JP7631077B2 - Aluminum clad plate material for space debris protection and its manufacturing method - Google Patents

Description

The present invention relates to an aluminum clad plate material for manufacturing bumper materials for protecting space debris, which are installed in outer space to protect spacecraft, artificial satellites, space stations, etc. from space debris.

Since space debris flies around in outer space, spacecraft, artificial satellites, space stations, etc. (hereinafter collectively referred to as spacecraft, etc.) are subject to collisions with space debris. For this reason, spacecraft, etc. are equipped with bumper materials for protecting against space debris in order to prevent damage to the hull of the craft due to collisions with space debris.

Conventionally, the bumper material used to protect space debris must have sufficient strength to withstand the acceleration and impacts that occur during launch, so JIS 6061 aluminum alloys have been used as the material for the bumper.

When space debris collides with a bumper material used to protect against space debris, secondary debris (ejectors) are generated, which leads to an increase in the amount of space debris. For example, Non-Patent Document 1 describes a test conducted to simulate the collision of space debris with a bumper material in outer space, in which an aluminum alloy 2017-T4 ball simulating space debris is collided at high speed with a JIS 6061-T6 aluminum alloy, and the amount of debris generated by the collision is measured. In this test, a large number of ejecta were generated.

“Scaling laws for size distribution of fragments resulting from hypervelocity impacts of aluminum alloy spherical projectiles on thick aluminum alloy targets: Effects of impact velocity and projectile diameter”, International Journal of Impact Engineering 109 (2017) 400-407

In this way, if space debris collides with space debris protection bumper materials and secondary debris (ejectors) are generated, the amount of space debris will increase. Therefore, in recent years, spacecraft and other space development projects have been required to take measures against ejections caused by collisions of space debris with space debris protection bumper materials.

The present invention therefore aims to provide an aluminum alloy plate material for manufacturing bumper materials for protecting against space debris, which have fewer ejections when impacted by space debris.

The above problems are solved by the present invention described below.
That is, the present invention (1) is an aluminum alloy clad material in which an aluminum alloy core material and an aluminum alloy skin material are laminated,
The aluminum alloy core material is made of JIS 6061 aluminum alloy, has a tensile strength of 295 MPa or more and a yield strength of 245 MPa or more,
the aluminum alloy skin material is made of an aluminum alloy having a lower tensile strength and a higher elongation than the aluminum alloy core material;
The present invention provides an aluminum clad plate material for space debris protection, characterized by the above.

The present invention (2) also provides an aluminum clad plate material for space debris protection according to (1), characterized in that the aluminum alloy core material is made of JIS 6061-T6 aluminum alloy or JIS 6061-T651.

The present invention (3) also provides an aluminum clad plate material for protecting space debris according to (1) or (2), characterized in that the aluminum alloy skin material is made of a JIS 1000 series aluminum alloy.

The present invention (4) also provides an aluminum clad plate material for protecting space debris according to (3), characterized in that the aluminum alloy skin material is made of JIS 1050 aluminum alloy.

The present invention (5) also provides an aluminum clad plate material for protecting space debris according to any one of (1) to (4), characterized in that the clad ratio of the aluminum alloy skin material is 5 to 20%.

The present invention (6) is a method for manufacturing an aluminum clad plate material for space debris protection,
a rolling step of clad-rolling the aluminum alloy core material and the aluminum alloy skin material;
A heat treatment process is performed on the clad material of the aluminum alloy core material and the aluminum alloy skin material, the heat treatment process being a solution treatment, a rapid cooling process, and an artificial aging treatment process.
The aluminum alloy core material of the aluminum clad plate material is made of JIS 6061 aluminum alloy, and has a tensile strength of 295 MPa or more and a yield strength of 245 MPa or more;
the aluminum alloy skin material of the aluminum clad plate material is made of an aluminum alloy having a lower tensile strength and a higher elongation than the aluminum alloy core material;
The present invention provides a method for manufacturing an aluminum clad plate material for space debris protection, characterized by the above.

The present invention provides an aluminum alloy plate material for manufacturing bumper materials for protecting against space debris that have fewer ejections when impacted by space debris.

1 is a graph showing the results of a projectile impact test (1.15 km/s) of Example 1 and the results of a projectile impact test (1.77 km/s) of Comparative Example 1. 1 is a graph showing the results of a projectile impact test (1.92 km/s) of Example 1 and the results of a projectile impact test (1.77 km/s) of Comparative Example 1. 1 is an X-ray CT image of the vicinity of the projectile impact site of the plate material after a projectile impact test (1.15 km/s) in Example 1. 1 is a graph showing the results of a projectile impact test (1.62 km/s) of Example 2 and the results of a projectile impact test (1.77 km/s) of Comparative Example 1. 1 is a graph showing the results of a projectile impact test (2.03 km/s) of Example 2 and the results of a projectile impact test (1.77 km/s) of Comparative Example 1.

The aluminum clad plate material for protecting space debris of the present invention is an aluminum alloy clad material in which an aluminum alloy core material and an aluminum alloy skin material are laminated,
The aluminum alloy core material is made of JIS 6061 aluminum alloy, has a tensile strength of 295 MPa or more and a yield strength of 245 MPa or more,
the aluminum alloy skin material is made of an aluminum alloy having a lower tensile strength and a higher elongation than the aluminum alloy core material;
This is an aluminum clad plate material for space debris protection, characterized by the following:

The aluminum clad plate material for protecting space debris of the present invention is an aluminum alloy clad material in which an aluminum alloy core material and an aluminum alloy skin material are laminated. In other words, the aluminum clad plate material for protecting space debris of the present invention is composed of an aluminum alloy core material and an aluminum alloy skin material clad on one side of the aluminum alloy core material.

The aluminum clad plate material for protecting space debris of the present invention is formed into the shape of a bumper material for protecting space debris, with the aluminum alloy skin facing outward (the side that will be hit by space debris). In other words, the aluminum clad plate material for protecting space debris of the present invention is a formed raw material for manufacturing a bumper material for protecting space debris.

The aluminum alloy core material of the aluminum clad plate material for space debris protection of the present invention is made of JIS 6061 aluminum alloy. The composition of the JIS 6061 aluminum alloy is as follows: Si: 0.40-0.80 mass%, Fe: 0.70 mass% or less, Cu: 0.15-0.40 mass%, Mn: 0.15 mass% or less, Mg: 0.80-1.20 mass%, Cr: 0.04-0.35 mass%, Zn: 0.25 mass% or less, Ti: 0.15 mass% or less, and the balance is aluminum and unavoidable impurities.

The aluminum alloy core material has a tensile strength of 295 MPa or more and a yield strength of 245 MPa or more. Because the aluminum alloy core material has a tensile strength of 295 MPa or more and a yield strength of 245 MPa or more, it will not break or deform due to the impact and acceleration at the time of launch. Examples of JIS 6061 aluminum alloys having a tensile strength of 295 MPa or more and a yield strength of 245 MPa or more include JIS 6061-T6 aluminum alloy (6061 alloy with T6 temper) and JIS 6061-T651 aluminum alloy (6061 alloy with T651 temper). In other words, the aluminum alloy core material is made of JIS 6061-T6 aluminum alloy or JIS 6061-T651 aluminum alloy.

JIS 6061-T6 aluminum alloy is a plate-shaped aluminum alloy that has the chemical composition of JIS 6061 alloy and has been subjected to solution treatment, quenching, and artificial aging treatment. JIS 6061-T6 aluminum alloy has a tensile strength of 295 MPa or more and a yield strength of 245 MPa or more. In addition, JIS 6061-T6 aluminum alloy has an elongation of 8% or more when the thickness is 0.4 mm or more and 0.5 mm or less, and an elongation of 10% when the thickness is more than 0.5 mm and 6.5 mm or less.

JIS 6061-T651 aluminum alloy is a plate-shaped aluminum alloy that has the composition of JIS 6061 aluminum alloy and has been subjected to solution treatment, quenching, tensile straightening, and artificial aging treatment. JIS 6061-T651 aluminum alloy has a tensile strength of 295 MPa or more and a yield strength of 245 MPa or more. In addition, JIS 6061-T651 aluminum alloy has an elongation of 10% when the thickness is 6.5 mm or more and 13.0 mm or less, an elongation of 9% when the thickness is more than 13.0 mm and 25.0 mm or less, an elongation of 8% when the thickness is more than 25.0 mm and 50.0 mm or less, and an elongation of 6% when the thickness is more than 50.0 mm and 100.0 mm or less.

In the present invention, the tensile strength, yield strength, and elongation of the aluminum alloy plate are measured in accordance with JIS H 4000.

The tensile strength of the aluminum alloy core material is 295 MPa or more, preferably 295 to 400 MPa, and particularly preferably 295 to 380 MPa. When the tensile strength of the aluminum alloy core material is within the above range, it will not be destroyed by the impact and acceleration during launch.

The aluminum alloy core material has a yield strength of 245 MPa, preferably 245 to 360 MPa, and particularly preferably 245 to 300 MPa. With the yield strength of the aluminum alloy core material in the above range, it will not deform due to the impact and acceleration at launch.

When Si coexists with Mg, it works to improve the strength of the aluminum alloy through precipitation strengthening. The Si content of the aluminum alloy core material is 0.40 to 0.80 mass%, preferably 0.45 to 0.75 mass%, and particularly preferably 0.50 to 0.70 mass%. When the Si content of the aluminum alloy core material is within the above range, the strength of the aluminum alloy is increased. On the other hand, if the Si content of the aluminum alloy core material is less than the above range, sufficient strength may not be ensured, and if it exceeds the above range, it may cause grain boundary cracking and reduce workability.

If the Fe content of the aluminum alloy core material is too high, coarse crystals will form and reduce ductility, so the Fe content of the aluminum alloy core material is restricted to 0.70 mass% or less, preferably 0.60 mass% or less, and particularly preferably 0.40 mass% or less.

Cu acts to increase the strength of the aluminum alloy by dissolving in the alloy. The Cu content of the aluminum alloy core material is 0.15 to 0.40 mass%, preferably 0.20 to 0.35 mass%, and particularly preferably 0.25 to 0.30 mass%. By having the Cu content of the aluminum alloy core material in the above range, the strength of the aluminum alloy is increased. On the other hand, if the Cu content of the aluminum alloy core material is less than the above range, there is a risk that sufficient strength cannot be ensured, and if it exceeds the above range, there is a risk that Cu compounds that cannot be completely dissolved will become the starting point of fracture, reducing toughness.

Mn has the function of refining the crystal grains of the aluminum alloy and improving its strength. The Mn content of the aluminum alloy core material is 0.15 mass% or less, preferably 0.12 mass% or less, more preferably more than 0.00 mass% to 0.12 mass% or less, and particularly preferably 0.03 to 0.10 mass%. If the Mn content of the aluminum alloy core material exceeds the above range, coarse crystals are formed, reducing toughness.

When Mg coexists with Si, it works to improve the strength of the aluminum alloy through precipitation strengthening. The Mg content of the aluminum alloy core material is 0.08 to 1.20 mass%, preferably 0.75 to 1.15 mass%, and particularly preferably 0.70 to 1.10 mass%. When the Mg content of the aluminum alloy core material is within the above range, the strength of the aluminum alloy is increased. On the other hand, if the Mg content of the aluminum alloy core material is less than the above range, sufficient strength may not be ensured, and if it exceeds the above range, deformation resistance may increase, making manufacturing difficult.

Cr has the function of refining the crystal grains of the aluminum alloy and improving its strength. The Cr content of the aluminum alloy core material is 0.04 to 0.35 mass%, preferably 0.06 to 0.30 mass%, and particularly preferably 0.08 to 0.25 mass%. When the Cr content of the aluminum alloy core material is within the above range, the crystal grains of the aluminum alloy become finer and the strength of the aluminum alloy increases. On the other hand, if the Cr content of the aluminum alloy core material is less than the above range, the crystal grains may become coarse and the toughness may decrease, and if it exceeds the above range, the quenching sensitivity may become high and sufficient strength may not be ensured.

Zn forms compounds by consuming Mg, which contributes to improving strength. Therefore, if the Zn content of the aluminum alloy core material is too high, the strength of the aluminum alloy becomes too low. Therefore, the Zn content of the aluminum alloy core material is restricted to 0.25% by mass or less, and preferably 0.20% by mass or less.

Ti has the effect of refining the crystal grains of aluminum alloy ingots and improving their strength, but if the Ti content of the aluminum alloy core material is too high, coarse crystals may form and toughness may decrease, so the Ti content of the aluminum alloy core material is 0.15 mass% or less, preferably 0.12 mass% or less, more preferably more than 0.00 mass% and 0.12 mass% or less, and particularly preferably more than 0.00 mass% and 0.10 mass% or less.

The aluminum alloy skin material of the aluminum clad plate material for protecting space debris of the present invention is made of an aluminum alloy that has a lower tensile strength and a higher elongation than the aluminum alloy core material.

The aluminum alloy skin material has a lower tensile strength than the aluminum alloy core material, preferably at least 195 MPa lower, and particularly preferably 200 to 340 MPa lower. In other words, the difference between the tensile strength of the aluminum alloy core material and the tensile strength of the aluminum alloy skin material (tensile strength of aluminum alloy core material - tensile strength of aluminum alloy skin material) exceeds 0 MPa, and is preferably at least 195 MPa, and particularly preferably 200 to 340 MPa.

The aluminum alloy skin material also has a greater elongation than the aluminum alloy core material, preferably at least 12%, and particularly preferably 12-32% greater. In other words, the difference between the elongation of the aluminum alloy skin material and the elongation of the aluminum alloy core material (elongation of the aluminum alloy skin material - elongation of the aluminum alloy core material) exceeds 0%, and is preferably at least 12%, and particularly preferably 12-32%.

In the aluminum clad plate material for protecting space debris of the present invention, the difference in tensile strength between the aluminum alloy core material and the aluminum alloy skin material is within the above range, and the difference in elongation between the aluminum alloy skin material and the aluminum alloy core material is also within the above range, so that ejections are reduced when space debris collides.

The tensile strength of the aluminum alloy skin material is preferably 60 to 100 MPa, and particularly preferably 65 to 95 MPa. The elongation of the aluminum alloy skin material is preferably 28 to 45%, and particularly preferably 30 to 40%. By having the tensile strength and elongation of the aluminum alloy skin material within the above ranges, it becomes easier to achieve the effect of reducing ejecta when space debris impacts.

The yield strength of the aluminum alloy skin material is preferably 20 to 100 MPa, and particularly preferably 25 to 80 MPa. By having the yield strength of the aluminum alloy skin material within the above range, it becomes easier to achieve the effect of reducing ejecta when space debris collides.

The composition of the aluminum alloy skin material is not particularly limited and may be selected as appropriate, so long as it satisfies the above tensile strength and elongation requirements.

The aluminum alloy that constitutes the aluminum alloy skin material includes JIS 1000 series aluminum alloys, with JIS 1050 alloy being preferred.

JIS 1000 series aluminum alloys are a general term for aluminum alloys with alloy numbers starting with 1 among those listed in JIS H 4000, and JIS 1000 series aluminum alloys have an Al purity of 99.0 mass% or more.

The chemical composition of JIS 1050 aluminum alloy is: Si: 0.25% by mass or less, Fe: 0.40% by mass or less, Cu: 0.05% by mass or less, Mn: 0.05% by mass or less, Mg: 0.05% by mass or less, Zn: 0.05% by mass or less, Ti: 0.03% by mass or less, with the remainder being aluminum and unavoidable impurities.

The Si, Fe, Cu, Mn, Mg and Zn in the aluminum alloy constituting the aluminum alloy skin material are impurities that may be mixed into the raw materials used in manufacturing. In the aluminum alloy constituting the aluminum alloy skin material, it is preferable that the Si content is 1.00 mass% or less, the Fe content is 1.00 mass% or less, the Cu content is 0.10 mass% or less, the Mn content is 0.10 mass% or less, the Mg content is 0.10 mass% or less, the Zn content is 0.10 mass% or less, and the total content of Si and Fe is 1.00 mass% or less. In the aluminum alloy constituting the aluminum alloy skin material, it is particularly preferable that the Si content is 0.25 mass% or less, the Fe content is 0.40 mass% or less, the Cu content is 0.05 mass% or less, the Mn content is 0.10 mass% or less, the Mg content is 0.05 mass% or less, and the Zn content is 0.05 mass% or less.

Ti has the function of refining the crystal grains of the aluminum alloy ingot and improving its strength. If the Ti content of the aluminum alloy that constitutes the aluminum alloy skin material is too high, coarse crystals may form and the toughness may decrease, so the Ti content is preferably 0.10 mass% or less, and particularly preferably 0.05 mass% or less.

In the aluminum clad plate material for protecting space debris of the present invention, the cladding ratio of the aluminum alloy skin material is preferably 5 to 20%, and particularly preferably 10 to 15%. By having the cladding ratio of the aluminum alloy skin material in the above range, it becomes easier to obtain the effect of reducing ejecta when space debris collides. The thickness of the aluminum clad material used as a bumper material for protecting space debris is usually about 0.50 to 20.0 mm, so by having the cladding ratio of the aluminum alloy skin material in the above range, the thickness of the aluminum alloy skin material becomes 0.025 to 4.0 mm, preferably 0.050 to 3.0 mm, which is suitable for obtaining the effect of reducing ejecta when space debris collides. In addition, in the aluminum clad plate material for protecting space debris of the present invention, the thickness of the aluminum alloy skin material is preferably 0.025 to 4.0 mm, and particularly preferably 0.050 to 3.0 mm.

In the aluminum clad plate material for protecting space debris of the present invention, the tensile strength of the aluminum alloy skin material is lower than the tensile strength of the aluminum alloy core material, preferably at least 195 MPa lower, and particularly preferably 200 to 340 MPa lower, and the elongation of the aluminum alloy skin material is greater than the elongation of the aluminum alloy core material, preferably at least 12% higher, and particularly preferably 12 to 32% higher. When space debris collides, the skin material near the impact site peels off from the core material and deforms by warping, but it is believed that energy is consumed in the peeling and deformation, which is presumably why there are fewer ejecta when space debris collides.

In addition, in the aluminum clad plate material for protecting space debris of the present invention, the cladding ratio of the aluminum alloy skin material is 5-20%, preferably 10-15%, so that when space debris collides, as shown in Figure 3, the skin material near the impact site peels off from the core material and deforms by warping (circled area in Figure 3). Therefore, it is believed that energy is consumed in the peeling and deformation, which is believed to enhance the effect of reducing ejecta when space debris collides.

The tensile strength of the aluminum clad plate material for protecting space debris of the present invention is preferably 248 MPa or more, more preferably 248 to 380 MPa, and particularly preferably 257 to 366 MPa. The thickness of the aluminum clad plate material for protecting space debris of the present invention is preferably 0.50 to 20.0 mm, more preferably 0.70 to 19.0 mm, and particularly preferably 1.0 to 18.0 mm.

The manufacturing method of an aluminum clad plate material for protecting space debris according to the present invention is a manufacturing method of an aluminum clad plate material for protecting space debris,
a rolling step of clad-rolling the aluminum alloy core material and the aluminum alloy skin material;
A heat treatment process is performed on the clad material of the aluminum alloy core material and the aluminum alloy skin material, the heat treatment process being a solution treatment, a rapid cooling process, and an artificial aging treatment process.
The aluminum alloy core material of the aluminum clad plate material is made of JIS 6061 aluminum alloy, and has a tensile strength of 295 MPa or more and a yield strength of 245 MPa or more;
the aluminum alloy skin material of the aluminum clad plate material is made of an aluminum alloy having a lower tensile strength and a higher elongation than the aluminum alloy core material;
This is a manufacturing method of an aluminum clad plate material for space debris protection, characterized by the above.

The manufacturing method of the present invention for producing aluminum clad plate material for space debris protection includes at least a rolling process and a heat treatment process.

The rolling process involves stacking an ingot for the aluminum alloy core material and an ingot for the aluminum alloy skin material, hot rolling them, and cladding the aluminum alloy skin material onto the aluminum alloy core material.

In the rolling process of the present invention, which is a method for manufacturing an aluminum clad plate material for space debris protection, aluminum alloy ingots having the desired component compositions to be used for the core material and the skin material are melted and cast, respectively, to produce an aluminum alloy ingot for the aluminum alloy core material and an aluminum alloy ingot for the aluminum alloy skin material. These ingots are then stacked and hot rolled.

The composition of the ingot for the aluminum alloy core material is that of JIS 6061 aluminum alloy. The composition of the ingot for the aluminum alloy skin material is not particularly limited as long as it is a composition that can produce a skin material with a predetermined tensile strength and elongation, and is preferably that of a JIS 1000 series aluminum alloy, and particularly preferably that of a JIS 1050 aluminum alloy. The composition of the JIS 6061 aluminum alloy, the composition of the JIS 1000 series aluminum alloy, and the composition of the JIS 1050 aluminum alloy are as described above.

The melting and casting methods for producing the ingots are not particularly limited, and conventional methods can be used.

The core ingot and the skin ingot are homogenized as necessary. The preferred temperature range for the homogenization is 470 to 590°C, and the homogenization time is 2 to 20 hours.

The cast core and skin ingots are milled to a specified thickness, and the skin ingot is then superimposed on one side of the core ingot. The superimposed core and skin ingots are then hot rolled at 200 to 550°C, preferably 250 to 500°C. The hot rolling is continued until the thickness of the aluminum clad plate material for space debris protection of the present invention is reached, preferably 0.5 to 50 mm, and particularly preferably 1 to 40 mm.

The heat treatment process in the manufacturing method of the aluminum clad plate material for space debris protection of the present invention is a process in which a plate-shaped clad material in which an aluminum alloy skin material is clad around an aluminum alloy core material is subjected to solution treatment, rapid cooling, and artificial aging treatment.

In the heat treatment process, first, the clad material, in which the aluminum alloy skin material is clad on the aluminum alloy core material obtained by the rolling process, is heated at 400 to 600°C, preferably 450 to 560°C, for 0.1 to 20 hours, preferably 0.5 to 10 hours to perform a solution treatment, and the solution-treated clad material is then quenched. The cooling rate of the clad material is preferably 10 to 500°C/sec. Water cooling is usually used to quench the clad material.

In the heat treatment process, the clad product, in which the aluminum alloy skin material is clad around the aluminum alloy core material, is then heated at 100 to 250°C, preferably 110 to 200°C, for 1 to 48 hours, preferably 2 to 24 hours, to perform aging treatment.

In the manufacturing method of the present invention for aluminum clad plate material for space debris protection, in addition to the rolling and heat treatment processes, tensile straightening may be performed as necessary.

Then, by carrying out the manufacturing method of the aluminum clad plate material for protecting space debris of the present invention, an aluminum clad plate material is obtained that is composed of an aluminum alloy core material and an aluminum alloy skin material clad on one side of the aluminum alloy core material. The aluminum alloy core material of the aluminum clad plate material obtained by carrying out the manufacturing method of the aluminum clad plate material for protecting space debris of the present invention is made of JIS 6061 aluminum alloy and has a tensile strength of 295 MPa or more and a yield strength of 245 MPa or more, and the aluminum alloy skin material of the aluminum clad plate material is made of an aluminum alloy that has a lower tensile strength and a higher elongation than the aluminum alloy core material. In other words, the manufacturing method of the aluminum clad plate material for protecting space debris of the present invention allows the aluminum clad plate material for protecting space debris of the present invention to be obtained.

The aluminum alloy core material and aluminum alloy skin material of the aluminum clad plate material obtained by the manufacturing method of the aluminum clad plate material for space debris protection of the present invention are the same as the aluminum alloy core material and aluminum alloy skin material of the aluminum clad plate material for space debris protection of the present invention.

The present invention will be specifically explained below with reference to examples, but the present invention is not limited to the examples shown below.

Example 1
<Production of Aluminum Clad Sheet Material>
By continuous casting, a core ingot and a skin ingot having the composition shown in Table 1 were produced. The core ingot was then homogenized and then face-cut to obtain a predetermined thickness. The skin ingot was then hot-rolled to obtain a predetermined thickness. The skin ingot was then stacked on the core ingot obtained in this manner, and the stack was hot-rolled to join the core ingot and the skin ingot, and hot-rolled to a thickness of 17.0 mm.
The obtained clad product was then subjected to a solution treatment at 530° C. for 2 hours, followed by water cooling. Then, an aging treatment was performed at 160° C. for 18 hours to obtain an aluminum clad plate material A. At this time, the clad ratio of the skin material of the aluminum clad plate material A was 10%.
The tensile strength, yield strength and elongation were also measured for the aluminum alloy core material and the aluminum alloy skin material constituting the aluminum clad plate material A. The results are shown in Table 2.
Next, a projectile impact test (projectile impact speeds of 1.15 km/s and 1.92 km/s) was conducted on the aluminum clad plate A obtained as a test material. The results are shown in Figures 1 and 2. In addition, the vicinity of the projectile impact site of the plate after the projectile impact test at a projectile impact speed of 1.15 km/s was photographed by X-ray CT. The results are shown in Figure 3.

<Preparation of samples for measuring physical properties>
Separately from the above, a core ingot was produced having the composition shown in Table 1. Next, the core ingot was homogenized and then surface-machined to give the core ingot a predetermined thickness.
Next, the thus obtained core ingot was hot rolled to a plate thickness of 2.0 mm.
The hot-rolled product was then subjected to a solution treatment at 530° C. for 2 hours, followed by water cooling, and then aging treatment at 160° C. for 18 hours to obtain a core material sample B for measuring physical properties.
Separately from the above, an ingot for skin material was produced having the composition shown in Table 1. Next, the ingot for skin material was hot-rolled to a plate thickness of 2.0 mm.
The hot-rolled product was then subjected to a solution treatment at 530° C. for 2 hours, followed by water cooling. Then, an aging treatment was performed at 160° C. for 18 hours to obtain a skin material sample C for measuring physical properties.
Next, the tensile strength, yield strength and elongation of the core material sample B for physical property measurement and the skin material sample C for physical property measurement were measured. The results are shown in Table 2.

<Projectile impact test>
A2017 aluminum spheres with a diameter of 2.4 to 2.5 mm were used as projectiles, and the projectiles were accelerated to a speed of 1.15 to 2.03 km/s and collided vertically with the test material. The scattered ejecta were collected, and the number of ejecta whose ejecta diameter (defined as the length of the longest part of the ejecta) was 1/5 or more of the projectile diameter was counted. Since it is known that the ejecta diameter is proportional to the projectile diameter, and the number of ejecta is proportional to the 1.5th power of the projectile speed (similarity law) (Non-Patent Document 1), "(ejector number)/(projectile speed) ^1.5 " for each "(ejector diameter)/(projectile diameter)" was compared.

Example 2
An aluminum clad plate material B was obtained in the same manner as in Example 1, except that the thicknesses of the core ingot and the skin ingot were adjusted so that the clad ratio of the skin material was 15%.
Next, a projectile impact test was carried out on the aluminum clad plate material B in the same manner as in Example 1, except that the impact velocity of the projectile was set to the impact velocity shown in Table 3. The results are shown in Figs. 4 and 5.

(Comparative Example 1)
By continuous casting, a core ingot having the composition shown in Table 1 was produced. Next, the core ingot was homogenized and then surface-machined to a predetermined thickness.
Next, the thus obtained core ingot was hot rolled to a plate thickness of 17.0 mm.
The hot-rolled product was then subjected to a solution treatment at 530° C. for 2 hours, followed by water cooling. Then, an aging treatment was performed at 160° C. for 18 hours to obtain an aluminum sheet material a.
Next, a projectile impact test was carried out on the aluminum plate material a in the same manner as in Example 1, except that the impact velocity of the projectile was set to the impact velocity shown in Table 3. The results are shown in Figures 1, 2, 4, and 5.

＊表中、「－」は検出下限値以下であることを示す。

*In the table, "-" indicates that the value was below the lower detection limit.

From Figures 1, 2, 4 and 5, it was found that in Examples 1 and 2 of the present invention, the number of ejections caused by collisions of flying objects is smaller than in Comparative Example 1, and therefore fewer ejections are generated when space debris collides.

Claims (6)

An aluminum alloy clad material in which an aluminum alloy core material and an aluminum alloy skin material are laminated,
The aluminum alloy core material is made of JIS 6061 aluminum alloy, has a tensile strength of 295 MPa or more and a yield strength of 245 MPa or more,
the aluminum alloy skin material is made of an aluminum alloy having a lower tensile strength and a higher elongation than the aluminum alloy core material;
An aluminum clad plate material for space debris protection, characterized by: The aluminum clad plate material for space debris protection according to claim 1, characterized in that the aluminum alloy core material is made of JIS 6061-T6 aluminum alloy or JIS 6061-T651. The aluminum clad plate material for space debris protection according to claim 1 or 2, characterized in that the aluminum alloy skin material is made of a JIS 1000 series aluminum alloy. The aluminum clad plate material for space debris protection according to claim 3, characterized in that the aluminum alloy skin material is made of JIS 1050 aluminum alloy. An aluminum clad plate material for protecting space debris according to any one of claims 1 to 4, characterized in that the clad ratio of the aluminum alloy skin material is 5 to 20%. A method for manufacturing an aluminum clad plate material for space debris protection, comprising the steps of:
a rolling step of clad-rolling the aluminum alloy core material and the aluminum alloy skin material;
A heat treatment process is performed on the clad material of the aluminum alloy core material and the aluminum alloy skin material, the heat treatment process being a solution treatment, a rapid cooling process, and an artificial aging treatment process.
The aluminum alloy core material of the aluminum clad plate material is made of JIS 6061 aluminum alloy, and has a tensile strength of 295 MPa or more and a yield strength of 245 MPa or more;
the aluminum alloy skin material of the aluminum clad plate material is made of an aluminum alloy having a lower tensile strength and a higher elongation than the aluminum alloy core material;
A manufacturing method of an aluminum clad plate material for protecting space debris, characterized by the above.

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