JP2008297629A - Titanium material, its production method and exhaust pipe - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a titanium material having excellent oxidation resistance, to provide the method of its production, and to provide the exhaust pipe. <P>SOLUTION: (1) A titanium material provided includes: a substrate of pure Ti or Ti alloy, and an Al-containing layer formed on the surface of the substrate, the Al-containing layer having a thickness no smaller than 1 μm and containing no less than 90 mass% Al or Al plus Si, wherein the Al-containing layer has a thickness such that, when the thickness is measured at three points (14 mm apart) selected in the lengthwise direction of the titanium material on the aluminum-containing layer, the difference between the thickness at the middle point and the thickness at the outer two points is no longer than 30% of the thickness at the middle point. (2) A titanium material provided includes: a substrate of pure Ti or Ti alloy; and an Al-containing layer formed on the surface of the substrate, the aluminum-containing layer having a thickness no smaller than 1 μm and containing no less than 90 mass% Al or Al plus Si, with a layer of Al-Ti intermetallic compound interposed between them; wherein the Al-containing layer has a thickness such that, when the thickness is measured at three points (14 mm apart) selected in the lengthwise direction of the titanium material on the Al-containing layer, the difference between the thickness at the middle point and the thickness at the outer two points is no longer than 30% of the thickness at the middle point. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention belongs to a technical field related to a titanium material, a manufacturing method thereof, and an exhaust pipe, and particularly to a technical field related to a titanium material used as a constituent material of an exhaust pipe for a two-wheeled vehicle or a four-wheeled vehicle. .

  Titanium alloys have a higher specific strength than common steel materials and are increasingly applied to the field of transportation equipment, particularly automobiles, which are strongly aimed at weight reduction. Among them, stainless steel is currently the mainstream as an exhaust pipe material for the exhaust system around the engine. However, for the purpose of reducing the weight, the use of titanium in the exhaust pipe is being studied. However, since the temperature of the exhaust pipe is 500 ° C. or higher depending on the part, oxidation of the untreated titanium alloy proceeds quickly (low oxidation resistance is insufficient), and there is a problem in durability.

In order to improve the oxidation resistance of a titanium alloy, a material in which an Al plate is clad on the surface of a titanium alloy (Japanese Patent Laid-Open No. 10-99976), a method of performing Al-Ti-based vapor deposition plating (Japanese Patent Laid-Open No. 6-88208) Or a method of forming a TiCrAlN film by PVD method (JP-A-9-256138) has been proposed. However, the cladding method is difficult to manufacture, is expensive, and is not economical. In addition, there is a problem that it is difficult to form an oxidation-resistant film on the inner surface of the pipe by the method of performing vapor deposition plating (a kind of PVD method) or the method by the PVD method.
Japanese Patent Laid-Open No. 10-99976 JP-A-6-88208 JP-A-9-256138

  The present invention has been made in view of such circumstances, and an object thereof is to provide a titanium material excellent in oxidation resistance, a method for manufacturing the same, and an exhaust pipe by improving the problems of the prior art. It is something to try.

  In order to achieve the above object, the present inventors have intensively studied, and as a result, completed the present invention. According to the present invention, the above object can be achieved.

  The present invention thus completed and capable of achieving the above object relates to a titanium material, a method for producing the same, and an exhaust pipe. This is a titanium material according to claims 1 to 7 (according to the first to seventh inventions). A titanium material), a method for producing a titanium material according to claims 8 to 9 (a method for producing a titanium material according to the eighth to ninth inventions), an exhaust pipe according to claim 10 (an exhaust pipe according to the tenth invention), It has the following configuration.

  That is, the titanium material according to claim 1 is titanium in which an Al-containing layer having a thickness of 1 μm or more and containing 90% by mass or more of Al or Al and Si is formed on a substrate made of pure Ti or a Ti-based alloy. 3 points are taken at intervals of 14 mm in the longitudinal direction of the titanium material, and the film thickness of the Al-containing layer at the central point among the three points and the film thickness of the Al-containing layer at the other two points The titanium material is characterized in that the difference is within 30% with respect to the film thickness of the Al-containing layer at the center point [first invention].

  The titanium material according to claim 2, wherein an Al-containing layer having a thickness of 1 μm or more containing 90 mass% or more of Al or Al and Si on a substrate made of pure Ti or a Ti-based alloy is an Al—Ti intermetallic compound. The titanium material is formed through layers, and three points are taken at intervals of 14 mm in the longitudinal direction of the titanium material, and the film thickness of the Al-containing layer at the central point among these three points and the other two points The titanium material is characterized in that the difference from the film thickness of the Al-containing layer in the film is within 30% with respect to the film thickness of the Al-containing layer at the center point [second invention].

The titanium material according to claim 3 is the titanium material according to claim 2, wherein the Al—Ti intermetallic compound is Al ₃ Ti [third invention].

  The titanium material according to claim 4 is the titanium material according to claim 2 or 3, wherein the average thickness of the Al—Ti intermetallic compound layer is 0.5 μm or more and 15 μm or less [fourth invention].

  The titanium material according to claim 5 is the titanium material according to any one of claims 1 to 4, wherein 0.5 to 10% by mass of Al is contained in the base material [fifth invention].

  The titanium material according to claim 6 is the titanium material according to claim 5, wherein the substrate is substantially made of Al and Ti [Sixth Invention].

  The titanium material according to claim 7 is the titanium material according to claims 1 to 6, wherein the Al-containing layer is formed by a hot dipping method [seventh invention].

  The method for producing a titanium material according to claim 8 is the method for producing a titanium material according to any one of claims 1 to 7, wherein an Al-containing layer is formed by a hot dipping method. A method for producing a titanium material, characterized in that the pulling rate of the titanium base material from the bath is 1 to 20 cm / second [8th invention].

  The method for producing a titanium material according to claim 9 is the method for producing a titanium material according to any one of claims 1 to 7, wherein an Al-containing layer is formed by a hot dipping method, and thereafter, hard particles are used. A titanium material production method characterized by performing a blast treatment [9th invention].

  An exhaust pipe according to claim 10 is an exhaust pipe for a two-wheeled vehicle or a four-wheeled vehicle manufactured using the titanium material according to any one of claims 1 to 9 [10th invention].

  The titanium material according to the present invention is excellent in oxidation resistance, and can be easily applied to a complicated shape portion such as an inner surface of a pipe. Therefore, it can be suitably used as a constituent material of an exhaust pipe for a two-wheeled vehicle or a four-wheeled vehicle, and there is an effect that the durability can be improved.

  Since the exhaust pipe for a two-wheeled vehicle or four-wheeled vehicle according to the present invention is manufactured using the titanium material, not only is the weight reduced, but the oxidation resistance is excellent and the durability is improved. .

  According to the method for producing a titanium material according to the present invention, a titanium material excellent in oxidation resistance can be obtained.

  In the titanium material according to the present invention, the titanium material according to the first invention contains Al or Al and Si containing 90% by mass or more of Al on a substrate made of pure Ti or a Ti-based alloy. A titanium material on which a layer is formed, and three points are taken at intervals of 14 mm in the longitudinal direction of the titanium material, and the film thickness of the Al-containing layer at the central point among these three points and the Al at the other two points The titanium material is characterized in that the difference from the film thickness of the containing layer is within 30% with respect to the film thickness of the Al-containing layer at the center point [first invention].

  This Al-containing layer is a layer (oxidation resistance improving layer) that has oxidation resistance and improves oxidation resistance. As this oxidation resistance improving layer, a layer (Al-containing layer) containing 90% by mass or more of Al or Al + Si (Al and Si) on the substrate made of pure Ti or Ti-based alloy as described above has a thickness of 1 μm. It is necessary to form the above. The reason for this is that Al or an alloy (layer) containing Al at a high concentration preferentially produces a dense aluminum oxide having a large negative free energy in a high-temperature oxidizing atmosphere. This is because this becomes a protective film and suppresses subsequent oxidation. Si is an element that improves the oxidation resistance. If Si is contained in the Al-containing layer, the oxidation resistance is improved. When Si is also contained in the Al-containing layer, the total amount of Al and Si in the Al-containing layer is 90% by mass or more.

  At this time, the concentration of Al or Al + Si in the Al-containing layer (oxidation resistance improving layer) needs to be 90% by mass or more, and if it is less than 90% by mass, the effect of improving oxidation resistance is low. (Wt%) was the lower limit.

  The ratio of Si in the amount of Al + Si is preferably 1 to 20% by mass. When Si is less than 1% by mass, the effect of improving oxidation resistance is low. When Si is contained in excess of 20% by mass, hot dip plating becomes difficult when the Al-containing layer is formed by hot dip plating. From this point, the ratio of Si in the amount of Al + Si is most preferably around 10%.

  In the Al-containing layer (a layer containing Al or Al + Si), as elements other than Al and Si, Mg, Cu, Fe, etc. which may enter by a normal hot dipping method are contained, and a base material (pure Ti or the like is contained from Ti or Ti-based alloy).

  If the thickness of the Al-containing layer is not 1 μm or more, the substrate is oxidized due to defects such as pinholes. The effect of oxidation resistance is that if there are no defects such as pinholes, the thicker one improves, so the upper limit of the thickness is not set, but if it is too thick, the workability of the substrate is impaired, so about 100 μm or less is a guide Become. In addition, the thickness of the Al-containing layer is obtained by an average value of thicknesses obtained by measuring the cross section of the titanium material at an arbitrary plurality of places, for example, three places.

  As a method for forming the Al-containing layer (oxidation resistance improving layer), a hot dipping method or the like is recommended as a typical method. This is because the hot dipping method can form a layer even on a complicated shape such as the inner surface, and is inexpensive and economical. In addition, according to the hot dipping method, the adhesion between the Al-containing layer and the base material is reduced because the natural oxide film on the surface of the molten Al and the base material (pure Ti or Ti-based alloy) is reduced when immersed in the molten Al. Is better. As conditions for hot dipping, a bath temperature of 700 to 800 ° C. and a soaking time of 5 to 20 minutes are recommended, but they vary depending on the heat capacity of the substrate and the type of material.

  In addition to this, an Al-containing layer can be formed also by a method in which an organic paint containing Al flakes is applied to a substrate.

As can be seen from the above, the titanium material according to the first invention of the present invention is excellent in oxidation resistance, and easily forms an oxidation resistance improving layer even in complicated shapes such as the inner surface of the pipe. In addition, it can be obtained by a surface treatment method such as a hot dipping method that can be formed at low cost and excellent in economic efficiency. That is, it is possible to improve the problems of the prior art and to have excellent oxidation resistance [first invention].
In addition, three points are taken at intervals of 14 mm in the longitudinal direction of the titanium material, and the difference between the film thickness of the Al-containing layer at the central point among these three points and the film thickness of the Al-containing layer at the other two points is By being within 30% of the film thickness of the Al-containing layer at the center point, the film thickness of the Al-containing layer is excellent, and as a result, the oxidation resistance of the titanium material is uniform. It excels in dimensional accuracy of plate thickness of titanium material.

When forming an Al-containing layer having excellent adhesion on a substrate [pure Ti or Ti-based alloy (hereinafter also referred to as titanium)], it is first necessary to remove the oxide film present on the surface of the substrate. The natural oxide film on the titanium surface has a thickness of about several tens of nanometers, and is reduced and removed by the reaction of 3TiO ₂ + 2Al → 2Al ₂ O ₃ + 3Ti by immersing titanium in high-temperature molten Al. However, this alone may not provide sufficient adhesion. In such a case, the Al-Ti intermetallic compound layer formed by the reaction between molten Al and Ti is continuously immersed in molten Al plating after the reduction and removal of the natural oxide film, thereby providing higher adhesion. It was found that it can be obtained. That is, an Al-Ti intermetallic compound layer is formed on a base material, and an Al-containing layer is formed thereon (that is, an Al-containing layer is formed on the base material via an Al-Ti intermetallic compound layer). It was found that the adhesion between the base material and the Al-containing layer was further improved by the Al—Ti intermetallic compound layer.

  Therefore, the titanium material according to the second invention of the present invention is an Al-containing layer having a thickness of 1 μm or more containing Al or Al and Si by 90 mass% or more on a substrate made of pure Ti or a Ti-based alloy. A titanium material formed through a Ti intermetallic compound layer, and three points are taken at intervals of 14 mm in the longitudinal direction of the titanium material, and the film thickness of the Al-containing layer at the central point among these three points The titanium material is characterized in that the difference from the film thickness of the Al-containing layer at the other two points is within 30% with respect to the film thickness of the Al-containing layer at the center point. 2 invention]. As can be seen from the above, this titanium material is superior in the adhesion between the base material and the Al-containing layer compared to the case of the titanium material according to the first invention, and the adhesion is not sufficient. It can more reliably (at a high level) have excellent adhesion.

It has been found that particularly excellent adhesion can be obtained when the Al—Ti intermetallic compound (Al—Ti intermetallic compound in the Al—Ti intermetallic compound layer) is Al ₃ Ti. Therefore, in the titanium material according to the third invention of the present invention, in the titanium material according to the second invention, the Al—Ti intermetallic compound (Al—Ti intermetallic compound of the Al—Ti intermetallic compound layer) is Al ₃ Ti. It is supposed to be [third invention]. As can be seen from the above, this titanium material has particularly excellent adhesion.

As Al—Ti compounds, Ti ₃ Al, TiAl, and Al ₃ Ti are known. Of these, the former two Al—Ti compounds (Ti ₃ Al, TiAl) are fragile and easily broken. When the compound layer is formed at the interface between the Al-containing layer and the base material [titanium (pure Ti or Ti-based alloy)], cracks occur in the compound layer, causing poor adhesion. In the past, there has been known a method in which an Al foil is clad on a Ti plate, a compound is formed at the interface by a solid-phase reaction by heat treatment, and the adhesion is improved. ₃ The formation of Al or TiAl layers could not be suppressed, causing poor adhesion.

In the third invention, since it is necessary to form an Al ₃ Ti layer on the base material (titanium), that is, at the interface between the base material and the Al-containing layer, such an Al ₃ Ti layer is formed. Need to be able to. The inventors have been able to form such an Al ₃ Ti layer. That is, although the mechanism of formation of such an Al ₃ Ti layer is not clear, the present inventors use the molten Al method, and appropriately set the immersion time and bath temperature, so that the substrate and the Al content are contained. The present inventors succeeded in forming an Al ₃ Ti layer made of only Al ₃ Ti (not containing Ti ₃ Al or TiAl) at the interface with the layer. At this time, the temperature of the molten Al (bath temperature) and the immersion time vary depending on the mass of the object to be treated (titanium), but the approximate bath temperature is between 700 to 800 ° C. and the immersion time is about 2 to 10 minutes. Become.

The thickness of the Al—Ti intermetallic compound layer is desirably 0.5 μm or more and 15 μm or less on average [fourth invention]. The thickness of the Al—Ti intermetallic compound layer such as the Al ₃ Ti layer can be controlled by the bath temperature and immersion time during hot dipping, and the higher the bath temperature and the longer the immersion time, the thicker the tendency However, when it is too thick, the Al-containing layer responsible for oxidation resistance is interdiffused with the base material (titanium) and becomes thin, and the adhesion of the Al-containing layer also tends to be reduced. The upper limit of the thickness of the Al—Ti intermetallic compound layer was 15 μm. On the other hand, if the thickness of the Al—Ti intermetallic compound layer is too thin, the effect of improving the adhesion is not reduced, so the lower limit of the thickness of the Al—Ti intermetallic compound layer is 0.5 μm. It was. The thickness of the Al—Ti intermetallic compound layer is determined by the average value of the thicknesses obtained by measuring the cross section of the titanium material at an arbitrary plurality of locations, for example, three locations. This measurement can be performed by, for example, 5000 times SEM observation. The amount of Al and Ti in the Al—Ti intermetallic compound layer (and hence the composition of the intermetallic compound) can be measured by, for example, EPMA. The thickness of the Al—Ti intermetallic compound layer is preferably more than 1 μm and 5 μm or less on average.

  In the present invention, the base material (pure Ti or Ti-based alloy) is not particularly limited, and various materials can be used, but when the base material contains Al, an Al-containing layer (improves oxidation resistance). The adhesion between the layer) and the substrate was further improved, and it was found that there was no problem such as peeling even if bending was performed after the formation of the Al-containing layer. Thus, Al content in a base material required in order to improve adhesiveness is 0.5 mass% or more, and the adhesive improvement effect is low below this (less than 0.5 mass%). In the case where the Al content is 0.5% by mass or more, the adhesion does not change greatly depending on the Al content. However, if the Al content is excessively large, there is a problem that the base material is easily cracked. It is desirable to set it as mass% or less. Accordingly, it is desirable to use a substrate containing 0.5 to 10% by mass of Al as the substrate [fifth invention].

  Thus, when 0.5-10 mass% Al is contained in a base material, when the point of the workability of a titanium material is further taken into consideration, the remainder other than Al may be substantially Ti. preferable. That is, from the viewpoint of workability of the titanium material, it is desirable that the substrate is substantially made of Al and Ti [Sixth Invention]. In addition, that a base material consists of Al and Ti substantially means that a base material consists of Ti alloy containing Al and an unavoidable impurity.

  In the present invention, a surface treatment method is used as a method for forming the Al-containing layer (oxidation resistance improving layer). In other words, the titanium material according to the present invention is a surface-treated titanium material. The surface treatment method is not particularly limited, and various surface treatment methods can be applied. For example, a hot dipping method or a method of applying an organic paint containing Al flakes as described above. Can be applied. Note that the method of cladding the Al plate does not correspond to the surface treatment method and is not included in the surface treatment method. As described above, various surface treatment methods can be applied as the surface treatment method for forming the Al-containing layer, and among them, a hot dipping method can be recommended. In the hot dipping method, as described above, a layer can be uniformly formed even on a complicated shape such as an inner surface, and it is inexpensive and excellent in economic efficiency. In addition, according to the hot dipping method, the natural oxide film on the surface of the base material (pure Ti or Ti alloy) is reduced when immersed in molten Al, so that the adhesion between the Al-containing layer and the base material is improved. . Furthermore, since the Al—Ti intermetallic compound layer can be formed on the substrate depending on the plating conditions such as the immersion time in the molten Al plating, the titanium material according to the second invention or further according to the third to fourth inventions. A titanium material can be obtained in one step called a hot dipping method. From this point, it is desirable that the Al-containing layer be formed by a hot dipping method [seventh invention].

  In the present invention, as one aspect of the method for forming the Al-containing layer, a hot dipping method (hot Al plating method) is recommended as a preferred mode. In the hot dipping method, in addition to the immersion time of the titanium base material in the hot dipping bath that affects the adhesion with the Al-containing layer, it is formed by the speed at which the titanium base material is lifted from the hot dipping bath (lifting speed) The properties of the Al-containing layer to be affected are affected. The pulling rate of the titanium substrate from the hot dipping bath is preferably 1 to 20 cm / second [8th invention]. The reason for this will be described below.

  In the hot dip plating method, when the substrate is lifted from the bath, if the pulling rate is too fast, the thickness of the formed Al-containing layer is greatly different between the upper portion and the lower portion of the pulled substrate. At the time of pulling up from the bath, Al adhering to the surface is pulled out of the bath without solidifying, and then moves to the lower part before being cooled, resulting in the formation of a thicker film at the lower part than the upper part.

  On the other hand, when the pulling speed is controlled to 20 cm / second or less, the moving speed of Al is a speed larger than the pulling speed, and the Al moved to the lower part is absorbed into the Al bath as it is. Therefore, there is no difference in film thickness between the upper part and the lower part. From this point, it is desirable that the pulling rate is 20 cm / second or less.

  When the pulling speed is 1 cm / sec, for example, it takes 100 seconds to pull up a 1 m long plate, and usually 1 to 2 minutes is sufficient for the dipping time. Then, the immersion time differs greatly. In this case, there is a possibility that the reaction between Al and the titanium base material proceeds excessively and the plate thickness of the titanium material becomes thin. From this point, it is desirable that the pulling rate is 1 cm / second or more.

  In view of the above, it is more desirable that the pulling rate is 2 to 15 cm / second. If it does so, the above film thickness differences will become smaller, and the possibility that the plate | board thickness of a titanium material will become thin becomes smaller.

  When the pulling speed of the titanium substrate from the hot dipping bath is 1 to 20 cm / second as described above, a film having a small difference in film thickness between the upper and lower Al-containing layers is obtained. For example, three points are taken at intervals of 14 mm in the longitudinal direction of the titanium material, and the difference between the film thickness of the Al-containing layer at the central point among these three points and the film thickness of the Al-containing layer at the other two points is A titanium material that is within 30% of the thickness of the Al-containing layer at the center point is obtained. This titanium material is excellent in the uniformity of the film thickness of the Al-containing layer. As a result, it is excellent in the uniformity of the oxidation resistance of the titanium material and the dimensional accuracy of the thickness of the titanium material.

  In the formation of the Al-containing layer by the hot-dip Al plating method, there may be a portion where no voids or plating is formed in the plating layer depending on the pulling-up conditions of the base from the hot-dip plating bath and the state of the base. Further, when molten Al is solidified on the titanium base material, a thin oxide film is formed on the outermost surface due to reaction with the atmosphere, so that the gloss of the surface may be lost. As a result of intensive studies to solve these problems, the present inventors do not form voids or plating generated in the Al layer by blasting with hard particles such as glass or metal spheres after forming the Al-containing layer. It was found that the portion can be filled and eliminated, and the oxidation resistance can be further improved. At the same time, it was also found that the oxide film on the surface was removed by the blast treatment, and a beautiful surface having a metallic luster was exhibited. Here, the oxide film to be removed is considerably thicker than the natural oxide film because the oxide film formed on the surface of the bath is involved when the oxide film is pulled up from the molten Al plating bath. When these thick oxide films are removed by blasting, a thin natural oxide film is formed, but it is very thin and does not impair the glossy and beautiful surface properties.

  Therefore, it is desirable to perform blasting with hard particles after forming the Al-containing layer by hot dipping method [9th invention]. When blasting is performed in this way, even when a gap or plating is not formed in the Al-containing layer formed by the hot dipping method, these can be filled and eliminated, and as a result, oxidation resistance can be further improved. In addition, the surface oxide film is removed, and a beautiful surface having a metallic luster can be obtained.

For the blast treatment, hard particles having a hardness higher than that of Al are used. However, if it is too hard, the Al-containing layer is scraped, so it is desirable to use a material having a hardness of alumina or less, and it is more desirable to use hard particles having a hardness of glass or less. Regarding the size of the hard particles, those having a size of about # 100 which is usually used for blasting can be used. In terms of particle size, those having a size of several hundred μm can be used. If the particle size is too small, the effect of filling the pores by collision is small, so that the particle size is preferably 10 μm or more. As a blasting method, the method of projecting hard particles by air pressure is the simplest and recommended in that respect, but if the air pressure is too high, the Al-containing layer is removed, so the air pressure should be 5 kg · cm ² or less. Recommended. Preferably, it is 3 kg · cm ² or less.

  As described above, the titanium material according to the present invention (the titanium materials according to the first to seventh inventions) is excellent in oxidation resistance, and also has an oxidation resistance improving layer even in complicated shapes such as the inner surface of the pipe. Can be easily formed, and can be obtained by a surface treatment method such as a hot dipping method that can be formed inexpensively and economically. Therefore, it can be suitably used as a constituent material of exhaust pipes for two-wheeled vehicles or four-wheeled vehicles, and the durability is improved [10th invention].

  Examples of the present invention and comparative examples will be described below. The present invention is not limited to this embodiment, and can be implemented with appropriate modifications within a range that can be adapted to the gist of the present invention, all of which are within the technical scope of the present invention. include.

[Reference Example 1, Comparative Example 1]
Using pure titanium (JIS 1 type, thickness 1 mm) as a base material, Al of the composition shown in Table 1 is formed on the base material by a hot dipping method, a vapor deposition method, or a spray method of spraying a material containing Al particles. The containing layer (oxidation-resistant layer) was formed, thereby obtaining titanium materials according to the reference examples and comparative examples of the present invention. At this time, in the hot dipping method, the base material was immersed under conditions of bath temperature: 700 to 750 ° C. and immersion time: 5 to 20 minutes to form an Al-containing layer.

  The titanium materials include those in which an Al—Ti intermetallic compound layer is formed at the interface between the base material and the Al-containing layer and those in which no Al-Ti intermetallic compound layer is formed. In order to confirm this, quantitative analysis of elements by EPMA was performed, and the presence or absence of an Al—Ti intermetallic compound layer was examined.

  In Table 1, the composition column indicates the composition of the Al-containing layer (oxidation resistant layer). In the column of this composition, Al100 of No. 2 to No. 3 is an Al amount: 100% by mass, and indicates that it consists of Al and inevitable impurities. No. 4 Al95Ti5 has an Al content of 95% by mass and a Ti content of 5% by mass, and indicates that Al: 95% by mass and Ti: 5% by mass are inevitable impurities. No. 6 Al95Si5 has an Al content of 95% by mass and an Si content of 5% by mass, indicating that Al: 95% by mass and Si: 5% by mass are unavoidable impurities. Other than these, the same reading as described above shall be performed, and the same reading as described above shall be performed in the columns of each composition after Table 2 described later.

  The titanium material thus obtained is subjected to a high-temperature oxidation test in which it is exposed to an air atmosphere at 800 ° C. for 100 hours, the thickness before and after the high-temperature oxidation test is measured, and the thickness due to oxidation in the high-temperature oxidation test is measured. The amount of decrease was determined, and thereby the oxidation resistance was evaluated. Further, pure titanium (pure Ti) was subjected to the same high-temperature oxidation test as described above, and the oxidation resistance was evaluated by the same method.

  The results are shown in Table 1. As can be seen from Table 1, in the case of pure Ti (No. 1), the thickness reduction due to oxidation in the high-temperature oxidation test is as large as 200 μm, and the oxidation resistance is not good. The titanium material according to the comparative example of No. 5 has a thickness reduction amount of 150 μm, and the oxidation resistance is slightly improved, but the degree of improvement is small.

  In contrast, the titanium material according to the reference example of the present invention of No. 7 has a small thickness reduction amount and excellent oxidation resistance, and further, No. 2-4, No. 6 and No. 8 The titanium material according to the reference example of the present invention has a very small thickness reduction amount and is extremely excellent in oxidation resistance.

  In the titanium materials according to the reference examples of the present invention of No. 2-4, No. 6 and No. 8, the total amount of Al and Si in the Al-containing layer (the amount of Al in the case of no Si) is When it is large, the thickness reduction amount is small and the oxidation resistance is excellent.

[Reference Example 2]
Using pure titanium (JIS 1 type, thickness 1 mm) as a base material and Ti-based alloys containing Al (Al amount: different), an Al-containing layer (oxidation-resistant layer) is formed on the base material by hot dipping. Thus, a titanium material according to a reference example of the present invention was obtained. In addition, as shown in Table 2, the composition of the Al-containing layer is Al100 (Al content: 100% by mass) in any case. The conditions of the hot dipping method are the same as those in Reference Example 1. In the column of the base material of Table 2, Ti-1.5Al is Ti-1.5% by mass Al, and contains Ti: 1.5% by mass, and the balance is a Ti-based alloy consisting of inevitable impurities. It shows that it is. Other than these, the same reading as described above is performed, and the same reading as described above is also performed in the column of each base material after Table 3 described later.

  The titanium material thus obtained was subjected to a 90 ° bending test, and the adhesion between the Al-containing layer and the substrate was evaluated based on the peeling state of the corner portion.

  Further, the titanium material after the bending test was subjected to the same high-temperature oxidation test as in Reference Example 1, and the oxidation resistance was evaluated by the same evaluation method.

  The results are shown in Table 2. As can be seen from Table 2, when the substrate is a Ti-15Al alloy (Al content: Ti alloy having a mass of 15% by mass), the substrate is cracked in the bending test (No. 6). In the case where the base material is pure titanium, the base material is not cracked in the bending test, but peeling occurs.

  On the other hand, when a Ti alloy containing Al as a base material and an Al amount satisfying Al amount: 0.5 to 10% by mass is used, peeling does not occur in the bending test, and Al content is included. Excellent adhesion between layer and substrate (No. 2-5).

  As for oxidation resistance, the No. 2 to 5 titanium materials all have a small reduction in thickness and are excellent in oxidation resistance. These titanium materials have no significant difference in thickness reduction, and the oxidation resistance is at the same level.

[Reference Example 3, Comparative Example 2]
Pure Ti (JIS 1 type, thickness 1 mm) was used as the base material, and an Al-containing layer (oxidation resistant layer) was formed on the base material by a hot dipping method, thereby obtaining a titanium material. At this time, in the hot dipping method, the base material was immersed under conditions of bath temperature: 750 ° C. and immersion time: 0.1 to 60 minutes to form an Al-containing layer. In addition, the said titanium material has the thing in which the Al-Ti intermetallic compound layer is formed in the interface of a base material and an Al content layer, and the thing which is not formed. For this confirmation, the presence or absence of an Al—Ti intermetallic compound layer was examined by the same method as in Reference Example 1 (quantitative elemental analysis by EPMA).

  Further, a material (Al clad titanium material) in which an Al plate was clad on a pure Ti surface was produced. And this Al clad titanium material was heat-processed by heating at 500 degreeC in air | atmosphere for 60 minutes, and, thereby, the Al-Ti compound layer was formed in the interface of a base material (pure Ti) and an Al board. For this confirmation, the presence or absence of an Al—Ti intermetallic compound layer was examined by the same method as described above (quantitative elemental analysis by EPMA).

  The titanium material thus obtained was subjected to a 90 ° bending test, and the adhesion between the Al-containing layer or Al plate and the substrate was evaluated according to the peeled state of the bent portion.

  Further, the titanium material after the bending test was subjected to the same high-temperature oxidation test as in Reference Example 1 (in the atmosphere, 800 ° C. × 100 hours), and the thickness was reduced by oxidation in the high-temperature oxidation test for the bent portion. The amount was determined and the oxidation resistance was evaluated.

The results are shown in Table 4. Moreover, an example of the electron micrograph about the interface of the base material of titanium material (after a hot-dip plating before a bending test) and an Al content layer and its vicinity is shown in FIG. FIG. 1 is for No. 3 titanium material in Table 4 (after hot dipping and before bending test). In the case of this titanium material, as can be seen from FIG. 1, an Al ₃ Ti layer (Al3Ti layer) is formed at the interface between the base material (Ti material) and the Al-containing layer (Al layer).

  As can be seen from Table 4, when the immersion time of the base material (pure Ti) in the hot dipping bath is 0.1 minutes, an Al-Ti intermetallic compound layer is formed at the interface between the base material and the Al-containing layer. No oxide film remains on the surface of the substrate (No. 1).

In contrast, when the immersion time of the base material in the hot dipping bath is increased, an Al ₃ Ti (shown as Al ₃ Ti in the table) layer is formed at the interface between the base material and the Al-containing layer (No. 2 to 6, No. 8). At this time, as the immersion time becomes longer, the thickness of the Al ₃ Ti layer is increased.

In the above titanium materials (No. 1-6, No. 8), No. 1 has no Al-Ti intermetallic compound layer formed at the interface between the base material and the Al-containing layer as described above. In the bending test, peeling occurred. In contrast, those of No.2~6, Al ₃ Ti layer is formed at the interface between the substrate and the Al-containing layer, the thickness (satisfy average 0.5~15μm) 1~10.5μm No peeling occurred in the bending test, and the adhesion between the Al-containing layer and the substrate is excellent. In No. 8, the thickness of the Al ₃ Ti layer formed at the interface between the base material and the Al-containing layer is 20 μm (which does not satisfy an average of 0.5 to 15 μm) and is thicker, and partly in the bending test. Peeling has occurred.

No. 7 is an Al-clad titanium material, and an Al-Ti intermetallic compound layer (thickness: 8.6 μm) containing Ti ₃ Al, TiAl, Al ₃ Ti at the interface between the base material (pure Ti) and the Al plate. Is formed. This Al clad titanium material also partially peeled in the bending test.

  The results of the high-temperature oxidation test on the titanium material after the bending test are as shown in Table 4. Compared with the case of the Al-clad titanium material, the titanium materials of No. 2 to 6 have a high-temperature oxidation test result. The reduction in thickness due to oxidation is small, and it has excellent oxidation resistance. Therefore, the titanium materials No. 2 to 6 are excellent in adhesion between the Al-containing layer and the base material and excellent in oxidation resistance.

Among the No. 2-6 titanium materials, the No. 3-4 titanium materials (thickness of Al ₃ Ti layer is 2.5-4.5 μm and more than 1 μm and less than 5 μm) are particularly oxidation resistant. Excellent in properties. Therefore, the titanium materials No. 3 to 4 are particularly excellent in the adhesion between the Al-containing layer and the base material and also in the oxidation resistance.

In the above No. 2 to No. 4 titanium materials, the thicker the Al ₃ Ti layer is, the better the oxidation resistance is.

  The No. 1 titanium material in Table 4 has the same or almost the same structure as the No. 1 titanium material in Table 2 and No. 3 to 5 in Table 1. After forming (after hot dipping) and before the bending test, it shows oxidation resistance equivalent to that of No.1 titanium material in Table 2 and No.3 to 5 in Table 1. Is excellent. However, the results of the high-temperature oxidation test on the titanium material (No. 1) after the bending test are as shown in Table 4. The thickness reduction due to oxidation in the high-temperature oxidation test is large, and the oxidation resistance is excellent. No results. This is because peeling occurred in the bending test as described above, and a high temperature oxidation test was performed on the peeled portion (the amount of thickness reduction due to oxidation in the high temperature oxidation test for this peeled portion was obtained). It is.

[Example 1, Comparative Example 3]
A pure titanium plate (shape: 30 cm × 10 cm, thickness: 1 mm) is immersed for 1 minute in a pure Al molten metal (containing about 2% Fe as impurities) at a bath temperature of 700 ° C., and then 0.05 mm in the longitudinal direction of the titanium plate. Lifting was performed at a pulling rate of ˜50 cm / sec. About the titanium material thus obtained, the film thickness of the Al-containing layer (Al layer) in the upper part (location 1 cm from the upper end), the center (location 15 cm from the upper end), and the lower portion (location 29 cm from the upper end). investigated.

  The results are shown in Table 5. As can be seen from Table 5, the higher the pulling speed of the titanium base material (pure titanium plate) from the hot dipping bath (pure Al molten metal), the thicker the film (Al layer) is formed. The film thickness of the Al layer increases, particularly the film thickness in the lower part, and the film thickness distribution increases as the film thickness of the Al layer in the lower part increases. That is, the difference in film thickness of the Al layer at the top, center, and bottom is increased.

  When the lifting speed is 50 cm / sec, the difference between the thickness of the Al layer at the center and the thickness of the Al layer at the top (the difference in the thickness of the Al layer at the center and the top) is the difference between the thickness of the Al layer at the center. 31.2% of the film thickness [= 100 × (80−55) / 80], and the difference between the film thickness of the Al layer in the center and the film thickness of the Al layer in the lower part (Al in the center and the lower part) The difference in layer thickness is 150% with respect to the thickness of the Al layer at the center. When the pulling rate is 30 cm / sec, the difference in the thickness of the Al layer between the center and the top is 27.7% with respect to the thickness of the Al layer at the center, and the thickness of the Al layer between the center and the bottom. The difference is 38.5% with respect to the film thickness of the Al layer at the center.

  When the pulling speed is 15 cm / sec, the difference in the thickness of the Al layer between the center and the top is 20% [= 100 × (55−44) / 55] with respect to the thickness of the Al layer at the center. The difference between the thickness of the Al layer at the center and the lower portion is 18.2% with respect to the thickness of the Al layer at the center. These are small as compared with the above-mentioned case of the lifting speed: 50 cm / sec, and are small even when compared with the case of the pulling speed: 15 cm / sec.

  Pulling speed: In the case of 10 cm / second, the ratio of the difference in the thickness of the Al layer at the center and the upper part with respect to the thickness of the Al layer at the center, the ratio of the difference in the thickness of the Al layer at the center and the lower part, The pulling speed is smaller than that in the case of 15 cm / sec. Lifting speed: In the case of 2 cm / sec, the ratio of the difference in the thickness of the Al layer at the center and the upper part relative to the thickness of the Al layer at the center, the ratio of the difference in the thickness of the Al layer at the center and the lower part, The pulling speed is smaller than that in the case of 10 cm / second.

  When the pulling speed is 15 cm / sec, 10 cm / sec, 2 cm / sec, in any case, “the pulling speed of the titanium substrate from the hot dipping bath is 1-20 cm / sec” (Requirements concerning the eighth invention) are satisfied. And in this case, as can be seen from the foregoing and Table 5, “three points are taken at intervals of 14 mm in the longitudinal direction of the titanium material, the film thickness of the Al-containing layer at the center point among these three points, and the like. The difference between the film thickness of the Al-containing layer at the two points is within 30% with respect to the film thickness of the Al-containing layer at the central point "(requirements relating to the first and second inventions) Things have been obtained.

  When the pulling rate is 0.05 cm / sec, the difference in the thickness of the Al layer between the center and the top is 2% with respect to the thickness of the Al layer at the center, The difference in film thickness is 6.1% with respect to the film thickness of the Al layer at the center, which is excellent in the uniformity of the film thickness of the Al-containing layer. In some cases, the reaction of the titanium base material progresses too much, and the thickness of the titanium material becomes thin.

Example 2 and Comparative Example 4
A pure titanium plate (shape 30 cm × 10 cm, thickness 1 mm) is immersed for 1 minute in pure Al molten metal (containing about 2% Fe as impurities) at a bath temperature of 700 ° C., and then this titanium plate is 3 cm / second in the longitudinal direction. Lifting was performed at a lifting speed of. The titanium material thus obtained was blasted with hard particles. At this time, glass beads were used as the hard particles. The pressure of compressed air during blasting was 2 kg / cm ² and the blasting time was 10 seconds.

  The titanium material after the blast treatment (hereinafter also referred to as titanium material A) is subjected to an atmospheric oxidation test in which it is exposed to an air atmosphere at 800 ° C. for 100 hours, and the mass before and after the atmospheric oxidation test is measured. The amount of increase in mass (oxidation increase) due to oxidation at 1 was obtained, and the oxidation resistance was evaluated from this. Further, a titanium material obtained by the same method as described above except for this point (that is, a titanium material obtained by pulling up from the same pure Al molten metal as described above at the same pulling speed). For the following (also referred to as titanium material B), the same atmospheric oxidation test as described above was performed, and the oxidation resistance was evaluated by the same method.

As a result, in the case of the titanium material B (not blasted), the increase in oxidation was 3 mg / cm ² . On the other hand, in the case of the titanium material A (the one subjected to blasting), the increase in oxidation was 1.9 mg / cm ² and was excellent in oxidation resistance.

  When the surface of the titanium material A and the titanium material B was observed, the titanium material A (those subjected to the blasting treatment) had a beautiful surface having a metallic luster, and the titanium material B (the blasting treatment was performed). The surface was more beautiful than

  Since the titanium material according to the present invention is excellent in oxidation resistance and can be easily applied to complicated shapes such as the inner surface of the pipe, the configuration of the exhaust pipe for two-wheeled vehicles or four-wheeled vehicles It can be suitably used as a material, and not only can its weight be reduced, but also has excellent oxidation resistance and improved durability.

Interface Al ₃ Ti layer of the substrate according to an embodiment of the present invention and (Ti material) Al-containing layer and the (Al layer) (Al 3 Ti layer) is a diagram showing that are formed.

Claims (10)

  A titanium material in which an Al-containing layer having a thickness of 1 μm or more containing 90% by mass or more of Al or Al and Si is formed on a substrate made of pure Ti or a Ti-based alloy, in the longitudinal direction of the titanium material Three points are taken at intervals of 14 mm, and the difference between the film thickness of the Al-containing layer at the central point among the three points and the film thickness of the Al-containing layer at the other two points is the Al-containing layer at the central point. Titanium material characterized by being within 30% of the film thickness.   Titanium in which an Al-containing layer having a thickness of 1 μm or more containing 90% by mass or more of Al or Al and Si is formed on a base material made of pure Ti or a Ti-based alloy via an Al—Ti intermetallic compound layer 3 points are taken at intervals of 14 mm in the longitudinal direction of the titanium material, and the film thickness of the Al-containing layer at the central point among the three points and the film thickness of the Al-containing layer at the other two points The titanium material, wherein the difference is within 30% with respect to the thickness of the Al-containing layer at the center point. The titanium material according to claim 2, wherein Al-Ti intermetallic compound is Al ₃ Ti.   The titanium material according to claim 2 or 3, wherein an average thickness of the Al-Ti intermetallic compound layer is 0.5 µm or more and 15 µm or less.   The titanium material according to claim 1, wherein 0.5 to 10% by mass of Al is contained in the base material.   The titanium material according to claim 5, wherein the base material is substantially made of Al and Ti.   The titanium material according to claim 1, wherein the Al-containing layer is formed by a hot dipping method.   It is a manufacturing method of the titanium material in any one of Claims 1-7, Comprising: Formation of an Al content layer is performed by the hot dipping method, The pulling-up speed of the titanium base material from a hot dipping bath is 1- A method for producing a titanium material, characterized by being 20 cm / second.   It is a manufacturing method of the titanium material in any one of Claims 1-7, Comprising: Formation of an Al content layer is performed by the hot dipping method, The blast process by a hard particle is performed after this, The titanium material characterized by the above-mentioned Production method.   An exhaust pipe for a two-wheeled vehicle or a four-wheeled vehicle manufactured using the titanium material according to any one of claims 1 to 9.

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