JP3767193B2 - Hardening heat treatment method for titanium alloy member - Google Patents

Description

【００２４】
（実施例２）
実施例１と同様に図１に示すφ８ｍｍ×１００ｍｍ長の形状を有する部材（各種チタン合金）を硬化処理するため、高周波加熱を用いた急速加熱による溶体化及び時効処理による硬化処理を施した。
【００２５】
図２に、各種チタン合金の短時間側からの時効曲線を示す。チタン合金の化学組成が本発明の範囲内であるＴｉ−４．５％Ａｌ−３％Ｖ−２％Ｍｏ−２％Ｆｅ合金では、極短時間での時効処理による高硬度化（３８０ＨＶ以上）が可能であった。
【００２６】
一方、チタン合金の化学組成が本発明の範囲外であるＴｉ−６％Ａｌ−４％Ｖ合金及びＴｉ−１５％Ｖ−３％Ａｌ−３％Ｃｒ−３％Ｓｎ合金では、いずれも極短時間での時効処理による高硬度化が達成されていない。
【００２７】
（実施例３）
図３に示す８ｍｍ厚×２００ｍｍ幅×１０００ｍｍ長の形状を有する部材において、長さ方向中央部の２０ｍｍ幅×２０ｍｍ長の部分を硬化処理するため、高周波加熱を用いた急速加熱による極短時間の溶体化及び時効処理による硬化処理を施した。溶体化処理の条件は、本発明範囲内の１０℃／秒の昇温速度にて８５０℃まで昇温しファン冷却後、１０℃／秒の昇温速度にて昇温し５００℃×５分→空冷の時効処理を施した。なお本実施例においては、チタン合金部材の素材として２相のα＋β型Ｔｉ合金であるＡＭＳ４８９９（公称組成：Ｔｉ−４．５％Ａｌ−３％Ｖ−２％Ｍｏ−２％Ｆｅ合金、β変態点：９００℃）を用いた。また図３に示す部材の位置Ａの部分は硬化処理が必要な部分であり、位置Ｂの部分は硬化処理が必要ではない部分である。また、ファン冷却時の冷却速度は、周囲の非熱処理部への抜熱があるため、水冷並の３０℃／秒であったが、周囲の非熱処理部からの拘束を受けるため熱歪は生じなかった。
【００２８】
当実施例に示す高周波加熱を用いた急速加熱による極短時間の溶体化及び時効処理による部分硬化処理においては、位置Ａの部分は処理前の素材に比較して大きく硬度が上昇しており、充分に溶体化−時効処理による硬化処理の効果が得られている。また硬化処理が必要とされない位置Ｂにおいては硬度上昇がほとんどなく、延性も保持されている。また時効処理の時間も短く、作業効率面でも良好である。さらに熱処理を受ける部分が硬化処理が必要な部分のみであり、且つ熱処理も短時間であるため、熱処理後の部材の表面手入れについても省略ないし著しい簡略化が可能であった。
【００２９】
以上のような実施例により、チタン合金からなる部材の部分的な硬化処理において、高周波加熱を用いた急速加熱による極短時間の溶体化処理及び時効処理を行うことによって、効率よくチタン合金の硬化処理が可能となるとともに、母材部分の材料特性を劣化させず、さらに硬化処理が施された部分においても矯正などに耐え得る加工性を保持することが達成可能となる。また、その高周波加熱を用いたチタン合金の部分硬化処理の条件としては、溶体化処理のための熱処理温度を（Ｔβ−１００）℃〜（Ｔβ−１０）℃とし、且つ時効処理のための熱処理時の昇温速度を５℃／秒以上として時効処理の温度を４００〜６００℃で、時効処理の時間を１〜１０分とし、少なくとも硬さがビッカース硬度で３８０ＨＶ以上であることが望ましい。さらに、高硬度化されるチタン合金部材を形成するチタン材の化学組成としては、重量％にてＡｌを４〜５％、Ｖを２．５〜３．５％、Ｍｏを１．８〜２．２％、Ｆｅを１．７〜２．３％、Ｏを０．１５％以下含有していることが望ましい。
【００３０】
【発明の効果】
以上説明したように本発明によれば、熱処理条件及びチタン合金組成を特定することにより、効率よくチタン合金の硬化処理が達成可能となり、工業上有用な効果がもたらされる。
【図面の簡単な説明】
【図１】実施例１及び２に係る被硬化物と熱処理の状況を示す図。
【図２】実施例２に係るチタン合金の時効曲線を示す図。
【図３】実施例３に係る被硬化物と熱処理の状況を示す図。[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a method for hardening heat treatment of a titanium alloy member by heat treatment using high frequency heating.
[0002]
[Prior art]
Titanium materials have high corrosion resistance, light weight, and high strength compared to steel materials including stainless steel, which is the most widely used structural material. It is used as a structural material when it is desired to minimize energy loss due to inertial force in a member that rotates and repetitively moves. However, even though it has high corrosion resistance, it is necessary to take measures such as surface hardening treatment in an environment where erosion corrosion is dominant, and in the rubbing part, the titanium material is originally an active metal and tends to cause seizure. Processing is required.
[0003]
Under such circumstances, steel materials including stainless steel can be plated with hard Cr plating, electroless Ni plating, or stellite. Measures such as wear and erosion resistance have been taken. However, titanium materials are difficult to plate because titanium is a noble metal, and easily form brittle intermetallic compounds with alloys based on Fe, Ni, Co, Cr, etc. In the case of depositing the metal, an intermetallic compound is formed at the bonding interface, and the cured layer may be peeled off during use of the treated member.
[0004]
For this reason, when using the titanium material in the environment, thermal spraying of Mo or the like or ion plating of a hard layer such as TiN is performed. These are methods in which a metal that does not form a brittle intermetallic compound with titanium is sprayed while being melted or a hard coating is deposited in an inert atmosphere such as vacuum or argon gas.
[0005]
In addition, a titanium alloy having age-hardening ability can achieve high hardness by heat treatment such as solution treatment and subsequent aging treatment. For example, in a typical β-type titanium alloy Ti-15V-3Al-3Cr-3Sn alloy, 800 ° C. × 1 hr → 480 ° C. to 540 ° C. × 10-20 hr after water cooling solution treatment → air cooling aging treatment, With a Vickers hardness of about HV = 420 to 430, and Ti-6Al-4V alloy, which is a typical α + β type titanium alloy, 480 ° C. to 510 ° C. × 1 to 6 hr after solution treatment of 950 ° C. × 1 hr → water cooling → air cooling With this aging treatment, a high hardness of about HV = 400 can be achieved. In addition, this method is applied, and a solution treatment is performed using a high-frequency heating coil, and thereafter, an aging treatment is performed by inserting the solution into a heat treatment furnace as usual.
[0006]
Furthermore, since titanium materials can be welded together, it is possible to build up a titanium alloy having age hardening ability or to join them by a welding method such as MIG or TIG. It is possible to cure the part by welding the titanium material having age-hardening ability to the member, and then applying aging treatment. It is also attempted to achieve wear resistance and erosion resistance by this method. Yes. In addition, a method of welding a titanium material hardened by solution-aging treatment with MIG or TIG is also performed.
[0007]
[Problems to be solved by the invention]
However, when a surface treatment method such as thermal spraying or ion plating that requires treatment in an inert atmosphere to achieve wear resistance and erosion resistance, a chamber for creating an inert atmosphere, etc. This is a processing method that is practically impossible when the object to be processed has to be inserted into the isolated room, and the object to be processed becomes large.
[0008]
Further, when a titanium alloy having age-hardening ability is used as a material for a member and cured by solution-aging treatment, the entire member is cured. The part to be scratched or subjected to erosion is almost a part of the member, and the member is required to have characteristics such as ductility and toughness in addition to wear resistance and erosion resistance. When it has hardened, it is impossible to satisfy the properties such as ductility required for the body of the member, even though it is possible to take measures in terms of wear resistance and erosion resistance. Become. Further, since rapid cooling such as water cooling is performed at the time of the solution treatment, thermal distortion occurs in the member, and an additional process for correcting the distortion is necessary, which causes inconvenience in terms of work efficiency and manufacturing cost. Furthermore, the normal aging treatment requires a short aging treatment time of 1 hr, and a long aging treatment time of 10 to 20 hr, and there is a disadvantage that a long time is required for the treatment.
[0009]
In addition, when a titanium material that is hardened or is hardened by aging treatment by overlaying or other welding, a structural change occurs due to thermal effects in the body in the vicinity of the joint, which is also ductile. The problem of deterioration arises.
[0010]
As described above, in the methods of improving the conventional wear resistance and erosion resistance such as surface treatment, conventional solution treatment-aging treatment or welding / welding, in terms of reality, manufacturing efficiency, and member characteristics, Has a number of challenges.
[0011]
An object of the present invention is to solve the above-mentioned problems, and to improve wear resistance and erosion resistance, in order to improve the wear resistance and erosion resistance, a titanium alloy member capable of partially hardening a titanium alloy member with high production efficiency. It is to provide a curing heat treatment method.
[0012]
[Means for Solving the Problems]
In order to solve the above problems and achieve the object, the present invention uses the following means.
The method of the present invention is at least % by mass , Al: 4-5%, V: 2.5-3.5%, Mo: 1.8-2.2%, Fe: 1.7-2 In a partial hardening treatment of a member made of a titanium alloy containing 0.3% and O: 0.15% or less, and the balance being Ti ,
Applying a solution treatment using high frequency heating to the titanium alloy member;
A titanium alloy member that has undergone solution treatment, and a step of performing aging treatment using high-frequency heating,
The solution treatment temperature in the solution treatment step is (Tβ-100) ° C. to (Tβ-10) ° C., and the temperature raising temperature in the aging treatment step is 5 ° C./second or more, and the aging treatment temperature is 400 to 400 ° C. It is a hardening heat treatment method for a titanium alloy member, characterized in that the aging treatment time is 1 to 10 minutes at 600 ° C., and the hardness is at least 380 HV in terms of Vickers hardness.
[0014]
DETAILED DESCRIPTION OF THE INVENTION
The present invention has been made in order to solve the above-mentioned problems, and as a result of conducting a detailed study on a treatment method in the case where a partial hardening treatment such as wear resistance and erosion resistance is required, a titanium alloy is obtained. It has been found that it is effective to perform solution treatment and aging treatment using high-frequency heating partially on the member.
[0015]
Based on this knowledge, the present inventors partially applied to the titanium alloy member that specified the chemical component, so as to control the solution treatment conditions and aging treatment conditions using high-frequency heating within a certain range, In order to improve wear resistance and erosion resistance, the inventors have found a titanium alloy member hardening heat treatment method capable of partially hardening a titanium alloy member with high production efficiency, and completed the present invention.
Embodiments of the present invention will be described below.
[0016]
The present invention is a titanium alloy hardening method characterized by performing rapid heating solution treatment and aging treatment using high-frequency heating in partial hardening treatment of a member made of a titanium alloy. By using a high-frequency heating coil or the like that matches the shape of the portion to be cured, only the necessary portion can be cured. Until now, heat treatment using a high-frequency heating coil has been carried out, but this is a rapid heat treatment using only a solution heat treatment using a high-frequency heating coil, and then inserted into a heat treatment furnace as before, for a long time. It was something to do. In the present invention, a rapid heat treatment using high-frequency heating is also performed in an aging treatment performed subsequent to the solution treatment. As a result, it is possible to control the precipitation during the temperature rising process during aging, and it is possible to achieve high hardness with an extremely short aging treatment.
[0017]
As the solution treatment conditions at that time, the temperature of the solution treatment is (Tβ (β transformation point) −100) ° C. to (Tβ (β transformation point) −10) ° C. Thereby, in order to achieve high hardness in the subsequent aging treatment, the precipitate can be re-dissolved and a supersaturated state can be achieved. In addition, since the maximum temperature achieved during the solution treatment is set to the β transformation point or less, it is slightly disadvantageous from the viewpoint of achieving high hardness, but the hardness is obtained as Vickers hardness of 380 HV or more and the two-phase structure can be maintained. Further, there is a feature that the ductility in the cured portion can be sufficiently secured. Further, as the subsequent aging treatment conditions, the temperature rising rate during the heat treatment is 5 ° C./second or more, the temperature of the aging treatment is 400 to 600 ° C., and the time of the aging treatment is 1 to 10 minutes. By setting the rate of temperature increase to 5 ° C./second or more, it becomes possible to suppress precipitation during the temperature increasing process during aging, and to achieve high hardness in a short time. Also, if the aging temperature is less than 400 ° C. or the aging time is less than 1 minute, sufficient aging is not achieved and high hardness cannot be obtained. Conversely, if the aging temperature is higher than 600 ° C., the aging precipitates become coarse and the high hardness is still high. If the aging time is longer than 10 minutes, it is a heat treatment using high-frequency heating, so that the treatment becomes a single product, resulting in inconvenience in terms of work efficiency.
[0018]
Furthermore, as a titanium alloy to be hardened, the chemical composition is at least 4% by weight, Al 4-5%, V 2.5-3.5%, Mo 1.8-2.2%, Fe 1 It is a titanium alloy containing 0.7 to 2.3% and 0.15% or less of O. By adopting this composition, it is possible to more easily achieve a high hardness by solution-aging in an extremely short time by rapid heating and aging treatment.
[0019]
In the titanium alloy, Al and O are essential elements for stabilizing the α phase, and when Al is less than 4%, there is no sufficient contribution to the strength. On the contrary, Al exceeds 5% and O is 0. If it exceeds 15%, ductility deteriorates, which is not desirable. V, Mo, and Fe are elements that stabilize the β phase. If V is less than 2.5%, the β phase is not sufficiently stabilized, and if it exceeds 3.5%, the β phase is too stable and solution- Sufficient hardness cannot be achieved by aging treatment for an extremely short time. Mo and Fe are less than 1.8% and 1.7%, respectively, and the β phase is not sufficiently stable. If each of them exceeds 2.2% and 2.3%, the β phase is too stable, so that solution is formed. In this aging treatment, sufficient hardness cannot be achieved. For this reason, in the rapid heating solution-aging treatment by high-frequency heating, the material is at least wt%, Al is 4 to 5%, V is 2.5 to 3.5%, Mo is 1.8 to 2. It is a titanium alloy containing 2%, Fe 1.7 to 2.3%, and O 0.15% or less.
Examples of the present invention will be given below to prove the effects of the present invention.
[0020]
【Example】
Example 1
In order to cure the member having the shape of φ8 mm × 100 mm shown in FIG. 1, solution treatment by rapid heating using high-frequency heating and curing treatment by aging treatment were performed. At that time, the cooling after the solution treatment was by He gas, and the cooling rate was about 20 ° C./second. Table 1 shows the characteristics of the members after the curing treatment shown in FIG. 1 together with the conditions at that time (A02, A04, A05, A07, A08: invention example, A01, A03, A06, A09: comparative example) ). In this example, as a material of the titanium alloy member, AMS4899 (nominal composition: Ti-4.5% Al-3% V-2% Mo-2% Fe alloy, β transformation) Point: 900 ° C.).
[0021]
As is apparent from Table 1, in the solution treatment and aging treatment using high-frequency heating, the solution treatment temperature within the scope of the present invention is (Tβ-100) ° C. of 800 ° C. or higher and (Tβ-10) ° C. of 890 ° C. If it is below ℃, high hardness of HV = 380 or more can be achieved by subsequent aging treatment. Further, in the aging treatment subsequent to the solution treatment, the heating rate during the aging treatment that is within the scope of the present invention is 5 ° C./second or more, the aging temperature is 400 to 600 ° C., and the aging time is 1 to 10 minutes. If so, a high hardness of HV = 380 or higher can be achieved. Furthermore, since the heat treatment temperature at the time of solution treatment is lower than the β transformation point, a two-phase structure can be maintained, so that the elongation in a tensile test using a tensile specimen taken from a hardened portion is 5% or more, and the present invention According to (Invention Examples A02, A04, A05, A07, A08), it is possible to achieve high hardness and maintain workability that can withstand distortion correction.
[0022]
However, when the solution treatment temperature is less than 800 ° C. outside the scope of the present invention (Comparative Example A09), the precipitate cannot be re-dissolved and cannot be brought into a supersaturated state. High hardness could not be achieved. Further, when the solution treatment temperature is 900 ° C. (Comparative Example A06) outside the range of the present invention, high hardness can be achieved, but since it is hardened excessively, the ductility at the hardened portion is lowered. Furthermore, if the temperature increase rate during the aging treatment is less than 5 ° C./second outside the scope of the present invention (Comparative Example A01), precipitation during the temperature increase cannot be suppressed at the aging temperature, and high hardness is achieved by short-term aging. When the aging temperature was less than 400 ° C. (Comparative Example A01) and the aging time was less than 1 minute (Comparative Example A03), the aging did not proceed sufficiently, and high hardness could not be achieved by the aging treatment. When the aging temperature was higher than 600 ° C. (Comparative Example A09), aging progressed too much, and the aging temperature was overaged in a very short time, and high hardness could not be achieved.
[0023]
[Table 1]

[0024]
(Example 2)
In the same manner as in Example 1, in order to cure the member (various titanium alloys) having a shape of φ8 mm × 100 mm shown in FIG. 1, solution treatment by rapid heating using high-frequency heating and curing treatment by aging treatment were performed.
[0025]
In FIG. 2, the aging curve from the short time side of various titanium alloys is shown. In Ti-4.5% Al-3% V-2% Mo-2% Fe alloy whose chemical composition is within the range of the present invention, the hardness is increased by aging treatment in an extremely short time (380 HV or more). Was possible.
[0026]
On the other hand, the Ti-6% Al-4% V alloy and the Ti-15% V-3% Al-3% Cr-3% Sn alloy whose chemical composition is outside the scope of the present invention are both extremely short. Hardening due to aging treatment over time has not been achieved.
[0027]
Example 3
In the member having the shape of 8 mm thickness × 200 mm width × 1000 mm length shown in FIG. 3, in order to cure the 20 mm width × 20 mm length portion of the central portion in the length direction, an extremely short time by rapid heating using high frequency heating is used. Curing treatment was performed by solution treatment and aging treatment. The solution treatment conditions were as follows: the temperature was increased to 850 ° C. at a temperature increase rate of 10 ° C./second within the range of the present invention, and after cooling with a fan, the temperature was increased at a temperature increase rate of 10 ° C./second and 500 ° C. × 5 minutes. → Air-cooled aging treatment was applied. In this example, as a material of the titanium alloy member, AMS4899 (nominal composition: Ti-4.5% Al-3% V-2% Mo-2% Fe alloy, β transformation) Point: 900 ° C.). Further, the portion at position A of the member shown in FIG. 3 is a portion that requires curing, and the portion at position B is a portion that does not require curing. In addition, the cooling rate at the time of cooling the fan was 30 ° C / second, which is equivalent to water cooling, because heat is extracted to the surrounding non-heat treated part, but thermal distortion occurs because it is constrained by the surrounding non-heat treated part. There was no.
[0028]
In the partial hardening treatment by the solution treatment and the aging treatment by the rapid heating using the high-frequency heating shown in the present embodiment, the portion A at the position A has greatly increased hardness compared to the material before the treatment, The effect of the hardening process by the solution-aging process is fully obtained. Further, at the position B where no curing treatment is required, there is almost no increase in hardness and ductility is maintained. In addition, the aging treatment time is short and the working efficiency is good. Furthermore, since the part subjected to the heat treatment is only the part requiring the curing treatment and the heat treatment is also short, the surface treatment of the member after the heat treatment can be omitted or significantly simplified.
[0029]
According to the embodiment as described above, in the partial curing treatment of the member made of titanium alloy, the titanium alloy is efficiently cured by performing the solution treatment and the aging treatment by the rapid heating using the high frequency heating. In addition to being able to perform processing, it is possible to achieve the workability that can withstand correction and the like even in a portion that has been subjected to curing processing without deteriorating the material properties of the base material portion. Moreover, as conditions for the partial hardening treatment of the titanium alloy using the high-frequency heating, the heat treatment temperature for the solution treatment is (Tβ-100) ° C. to (Tβ-10) ° C., and the heat treatment for the aging treatment. It is desirable that the temperature rising rate is 5 ° C./second or more, the aging treatment temperature is 400 to 600 ° C., the aging treatment time is 1 to 10 minutes, and at least the hardness is 380 HV or more in terms of Vickers hardness. Furthermore, as a chemical composition of the titanium material forming the titanium alloy member to be hardened, Al is 4 to 5% by weight, V is 2.5 to 3.5%, Mo is 1.8 to 2 It is desirable to contain 0.2%, 1.7 to 2.3% of Fe, and 0.15% or less of O.
[0030]
【The invention's effect】
As described above, according to the present invention, by specifying the heat treatment conditions and the titanium alloy composition, it is possible to efficiently achieve the hardening treatment of the titanium alloy, which brings about an industrially useful effect.
[Brief description of the drawings]
FIG. 1 is a diagram showing a state of a cured product and heat treatment according to Examples 1 and 2. FIG.
2 is a graph showing an aging curve of a titanium alloy according to Example 2. FIG.
FIG. 3 is a diagram showing a state of a material to be cured and heat treatment according to Example 3.

Claims (1)

At least by mass% , Al: 4 to 5%, V: 2.5 to 3.5%, Mo: 1.8 to 2.2%, Fe: 1.7 to 2.3%, O In a partial curing treatment of a member made of a titanium alloy containing 0.15% or less and the balance being Ti ,
Applying a solution treatment using high frequency heating to the titanium alloy member;
A titanium alloy member that has undergone solution treatment, and a step of performing aging treatment using high-frequency heating,
The solution treatment temperature in the solution treatment step is (Tβ-100) ° C. to (Tβ-10) ° C., and the temperature raising temperature in the aging treatment step is 5 ° C./second or more, and the aging treatment temperature is 400 to 400 ° C. A method for hardening heat treatment of a titanium alloy member, characterized in that the aging treatment time is 1 to 10 minutes at 600 ° C. and at least the hardness is 380 HV or more in terms of Vickers hardness.

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