JP6045446B2 - Method for producing heat-treated Al-Mg-Si alloy with excellent appearance uniformity - Google Patents

Description

  The present invention relates to an aluminum alloy material having excellent appearance uniformity applied to a lens barrel or the like of an optical apparatus.

  Optical equipment such as a rifle scope and a telescope includes a lens barrel that houses a lens. Since these devices are mainly used in an outdoor environment, there has been a demand for a device that is lightweight and corrosion-resistant as well as strength. In order to satisfy this requirement, for example, Patent Document 1 presents a lens barrel made of an aluminum alloy.

  An aluminum alloy is a material that is lightweight and excellent in strength and durability, and is subjected to processing and heat treatment to become a product having predetermined shape dimensions and mechanical properties. A JIS6000-based heat-treatable Al—Mg—Si-based alloy has high mechanical strength and is used as a material for structural parts. For example, in Patent Documents 2 and 3, a forged product is manufactured by subjecting an ingot or its extruded material to hot forging and then subjecting it to a tempering treatment such as a T6 treatment.

Japanese Patent Laid-Open No. 9-318296 JP 2001-107168 A Japanese Patent Laid-Open No. 9-249952

  A forged product made of an Al—Mg—Si alloy is formed by cold forging, which is excellent in productivity and processing accuracy, depending on the application, not hot forging. For example, after cold forging the extruded material, a forged product is manufactured by performing a T6 treatment, and thereafter, a surface treatment such as anodizing coating is performed in order to improve corrosion resistance and design properties.

However, in the process of performing the cold forging or heat treatment, recrystallization may occur and the metal structure may change greatly. Cold forging is a processing for forming into a predetermined shape, but since a necessary amount of processing is performed according to the product shape, accumulation of processing strain may be unevenly distributed. In a region where the accumulated amount of processing strain is large, a fine processed structure is obtained, and the fine structure is maintained even if recrystallization occurs by subsequent heating. In the region where the accumulated amount of processing strain is small, the driving force for recrystallization is insufficient, and the recovery of the crystal structure only occurs.
On the other hand, in areas where moderate processing strain is accumulated, crystal grains become coarse due to recrystallization, causing a large unevenness in the product appearance and product color tone after anodized coating, and reducing the appearance of the surface. . Optical devices such as sighting scopes for hunting rifles and telescopes for astronomical observation are products that are also used as hobbies and entertainment, so if there is unevenness in the color of the aluminum alloy material, the appearance of the product And the product value will be reduced.

  This invention is made in view of such a subject, and provides the heat processing material of the Al-Mg-Si type | system | group alloy which has the outstanding design property which is uniform in the product external appearance and the product color tone after anodic oxidation coating. For the purpose.

  The present inventor performs cold working on the extruded material at a predetermined degree of processing to form a structure in which sufficient working strain is accumulated in the entire material, and subsequently performs T6 treatment or cold forging and T6 treatment. However, the present inventors have found that the appearance of a beautiful product with no uneven color tone is exhibited without causing partial crystal grain coarsening, and the present invention has been completed.

(1) The present invention is a method for producing an aluminum heat treatment material comprising a step of performing cold forging after obtaining an extruded material made of an Al—Mg—Si based alloy and then performing a T6 treatment, An Al—Mg—Si based alloy for optical parts, including a step of cold working the extruded material before forging, and an average crystal grain size of the aluminum heat treated material after the T6 treatment being 50 μm or more and less than 1 mm The above-described problems are solved by a method for producing an aluminum heat treatment material.

  In the present invention, by performing cold working on the extruded material before performing cold forging, sufficient working strain is accumulated in the entire material. Therefore, after performing cold forging subsequently, T6 Even if the treatment is performed, the recrystallized grains generated during the solution treatment are not coarsened because the grain growth is suppressed by the fine processed structure. Therefore, a uniform fine structure having an average crystal grain size of 50 μm or more and less than 1 mm is obtained, and the color tone of the aluminum alloy surface is not uneven, and exhibits a uniform appearance.

(2) The present invention includes a step of performing cold drawing on the extruded material after obtaining an extruded material made of an Al—Mg—Si based alloy, and then subjecting the extruded material to a T6 treatment, and an aluminum heat treatment after the T6 treatment. An average crystal grain size of the material is 50 μm or more and less than 1 mm, and solves the above-mentioned problems by a method for producing an Al—Mg—Si alloy aluminum heat treatment material with excellent appearance uniformity. is there.

  In the present invention, by performing cold drawing on the extruded material, sufficient processing strain is accumulated in the entire material. Therefore, even if the T6 treatment is subsequently performed, it is generated during the solution treatment. The recrystallized grains do not become coarse because grain growth is suppressed by a fine processed structure. Therefore, a uniform fine structure having an average crystal grain size of 50 μm or more and less than 1 mm is obtained, and the color tone of the aluminum alloy surface is not uneven, and exhibits a uniform appearance.

(3) In the present invention, it is preferable that the cold working is a drawing process with a cross-section reduction rate of 15% to 60%.
The cold working performed before the cold forging is preferably performed with a cross-sectional reduction rate (working degree) of 15% or more in order to impart sufficient working strain to the entire material. On the other hand, if the cross-section reduction rate is excessive, cracks or the like occur in the material to be processed due to an increase in the amount of deformation, and the load on the processing apparatus increases, so a cross-section reduction rate of 60% or less is preferable.

(4) In the present invention, the cold forging is preferably performed at a cross-sectional reduction rate of 100% or less.
After cold working, cold forging is performed to form the product into a predetermined shape and dimensions. However, if the cross-section reduction rate is excessive, the material to be processed is cracked due to an increase in deformation, and the load on the forging device is increased. Therefore, the cross-sectional reduction rate is preferably 100% or less.

(5) In the present invention, it is preferable that the cold drawing process is a process of performing a drawing process with a cross-section reduction rate of 15% to 60%.
The cold drawing is preferably performed with a cross-sectional reduction rate (working degree) of 15% or more in order to impart sufficient working strain to the entire material. On the other hand, if the cross-section reduction rate is excessive, cracks or the like occur in the material to be processed due to an increase in the amount of deformation, and the load on the processing apparatus increases, so a cross-section reduction rate of 60% or less is preferable.

(6) In the present invention, Si 0.5 to 1.0 mass%, Fe 0.1 to 0.3 mass%, Cu 0.05 to 1.0 mass%, Mg 0.5 to 1.1 mass%, Ti 0.005 -0.2 mass%, B0.0005-0.05 mass%, and Mn 0.03-0.5 mass%, Cr 0.03-0.3 mass%, Zr 0.03-0.2 mass It is preferable that it is an aluminum material consisting of the balance Al and unavoidable impurities, which contains at least one or more of the total amount of 0.03% by mass and 0.5% by mass or less.

Si and Mg are elements that improve strength by precipitation of Mg ₂ Si in the matrix by aging treatment during T6 treatment, and Si 0.5 wt% or more and Mg 0.5 wt% or more are required. On the other hand, when Si exceeds 1.0 mass%, grain boundary embrittlement due to grain boundary precipitation of Si is likely to occur, and workability is reduced. When Mg exceeds 1.1 mass%, in addition to saturation of precipitation hardening effect | action, workability will be reduced.

Fe forms a crystallized product of an Al—Fe—Si compound and increases the strength. However, if it exceeds 0.3 mass%, the elongation and corrosion resistance are adversely affected. It was set as mass%.
Cu is an element that increases the strength by solid solution strengthening or precipitation strengthening, but if it exceeds 1.0 mass%, the corrosion resistance is reduced, so 0.05 to 1.0 mass% was set.
Ti is an element that refines the cast structure, but if it exceeds 0.2% by mass, the toughness is reduced, so 0.005 to 0.2% by mass was set.

  Mn, Cr, and Zr are effective elements for suppressing the growth of recrystallized grains and maintaining the microstructure after the T6 treatment. These elements produce fine intermetallic compounds during casting and homogenization treatment, and are not dissolved by the solution treatment, and have the effect of suppressing recrystallization grain coarsening during the solution treatment of the T6 treatment. 0.03% by mass or more is required. On the other hand, if excessively contained, workability is adversely affected, so the upper limit is Mn 0.5 mass%, Cr 0.3 mass%, Zr 0.2 mass%, and the total amount of these elements is 0.03 to 0.03. The content was 0.5% by mass.

(7) In the present invention, the T6 treatment is preferably solution treatment 500 ° C to 580 ° C, water cooling, and aging treatment 160 ° C to 220 ° C. The solution treatment requires 500 ° C. or higher in order to sufficiently dissolve the components of the compound precipitated during the subsequent aging treatment, but if it exceeds 580 ° C., burning (melting loss) occurs. ˜580 ° C. After forming a supersaturated solid solution by water cooling, fine compounds such as Mg ₂ Si are precipitated by T6 treatment (artificial aging), so the temperature of the aging treatment was set to 160 ° C. to 220 ° C.

(8) The present invention provides an optical component in which the aluminum heat treatment material is a material for a lens barrel of an optical device and has excellent appearance uniformity after anodic oxidation coating.

(9) This invention provides the optical component which consists of an Al-Mg-Si type alloy manufactured by said manufacturing method.

  Since the heat treatment material of the present invention is excellent in the design of the surface appearance, it is suitable for materials such as a barrel of an optical instrument used for hobbies such as an aiming scope and entertainment. Even when anodized, the base is composed of a uniform structure, so that the appearance is excellent in uniformity.

  According to the present invention, in the heat-treatable aluminum alloy, even if the T6 treatment or the cold forging and the T6 treatment are performed, partial crystal grain coarsening does not occur, and color unevenness resulting therefrom does not occur. There is nothing. Even after anodizing the surface of the aluminum alloy material, it has an excellent design, so that it has a useful effect as a material for optical components. It is also suitable for materials for structural parts that are lightweight and require design, such as bicycle drive shafts.

It is a figure which shows the metal structure before and behind T6 process about the extruded tube which performed the cold work. It is the figure which expanded the metal structure of FIG. It is a figure which shows the metal structure of the heat processing material of this invention, and the heat processing material of a comparative example.

Next, an embodiment of the present invention will be described.
(Test Example 1) Effect of cold working on extruded rod Alloy No. 1 of the present invention shown in Table 1 1-No. 3. Comparative Alloy No. DC casting was performed using an aluminum alloy having a component composition of 4 to obtain a billet having a diameter of 325 mm. The billet was subjected to a homogenization treatment at 560 ° C. for 4 hours, and then the specimen Nos. Shown in Table 2 were used. 1-6 were obtained. The test body was extruded to obtain an extruded bar having a diameter of 65 mm (test bodies No. 1 to No. 4, No. 6) and an extruded bar having a diameter of 56 mm (test body No. 5). The extruded bar was cold drawn to obtain a drawn material having a diameter of 54 mm. The cross-sectional reduction rate (drawing rate) by this drawing process corresponds to about 30% for the former and about 7% for the latter. The drawn material was subjected to solution treatment, water cooling, and aging treatment under the heat treatment conditions shown in Table 2 to obtain a heat treatment material by T6 treatment.
The test specimen was divided into two in the longitudinal direction (drawing direction), the cross section was polished, and then etched, and the cross sectional structure was observed. Then, the average crystal grain size (mm) was measured at a depth of 10 mm from the outer periphery. The average crystal grain size was calculated using the number of crystal grains obtained by a cutting method (a method for measuring the number of crystal grains divided at a certain length). Furthermore, a JIS No. 4 test piece was sampled from the outer periphery of the test body around a half of the radius, a tensile test was performed, and a tensile strength (MPa) was measured. The measurement results of the average crystal grain size and tensile strength are shown in Table 2.

As shown in Table 2, the specimen having a cross-section reduction rate of 30% had an average particle size of 0.2 to 0.4 mm, had a fine structure, and had a good appearance with no uneven color tone. It was. On the other hand, the specimen No. 1 was subjected to drawing with a cross-section reduction rate of 7%. In No. 5, coarsening of crystal grains partially occurred in the recrystallization process by the solution treatment of the T6 treatment, and the average grain size was 2.0 mm. Therefore, the color tone is uneven, and the appearance of the appearance is impaired.
Furthermore, alloy no. 1-No. Specimen No. 3 made of aluminum alloy No. 3 1-No. No. 3 had a tensile strength exceeding 300 MPa and exhibited excellent characteristics in terms of mechanical strength. In addition, the specimen No. having a solution treatment of less than 500 ° C. 6 is Alloy No. Even the aluminum alloy consisting of 1 had a mechanical strength of less than 300 MPa.

(Test Example 2) Effect of cold working on extruded tube Alloy No. 1 of the present invention shown in Table 1 DC casting was performed using an aluminum alloy having a component composition of 1 to obtain a billet having a diameter of 325 mm. After this billet was homogenized at 560 ° C. for 4 hours, the specimen Nos. Shown in Table 3 were used. 7-No. 10 was obtained. The test body was extruded and extruded tubes (test bodies No. 7 and No. 8) having an outer diameter of 69.5 mm and an inner diameter of 28 mm, and extruded tubes (test body No. 9) having an outer diameter of 73.5 mm and an inner diameter of 28 mm. ), An extruded tube (test body No. 10) having a diameter of 77.5 mm and an inner diameter of 28 mm was obtained. Among these, test body No. The 8 to 10 extruded tubes were cold drawn to obtain a drawn tube having an outer diameter of 64.5 mm and an inner diameter of 22 mm. The cross-sectional reduction rate (drawing rate) by this drawing process corresponds to about 10%, about 20%, and about 30% in order. As shown in Table 3, the extruded material (test body No. 7) and the drawn material (test bodies No. 8 to No. 10) were subjected to the same heat treatment as in Example 1, and the heat treatment by the T6 treatment. A material was used.
The test specimen was divided into two in the longitudinal direction (drawing direction, extrusion direction), the cross section was polished, etched, and the average crystal grain size (mm) was measured by a cutting method at a depth of 5 mm from the outer periphery. Furthermore, a JIS13B test piece was collected from the expanded portion of the test body in the forging direction, subjected to a tensile test, and measured for tensile strength (MPa). Table 3 shows the measurement results of the average crystal grain size and tensile strength.

FIG. 1 shows the metal structure before and after the T6 treatment for the heat treated material by the T6 treatment. FIG. 2 shows the enlarged metal structure of FIG.
As shown in FIG. 1 (a) and FIG. 2 (a), before the T6 treatment, all specimens show a fine structure. After the T6 treatment, the test specimens with the cross-sectional reduction rate of the drawing process of 0%, 20%, and 30% are not uneven. As shown in Table 3, the average particle size is 0.7 mm or less.
On the other hand, as is apparent from FIGS. 1B and 2B, the specimen subjected to the drawing process with a cross-sectional reduction rate of 10% has uneven color tone after the T6 treatment. In the process in which recrystallization occurs due to the solution treatment of the T6 treatment, crystal grains become coarse, and the average particle size reaches 1.4 mm.

  These results show that by performing a drawing process with a cross-section reduction rate of 20% and 30%, a fine structure can be maintained even if a subsequent heat treatment is performed. That is, a certain amount or more of processing strain is given by the drawing process. This indicates that no coarsening occurs even if recrystallization occurs due to the solution treatment of the subsequent T6 treatment.

  Therefore, in order to obtain a heat-treated material having an appearance that is free of uneven color tone by subjecting the extruded material or cold forged material to a T6 treatment, a cold working that imparts a certain amount of processing strain to the extruded material ( It is clear that it is useful to perform a cold drawing process, and the cross-section reduction rate needs to be 15% or more.

  As described above, when cold forging is performed in order to realize the final shape and dimensions, if a certain amount or more of processing strain is applied by a cross-section reduction rate of 15% or more before cold forging, the subsequent cold forging is performed. It means that coarsening does not occur in the T6 heat treatment even if the processing strain due to hot forging is not uniformly distributed over the entire material. Therefore, the following tests were conducted.

(Test Example 3) Effect of cold working and cold forging in extruded tube Alloy No. 1 of the present invention shown in Table 1 DC casting was performed using an aluminum alloy having a component composition of 1 to obtain a billet having a diameter of 325 mm. After this billet was homogenized at 560 ° C. for 4 hours, the test specimen Nos. Shown in Table 4 were used. 11, no. 12 was obtained. The test body was extruded to obtain an extruded tube (test body No. 11) having an outer diameter of 58.5 mm and an inner diameter of 28 mm, and an extruded tube (test body No. 12) having an outer diameter of 48 mm and an inner diameter of 22 mm. The former extruded tube (test body No. 11) was cold drawn to obtain a drawn tube having an outer diameter of 48 mm and an inner diameter of 22 mm. The cross-sectional reduction rate (drawing rate) by this drawing process corresponds to about 30%. Next, the drawn tube (test body No. 11) and the extruded tube (No. 12) were subjected to a tube expansion process by cold forging at a working degree (tube expansion rate) of about 36%. Thereafter, as shown in Table 4, the same heat treatment as in Example 2 was performed to obtain a heat treatment material by T6 treatment.
In the same manner as in Example 2, the average crystal grain size (mm) and the tensile strength (MPa) were measured. The measurement results are shown in Table 4.

  As shown in Table 4, the specimen No. 1 of the present invention was subjected to cold working (drawing) and cold forging (expanded tube). No. 11 had an average particle size of 0.5 mm and maintained a fine structure even after T6 treatment. On the other hand, the comparative specimen No. which was not subjected to cold working (drawing). In No. 12, crystal grain coarsening occurred due to the solution treatment of the T6 treatment, and the average particle size reached 5 mm. For this reason, uneven color tone occurs, and the appearance of the appearance is impaired.

(Test Example 4) Manufacturing Example of Optical Component A lens barrel of an aiming scope was formed by the manufacturing method of the present invention. After extruding the extruded material with a cross-section reduction rate of 30%, the heat-treated material of the present invention subjected to cold forging and T6 treatment, and the extruding material subjected to tube expansion processing by cold forging and then subjected to T6 treatment. The respective macrostructures of the heat treatment material of the comparative example are shown in FIG. Each heat-treated material had a total length of 295 mm in the longitudinal direction (extrusion direction).
As shown in FIG. 3 (a), the heat treatment material of the present invention is given a sufficient work strain by drawing with a cross-section reduction rate of 30% to obtain a uniform microstructure, and then cold forging and T6 treatment. As a result, no partial coarsening of the crystal grains occurred, so that no unevenness was observed in the product color tone.
On the other hand, as shown in FIG. 3B, in the comparative example in which the drawing process was not performed, the distribution of the processing strain due to cold forging is not uniform throughout the material, Due to strain in the compression direction and moderate processing strain accumulated, in that region, a non-uniform grain structure resulting from grain coarsening was exhibited by the solution treatment of the T6 treatment. Therefore, the product color tone was greatly uneven and the appearance was impaired.

Claims (6)

After obtaining an extruded material made of an Al-Mg-Si-based alloy, cold forging, and then a method for producing an aluminum heat treatment material including a step of performing T6 treatment, before performing the cold forging, includes a step of performing cold drawn to the extrusion material, the T6 average crystal grain size of the aluminum heat-treated after treatment 50μm or more, 1 mm less der is, the cold drawing processing, reduction of area of 15% or more, A method for producing an Al—Mg—Si alloy aluminum heat treatment material with excellent appearance uniformity, characterized by being a step of drawing at 60% or less . After obtaining an extruded material made of an Al—Mg—Si based alloy, the extruded material is subjected to cold drawing and then subjected to T6 treatment, and the average crystal grain size of the aluminum heat treated material after the T6 treatment is 50μm or more, 1 mm less der is, the cold drawing processing, reduction of area of 15% or more, characterized in that it is a step of performing the following drawing 60 percent, excellent uniformity of appearance Al-Mg -Manufacturing method of Si alloy aluminum heat treatment material. 2. The method for producing an aluminum heat treatment material according to claim 1 , wherein the cold forging is performed with a cross-sectional reduction rate of 100% or less, and an Al—Mg—Si based alloy having excellent appearance uniformity. 3. Manufacturing method of heat treatment material. A manufacturing method of an aluminum heat-treated according to any one of claims 1~ 3, Si0.5~1.0 wt%, Fe0.1~0.3 wt%, Cu0.05~1.0 Mass%, Mg 0.5-1.1 mass%, Ti 0.005-0.2 mass%, Mn 0.03-0.5 mass%, Cr 0.03-0.3 mass%, Zr0. It is an aluminum material consisting of the balance Al and unavoidable impurities, which is at least one or more from 03 to 0.2% by mass, the total amount of which is 0.03% by mass or more and 0.5% by mass or less. A method for producing an Al—Mg—Si based alloy heat treated material having excellent appearance uniformity. It is a manufacturing method of Claim 4 , Comprising: The said T6 process is solution treatment 500 degreeC-580 degreeC, water cooling, aging treatment 160 degreeC-220 degreeC, It was excellent in the uniformity of the external appearance characterized by the above-mentioned. A method for producing an Al—Mg—Si alloy heat treatment material. It is a manufacturing method of the aluminum heat processing material of any one of Claims 1-5 , Comprising: The said aluminum heat processing material is a raw material for lens barrels of an optical apparatus, The external appearance after anodic oxidation coating characterized by the above-mentioned For producing an Al—Mg—Si based alloy heat treatment material for optical parts having excellent uniformity of heat.