JPH1161366A - Titanium product having mother-of-pearl-like texture - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a lighweight Ti product free form rust, high in hardness and having a mother-of-pearl-like texture excellent in taste by subjecting a molding of a Ti alloy of α-β phases or β phases to specified primary age hardening treatment, Ti crystal precipitating treatment, crystal precipitation density strengthening and secondary age hardening treatment in succession. SOLUTION: A rolling material of a Ti alloy of α-β phases or β phases contg. >=70% metallic Ti is molded by mechanical working. This molding is subjected to primary age hardening treatment which holding at 350 to 600 deg.C for contain time in the air, in a vacuum or in an inert gas atmophere to increase its hardness to >=30 deg. HRC. Next, the molding is subjected to finish working such as grinding, polishing or the like as necessary and is thereafter subjected to crystal precipitating treatment of executing heating at 1000 to 1400 deg.C in a vacuum furnace to precipitate Ti crystals on the surface. The molding after this treatment is held at 350 to 600 deg.C for a certain time in a process of executing air-cooling in the air, in a vacuum or in an inert gas atmosphere to strengthen the precipitation density of the Ti crystals and is furthermore subjected to secondary age hardening treatment to increase its hardness to >=35 deg. HRC.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

TECHNICAL FIELD The present invention relates to molding of a titanium alloy,
It belongs to the technical field of metallurgy. Further, the present invention relates to a means for producing knives and various articles used daily at home, such as various knives. Further, the present invention relates to means for providing hobby accessories such as wristwatch bands and bracelets, and sporting fishing gear such as artificial bait.

[0002]

The kitchen knives, especially kitchen knives as kitchen utensils at home, are more enjoyable because they are mainly cooking utensils used daily by domestic ladies. Also, unlike household tools, such tools for household use are unlikely to rust even though blades and other care are inadequate, so stainless steel tools are now widely used. doing. However, while stainless steel instruments have the advantage of being less likely to rust, they generally have relatively low hardness, and thus have the disadvantage that the sharpness of the tool is quickly reduced without sharpening. Alloy steel is sometimes used as a material to increase the sustainability of sharpness, but due to high production costs,
It is difficult to spread as a household knife. Also, a lightweight kitchen knife cannot be obtained.

[0003] On the other hand, with the progress of titanium refining technology in recent years, carbon steel or stainless steel has been replaced from the viewpoint of cost.
Titanium can be used as a material for cutting tools. Moreover, titanium is remarkably lighter, more rustless and harder than steel, so it is possible to obtain materials with high hardness, such as household knives such as kitchen knives and ornaments such as watch bands. It is considered to be suitable as a material for the first time.

However, a cold rolled product of pure titanium or a titanium alloy, which is to be used as a material for kitchen knives, table knives, ornaments, etc., not only has a lower hardness than carbon steel or the like, but also has a gray background color and an appearance. Because of a poor impression, these points lack the suitability as a material for processing into the above-mentioned household knives and ornaments. Therefore, for titanium alloy, by improving these physical properties, excellent practicality,
It is an object of the present invention to provide a means for producing a titanium product that is also attractive in taste.

[0005]

SUMMARY OF THE INVENTION The present invention provides a primary age hardening treatment and crystal precipitation for a rolled material of a titanium alloy, which is subjected to machining such as cutting and bending to form a target product. The treatment and the secondary age hardening treatment are sequentially performed in the order described here.

However, the above-mentioned titanium alloy contains at least 70% of metallic titanium in α / β phase or β phase. The above-mentioned primary age hardening treatment is the above-mentioned molded article in the air,
350 ° C. to 6 in vacuum or in an inert gas atmosphere
This is a process of increasing the material hardness to 30 ° C. or higher by holding the material at a relatively low temperature of 00 ° C. for a certain period of time. Next, the above-mentioned crystal precipitation treatment means that the molded product which has been subjected to the primary age hardening treatment is subjected to finishing such as grinding and polishing, if necessary, in a vacuum furnace.
Heat treatment at a high temperature of 00 ° C to 1400 ° C to precipitate titanium crystals on the surface. Next, the secondary age hardening treatment, the molded product after the crystal precipitation treatment, in the air, in a vacuum, or in the process of cooling in an inert gas atmosphere, the primary age hardening treatment and Similarly, by maintaining the temperature at 350 ° C. to 600 ° C. for a certain period of time, it refers to a process of strengthening the precipitation density of titanium crystals on the surface of the molded article and increasing the material hardness of the molded article to 35 ° C. or higher.

[0007]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, a kitchen knife as a cooking utensil will be described as an embodiment of the present invention. As described above, the present invention provides a primary age hardening treatment, a crystal precipitation treatment, for a molded product obtained by subjecting a rolled material of a titanium alloy to machining to form the outer shape of a target product.
And a secondary age hardening treatment.

[0008] Molded product: Ti = 76%, V = 1 in the total weight
The molded product is obtained by punching a flat plate of a rolled β-phase titanium alloy material having a composition of 5%, Al = 3%, Sn = 3%, and Cr = 3% into the outer shape of a kitchen knife.

Primary age hardening treatment: The above molded product is kept in a vacuum furnace at about 500 ° C. for 24 hours. As a result, the material hardness becomes HRC 30 ° C.

[0010] Crystal precipitation treatment: The molded product subjected to the primary age hardening treatment already has the outer shape of a kitchen knife, but after grinding and polishing for removing burrs generated at the time of punching and cutting with a blade. And heated at 1400 ° C. for about 1 hour in a vacuum furnace. As a result, the hardness of the material decreases, but a crystal structure of titanium appears on the surface.

Secondary Age Hardening Treatment The molded product having undergone the crystal precipitation treatment is allowed to cool in a furnace, and is kept at about 500 ° C. for 16 hours in the process of cooling as in the case of the primary age hardening treatment. As a result, crystals of the α phase of titanium precipitate on the surface, and the entire surface is covered with a fine pattern of the crystal plane at a high density. For this reason, the scalp of the kitchen knife after cooling is beautifully brilliant, with a complex of white, pale blue and pink fine sections, as if it were a screw-work made of pearl mothers. When the surface hardness was measured, the Vickers hardness was 750 (63 in terms of HRC hardness).
°) or more, the material hardness is HRC 49 ° or more.

[0012]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Although a kitchen knife has been described as a suitable example of the above-mentioned embodiment of the present invention, the present invention is not limited to the above-mentioned kitchen knife, but is applied to all articles made of metal. It is possible. In particular, it is preferably applied to articles that require durability against moisture, salt, friction, and the like, such as ornaments such as wristbands and bracelets and lures of fishing gear.

In the above embodiment, the composition of the titanium alloy is as follows: Ti = 76%, V = 15%, Al = 3%, Sn = 3
%, Cr = 3%, but for example, Ti =
A titanium alloy having a composition of α and β phases, such as 90%, A1 = 6%, and V = 4%, and having a Ti content of 70% or more can be used as a material for carrying out the present invention.

The conditions of the temperature and the holding time of the primary aging hardening treatment or the secondary aging hardening treatment are 350 ° C. to 600 ° C.
A range of 1 hour to 100 hours is allowed. The atmosphere in the heating furnace for performing the age hardening treatment may be air other than the above-described vacuum, or may be an inert gas such as argon gas.

The processing temperature and time conditions in the above-mentioned crystal precipitation treatment are in the range of 1000 ° C. to 1400 ° C. for 1 hour to 3 hours.

[0016]

According to the present invention, as described above, 350 ° C. to 600 ° C. is applied to the α · β or β phase titanium alloy.
When the age hardening treatment is performed, and then when the high temperature treatment of 1000 ° C. or more is performed as in the crystal precipitation treatment described above,
It was known before the present invention that titanium crystals were deposited on the surface of the workpiece. Heating at 1000 ° C. or higher corresponds to annealing treatment, and the material hardness of the object to be treated is significantly reduced. To give an example, the hardness of the workpiece after the primary age hardening treatment in the above embodiment was HRC48 ° which was the highest value that the present inventor experimented, but after annealing treatment such as crystal precipitation treatment according to the present invention. Decreased to 30% or less of HRC. After subjecting the workpiece after such high-temperature treatment to age hardening again under the same conditions as the primary age hardening,
Exceeds HRC 48 °, which was the hardness before high temperature treatment, and
A material hardness of C49 ° was obtained. Even when the composition of the titanium alloy is different from that of the embodiment, a material hardness of at least 35 ° C. or more in HRC can be obtained. Not only that, the surface hardness was Vickers hardness 750, that is, a very high hardness of 63 ° HRC in terms of Rockwell hardness. It has been found for the first time by the present inventor that the age hardening treatment after the high-temperature treatment causes the hardness to exceed the initial hardness and increase the surface hardness abnormally and unexpectedly.

Thus, according to the present invention, a knife such as a kitchen knife, which is not only lightweight and stainless steel but also has a particularly high surface hardness and has a screw-like ground like a studded gem,
Since it is possible to provide attractive hard titanium products such as ornaments such as wristwatch bands and bracelets, the present invention greatly contributes to expansion of uses of titanium metal and diversification of products.

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Claims (1)

[Claims] 1. A rolled material of a titanium alloy containing 70% or more metallic titanium in an α / β phase or a β phase is subjected to machining such as cutting and bending to obtain a molded product formed into an outer shape of a target product. A first age hardening treatment for increasing the material hardness to HRC 30 ° or more by maintaining the molded product at a temperature of 350 ° C. to 600 ° C. for a certain time in an atmosphere, a vacuum or an inert gas atmosphere; The processed molded product is subjected to finishing such as grinding and polishing, if necessary, and heated to 1000 ° C. to 1400 ° C. in a vacuum furnace to precipitate titanium crystals on the surface of the molded product. Crystal precipitation treatment, In the process of allowing the molded product after the crystal precipitation treatment to cool in air, vacuum, or an inert gas atmosphere,
By maintaining the temperature at 350 ° C. to 600 ° C. for a certain period of time, while strengthening the precipitation density of titanium crystals on the surface of the molded product, a secondary aging hardening treatment for increasing the material hardness of the molded product to HRC 35 ° C. or more is performed. A titanium product with a screw-like surface, which is applied sequentially in the order described in.