JP6690288B2 - Titanium-encapsulating structure and method for producing titanium multilayer material - Google Patents

Description

The present invention relates to a titanium-containing structure and a method for producing a titanium multilayer material .

  Titanium material is a metal material having excellent corrosion resistance, and is therefore used in heat exchangers using seawater and various chemical plants. Further, since it has a smaller density than carbon steel and is superior in specific strength (strength per unit weight), it is often used in aircraft fuselages. Further, if titanium materials are used for land transportation equipment such as automobiles, the weight of the land transportation equipment can be reduced and fuel consumption can be expected to be improved.

  However, since the Young's modulus of the titanium material is smaller than that of the steel material, the titanium material is easily bent (the rigidity is low). Therefore, in order to ensure rigidity, the thickness is increased, which increases the weight and reduces the characteristic of excellent specific strength. Further, if the weight increases, the manufacturing cost also increases, which is not preferable.

  In order to improve the rigidity of the metal plate without increasing the weight so much, a method is known in which the inside of the metal plate is made into a void (a void is provided).

  For example, in Patent Document 1, industrial pure Ti or Ti alloy is used as a base material, and heating / bonding is performed at a β transformation point or at a temperature in a β transformation point range or more, so that a line between the laminated base materials is formed. A titanium honeycomb structure that is spread after being diffusion-bonded in a circular shape is disclosed. In Patent Document 2, a metal brazing powder, a foaming agent powder, and a flux are sandwiched between Al alloy skins and heated to generate a foaming ratio of 30 to 50. Disclosed is a lightweight, high-rigidity panel having voids inside by foaming the blowing agent in%. Further, Patent Document 3 discloses a method for producing a porous titanium thin film in which a paste composition containing titanium powder, a binder component, and a solvent component is formed into a film, the solvent component is volatilized, and the binder is removed, followed by sintering. Has been done.

  On the other hand, Patent Document 4 discloses a titanium ingot manufactured by omitting the melting step. This titanium ingot (slab) is manufactured by forming porous titanium (sponge titanium) into an ingot and briquetting it, and irradiating the surface of the briquette with an electron beam under vacuum to melt it. It is made of titanium and its entire surface is covered with dense titanium.

Patent No. 3597684 JP, 2004-225086, A Japanese Unexamined Patent Application Publication No. 2014-065968 JP, 2005-45040, A

  The honeycomb structure and the foam metal disclosed in Patent Documents 1 to 3 can certainly improve the rigidity while maintaining the light weight, but the manufacturing process is complicated because the wrought material (thin plate) or powder is used. Therefore, there are problems that the manufacturing cost is increased and that the flux and the like remain inside the plate to adversely affect the characteristics of the product.

  In the invention disclosed by Patent Document 4, titanium in the surface layer portion is a coarse solidified structure because it is manufactured on the premise of an ingot, and an interface between the dense and dense titanium melted in the surface layer and titanium sponge inside, The bond strength between titanium sponge inside is very low or not bonded. For this reason, the product properties such as tensile properties and bending are significantly inferior, and they cannot be used as they are.

  The surface of the titanium ingot disclosed in Patent Document 4 has a rough casting structure (coarse crystal grains) because it is once melted and solidified by being irradiated with an electron beam. Therefore, during hot working such as rolling, forging or extrusion in the next step, the coarse cast structure (coarse crystal grains) of the surface layer of the titanium ingot is caused by the strong plastic anisotropy due to the difference in crystal orientation. Unevenness occurs on the surface, and a large number of heavier surface defects occur.

  Further, since a part of the surface of the ingot-shaped porous titanium is sequentially melted and solidified, the surface of the obtained titanium ingot is locally expanded due to thermal expansion around the melted portion or contraction when the melted portion is solidified. Residual stress is generated, and surface cracks are likely to occur.

  When large cracks occur, air penetrates through dense titanium and flows into the titanium ingot, and porous titanium inside the titanium ingot oxidizes during heating before hot working, so hot working cannot be performed.

  Even a small crack that does not penetrate will expand during the hot rolling such as rolling, forging or extrusion in the next step, or become a cover-like surface defect, and many surface defects occur in the product.

  Further, by hot rolling this titanium ingot at a rolling ratio of 70% or more, it is possible to crimp the vacuum voids existing in the titanium sponge inside, and to manufacture a titanium plate that is dense inside. However, the titanium plate thus obtained is the same as the titanium plate manufactured through the usual melting process, and the rigidity cannot be secured unless the plate thickness is increased.

  The present invention has been made in view of such circumstances, and provides a titanium material, in particular, a lightweight and highly rigid titanium material having voids inside, and a method for efficiently manufacturing the titanium material at low cost. The purpose is to

  As a result of repeated intensive studies to solve the above problems, the present inventors omit the usual melting step and forging step, use titanium sponge as it is, and perform direct processing (hot rolling etc.), It has been found that by manufacturing a titanium plate, a lightweight and rigid titanium multilayer material can be manufactured while greatly simplifying the manufacturing process.

  As a raw material to be used, amorphous and massive sponge titanium is used. Since the lump-shaped titanium sponge is manufactured by the conventional process, it can be obtained relatively inexpensively. Further, since the main impurities (oxygen etc.) are removed in the smelting process, there is no problem in chemical composition even if the titanium material is directly produced from titanium sponge.

  A briquette shape made by compression-molding titanium sponge (hereinafter referred to as "titanium briquette"), or a titanium material such as a scrap that does not become a product (hereinafter referred to as "titanium scrap") is relatively inexpensive. Available at. However, since these materials are amorphous, they cannot be processed directly.

  The present inventors have found a sealed titanium-containing structure in which a container made of an industrial pure titanium wrought material (hereinafter referred to as “packing material”) contains a filler such as sponge titanium. . With the titanium-encapsulated structure having such a structure, it is possible to suppress the occurrence of surface defects such as surface cracks and whiskers during hot working.

  In particular, by making the chemical composition of the filler the same type as the industrial pure titanium wrought material, it is not necessary to peel off the cover material after rolling like the conventional pack rolling and discard it, and the packaging material is processed. After that, it can be used as it is as a part of the titanium multilayer material (product).

  Further, the inventors of the present invention prevent the filler such as titanium sponge from being oxidized when heated before hot working, and exist between the fillers or between the filler and the packing material during hot working. It was also found that it is important to reduce the internal pressure of the packaging material as much as possible so that the voids can be easily reduced.

  Furthermore, the present inventors need to increase the internal porosity in order to reduce the weight of the titanium multilayer material. Therefore, when the titanium-containing structure is hot-worked or cold-worked, In order to prevent the peeling of the boundary between the surface layer (original titanium wrought material) and the inside (original titanium sponge or titanium scrap) of the processed titanium multi-layer plate after processing, it is important to apply pressure after processing. It was found that it is important to heat while adding.

  The present invention has been completed based on these novel findings, and is as listed below.

(1) It has a chemical composition belonging to JIS 1 to 4 types, a compression molded body is provided inside, and a titanium wrought material is provided on the surface layer.
The compression-molded body is a titanium multilayer material, which comprises one or more kinds selected from titanium sponge and titanium scrap, and has a porosity of more than 30% and 60% or less.

(2) A titanium-containing structure including a packing material made of an industrial pure titanium wrought material and a packing material filled inside the packing material.
The internal pressure of the packaging material is 10 Pa or less in absolute pressure,
The compression processing of the titanium multilayer material according to item 1, wherein the filler is composed of one or more kinds selected from titanium sponge and titanium scrap, and has the same chemical composition as the industrial pure titanium wrought material. Material.

  (3) A packing material made of an industrial pure titanium wrought material and a packing material filled inside the packing material, the internal pressure of the packing material is 10 Pa or less in absolute pressure, and the packing material is After compressing a titanium-containing structure that is composed of one or more selected from titanium sponge and titanium scrap and has the same chemical composition as the industrial pure titanium wrought material, pressure is applied in the thickness direction. The titanium multi-layer material as described in 1 above, which is obtained by heat treatment.

  (4) A packing material made of an industrial pure titanium wrought material and a packing material filled inside the packing material, wherein the packing material has an internal pressure of 10 Pa or less in absolute pressure, and the packing material is The titanium multi-layer according to item 1, which is composed of at least one selected from titanium sponge and titanium scrap, and which is compression-processed into a titanium-containing structure having the same chemical composition as the industrial pure titanium wrought material. Method of manufacturing wood.

  (5) The method for producing a titanium multilayer material according to item 4, wherein after the compression processing, heat treatment is performed while applying pressure in the thickness direction.

  According to the present invention, since the surface layer is made of titanium wrought material and the inside is made of sponge titanium with many voids, it is possible to obtain a titanium multilayer material which is lightweight, has high rigidity, and is inexpensive.

  Further, according to the present invention, by using the titanium-containing structure, it is possible to perform the processing by omitting the conventional melting step and forging step, and to manufacture the titanium multilayer material according to the present invention. Therefore, the energy (electric power, gas, etc.) required for manufacturing these can be significantly reduced.

  Further, according to the present invention, a large amount of titanium material is removed by cutting, such as cutting and removing many defective portions on the surface layer and bottom surface of a titanium ingot, and removing surface cracks and bad front and rear ends (crops) after forging. Since the titanium multilayer material according to the present invention can be manufactured without cutting or removing, the manufacturing yield is significantly improved. Therefore, according to the present invention, the manufacturing cost of the titanium multilayer material can be significantly reduced.

FIG. 1 is an explanatory view schematically showing the structure of a titanium multilayer plate according to the present invention. FIG. 2 is an explanatory view schematically showing the structure of the titanium-containing structure according to the present invention.

  Hereinafter, the titanium-containing structure and the titanium multilayer material according to the present invention will be described. In the following description, the case where the titanium multi-layer material according to the present invention is a titanium multi-layer plate will be mainly taken as an example, but the present invention is not limited to the titanium multi-layer plate, and the titanium multi-layer pipe or the titanium multi-layer plate. The same applies to layer bars and the like. Further, in the following description, “%” regarding the chemical composition means “mass%” unless otherwise specified.

1. Overall Structure FIG. 1 is an explanatory view schematically showing the structure of a titanium multilayer plate 10 according to the present invention, and FIG. 2 is an explanatory view schematically showing the structure of a titanium-containing structure 1 according to the present invention. is there.

  The titanium-containing structure 1 as a material of the titanium multilayer plate 10 according to the present invention has a vacuum inside the titanium packing material 2 and contains titanium sponge.

  As shown in FIG. 2, a titanium-containing structure 1 according to the present invention is a titanium material including a packing material 2 formed of a pure titanium material and a packing material 3 filled in the packing material 2. The packing material 2 has an internal pressure of 10 Pa or less, the filler 3 is composed of one or more kinds selected from titanium sponge, titanium briquette and titanium scrap, and has the same chemical composition as the pure titanium material of the packing material 2. It is a processing material that we have.

2. Filling material 3
First, the filler 3 will be described.

(2-1) Size When sponge titanium is used as the filler 3, a filler manufactured by a conventional smelting process such as the Kroll method can be used. The sponge titanium obtained in this smelting step is usually a large lump of several tons, so it is desirable to crush it into particles having an average particle size of 30 mm or less, as in the conventional step.

  The size of the particles of the filling material 3 must be smaller than the size of the internal space of the packing material 2. The packing material 2 may be directly packed in the packing material 2, but in order to make it more efficient, it may be a molded body (titanium briquette) in which sponge titanium is compression-molded in advance. In particular, when obtaining the titanium multilayer plate 10 having a small porosity, it is desirable to fill the inside of the packing material 2 with a titanium briquette as a filling material.

  It is desirable to perform compression molding so that the porosity of the titanium briquette exceeds 30% and is 60% or less. When the porosity of the titanium briquette is 30% or less, the desired properties cannot be obtained because the porosity of the obtained titanium multilayer plate 10 is also 30% or less. Furthermore, in order to join the filler (titanium briquette) 3 and the packing material 2 by the hot working and heat treatment in the post process, it is desirable that the porosity of the titanium briquette is 40% or more. On the other hand, when the porosity of the titanium briquette exceeds 60%, the strength of the titanium briquette is small and the brittleness becomes brittle, so that it is difficult to maintain its shape.

  It is desirable that the filler 3 has an average particle size of 1 mm or more and 30 mm or less. If the average particle size is less than 1 mm, it takes time to crush and a large amount of fine dust is scattered, resulting in poor manufacturing efficiency. On the other hand, when the average particle size is larger than 30 mm, the size and distribution of the voids in the titanium multilayer plate 10 become uneven.

(2-2) Chemical Composition The filler 3 needs to have the same chemical composition as the packaging material 2, that is, the pure titanium material. For example, the chemical composition corresponds to JIS type 1, JIS type 2, JIS type 3 or JIS type 4. Here, having the same kind of chemical composition means specifically belonging to the same JIS standard. For example, when the chemical composition of the packing material 2 belongs to JIS type 1, the packing material also has a chemical composition belonging to JIS type 1. In this way, by setting the chemical composition of the filler 3 to be the same as that of the pure titanium material, the surface layer and the inside of the processed titanium multilayer plate 10 can be made to have the same chemical composition, and as it is. It can be treated as industrial pure titanium.

The JIS class 1 means oxygen: 0.15% or less, iron: 0.20% or less, nitrogen: 0.03% or less, carbon: 0.08% or less, hydrogen: 0.013% or less,
JIS type 2 means oxygen: 0.20% or less, iron: 0.25% or less, nitrogen: 0.03% or less, carbon: 0.08% or less, hydrogen: 0.013% or less,
JIS class 3 means oxygen: 0.30% or less, iron: 0.30% or less, nitrogen: 0.05% or less, carbon: 0.08% or less, hydrogen: 0.013% or less,
JIS 4 type is oxygen: 0.40% or less, iron: 0.50% or less, nitrogen: 0.05% or less, carbon: 0.08% or less, hydrogen: 0.013% or less.

  Next, a titanium scrap that can be used as the filler 3 will be described.

  Titanium scrap is used as a product such as a scrap material that does not become a product generated in the manufacturing process of industrial pure titanium material, titanium chips generated when cutting and grinding to make the industrial pure titanium material into a product shape. It is a pure titanium material for industrial use that is no longer needed.

  It is desirable that the size of the titanium scrap be cut or crushed so that the average particle size is the same as that of titanium sponge and is 1 mm or more and 30 mm or less. If the average particle size is less than 1 mm, it takes time to cut or crush, and many fine dust particles are scattered, resulting in poor production efficiency. On the other hand, when the average particle diameter is larger than 30 mm, the size and distribution of the voids in the titanium multilayer plate 10 become uneven.

  Titanium scrap may be packed in the packing material 2 as it is, but titanium chips or the like having a low bulk specific gravity should be mixed in advance with titanium sponge in order to be packed more efficiently or more. The packing material 2 may be filled as a molded body that is compression molded or compression molded only with titanium scrap. As in the case of titanium sponge alone, it is desirable to perform compression molding so that the porosity of the titanium scrap compact exceeds 30% and 60% or less.

3. Packing material 2
Next, the pure titanium material forming the packing material 2 will be described.

  Examples of pure titanium materials include titanium wrought materials. The titanium wrought material is a titanium plate or a titanium tube produced by hot or cold plastic working such as rolling, extrusion, drawing, or forging. Since the industrial pure titanium wrought material is plastically worked, it has the advantage of having a smooth surface and a fine structure (small crystal grains).

(3-1) Thickness When the packaging material 2 is a rectangular parallelepiped, the thickness of the pure titanium material is preferably 0.5 mm or more, although it depends on the size of the packaging material 2 to be manufactured. As the packing material 2 is larger, the strength and rigidity are required, so a thicker pure titanium material is used.

  If the thickness of the pure titanium material is less than 0.5 mm, the packaging material 2 may be deformed at the time of heating before hot working or may be broken at the beginning of hot working, which is not preferable. There is no particular upper limit on the thickness of the pure titanium material, and it is determined by the desired thickness of the titanium multilayer plate 10.

  Further, the thickness of the pure titanium material is preferably 3% or more and 40% or less of the thickness of the titanium-containing structure 1. If the thickness of the pure titanium material is less than 3% of the thickness of the titanium-containing structure 1, it becomes difficult to hold the filler, and the filler is largely deformed during heating before hot working, and the welded portion of the packaging material 2 is It breaks. On the other hand, if the thickness of the pure titanium material is more than 40% of the thickness of the titanium-containing structure, there is no particular problem in manufacturing, but the proportion of the pure titanium material in the thickness of the titanium-containing structure 1 is large. Since the filling amount of the filler 3 is reduced, the light weight effect of the obtained titanium multilayer plate 10 is reduced.

  The same applies to the case where the packing material 2 is a tube, and the thickness of the pure titanium material is preferably 0.5 mm or more, although it varies depending on the size of the packing material 2 to be manufactured. Furthermore, as in the case of the rectangular parallelepiped, the thickness of the pure titanium material is preferably 3% or more and 40% or less of the diameter of the titanium-containing structure 1.

(3-2) Component The packaging material 2 needs to have the same chemical composition as the filler 3, as described above.

(3-3) Size of Crystal Grain The crystal grain of the pure titanium material can be adjusted by subjecting it to appropriate plastic working and heat treatment. The average crystal grain size of the pure titanium material used for the packing material 2 is 500 μm or less in terms of circle equivalent diameter. As a result, it is possible to suppress the occurrence of surface defects due to the difference in crystal orientation of coarse crystals that occurs when the titanium-containing structure 1 is hot-worked.

  The lower limit of the average crystal grain size of the pure titanium material used for the packing material 2 is not particularly specified, but in order to make the crystal grain size extremely small in the case of industrial pure titanium, increase the processing ratio during plastic working. Therefore, the thickness of the pure titanium material that can be used as a packaging material is limited. Therefore, the average crystal grain size of the pure titanium material used for the packing material 2 is preferably 10 μm or more, and more preferably 15 μm. The crystal grains of interest here are α-phase crystal grains that account for the majority of industrial pure titanium.

  The average crystal grain size is calculated as follows. That is, the structure of the cross section of the pure titanium material was observed with an optical microscope and photographed, and from the structure photograph, the average crystal grain size of the surface layer of the pure titanium material was determined by a cutting method according to JIS G 0551 (2005). Ask.

4. Titanium inclusion structure 1
Next, the titanium-containing structure 1 will be described.

(4-1) Shape The shape of the titanium-containing structure 1 is not particularly limited, but is determined by the shape of the manufactured multilayer titanium plate 10. When manufacturing a titanium thin plate or a titanium thick plate, the titanium-containing structure 1 has a rectangular parallelepiped shape (slab). The thickness, width and length of the titanium-containing structure 1 are determined by the thickness, width and length of the product, the production amount (weight), and the like.

  When manufacturing a titanium round bar, a wire rod, or an extruded shape member, the titanium-containing structure 1 has a polygonal columnar shape (billet) such as a columnar shape or an octagonal column. The size (diameter, length) is determined by the size, thickness, width and length of the product, the production amount (weight), and the like.

(4-2) Inside The inside of the titanium-containing structure 1 is filled with a filler 3 such as titanium sponge. Since the filler 3 is a lumpy grain, there is a void 4 between the grains. When air is present in the voids 4, the filler 3 is oxidized or nitrided when heated before hot working, and the titanium multilayer plate 10 obtained by the subsequent working becomes brittle, which is necessary. It becomes impossible to obtain good material properties. Further, when an inert gas such as Ar gas is filled, oxidation or nitridation of titanium sponge can be suppressed. However, during heating, the Ar gas thermally expands, spreads the packing material 2, and the titanium-containing structure 1 is deformed, which makes hot working impossible.

From the above, the voids 4 between the particles of the filler 3 should be decompressed as much as possible. Specifically, the internal pressure of the packaging material 2 (pressure in the void 4) is 10 Pa or less, preferably 1 Pa or less. When the internal pressure of the packing material 2 is larger than 10 Pa, the filler 3 is oxidized or nitrided by the remaining air. The lower limit of the internal pressure of the packing material 2 is not particularly limited. However, in order to reduce the internal pressure to an extremely low level, the manufacturing cost is increased by increasing the airtightness of the device or increasing the vacuum exhaust equipment. Therefore, the lower limit of the internal pressure of the packaging material 2 is 1 × 10 ⁻³ Pa. It is desirable to do.

(4-3) Decompression Method Next, a method of decompressing the inside of the packaging material 2 to maintain a vacuum will be described.

  After the packing material 2 is filled with the packing material 2, the packing material 2 is depressurized to a predetermined internal pressure or less and hermetically sealed. Alternatively, the packing materials 2, which are pure titanium materials, may be partially joined together, and then the pressure may be reduced and sealed. By hermetically sealing, air does not enter and the filler 3 inside is not oxidized during heating before hot working.

  The sealing method is not particularly limited, but it is preferable to weld and seal the packing materials 2 that are pure titanium materials. In this case, at the welding position, all the seams of the pure titanium material are welded to form the welded portion 5, that is, the entire circumference welding is performed. The method of welding the pure titanium material may be arc welding such as TIG welding or MIG welding, electron beam welding or laser welding, and is not particularly limited.

  Welding is performed in a vacuum atmosphere or an inert gas atmosphere so that the inner surfaces of the filler 3 and the packing material 2 are not oxidized or nitrided. When the joint of the packing material 2 which is a pure titanium material is to be welded last, it is desirable to put the packing material 2 in a container (chamber) in a vacuum atmosphere and perform welding to keep the inside of the packing material 2 in a vacuum.

  In addition, by providing piping in part of the packing material 2 in advance and welding the entire circumference in an inert gas atmosphere, the pressure is reduced to a predetermined internal pressure through the piping, and the piping is sealed by crimping or the like. The inside of 2 may be evacuated. In this case, it is desirable that the pipe is installed at a position that does not cause a problem during the hot working in the subsequent process, for example, at the rear end face.

5. Titanium multilayer board 10
(5-1) Overall Configuration Next, the titanium multilayer plate 10 will be described.

  The titanium multilayer board 10 according to the present invention has a chemical composition belonging to JIS type 1, JIS type 2, JIS type 3 or JIS type 4, has a compression molded body 11 inside, and has a titanium wrought material 12 on the surface layer.

  The compression molded body 11 is made of one or more kinds selected from titanium sponge and titanium scrap, and has a porosity of more than 30% and 60% or less. Specifically, the titanium multilayer plate 10 according to the present invention is industrial pure titanium obtained by heating the titanium-containing structure 1 and then hot working or further cold working.

  The titanium multilayer plate 10 has two structures of an outer layer which is the packing material 2 and an inner layer which is the filling material 3 in the titanium-containing structure 1 before processing. Hereinafter, the inside of the titanium multilayer plate 10 means this inner layer.

  As described above, since the packing material 2 and the filling material 3 have the same chemical composition, the titanium multilayer plate 10 has the same chemical composition in the outer layer and the inner layer. Specifically, it has a chemical composition belonging to JIS 1 to 4.

(5-2) Porosity The voids 4 existing inside the titanium-containing structure 1 are reduced by hot working or cold working of the titanium-containing structure 1, but are left in a predetermined amount. That is, the porosity is more than 30% and 60% or less. When the porosity is less than 30%, the bulk specific gravity of the titanium multilayer plate 10 increases and the weight increases, so that it is not possible to reduce the weight of the titanium multilayer plate 10. On the other hand, if the porosity exceeds 60%, the strength of the inside of the titanium multilayer plate 10 (the part that was the filler 3 before hot working) is low, so that the titanium multilayer plate 10 is not subjected to bending or the like. When processed, the inside of the titanium multilayer plate 10 collapses and the shape cannot be maintained. That is, in order to obtain a lightweight titanium material that can secure rigidity, strength, and ductility that can be used as a product, the titanium multilayer plate 10 has voids with a volume ratio of more than 30% and 60% or less.

  The ratio of voids remaining inside the titanium multilayer plate 10 (void ratio) is calculated as follows. The titanium multilayer plate 10 is cut so that the internal cross section of the titanium multilayer plate 10 can be observed, and the observation surface of the cross section is polished to give a mirror finish with an average surface roughness Ra of 0.2 μm or less. , Prepare an observation sample. During polishing, diamond or alumina suspension is used.

  The observation sample that has been mirror-finished is photographed with an optical microscope at 20 different central portions. Here, the central portion is the center of the plate thickness in the case of the titanium multilayer plate 10 and the center of the circular cross section in the case of the titanium multilayer round bar. The area ratio of the voids observed by the optical micrograph is measured, and the result of averaging the values of the void ratios of the 20 photographs is calculated as the void ratio.

  When taking a photograph with an optical microscope, an appropriate magnification is selected according to the size and the porosity of the titanium multilayer plate 10. Since the titanium multilayer plate 10 according to the present invention has a large porosity of more than 30%, it is desirable to observe and photograph at a low magnification of about 10 to 20 times.

  The reason why the voids are generated inside the titanium multilayer plate 10 is that the voids 4 are formed between the sponge titanium particles of the filler 3 and titanium scrap pieces, or between the filler 3 and the packing material 2. It is a void. The voids formed in the titanium-containing structure 1 become smaller by hot working and subsequent cold working, but the working rate at the time of hot working or cold working of the titanium containing structure 1 is appropriately set. As a result, the porosity is set to more than 30% and 60% or less.

(5-3) Hot Working Method The titanium multilayer plate (product) 10 is formed by subjecting the titanium-containing structure 1 to hot working. The method of hot working differs depending on the shape of the titanium multilayer material. When manufacturing the titanium multilayer plate 10, the rectangular parallelepiped (slab) titanium-containing structure 1 is heated and hot-rolled to obtain the titanium multilayer plate 10. If necessary, as in the conventional process, the oxide layer may be removed by pickling or the like, followed by cold rolling to further reduce the thickness.

  When manufacturing titanium multi-layer rods and titanium multi-layer wire rods, the titanium inclusion structure in the shape of a cylinder or polygonal column is heated and hot-forged, hot-rolled or hot-extruded. Use rods and titanium multi-layer wire rods. If necessary, as in the conventional process, the oxide layer may be removed by pickling or the like, and then cold rolling or the like may be performed to further reduce the thickness.

  In the case of producing a titanium multi-layer extruded shape material, a titanium-containing structure in the shape of a cylinder or a polygonal pillar is heated and hot extruded to obtain titanium shape materials having various cross-sectional shapes.

(5-4) Heating Temperature The heating temperature before hot working is 600 ° C. or more and 1200 ° C. or less, although it depends on the size of the titanium-containing structure 1 and the working rate of hot working. If the heating temperature is less than 600 ° C., the high temperature strength of the titanium-containing structure 1 is high and a sufficient processing rate cannot be imparted. On the other hand, when the heating temperature is higher than 1200 ° C., the structure of the obtained titanium multilayer plate 10 becomes coarse and sufficient material properties cannot be obtained, and the outer surface of the titanium-containing structure 1 is oxidized, resulting in a thick structure. Scale is generated, the titanium-containing structure 1 is thinned, and perforation may occur in some cases, which is not preferable.

(5-5) Working ratio Degree of working during hot working or cold working, that is, working ratio (the difference between the cross-sectional area before working and the cross-sectional area of the titanium multilayer material 10 after working is determined by cutting before working. The ratio divided by the area) is adjusted according to the required characteristics of the titanium multilayer material 10. Depending on the processing rate of the titanium-containing structure 1, the void ratio inside the titanium multilayer material 10 (portion derived from the filler 3) can be adjusted.

  When large processing (processing for greatly reducing the cross-sectional area of the titanium-containing structure 1) is applied, voids are almost eliminated, and tensile properties similar to those of the titanium multilayer material manufactured by a normal manufacturing method can be applied. On the other hand, with small processing, many voids are left inside the titanium multi-layer material, and a lightweight titanium material can be obtained accordingly.

  It is desirable that the combined working ratio (reduction ratio) of hot working and cold working be 10% or more. The reason for this is that if the processing rate is less than 10%, the packing material 2 and the packing material 3 are not in close contact with each other over the entire surface, so that the surface layer of the titanium multilayer plate 10 (original packing The joining of the material 2) and the inside (original filler 3) is not sufficient. The upper limit of the rolling reduction is determined by the thickness of the titanium-containing structure 1, the thickness of the titanium multilayer plate 10, and the porosity. If the processing rate is too large, the porosity cannot be increased to 30% or more.

(5-6) Heat Treatment When hot working the titanium-containing structure 1, if the working rate is large (a rolling reduction of 35% or more), the packing material (titanium wrought material) 2 is in contact with the filler (titanium sponge or titanium). Since the scrap 3 is sufficiently processed and pressed against the packing material 2 with a high pressure, the boundary portion between the surface layer (original packing material 2) and the inside (original packing material 3) of the titanium multilayer plate 10 is firm. To be joined to. For this reason, it is not necessary to subject the titanium multilayer plate 10 after hot working to a heat treatment for increasing the bonding strength between the boundary between the surface layer and the inside. If necessary, the usual annealing may be performed.

  On the other hand, when the processing rate is small (reduction rate is less than 35%), the bonding strength at the boundary between the surface layer (original packing material 2) and the inside (original filler material 3) of the titanium multilayer plate 10 after processing is not sufficient. Absent. In order to prevent peeling of the titanium multilayer plate 10, it is necessary to perform a heat treatment of heating while applying pressure in the plate thickness direction after processing. By this heat treatment, the boundary between the surface layer and the inside of the titanium multilayer plate 10 is integrated and firmly joined.

The heat treatment method is a method in which the processed titanium multilayer plate 10 is charged into a heating furnace, and a weight is placed on the titanium multilayer plate 10 to heat it (weight system), and the titanium multilayer plate 10 is a thin metal plate. The method of charging the inside of the capsule , decompressing the inside of the capsule to a vacuum , enclosing, and then charging in a heating furnace (metal thin plate method), covering the titanium multilayer plate 10 with a heat source and a plastic heat insulating material. , There is a method (sheet method) of sealing with a non-breathable sheet and heating the inside after reducing the pressure to a vacuum.

  The heating temperature is 650 ° C. or higher and 900 ° C. or lower. If the heating temperature is lower than 650 ° C., the surface layer and the inside of the titanium multilayer plate 10 cannot be sufficiently joined. When the heating temperature is higher than 900 ° C., the structure of the surface layer of the titanium multilayer plate 10 becomes coarse, and the strength and elongation of the titanium multilayer plate 10 decrease.

In the case of the weight method, the weight used is a material that can withstand the above heating temperature, and is a metal such as steel, copper, nickel, molybdenum, or tungsten, or a ceramic such as alumina or zirconia. Weight of the weight is preferably in the load per unit area is 0.3 kg / cm ² or more 3 kg / cm ² or less. If the weight of the weight is less than 0.3 kg / cm ² , the surface layer and the inside of the titanium multilayer plate 10 cannot be sufficiently joined. On the other hand, when the weight of the weight is more than 3 kg / cm ² , the titanium multilayer material 10 is deformed, which is not preferable.

  In the case of the metal thin plate method, a metal thin plate such as carbon steel, stainless steel, or nickel that can withstand the above heating temperature is used. The thickness of the metal plate is preferably 0.1 mm or more and 1 mm or less. If the thickness of the metal thin plate is less than 0.1 mm, the strength becomes small, and therefore the metal sheet is easily damaged when it is taken in and out of the heating furnace. On the other hand, if the thickness of the metal thin plate is larger than 1 mm, the strength is increased and it is difficult to process the titanium multi-layer plate when it is sealed, which is not preferable.

The titanium multilayer plate 10 is placed in a metal thin plate capsule, and the inside of the capsule is depressurized to 10 Pa or less and sealed . As a result, a pressure of about 1.0 kg / cm ² is applied to the titanium multilayer plate 10 with a load per unit area. When the internal pressure is higher than 10 Pa, the remaining air causes the titanium multilayer plate 10 to be oxidized or nitrided. The lower limit of the internal pressure is not particularly limited, but in order to make the internal pressure extremely small, it is necessary to improve the airtightness of the device or to enhance the vacuum exhaust equipment, which increases the manufacturing cost. It is desirable to set it to 1 × 10 ⁻³ Pa.

In the case of the sheet type, as the heat insulating material, refractory ceramic particles made of plastic alumina, silica, zirconia, or the like or fibrous refractory sheet is used. By covering the titanium multi-layer plate 10 and the heat source such as an electric heater with a heat insulating material, the temperature of the outer periphery can be suppressed to about 100 ° C. or less. Therefore, a plastic film such as polyester or polycarbonate should be used for the non-breathable sheet. You can use it. The depressurization inside is the same as the case of encapsulating with the above-mentioned metal thin plate capsule .

  The present invention will be described more specifically with reference to Examples.

  The titanium-containing structure 1 shown in Table 1 was manufactured, and the titanium-containing multilayer structure 10 shown in Table 1 was manufactured on the titanium-containing structure by the manufacturing process shown in Table 1.

  Titanium sponge used as the filler 3 is titanium sponge (particle size = 0.25 mm or more and 19 mm or less) produced by the Kroll method, and titanium sponge A (sample No. 19) has a chemical component equivalent to JIS Class 1 sponge. Titanium B (Sample Nos. 1-18, 22, 24, 25) has a chemical component equivalent to JIS type 2, and Sponge Titanium C (sample No. 20) has a chemical component equivalent to JIS type 3 sponge titanium. As D (Sample No. 21), those having chemical components corresponding to JIS 4 types were used.

  In addition, as titanium scrap, JIS type 2 (oxygen content 0.06%, iron content 0.05%, nitrogen content 0.002%, carbon content 0.003%, hydrogen content 0.028%) can be used. The thin plate cut into 10 to 20 mm square was used in part (Sample Nos. 22 and 23).

  Furthermore, in some (Sample Nos. 24 and 25), sponge titanium B was compression-molded and filled in the packing material 2 as a titanium briquette having a porosity of 40%.

  As a material of the packing material 2, the industrial pure titanium wrought material is JIS type 1 (TP270H) (sample No. 19), JIS type 2 (TP340H) (samples No. 1 to 18, 22, 24, 25), JIS type 3 (TP480H) (Sample No. 20) and JIS4 type (TP550H) (Sample No. 21) pickled thick plates were used. The cross-sectional structures of these thick plates were observed in advance with an optical microscope, and the average crystal grain size of the α phase of the surface layer of the thick plates was determined by the cutting method based on JIS G 0551 (2005). The results were all in the range of 17 μm or more and 30 μm or less, and were confirmed to be fine.

  Five pieces of industrial pure titanium materials were temporarily assembled, and titanium sponge, titanium scrap, and titanium briquette were filled therein, and the lid was covered with the remaining titanium packing material 2 which was pure titanium expanded material for industrial use.

In this state, it was placed in a vacuum chamber and depressurized (vacuum) to a predetermined pressure, and then the seam of the packaging material 2 was welded with an electron beam around the entire circumference. The pressure in the chamber at this time was 1.2 × 10 ^{−2 to} 9.4 × 10 ⁻² Pa.

In some titanium-encapsulated structures 1 (Sample Nos. 5, 16, and 18), an industrial pure titanium wrought titanium packing material in which a titanium tube having a hole of the center of the titanium packing material 2 and a titanium pipe having an inner diameter of 6 mm is TIG-welded. 2 is prepared, and the titanium enclosing structure 1 is temporarily assembled so that the industrial pure titanium wrought titanium packing material 2 becomes the rear end face during rolling, and then the titanium packing structure 1 is packed in an Ar gas atmosphere. The seam of material 2 was TIG welded all around. After that, through the titanium pipe, the inside of the titanium packing material 2 is depressurized to a predetermined vacuum degree pressure (9.2 × 10 ^{−2 to} 80 Pa), and after the depressurization, the titanium pipe is pressure-bonded to the inside of the titanium packing material 2. The vacuum pressure was maintained.

As described above, titanium-containing structures 1 to 25 were prepared by filling the inside with titanium sponge or titanium scrap and having an atmosphere of vacuum (vacuum degree of 1.2 × 10 ^{−2 to} 80 Pa).

  The produced titanium-containing structures 1 to 25 were heated to 820 to 900 ° C. in an air atmosphere and then hot-rolled at a working rate (reduction rate) of 7 to 54% to produce titanium multilayer plates 1 to 25. .

  A part of the obtained titanium multilayer material (Sample No. 4, 8, 12, 15, 16, 22, 23) was evaluated as it was.

In addition, another part of the obtained titanium multilayer material (Sample Nos. 13, 14, 17, 18, 24, 25) is a weight method in which a weight is placed on a titanium multilayer plate and heated by Ar. Heat treatment was performed at 750 ° C. using an atmosphere heating furnace. A weight made of a stainless (SUS304) block was placed on the entire upper surface of the titanium multilayer material so that a load of 0.9 kg / cm ² was applied, and heating was performed.

The remaining titanium multi-layer material (No. 1-3, 5-7, 9-11, 19-21) is placed in a capsule of a thin metal plate , the inside of the capsule is depressurized to a vacuum, and the capsule is heated. The heat treatment was performed by a thin metal plate method in which the material was charged into a furnace and heated. As a thin metal plate, stainless steel (SUS304) having a thickness of 0.3 mm was used. After a titanium multi-layer material was put inside, the inside was depressurized to 5 × 10 ⁻² Pa and sealed. The sealed body containing the titanium multilayer material was placed in a heating furnace in the air atmosphere and heated to 700 ° C to 850 ° C.

  The titanium multilayer material after the heat treatment was cut along the thickness direction together with the titanium multilayer material that was not heat treated, and the cross section was observed and evaluated.

  The results are summarized in Table 1. The underline in Table 1 indicates that it is outside the scope of the present invention.

  Sample No. in Table 1 Sample Nos. 1, 2, 7, 9 to 24 are examples of the present invention that satisfy all the conditions of the present invention. 3 to 6, 8 and 25 are comparative examples which do not satisfy the conditions of the present invention.

  Sample No. 1, 2, 7, 9 to 24 have porosity of 31 to 59%, which satisfies the range of the present invention, and the titanium multilayer material 10 having a light weight and a high rigidity was obtained.

  In particular, the sample No. In Nos. 12, 15, 16, 22, and 23, the reduction ratio of hot rolling is as large as 38% to 54%, so that the surface layer and the inside are sufficiently satisfactorily processed by hot working without heat treatment after hot working. A good joined titanium multilayer board 10 is obtained.

  In addition, Sample No. 1 using a titanium-containing structure filled with sponge titanium, titanium scrap, or titanium briquette. Nos. 22 to 24 are subjected to hot working with a working rate of 12 to 54%, and when the working rate is small (less than 35%), heat treatment is performed thereafter to obtain a good titanium multilayer material 10 without peeling.

  On the other hand, the sample No. In No. 3, since the porosity inside the titanium multilayer material 10 was 65%, which was above the upper limit of the range of the present invention, a large number of peeling occurred inside and it could not be used as a product.

  Sample No. In No. 4, the rolling reduction during hot rolling was as small as 20%, and no heat treatment was performed, so that the surface layer and the inside of the obtained titanium multilayer material 10 were separated. In addition, the sample No. In No. 8 as well, since the rolling reduction during hot rolling was as small as 31% and no heat treatment was performed, the surface layer and the inside of the obtained titanium multilayer material were peeled off. Therefore, they cannot be used as products.

  Sample No. In No. 5, when the titanium-containing structure 1 was manufactured, the internal pressure was set to 80 Pa. Therefore, the surface of titanium sponge inside is oxidized during heating during hot rolling, and the sponge titanium is weakly bonded to each other in subsequent hot rolling or heat treatment, and a part of the inside of the titanium multilayer material 10 is peeled off. Therefore, it cannot be used as a product.

  Further, the sample No. For No. 25, a titanium briquette having a porosity of 40% was processed at a rolling reduction of 7% during hot working to manufacture a titanium multilayer plate 10 having a porosity of 35%. Although the heat treatment was applied after the hot working, the packing material 2 of the titanium-containing structure 1 and the titanium briquette 3 could not be adhered on the entire surface because the rolling reduction during the hot working was small. Then, peeling occurred at the boundary between the surface layer and the inside. Therefore, it cannot be used as a product.

  According to the present invention, a conventional titanium melting structure and a forging process are omitted, a titanium-containing structure is manufactured, and compression processing such as rolling is performed to manufacture a lightweight and rigid titanium multilayer material. Therefore, the energy required for manufacturing can be reduced.

  Furthermore, according to the present invention, a large amount of titanium material is removed by cutting, such as cutting and removing many defects on the surface layer and bottom surface of a titanium ingot, and removing surface cracks and bad front and rear ends (crops) after forging. Since it can be manufactured without cutting and removing, the manufacturing yield is significantly improved, and the manufacturing cost can be significantly reduced.

  Thus, the industrial applicability of the present invention is high.

Claims (3)

A titanium-containing structure used for producing a titanium multilayer material,
The titanium multilayer material has a chemical composition belonging to JIS 1 to 4 types, a compression molded body is provided inside and a titanium wrought material is provided on the surface layer, and the compression molded body and the surface layer are joined, the compression molded body state, and are porosity of less than 30% to 60% with composed of one or more selected from the sponge titanium and titanium scrap,
The titanium-containing structure comprises a packing material made of an industrial pure titanium wrought material, and a packing material filled inside the packing material,
The internal pressure of the packaging material is 10 Pa or less in absolute pressure,
A titanium-containing structure in which the filler is composed of one or more kinds selected from titanium sponge and titanium scrap, and has the same chemical composition as the industrial pure titanium wrought material. The titanium-containing structure according to claim 1 is subjected to compression processing with a rolling reduction of 35% or more.
Method for manufacturing titanium multilayer material. The titanium-encapsulated structure according to claim 1, after being subjected to compression processing with a reduction rate of 10% or more and less than 35%, heat treatment while applying pressure in the thickness direction.
Method for manufacturing titanium multilayer material.

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