti-based alloy.
- the ⁇ phase is a high-temperature phase of a solid solution. Therefore, as described in the specification of the prior art, by adding a ⁇ -stabilizing element such as Nb, V, or Mo, it exists even at room temperature.
- the ⁇ phase can be stabilized as possible.
- the ⁇ phase is a soft solid solution rich in deformability from room temperature to high temperature. Therefore, although the hot forgeability at high temperature is good, there is a limit to improving the hardness at room temperature as in the prior art.
- the present inventors considered to increase the Al concentration significantly compared to the prior art.
- a Ti-Al alloy with an increased Al concentration when the ⁇ phase is stabilized by a ⁇ stabilizing additive element, this ⁇ phase remains a solid solution at a high temperature, but at room temperature it is ordered as a B2 phase of an intermetallic compound. Metamorphosis. Since the intermetallic compound phase is a hard phase having a small deformability, an improvement in hardness can be expected.
- the phase crystal structure itself does not depend on the type of the additive element, but the mechanical properties of the phase, for example, high temperature ductility, room temperature hardness, The brittleness at room temperature differs depending on the additive element and the amount of the solid solution. Also, the influence of Al concentration is very large. Therefore, in order to obtain an alloy that is hard at room temperature, not extremely brittle, and excellent in forgeability at high temperatures, it is necessary to find appropriate values for the types of additive components, the amount added, and the concentration of Al. The inventors conducted a number of experiments from these viewpoints. The present invention has been made based on such an experiment, and is characterized by the following configuration.
- the titanium alloy according to one embodiment of the present invention includes aluminum in a proportion of 28.0 atomic percent to 38.0 atomic percent and iron in a proportion of 2.0 atomic percent to 6.0 atomic percent. And titanium and unavoidable impurities as the balance.
- the titanium alloy according to [1] may further contain silicon in a proportion of 0.3 atomic% to 1.5 atomic%.
- a titanium alloy according to another embodiment of the present invention includes aluminum in a proportion of 28.0 atomic% to 38.0 atomic%, and manganese of 4.0 atomic% to 8.0 atomic%.
- a method for manufacturing a watch exterior part material according to one aspect of the present invention includes a step of hot working the titanium alloy according to any one of [1] to [3], A step of heat treating the titanium alloy.
- the titanium alloy of the present invention contains aluminum at a higher concentration than the conventional one and contains iron or manganese as a ⁇ -stabilizing element.
- the concentrations of aluminum and these additive elements are optimized. Therefore, the ⁇ phase, which is a phase constituting this alloy, remains a solid solution phase having ductility at a high temperature, but has a property of regularly transforming into a hard intermetallic compound phase (B2 phase) at room temperature. Therefore, the titanium alloy of the present invention can avoid the problem of being damaged during forging in a high temperature environment during hot forging, and can add processing strain to a necessary degree.
- the microstructure required for the material can be made uniform.
- the titanium alloy according to the first embodiment of the present invention contains aluminum (Al) in a proportion of 28.0 atomic% (at%) or more and 38.0 atomic% or less, and includes iron (Fe) that is a ⁇ -stabilizing element. It is contained in a ratio of 2.0 atomic% or more and 6.0 atomic% or less, and contains titanium (Ti) and inevitable impurities as the balance.
- Al is about 17.8% to 25.6% by weight
- Fe is about 2.6% to 8.3% by weight.
- a titanium alloy is obtained by melting aluminum, iron, and titanium raw materials in a melting furnace, putting the molten metal in a mold and solidifying the alloy (alloy forming step).
- this titanium alloy is put into a heating furnace and heated at a temperature of 1200 ° C. or higher and 1300 ° C. or lower. Thereafter, the material is taken out from the furnace and hot forged in the atmosphere at room temperature (hot forging process).
- hot forging process for example, upsetting (a method of compressing the material in the length direction) and stretching (a method of extending the material perpendicular to the length direction of the material) can be used.
- the hot forged titanium alloy is put into a heat treatment furnace and heat treated.
- heating is performed at a temperature of 1200 ° C. or higher and 1300 ° C. or lower, and then taken out of the furnace and cooled (heat treatment step).
- the cooling rate needs to be fast, and a cooling rate higher than air cooling is desirable.
- the watch exterior part material obtained by the above manufacturing method is made of the titanium alloy according to the present embodiment, and its microstructure is made uniform.
- the material itself is hard and does not require surface treatment and can be mirror-polished, it is characterized by little unevenness in color tone and light intensity and is hardly scratched.
- the titanium alloy according to the second embodiment of the present invention contains aluminum (Al) at a ratio of 28.0 atomic% to 38.0 atomic%, and contains 4.0 atoms of ⁇ -stabilizing element manganese (Mn). % And 8.0 atomic% or less, and titanium (Ti) and inevitable impurities are included as the balance.
- Al aluminum
- Mn ⁇ -stabilizing element manganese
- Ti titanium
- the titanium alloy according to this embodiment has the same configuration as that of the titanium alloy according to the first embodiment except that it contains Mn instead of Fe as a ⁇ -stabilizing element, and the titanium alloy according to the first embodiment. It has the same effect as. Accordingly, the watch exterior component material manufacturing method described as the first embodiment can be applied to the titanium alloy according to the present embodiment, and the watch exterior component material having the same configuration as that of the first embodiment is applicable. Can be obtained.
- the titanium alloy according to the third embodiment of the present invention contains aluminum (Al) and iron (Fe) in the same proportion as the titanium alloy of the first embodiment, and further contains silicon (Si) at 0.3 atoms. % To 1.5 atomic%.
- the titanium alloy according to the third embodiment contains titanium (Ti) and inevitable impurities as the balance.
- the configuration of the titanium alloy according to the third embodiment is the same as the configuration of the titanium alloy according to the first embodiment except for the point containing Si, and even at a slower cooling rate, the titanium alloy according to the first embodiment It is the feature that equivalent hardness is obtained.
- the present invention it is necessary to heat-treat a hot forged titanium alloy in a heat treatment furnace.
- heating is performed at a temperature of 1230 ° C. or higher and 1330 ° C. or lower, and thereafter, the heat is taken out of the furnace and cooled.
- the cooling rate needs to be fast, and it is desirable that the cooling rate be higher than air cooling.
- the treatment in which the cooling rate is equal to or higher than air cooling include air cooling, oil cooling, water cooling, and the like in order of increasing cooling rate, and the hardness of the obtained titanium alloy is also improved in this order.
- the material size is large, the thermal stress generated during cooling becomes large. Accordingly, when cooling is performed at a very high speed, such as water cooling or oil cooling, there is a possibility that the material will break in a material of a certain size or more.
- the titanium alloy according to the third embodiment is intended to avoid this possibility.
- the titanium alloy is necessary at a cooling rate of air cooling slower than oil cooling and water cooling. There is an effect that hardness is obtained.
- the titanium alloy of 3rd embodiment can also be obtained by oil cooling and water cooling, and in that case, it becomes harder than the titanium alloy of 1st embodiment and 2nd embodiment.
- Ingots of various compositions were prepared by melting and casting, and the regular transformation from ⁇ phase to B2 phase, which is the object of the present invention, was implemented by heat treatment tests on small pieces.
- a Vickers hardness test was performed on the polished surface of the cross section of the heat-treated test piece to obtain the Vickers hardness, and the presence or absence of a crack from the end of the indentation was investigated. This test evaluated the hardness at room temperature and the degree of brittleness, which are the objects of the present invention.
- a hot forging test was conducted at 1250 ° C., and the presence or absence of cracks in the material after forging was investigated. This test evaluated hot forgeability, which is another object of the present invention.
- it demonstrates more concretely using drawing.
- Example 1 Sponge Ti, Al pellets, and granular Fe (additive element) were accommodated in a yttria crucible as a melting raw material.
- the melting raw material was prepared so as to contain Al at a ratio of 30.0 atomic% and Fe at a ratio of 2.0 atomic%, and Ti as a main balance, so that the total amount was about 500 g.
- the inside of the chamber of the high-frequency melting furnace in which the crucible was installed was evacuated and then melted in a state where argon gas was introduced. After all the raw materials were dissolved, the material was kept in that state for about 3 minutes with high frequency output applied, and then cast.
- an iron mold having a cast portion with a diameter of 30 mm and a length of 100 mm was used.
- an alumina funnel was placed at the opening end of the cast-in portion, and a part of the funnel was filled with the molten metal. The molten metal in the funnel functioned as a hot water for reducing casting defects of the ingot in the mold.
- the appearance photograph of the obtained ingot 100 is shown in FIG.
- the ingot 100 is composed of a conical portion 100A and a rod-shaped portion 100B, and the conical portion 100A is a feeder portion solidified in the funnel, so it is cut off and the remaining rod-shaped portion 100B (diameter 30 mm, long) 90 mm) was used as a sample for a heat treatment test, a Vickers hardness test, and a hot forging test described later.
- Example 2 the prepared melting raw material was melted and cast in the same procedure as in Example 1 to obtain a rod-shaped ingot serving as a sample for a heat treatment test, a Vickers hardness test, and a hot forging test.
- FIG. 2A and 2B show reflected electron images at the center of the cut surface of the small piece after the heat treatment test obtained using a scanning electron microscope.
- 2A corresponds to Example 1
- FIG. 2B corresponds to Comparative Example 11.
- the Vickers hardness was HV653. From this result, it can be seen that the sample of Example 1 has sufficient hardness as an exterior part such as a watch. On the other hand, in the sample of Comparative Example 11, the Vickers hardness was HV566. From this result, it can be seen that the sample of Comparative Example 11 is significantly harder than the conventional Ti alloy, but is insufficient for HV600 as a measure of hardness that does not require surface treatment.
- FIGS. 3A and 3B show photographs taken by an optical microscope of a portion recessed by the Vickers test in each of the sample of Example 1 and the sample of Comparative Example 11.
- FIG. 3A corresponds to Example 1
- FIG. 3B corresponds to Comparative Example 11. Since the crack of the Vickers hardness test does not occur on the surface of the sample of Example 1, it can be seen that the sample of Example 1 has a certain degree of toughness. On the other hand, on the surface of the sample of Comparative Example 11, since the crack accompanying the Vickers hardness test is generated at the end of the recess (end of the indentation), the sample of Comparative Example 11 has the necessary toughness. I understand that there is no.
- Example 1 A hot forging test was performed on the sample of Example 1 and the sample of Comparative Example 11 (both 30 mm in diameter and 90 mm in length). Specifically, each sample was first placed in a heating furnace, held at 1250 ° C. for about 30 minutes, and then removed from the heating furnace. Next, a 300-ton hydraulic press was performed on each sample taken out, and upset forging was performed once until the length became 20 mm.
- FIG. 4A and 4B show photographs of the sample of Example 1 and the sample of Comparative Example 11 after the hot forging test, respectively.
- FIG. 4A shows that the sample of Example 1 has no cracks associated with hot forging, and the sample of Example 1 is excellent in hot forgeability. Therefore, if it is a sample of Example 1, a hot forging can be performed without a problem and the titanium alloy as a timepiece exterior component with which the fine structure was equalized can be obtained.
- FIG. 4B shows that the sample of Comparative Example 11 has cracks associated with hot forging, and the sample of Comparative Example 11 is not excellent in hot forgeability. Therefore, in the sample of Comparative Example 11, it is difficult to obtain a titanium alloy as a timepiece exterior part having obstacles in performing hot forging and having a uniform microstructure.
- Example 1 and Comparative Example 11 titanium alloys (ingots) having compositions different from those of Example 1 and Comparative Example 11 were prepared as Comparative Examples 1 to 10, 12 to 24, and Examples 2 to 13. These samples were subjected to a Vickers hardness test after heat treatment under the same conditions as above and a hot forging test under the same conditions as above.
- Table 1 shows the compositions and test results of the samples of Comparative Examples 1 to 9 containing any of Cu, V, Nb, Mo, and W as ⁇ -stabilizing elements.
- Table 2 shows the compositions and test results of the samples of Comparative Examples 10 to 16 and Examples 1 to 7 containing Fe as a ⁇ -stabilizing element.
- Table 3 shows the compositions and test results of samples of Comparative Examples 17 to 24 and Examples 8 to 13 containing Mn as a ⁇ -stabilizing element.
- Comparative Example 1 (Alloy No. 1) is obtained by adding 3 atomic% of Cu and has good hardness and forgeability, but there is a problem in toughness because cracks are generated from the end of the Vickers indentation. This is an incorrect sample.
- Comparative Example 2 (Alloy No. 2) is an inadequate sample because 8 atomic% of Cu is added and cracking is caused by a forging test, and thus there is a problem with forgeability.
- Comparative Example 3 (Alloy No. 3) is obtained by adding 12.5 atomic% of V. Since the Vickers hardness is less than 600, there is a problem in hardness, and further cracking due to a forging test occurs. Since it is generated, there is a problem with forgeability, so it is an inappropriate sample.
- Comparative Example 4 (Alloy No. 4) is obtained by adding 9 atomic% of Nb. Since the Vickers hardness is less than 600, there is a problem with the hardness, and further, cracking due to the forging test occurs. Therefore, there is a problem with forgeability, so it is an inappropriate sample.
- Comparative Example 5 (Alloy No. 5) is obtained by adding 17.5 atomic% of Nb and has a problem in toughness because cracks are generated from the end of the Vickers indentation. Since there is a problem in forgeability due to the occurrence of cracks, it is an inappropriate sample.
- Comparative Example 6 (Alloy No. 6) is obtained by adding 3.0 atomic% of Mo and has a problem in toughness because cracks are generated from the end of the Vickers indentation. Since there is a problem in forgeability due to the occurrence of cracks, it is an inappropriate sample.
- Comparative Example 7 (Alloy No. 7) is obtained by adding 6.0 atomic percent of Mo and has a problem in hardness because the Vickers hardness is less than 600, and cracks occur from the end of the Vickers indentation. Since it has occurred, there is a problem in toughness, and since cracks in the forging test have occurred, there is also a problem in forgeability, so this is an inappropriate sample.
- Comparative Example 8 (Alloy No. 8) is obtained by adding 5.0 atomic% of W. Since cracks are generated in the forging test, there is a problem with forgeability. is there.
- Comparative Example 9 (Alloy No. 9) is obtained by adding 10.0 atomic% of W, and since there is a problem in forgeability due to the occurrence of cracks in the forging test, it is an inappropriate sample. is there.
- Comparative Example 10 (Alloy No. 10) is obtained by adding 27.0 atomic% of Al and 6.0 atomic% of Fe, and the Al content is less than the range specified in the present invention. Since there is a problem in forgeability due to the occurrence of cracks due to, it is an inappropriate sample.
- the sample of Comparative Example 11 (Alloy No. 11) has a problem in hardness because the Vickers hardness is less than 600, and there is a problem in toughness because cracks are generated from the end of the Vickers indentation. There is a problem in forgeability because cracks are generated by the forging test, and it is an inappropriate sample.
- Example 1 (Alloy No. 12) is obtained by adding 30.0 atomic% Al and 2.0 atomic% Fe as described above.
- the sample of Example 2 (Alloy No. 13) is obtained by adding 30.0 atomic% Al and 6.0 atomic% Fe.
- the sample of Example 3 (Alloy No. 14) is obtained by adding 31.0 atomic% Al and 3.0 atomic% Fe.
- the sample of Example 4 (Alloy No. 15) is obtained by adding 31.0 atomic% Al and 5.0 atomic% Fe.
- Example 5 (Alloy No. 16) is obtained by adding 32.0 atomic% Al and 6.0 atomic% Fe.
- the sample of Comparative Example 12 (Alloy No. 17) is obtained by adding 32.0 atomic% Al and 8.0 atomic% Fe, and the Fe content is larger than the range specified in the present invention.
- the sample of Comparative Example 12 is an improper sample because there is a problem in forgeability because cracks have occurred in the forging test.
- Example 6 (alloy number 18) is obtained by adding 35.0 atomic% Al and 4.0 atomic% Fe.
- the sample of Example 6 has sufficient hardness because the Vickers hardness exceeds 600, and has sufficient toughness since cracks do not occur from the end of the Vickers indentation, Moreover, since it has sufficient forgeability since the crack by a forge test does not generate
- the sample of Comparative Example 13 (Alloy No. 19) is obtained by adding 35.0 atomic% Al and 7.0 atomic% Fe, and the Fe content is larger than the range specified in the present invention.
- the sample of Comparative Example 13 is an unsuitable sample because there is a problem in forgeability because cracks are generated by the forging test.
- the sample of Comparative Example 14 (Alloy No. 20) is obtained by adding 35.0 atomic% Al and 10.0 atomic% Fe, and the Fe content is larger than the range specified in the present invention.
- the sample of Comparative Example 14 has a problem in toughness because cracks occur from the end of the Vickers indentation, and also has a problem in forgeability because cracks occur in the forging test. Sample.
- Example 7 (alloy number 21) is obtained by adding 38.0 atomic% Al and 4.0 atomic% Fe.
- the sample of Example 7 has sufficient hardness because the Vickers hardness exceeds 600, and has sufficient toughness because no cracks are generated from the end of the Vickers indentation. Since it has sufficient forgeability since no cracks are generated by the forging test, it is an appropriate sample.
- the sample of Comparative Example 15 (Alloy No. 22) is obtained by adding 38.0 atomic% Al and 8.0 atomic% Fe, and the content of Fe is larger than the range specified in the present invention.
- the sample of Comparative Example 15 is an improper sample because there is a problem in forgeability due to the occurrence of cracks in the forging test.
- the sample of Comparative Example 16 (Alloy No. 23) is obtained by adding 39.0 atomic% Al and 4.0 atomic% Fe, and the content of Fe is larger than the range specified in the present invention. Since the sample of Comparative Example 16 has a problem in forgeability because cracks are generated by the forging test, it is an inappropriate sample.
- the sample of Comparative Example 17 (Alloy No. 24) is obtained by adding 27.0 atomic% Al and 5.0 atomic% Mn, and the Al content is less than the range specified in the present invention.
- the sample of Comparative Example 17 is an inappropriate sample because there is a problem in toughness because cracks are generated from the end of the Vickers indentation.
- the sample of Comparative Example 18 (Alloy No. 25) is obtained by adding 28.0 atomic% Al and 3.0 atomic% Mn, and the Mn content is less than the range specified in the present invention.
- the sample of Comparative Example 18 is an improper sample because there is a problem in forgeability because cracks are generated in the forging test.
- Example 8 (Alloy No. 26) is obtained by adding 30.0 atomic% Al and 8.0 atomic% Mn.
- the sample of Example 9 (Alloy No. 27) is obtained by adding 32.0 atomic% Al and 4.0 atomic% Mn.
- the sample of Example 10 (Alloy No. 28) is obtained by adding 32.0 atomic% Al and 6.0 atomic% Mn.
- Each of the samples of Examples 8 to 10 has a sufficient hardness because the Vickers hardness exceeds 600, and has sufficient toughness because no crack occurs from the end of the Vickers indentation. In addition, since it has sufficient forgeability because no cracks are generated by the forging test, it is an appropriate sample.
- the sample of Comparative Example 19 (Alloy No. 29) is obtained by adding 34.0 atomic% Al and 3.0 atomic% Mn, and the Mn content is less than the range specified in the present invention.
- the sample of Comparative Example 19 has a problem in toughness because cracks have occurred from the end of the Vickers indentation, and has a problem in forgeability because cracks have occurred in the forging test. It is.
- Example 11 (alloy number 30) is obtained by adding 34.0 atomic% Al and 6.0 atomic% Fe.
- the sample of Example 11 has sufficient hardness because the Vickers hardness exceeds 600, and has sufficient toughness since cracks do not occur from the end of the Vickers indentation, Moreover, since it has sufficient forgeability since the crack by a forge test does not generate
- the sample of Comparative Example 20 (Alloy No. 31) is obtained by adding 34.0 atomic% Al and 9.0 atomic% Mn, and the content of Mn is larger than the range specified in the present invention.
- the sample of Comparative Example 20 is an inappropriate sample because there is a problem in toughness because cracks are generated from the end of the Vickers indentation.
- the sample of Comparative Example 21 (Alloy No. 32) is obtained by adding 35.0 atomic% Al and 10.0 atomic% Mn, and the content of Mn is larger than the range specified in the present invention.
- the sample of Comparative Example 21 has a problem in toughness because cracks have occurred from the end of the Vickers indentation, and has a problem in forgeability because cracks have occurred in the forging test. It is.
- Example 12 (alloy number 33) is obtained by adding 37.0 atomic% Al and 6.0 atomic% Mn.
- the sample of Example 13 (Alloy No. 34) is obtained by adding 38.0 atomic% Al and 6.0 atomic% Mn.
- the samples of Examples 12 and 13 both have sufficient hardness because the Vickers hardness exceeds 600, and have sufficient toughness because no cracks are generated from the end of the Vickers indentation. It is a proper sample because it has sufficient forgeability because it has no cracks caused by a forging test.
- the sample of Comparative Example 22 (Alloy No. 35) is obtained by adding 39.0 atomic% Al and 9.0 atomic% Mn, and the content of Al and Mn is larger than the range specified in the present invention.
- the sample of Comparative Example 22 is an inappropriate sample because there is a problem in toughness because cracks are generated from the end of the Vickers indentation.
- the sample of Comparative Example 23 (Alloy No. 36) is obtained by adding 39.5 atomic% Al and 12.0 atomic% Mn, and the content of Al and Mn is larger than the range specified in the present invention.
- the sample of Comparative Example 23 has a problem in toughness because cracks have occurred from the end of the Vickers indentation, and has a problem in forgeability because cracks have occurred in the forging test. It is.
- the sample of Comparative Example 24 (Alloy No. 37) is obtained by adding 42.0 atomic% Al and 6.0 atomic% Mn, and the Al content is larger than the range specified in the present invention.
- the sample of Comparative Example 24 has a problem in hardness because the Vickers hardness is less than 600, and has a problem in toughness because a crack is generated from the end of the Vickers indentation. Therefore, there is a problem with forgeability, so it is an inappropriate sample.
- Example 3 shown in Table 4 (Alloy No. 14) is obtained by adding 31.0 atomic% Al and 3.0 atomic% Fe, and cooling with water cooling and air cooling. Obtained in both cases.
- the Vickers hardness of the sample of Example 3 is less than 600 when air-cooled, but exceeds 600 when water-cooled, so that it has sufficient hardness, and the Vickers indentation end. It is a suitable sample because it has sufficient toughness since cracks do not occur and has sufficient forgeability because cracks do not occur in the forging test.
- Example 14 (Alloy No. 38) was obtained by adding 31.0 atomic% Al, 3.0 atomic% Fe, and 0.2 atomic% Si, and the content of Si was in the present invention. Less than the specified range.
- the Vickers hardness of the sample of Example 14 is less than 600 when air-cooled, but exceeds 600 when water-cooled, so that it has sufficient hardness, and the Vickers indentation end. It is a suitable sample because it has sufficient toughness since cracks do not occur and has sufficient forgeability because cracks do not occur in the forging test.
- Example 15 (alloy number 39) is obtained by adding 31.0 atomic% Al, 3.0 atomic% Fe, and 0.3 atomic% Si.
- the sample of Example 16 (Alloy No. 40) is obtained by adding 31.0 atomic% Al, 3.0 atomic% Fe, and 0.9 atomic% Si.
- the sample of Example 17 (Alloy No. 41) is obtained by adding 31.0 atomic% Al, 3.0 atomic% Fe, and 1.5 atomic% Si.
- the cooling method is water cooling or air cooling
- the Vickers hardness exceeds 600, so that it has sufficient hardness, and since there is no crack from the end of the Vickers indentation, sufficient toughness is provided. It is a proper sample because it has sufficient forgeability because it has no cracks caused by a forging test.
- the sample of Comparative Example 25 (Alloy No. 42) is obtained by adding 31.0 atomic% Al, 3.0 atomic% Fe, 1.7 atomic% Si, and the Si content is in the present invention. More than the specified range.
- the sample of Comparative Example 25 has a problem in toughness because cracks have occurred from the end of the Vickers indentation, and has a problem in forgeability because cracks have occurred in the forging test. It is.
- Example 6 shown in Table 4 (Alloy No. 18) is obtained by adding 35.0 atomic% Al and 4.0 atomic% Fe, and cooling with water cooling and air cooling. Obtained in both cases.
- the Vickers hardness of the sample of Example 6 is less than 600 when air-cooled, but exceeds 600 when water-cooled, so that it has sufficient hardness, and the Vickers indentation end. It is a suitable sample because it has sufficient toughness since cracks do not occur and has sufficient forgeability because cracks do not occur in the forging test.
- Example 18 (Alloy No. 43) was obtained by adding 35.0 atomic% Al, 4.0 atomic% Fe, and 0.2 atomic% Si, and the content of Si was in the present invention. Less than the specified range.
- the Vickers hardness of the sample of Example 18 is less than 600 when air-cooled, but exceeds 600 when water-cooled, so that it has sufficient hardness, and the Vickers indentation end. It is a suitable sample because it has sufficient toughness since cracks do not occur and has sufficient forgeability because cracks do not occur in the forging test.
- Example 19 (alloy number 44) is obtained by adding 35.0 atomic% Al, 4.0 atomic% Fe, and 0.3 atomic% Si.
- the sample of Example 20 (Alloy No. 45) is obtained by adding 35.0 atomic% Al, 4.0 atomic% Fe, and 0.9 atomic% Si.
- the sample of Example 21 (Alloy No. 46) is obtained by adding 35.0 atomic% Al, 4.0 atomic% Fe, and 1.5 atomic% Si.
- the cooling method is either water cooling or air cooling, since the Vickers hardness exceeds 600, it has sufficient hardness, and since there is no crack from the end of the Vickers indentation, it is sufficient It is a proper sample because it has toughness and has sufficient forgeability because no cracks are generated by a forging test.
- the sample of Comparative Example 26 (Alloy No. 47) was obtained by adding 35.0 atomic% Al, 4.0 atomic% Fe, 1.7 atomic% Si, and the content of Si in the present invention. More than the specified range.
- the sample of Comparative Example 26 has a problem in toughness because cracks have occurred from the end of the Vickers indentation, and has a problem in forgeability because cracks have occurred in the forging test. It is.
- the titanium alloy of the present invention requires hardness, and can be widely used as a material constituting a watch exterior part or the like used in contact with a human body.
Abstract
Description
本願は、2016年4月14日に、日本に出願された特願2016-081506号に基づき優先権を主張し、その内容をここに援用する。
(チタン合金の構成)
本発明の第一実施形態に係るチタン合金は、アルミニウム(Al)を28.0原子%(at%)以上38.0原子%以下の割合で含み、β安定化元素である鉄(Fe)を2.0原子%以上6.0原子%以下の割合で含み、かつチタン(Ti)および不可避不純物を残部として含んでいる。これらの組成は、重量%で換算すると、およそAlが17.8重量%以上25.6重量%以下、Feが2.6重量%以上8.3重量%以下となる。
まず、溶解炉でアルミニウム、鉄、チタンの原料を溶解させ、溶湯を鋳型に入れて凝固させることでチタン合金を得る(合金形成工程)。
上記製造方法によって得られた時計外装部品用素材は、本実施形態に係るチタン合金からなり、その微細組織が均一化されている。また、素材自身が硬く、表面処理が不要で鏡面研磨加工が可能なことから、色調や光度のむらが少なく、傷が付きにくいことが特徴である。
本発明の第二実施形態に係るチタン合金は、アルミニウム(Al)を28.0原子%以上38.0原子%以下の割合で含み、β安定化元素であるマンガン(Mn)を4.0原子%以上8.0原子%以下の割合で含み、かつチタン(Ti)および不可避不純物を残部として含んでいる。これらの組成は、重量%で換算すると、およそAlが17.7重量%以上25.5重量%以下、Mnが5.2重量%以上10.9重量%以下となる。
本発明の第三実施形態に係るチタン合金は、アルミニウム(Al)および鉄(Fe)を、それぞれ、第一実施形態のチタン合金と同じ割合で含み、さらに、シリコン(Si)を0.3原子%以上1.5原子%以下の割合で含んでいる。また、第三実施形態に係るチタン合金は、チタン(Ti)および不可避不純物を残部として含んでいる。
スポンジTi、Alペレット、および粒状のFe(添加元素)を、溶解原料としてイットリアるつぼ内に収容した。溶解原料は、Alを30.0原子%、Feを2.0原子%の割合で含み、Tiを主な残部として含み、合計量が約500gとなるように調製した。
スポンジTi、Alペレット、および粒状のFe(添加元素)を、溶解原料としてイットリアるつぼ内に収容した。溶解原料は、Alを28.0原子%、Feを1.0原子%の割合で含み、Tiを主な残部として含み、合計量が約500gとなるように調製した。
実施例1のサンプル、比較例11のサンプルの各々から、押し湯部分との切断面を含む10mm×10mm×10mmの部分の小片を切り出し、各々の小片に対して熱処理試験を行った。具体的には、各々の小片に対して、1250℃で2時間保持する熱処理を行い、続いて水冷を行った。この小片の中央を切断し、樹脂に埋め込み後研磨することで組織観察、ならびに硬さ測定用の試験片とした。
実施例1のサンプル、比較例11のサンプルに対して、上記と同じ試験片を用いてビッカース硬さ試験を行った。荷重20kgfで研磨面にダイヤモンド圧子を押しつけ、窪んだ部分の対角線の長さを測定することで、ビッカース硬さとして算出した。
実施例1のサンプル、比較例11のサンプル(いずれも直径30mm、長さ90mm)に対して、熱間鍛造試験を行った。具体的には、まず、各々のサンプルを加熱炉に入れて、1250℃で約30分保持した後に、加熱炉から取り出した。次に、取り出した各々のサンプルに対して300tonの油圧プレスを行い、長さが20mmとなるまで、1回で据え込み鍛造を行った。
〔判断基準〕
表1~3について:
(a)1250℃×2hの熱処理後、水冷した小片の試験片の断面の研磨面のビッカース硬さについて、20kgfの荷重で試験し、HV600以上のものを適正なサンプルとし、HV600未満のものを不適正なサンプルとする。
(b)上記ビッカース硬さ試験での圧痕端部からの割れについて、発生しなかったものを適正なサンプルとし、発生したものを不適正なサンプルとする。
(c)直径30mm、長さ90mmのインゴットを用いて実施した1250℃での鍛造試験の結果、鍛造後の素材に割れが発生しなかったものを適正なサンプルとし、発生したものを不適正なサンプルとする。
表4について:
(d)1250℃×2hの熱処理後、空冷または水冷した小片の試験片の断面の研磨面のビッカース硬さについて、20kgfの荷重で試験し、HV600以上のものを適正なサンプルとし、HV600未満のものを不適正なサンプルとする。
(e)上記(b)と同じ。
(f)上記(c)と同じ。
実施例2のサンプル(合金番号13)は、30.0原子%のAl、6.0原子%のFeを添加したものである。
実施例3のサンプル(合金番号14)は、31.0原子%のAl、3.0原子%のFeを添加したものである。
実施例4のサンプル(合金番号15)は、31.0原子%のAl、5.0原子%のFeを添加したものである。
実施例5のサンプル(合金番号16)は、32.0原子%のAl、6.0原子%のFeを添加したものである。
実施例1~5のサンプルは、いずれもビッカース硬さが600を超えていることから十分な硬さを有しており、ビッカース圧痕端部より割れが発生していないことから十分な靱性を有しており、また、鍛造試験による割れが発生していないことから十分な鍛造性を有しているため、適正なサンプルである。
実施例9のサンプル(合金番号27)は、32.0原子%のAl、4.0原子%のMnを添加したものである。
実施例10のサンプル(合金番号28)は、32.0原子%のAl、6.0原子%のMnを添加したものである。
実施例8~10のサンプルは、いずれもビッカース硬さが600を超えていることから十分な硬さを有しており、ビッカース圧痕端部より割れが発生していないことから十分な靱性を有しており、また、鍛造試験による割れが発生していないことから十分な鍛造性を有しているため、適正なサンプルである。
Claims (4)
- アルミニウムを28.0原子%以上38.0原子%以下の割合で含み、
鉄を2.0原子%以上6.0原子%以下の割合で含み、
かつチタンおよび不可避不純物を残部として含むことを特徴とするチタン合金。 - さらに、シリコンを0.3原子%以上1.5原子%以下の割合で含むことを特徴とする請求項1に記載のチタン合金。
- アルミニウムを28.0原子%以上38.0原子%以下の割合で含み、
マンガンを4.0原子%以上8.0原子%以下の割合で含み、
かつチタンおよび不可避不純物を残部として含むことを特徴とするチタン合金。 - 請求項1~3のいずれか一項に記載のチタン合金を熱間鍛造する熱間鍛造工程と、
熱間鍛造した前記チタン合金を熱処理する熱処理工程と、を有することを特徴とする時計外装部品用素材の製造方法。
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EP17782465.3A EP3444365B1 (en) | 2016-04-14 | 2017-04-13 | Titanium alloy and method for producing material for timepiece exterior parts |
US16/092,401 US11131010B2 (en) | 2016-04-14 | 2017-04-13 | Titanium alloy and method of manufacturing material for timepiece exterior part |
CN201780022390.4A CN108884517B (zh) | 2016-04-14 | 2017-04-13 | 钛合金、时钟外装部件用材料的制造方法 |
JP2018512063A JP6739735B2 (ja) | 2016-04-14 | 2017-04-13 | 時計外装部品用素材の製造方法 |
HK19101822.1A HK1259420A1 (zh) | 2016-04-14 | 2019-01-31 | 鈦合金、時鐘外裝部件用材料的製造方法 |
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JP7129057B2 (ja) | 2018-03-30 | 2022-09-01 | 国立研究開発法人物質・材料研究機構 | Ti系合金の製造方法 |
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