JP7262947B2 - Al-Mg-Si alloy plate - Google Patents

Description

The present invention relates to an Al--Mg--Si based alloy plate, particularly to an Al--Mg--Si based alloy plate having excellent thermal conductivity, electrical conductivity and strength.

Flat-screen TVs, flat-screen monitors for personal computers, notebook computers, tablet computers, car navigation systems, portable navigation systems, chassis of products such as mobile terminals such as smartphones and mobile phones, metal base printed circuit boards, and heat generating elements such as internal covers The member materials to be incorporated or attached are required to have excellent thermal conductivity, strength and workability for rapid heat dissipation.

Pure aluminum alloys such as JIS 1100, 1050 and 1070 are excellent in thermal conductivity but low in strength. Al--Mg alloys (5000 series alloys) such as JIS5052, which are used as high-strength materials, are significantly inferior in thermal conductivity and electrical conductivity to pure aluminum alloys.

On the other hand, Al-Mg-Si alloys (6000 series alloys) have good thermal conductivity and electrical conductivity, and can be improved in strength by age hardening. A method for obtaining an aluminum alloy plate having excellent conductivity and workability has been investigated.

For example, Patent Document 1 contains 0.1 to 0.34% by mass of Mg, 0.2 to 0.8% by mass of Si, 0.22 to 1.0% by mass of Cu, and the balance is Al and An alloy containing unavoidable impurities and having a Si/Mg content ratio of 1.3 or more is semi-continuously cast into an ingot having a thickness of 250 mm or more, preheated at a temperature of 400 to 540 ° C., hot rolled, and 50 A method for producing a rolled sheet is disclosed, which comprises cold rolling at a rolling reduction of ∼85%, followed by annealing at a temperature of 140 to 280°C.

Patent Document 2 contains Si: 0.2 to 1.5% by mass, Mg: 0.2 to 1.5% by mass, Fe: 0.3% by mass or less, and Mn: 0.02 to 0.15% by mass, containing one or two of Cr: 0.02 to 0.15%, the balance being Al and Ti in the inevitable impurities being regulated to 0.2% or less, or An aluminum alloy plate having a composition containing one or two of Cu: 0.01 to 1% by mass or rare earth element: 0.01 to 0.2% by mass is produced by continuous casting and rolling, and then cold rolled. Then, solution treatment is performed at 500 to 570 ° C., cold rolling is performed at a cold rolling rate of 5 to 40%, and aging treatment is performed by heating at 150 to less than 190 ° C. after cold rolling. A method for producing an aluminum alloy plate characterized by excellent thermal conductivity, strength and bending workability is described.

Patent Document 3 discloses a heat dissipating member manufactured by homogenizing an Al-Mg-Si alloy ingot, performing hot rough rolling and hot finish rolling, and then cold rolling the alloy plate into a desired shape. It contains Si: 0.2 to 0.8 wt%, Mg: 0.3 to 0.9 wt%, Fe: 0.35 wt% or less, Cu: 0.20 wt% or less, and the balance is Al and inevitable impurities An aluminum heat dissipating member is disclosed which is characterized by comprising:

In addition, in the Al-Mg-Si alloy, the thermal conductivity and the electrical conductivity show a good correlation, and the aluminum alloy plate having excellent thermal conductivity has excellent electrical conductivity. It can be used as a conductive member material.

JP 2012-62517 A JP-A-2007-9262 JP-A-2000-226628

Workability is affected by the relationship between tensile strength and yield strength. When the proof stress is lower than the tensile strength, work hardening occurs, and workability decreases in the case of multi-step molding. The workability also changes depending on the metallographic structure of the Al--Mg--Si alloy plate.

However, in Patent Literature 1, the examination of the process conditions is insufficient, and the yield strength is not examined. In addition, in Patent Document 1, the tensile strength is improved by the contribution of Si or Cu, the next most element after Al is Si or Cu, the content of Mg is relatively low, and Si and Mg is not included in the scope of the patent document 1. In addition, the claims of Patent Document 1 do not include the characteristics of the plate material and the thickness of the plate.

In Patent Document 2, although relatively high strength can be obtained, the electrical conductivity described in the examples is low.

In Patent Document 3, invention 1 described in the example has a small difference in tensile strength and yield strength but low thermal conductivity, and invention 2 has a higher thermal conductivity than invention 1, but a difference in tensile strength and yield strength. The difference is greater than invention 1.

Moreover, Patent Documents 2 and 3 do not describe the metal structure of the obtained Al--Mg--Si alloy plate.

As described above, in Patent Documents 1 to 3, it is very difficult to obtain an Al--Mg--Si alloy plate having a high electrical conductivity with values of tensile strength and yield strength close to each other.

In view of the above-described technical background, the present invention provides an Al-Mg-Si alloy plate having a high value obtained by dividing 0.2% proof stress (MPa) by tensile strength (MPa), high electrical conductivity, and high strength. intended to provide

The above problems are solved by the following means.
(1) The chemical composition contains Si: 0.2 to 0.8% by mass, Mg: 0.3 to 1% by mass, Fe: 0.5% by mass or less, and Cu: 0.5% by mass or less, Furthermore, it contains at least one of Ti: 0.1% by mass or less or B: 0.1% by mass or less, and the balance is Al and inevitable impurities, and has a tensile strength of 170 MPa or more and a 0.2% yield strength (MPa ) divided by the tensile strength (MPa) is 0.91 or more and 1.00 or less, the conductivity is 50% < conductivity < 54% (IACS), and the plate thickness is 3 mm ≤ plate thickness ≤ 9 mm. Al-Mg-Si alloy plate having.
(2) The Al--Mg--Si alloy plate as described in (1) above, wherein each of Mn, Cr, and Zn as impurities is restricted to 0.1% by mass or less.
(3) The Al--Mg--Si alloy material according to (1) or (2) above, wherein Ni, V, Ga, Pb, Sn, Bi, and Zr as impurities are each restricted to 0.05% by mass or less.
(4) The Al--Mg--Si alloy sheet according to any one of the preceding items 1 to 3, wherein Ag as an impurity is regulated to 0.05% by mass or less.
(5) The Al--Mg--Si alloy plate according to any one of (1) to (4) above, wherein the total content of rare earth elements as impurities is regulated to 0.1% by mass or less.

According to the invention described in the preceding item (1), the chemical composition is Si: 0.2 to 0.8% by mass, Mg: 0.3 to 1% by mass, Fe: 0.5% by mass or less and Cu: 0 .5% by mass or less, further contains at least one of Ti: 0.1% by mass or less or B: 0.1% by mass or less, and the balance is Al and inevitable impurities. .2% proof stress (MPa) divided by tensile strength (MPa) is large, the Al-Mg-Si alloy plate having a plate thickness of 3 mm ≤ plate thickness ≤ 9 mm having a fiber structure with high conductivity can be obtained. .

According to the invention described in the preceding item (2), Mn, Cr, and Zn as impurities are each regulated to 0.1% by mass or less, so that the tensile strength is high and the 0.2% yield strength (MPa ) divided by the tensile strength (MPa), an Al--Mg--Si alloy plate having a fibrous structure with high electrical conductivity can be obtained.

According to the invention described in the preceding item (3), Ni, V, Ga, Pb, Sn, Bi and Zr as impurities are each regulated to 0.05% by mass or less, so the tensile strength is high, An Al--Mg--Si alloy plate having a large value obtained by dividing 0.2% proof stress (MPa) by tensile strength (MPa) and having a fiber structure with high electrical conductivity can be obtained.

According to the invention described in the preceding item (4), since Ag as an impurity is regulated to 0.05% by mass or less, the tensile strength is high, and the 0.2% proof stress (MPa) is the tensile strength (MPa ), and an Al--Mg--Si alloy plate having a fibrous structure with high electrical conductivity can be obtained.

According to the invention described in the preceding item (5), since the total content of rare earth elements as impurities is regulated to 0.1% by mass or less, the tensile strength is high and the 0.2% proof stress (MPa) is achieved. An Al--Mg--Si alloy plate having a fibrous structure having a large value divided by the tensile strength (MPa) and high electrical conductivity can be obtained.

1 is a model diagram of a fiber structure of an Al--Mg--Si alloy plate of the present application; FIG.

The inventors of the present application have found that, in a method for manufacturing an Al-Mg-Si alloy plate in which hot rolling and cold rolling are successively performed, the surface temperature of the alloy plate after hot rolling is set to a predetermined temperature or less, thereby reducing the The present inventors have found that an Al--Mg--Si alloy sheet having a large value obtained by dividing .2% proof stress (MPa) by tensile strength (MPa), high electrical conductivity, and high strength can be obtained, leading to the present invention.

The Al--Mg--Si alloy plate of the present application will be described in detail below.

In the composition of the Al--Mg--Si alloy plate of the present application, the purpose of adding each element and the reason for limiting the content are as follows.

Mg and Si are elements necessary for developing strength, and the content of each of Si is 0.2 mass % or more and 0.8 mass % or less, and Mg is 0.3 mass % or more and 1 mass % or less. If the Si content is less than 0.2% by mass or the Mg content is less than 0.3% by mass, sufficient strength cannot be obtained. On the other hand, if the Si content exceeds 0.8% by mass and the Mg content exceeds 1% by mass, the rolling load in hot rolling increases, resulting in a decrease in productivity and poor formability of the resulting aluminum plate. Become. The Si content is preferably 0.2% by mass or more and 0.6% by mass or less, and more preferably 0.32% by mass or more and 0.60% by mass or less. The Mg content is preferably 0.45% by mass or more and 0.9% by mass or less, and more preferably 0.45% by mass or more and 0.55% by mass or less.

Fe and Cu are components necessary for molding, but when contained in a large amount, the corrosion resistance is lowered. In the present application, the Fe content and the Cu content are each restricted to 0.5% by mass or less. The Fe content is preferably restricted to 0.35% by mass or less, more preferably 0.1% by mass or more and 0.25% by mass or less. The Cu content is preferably 0.1% by mass or less.

Ti and B have the effect of refining crystal grains and preventing solidification cracks when the alloy is cast into slabs. The above effect is obtained by adding at least one of Ti and B, and both may be added. However, if it is contained in a large amount, a large amount of large-sized crystallized substances are formed, and the workability, thermal conductivity and electrical conductivity of the product are lowered. The Ti content is preferably 0.1% by mass or less, more preferably 0.005% by mass or more and 0.05% by mass or less. Also, the B content is preferably 0.1% by mass or less, and particularly preferably 0.06% by mass or less.

In addition, various impurity elements are inevitably contained in alloy elements, but Mn and Cr reduce the conductivity and electrical conductivity, and Zn decreases the corrosion resistance of the alloy material when the content is high, so it is necessary to reduce it. preferable. The content of each of Mn, Cr, and Zn as impurities is preferably 0.1% by mass or less, more preferably 0.05% by mass or less.

Impurity elements other than those mentioned above include Ni, V, Ga, Pb, Sn, Bi, Zr, Ag, and rare earth elements, but are not limited to these. Other than that, the content of each element is preferably 0.05% by mass or less. Among the other impurity elements, the rare earth elements may contain one or more elements, or may be derived from the raw material for casting contained in the state of misch metal, but the total content of the rare earth elements is The amount is preferably 0.1% by mass or less, more preferably 0.05% by mass or less.

Next, the processing steps for obtaining the Al--Mg--Si alloy plate specified in the present application will be described.

The dissolved components are adjusted by a conventional method to obtain an Al--Mg--Si alloy ingot. It is preferable to subject the obtained alloy ingot to a homogenization treatment as a step prior to the heating before hot rolling.

The homogenization treatment is preferably performed at 500° C. or higher.

The heating before hot rolling is carried out in order to dissolve the crystallized substances, Mg, and Si in the Al--Mg--Si alloy ingot to form a uniform structure, but if the temperature is too high, eutectic melting will occur. Therefore, it is preferable to carry out the heating at 450° C. or higher and 580° C. or lower, and particularly preferably at 500° C. or higher and 580° C. or lower.

The Al—Mg—Si alloy ingot may be homogenized and then cooled and then heated before hot rolling, or the homogenization and heating before hot rolling may be performed continuously. The homogenization treatment and the heating before hot rolling may be performed at the same temperature within the preferable temperature range for the homogenization treatment and the heating before hot rolling.

In order to remove an impurity layer near the surface of the ingot after casting and before heating before hot rolling, the ingot is preferably chamfered. Chamfering may be performed after casting and before homogenization, or after homogenization and before hot rolling.

The Al—Mg—Si alloy ingot after heating before hot rolling is subjected to hot rolling.

Hot rolling consists of rough hot rolling and finish hot rolling. Finish hot rolling is performed using In the present application, when the final pass in the roughing hot rolling mill is the final pass of hot rolling, the finishing hot rolling can be omitted.

In the present application, finish hot rolling is performed by introducing an Al-Mg-Si alloy material from one direction using a rolling mill in which one set of upper and lower work rolls or two or more sets of work rolls are continuously installed. is carried out on the path of

When the cold rolling is performed in a coil, the Al--Mg--Si alloy material after finish hot rolling may be wound up by a winding device to form a hot-rolled coil. When finish hot rolling is omitted and the final pass of rough hot rolling is the final pass of hot rolling, after rough hot rolling, the Al-Mg-Si alloy material is wound with a winding device. It may be used as a hot-rolled coil.

In rough hot rolling, after maintaining the state in which Mg and Si are dissolved according to solution treatment, the Al-Mg-Si alloy material is cooled by a pass of rough hot rolling, or after rough hot rolling. The effect of quenching can be obtained by the temperature drop due to the forced cooling after the pass and the pass.

In the present application, among the multiple passes of rough hot rolling, the surface temperature of the Al-Mg-Si alloy material immediately before the pass is 350 ° C. or more and 470 ° C. or less, and the Al-Mg-Si alloy material is cooled by the pass, or the pass A pass with an average cooling rate of 50° C./min or more due to forced cooling after the pass is called a control pass. The reason why the surface temperature of the Al-Mg-Si alloy material immediately before the control pass is 350 ° C. or higher and 470 ° C. or lower is that below 350 ° C., the effect of quenching by rapid cooling in rough hot rolling is small, and the temperature higher than 470 ° C. This is because it is difficult to rapidly cool the Al--Mg--Si alloy material that has passed through.

The above average cooling rate is from the start to the end of the control pass when forced cooling is not performed in the control pass, and from the start of the control pass to the end of forced cooling when forced cooling is performed after the control pass. It is the value obtained by dividing the temperature drop (°C) of the material by the required time (minutes).

Forced cooling after the control pass may be performed sequentially on the rolled portions while rolling the Al—Mg—Si alloy material, or may be performed after rolling the entire Al—Mg—Si alloy material. good too. The method of forced cooling is not limited, but may be water cooling, air cooling, or use of coolant.

The control path is preferably performed at least once, and may be performed multiple times. When performing multiple control passes, it is possible to select whether or not to perform forced cooling after each control pass. If the surface temperature of the Al—Mg—Si alloy material immediately before the pass is 470 to 350° C. and the cooling rate is 50° C./min or more, the control pass can be performed multiple times. By lowering the temperature of the Al—Mg—Si alloy material to less than 350° C., quenching can be efficiently and effectively performed.

In the present application, when forced cooling is not performed after the final pass of rough hot rolling, the surface temperature of the Al—Mg—Si alloy material immediately after the final pass of hot rolling is the temperature after rough hot rolling. When forced cooling is performed after the final pass of rolling, the surface temperature of the Al--Mg--Si alloy material immediately after the end of forced cooling is taken as the temperature after rough hot rolling.

In the present application, when finish hot rolling is performed, hot rolling is completed at the end of finish hot rolling, and when finish hot rolling is not performed, hot rolling is completed at the end of the final pass of rough hot rolling. The surface temperature of the Al--Mg--Si alloy material is preferably 170.degree. C. or lower.

An effective quenching effect can be obtained by setting the temperature of the alloy material to 170° C. or lower immediately after hot rolling.

If the surface temperature of the Al-Mg-Si alloy material immediately after hot rolling is too high, the effect of quenching will be insufficient, and the strength will be improved even if heat treatment is performed after hot rolling and before cold rolling. is insufficient. The surface temperature of the aluminum plate immediately after hot rolling is more preferably 150° C. or lower, particularly preferably 130° C. or lower.

When finish hot rolling is performed after rough hot rolling, the surface temperature of the Al—Mg—Si alloy plate immediately before finish hot rolling is set to It is preferably 280° C. or less.

Similarly, when finish hot rolling is not performed and the final pass of rough hot rolling is not a control pass, the surface temperature of the Al--Mg--Si alloy plate immediately before the final pass of rough hot rolling is 280° C. or less. preferable.

On the other hand, when the final pass of rough hot rolling is the control pass without finishing hot rolling, the control pass is the final pass of hot rolling. The surface temperature of the alloy plate is 470 to 350°C, and the control pass is performed so that the surface temperature of the alloy plate is 170°C or less at a cooling rate of 50°C/min or more by forced cooling after rolling or rolling and rolling. preferably.

The Al--Mg--Si based alloy material of the present application may be produced in a coil or in a single plate.

According to the manufacturing method described above, an Al--Mg--Si alloy plate having improved strength while maintaining high electrical conductivity can be obtained.

The Al--Mg--Si alloy material of the present application has a fibrous structure. A fiber structure is a metal structure elongated by plastic working.

FIG. 1 shows a model diagram of the fiber structure of the Al--Mg--Si alloy plate of the present application.

As shown in FIG. 1, in the present application, the metal structure is exposed so that the normal of the observation surface is perpendicular to both the processing direction vector of the Al-Mg-Si alloy plate and the normal direction vector of the processing surface, The grain boundary in the normal direction of the working surface of the metal structure of the observation surface observed with an optical microscope is 3 / 100 µm or more, and the metal structure in which the grain boundary with a length of 300 µm or more in the processing direction exists is defined as the fiber structure. . When the plastic working is rolling, the working direction is the rolling direction, the working surface is the rolling surface, and the observation surface is a cross section in the thickness direction cut parallel to the rolling direction.

As a method of exposing the metal structure, the surface of the Al-Mg-Si alloy material whose normal is perpendicular to both the processing direction vector of the Al-Mg-Si alloy material and the normal direction vector of the processing surface is polished. After that, a method of anodizing the polished surface can be exemplified. Barker's solution (3% hydroborofluoric acid aqueous solution) can be preferably used as the anodizing treatment solution.

The Al--Mg--Si alloy plate of the present application is defined to have a conductivity of 50%<conductivity<54% (IACS), a plate thickness of 3 mm≦plate thickness≦9 mm, and a tensile strength of 170 MPa or more. The value obtained by dividing the 0.2% proof stress (MPa) of the Al--Mg--Si alloy material of the present application by the tensile strength (MPa) is defined as 0.91 or more and 1.00 or less. An Al--Mg--Si alloy plate having a fibrous structure which satisfies the value obtained by dividing the 0.2% proof stress (MPa) by the tensile strength (MPa) and the tensile strength specified in the present application. The value obtained by dividing the 0.2% proof stress (MPa) by the tensile strength (MPa) is preferably 0.92 or more and 1.00 or less, particularly 0.93 or more and 1.00 or less.

Examples of the present invention and comparative examples are shown below.

Aluminum alloy slabs with different chemical compositions shown in Table 1 were obtained by DC casting. For the ingot of chemical composition number 20 containing rare earth elements, a raw material containing misch metal was used for casting.
[Example 1]
The aluminum alloy slab of chemical composition number 1 in Table 1 was subjected to facing. Next, the alloy slab after facing was subjected to homogenization treatment at 570° C. for 3 hours in a heating furnace, and then heated at 540° C. for 4 hours before hot rolling in the same furnace while changing the temperature. The slab at 540° C. after heating before hot rolling was taken out from the heating furnace, and rough hot rolling was started. After the thickness of the alloy plate during rough hot rolling reaches 25 mm, the final pass of rough hot rolling is performed at an average cooling rate of 80 ° C./min from the alloy plate temperature of 451 ° C. immediately before the pass, and rough heat. An alloy plate having a thickness of 12 mm was obtained at a rolling temperature of 222°C. In the final pass of the rough hot rolling, the alloy sheet was moved while rolling, and forced cooling by water cooling was performed by sequentially spraying water from above and below on the alloy sheet after rolling.

After the rough hot rolling, the alloy sheet was subjected to finish hot rolling at a temperature of 220° C. just before finish hot rolling to obtain an alloy sheet having a thickness of 7.0 mm. The temperature of the alloy sheet immediately after finish hot rolling was 111°C.

[Examples 2 to 32, Comparative Examples 1 to 6]
After facing the aluminum alloy slabs shown in Table 1, they were treated under the conditions shown in Tables 2 to 5 to obtain aluminum alloy plates. As in Example 1, in all examples and comparative examples, homogenization treatment and heating before hot rolling were performed continuously in the same furnace, and forced cooling after the final pass of rough hot rolling was performed while rolling. Either water cooling in which the alloy plate is moved and water is sprayed on the alloy plate from above and below successively to the parts of the alloy plate after rolling or air cooling in which air cooling is performed after completion of the final pass of rough hot rolling was selected.

In Example 18, the final pass of rough hot rolling was the final pass of hot rolling, and finish hot rolling was not performed.

In Comparative Examples 1 and 2, a heat treatment was performed at 550° C. for 1 minute during cold rolling, and then a solution treatment was performed in which cooling was performed at a rate of 5° C./second or more. In Comparative Examples 1 and 2, the cold rolling rate is the total rolling rate of cold rolling before and after the solution treatment, and the cold rolling after the solution treatment is based on the thickness of the alloy material after the solution treatment. was carried out so that the cold rolling rate of was 30%.

The tensile strength, 0.2% yield strength, electrical conductivity, and fiber structure of the obtained alloy plate were evaluated by the following methods.

Tensile strength and 0.2% yield strength were measured on JIS No. 5 test pieces at normal temperature by a conventional method.

The electrical conductivity was obtained as a relative value (%IACS) when the electrical conductivity of an internationally adopted standard annealed annealed copper (volumetric low efficiency of 1.7241×10 ⁻² μΩm) was defined as 100%IACS.

In the examples and comparative examples, when the metal structure of the cross section of the Al-Mg-Si alloy plate in the thickness direction cut parallel to the rolling direction is exposed, the normal line of the rolled surface of the metal structure observed with an optical microscope. A metal structure having grain boundaries of 3 grain boundaries per 100 µm or more in the rolling direction and having a length of 300 µm or more in the rolling direction was defined as a fiber structure.

As a method for exposing the metal structure, the cross section of the Al-Mg-Si alloy plate cut parallel to the rolling direction is polished with emery paper, rough buffed and finished, washed with water and dried. Furthermore, a method of anodizing in Barker's solution (3% hydroborofluoric acid aqueous solution) under conditions of bath temperature: 28° C., applied voltage: 30 V, and applied time: 90 seconds was applied.

Evaluation results of tensile strength, 0.2% yield strength, 0.2% yield strength (MPa) divided by tensile strength (MPa), conductivity, and workability, and Al-Mg-Si alloy plate Tables 6 and 7 show whether or not there is a fibrous structure.

Each example satisfies the chemical composition, tensile strength, value obtained by dividing 0.2% yield strength (MPa) by tensile strength (MPa), electrical conductivity, and plate thickness specified in the present application, and has a fiber structure. It is an Al-Mg-Si based alloy plate with excellent workability. On the other hand, Comparative Examples 1 and 2, in which solution treatment was performed during cold rolling, did not have a fibrous structure and were inferior in electrical conductivity to Examples, and in Comparative Examples 3 and 3, which did not satisfy the range specified in the present application for chemical compositions. Example 6 is inferior to the examples in at least one of tensile strength and electrical conductivity, and some are inferior in workability.

Claims (1)

The chemical composition contains Si: 0.2 to 0.8% by mass, Mg: 0.3 to 1% by mass, Fe: 0.5% by mass or less and Cu: 0.5% by mass or less, and Ti: 0.1% by mass or less or B: containing at least one of 0.1% by mass or less, the balance being Al and inevitable impurities,
Mn, Cr, and Zn as inevitable impurities are each 0.1% by mass or less, Ni, V, Ga, Pb, Sn, Bi and Zr are each 0.05% by mass or less, Ag is 0.05% by mass or less, The total content of rare earth elements is regulated to 0.1% by mass or less,
The tensile strength is 170 MPa or more, the value obtained by dividing the 0.2% yield strength (MPa) by the tensile strength (MPa) is 0.91 or more and 1.00 or less, and the conductivity is 50% < conductivity < 54% ( IACS), the plate thickness is 3 mm ≤ plate thickness ≤ 9 mm,
In the observation surface where the metal structure is exposed so that the normal is perpendicular to both the rolling direction vector and the normal direction vector of the rolling surface, grain boundaries with a length of 300 μm or more extending in the rolling direction are normal to the rolling surface An Al--Mg--Si alloy plate having a fiber structure with 3 fibers/100 μm or more in the direction.

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