JP6695725B2 - Al-Mg-Si alloy plate - Google Patents

Description

  The present invention relates to an Al-Mg-Si alloy plate, and more particularly to an Al-Mg-Si alloy plate having a thickness of 0.9 mm or more, which is excellent in thermal conductivity, conductivity, strength and workability.

  Heat generating elements such as flat panel TVs, flat panel monitors for personal computers, laptops, 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 internal covers. The material of the member to be built in or mounted is required to have excellent thermal conductivity, strength and workability for prompt heat dissipation.

  Pure aluminum alloys such as JIS 1100, 1050, and 1070 have excellent thermal conductivity but low strength. An Al-Mg alloy (5000 series alloy) such as JIS 5052 used as a high strength material is significantly inferior in thermal conductivity and conductivity to a pure aluminum series alloy.

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

  For example, in patent document 1, 0.1-0.34 mass% of Mg, 0.2-0.8 mass% of Si, 0.22-1.0 mass% of Cu are contained, and the balance contains Al and An Al-Mg-Si based alloy, which consists of unavoidable impurities and has 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, and preheated at a temperature of 400 to 540 ° C. After that, hot rolling, cold rolling at a reduction rate of 50 to 85%, and then annealing at a temperature of 140 to 280 ° C. are performed, and a method for producing an Al—Mg—Si alloy rolled sheet is provided. It is disclosed.

  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 0.02% by mass. 0.15 mass%, Cr: 0.02 to 0.15% of 1 type or 2 types, and the balance regulates Al and Ti in unavoidable impurities to 0.2% or less, or Cu: 0.01 to 1 mass% or rare earth element: 0.01 to 0.2 mass% An aluminum alloy plate having a composition containing one or two is produced by continuous casting and rolling, and then cold rolling. Then, a solution treatment at 500 to 570 ° C. is performed, a cold rolling is further performed at a cold rolling ratio of 5 to 40%, and an aging treatment of heating to 150 to less than 190 ° C. is performed after the cold rolling. And a method for producing an aluminum plate having excellent heat conductivity, strength and bending workability.

  Patent Document 3 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: 0.1% by mass or less, and the balance Al and unavoidable impurities, or Mn and Cr as impurities are Mn: 0.1% by mass. %, Cr: 0.1% by mass or less of an Al-Mg-Si alloy ingot, which is regulated to not more than 0.1% by mass, is a method for manufacturing an alloy sheet, which includes a step of hot rolling and further cold rolling. It shows a method for producing an Al-Mg-Si alloy plate, which is characterized by performing heat treatment by holding at 200 to 400 ° C for 1 hour or more between hot rolling and completion of cold rolling.

  As described in Patent Document 3, in the JIS 1000 to 7000 aluminum alloys, the thermal conductivity and the electrical conductivity show a good correlation, and an aluminum alloy plate having excellent thermal conductivity has an excellent electrical conductivity. And can be used as a conductive member material as well as a heat dissipation member material.

JP 2012-62517 A JP, 2007-9262, A JP, 2003-321755, A

  As described above, the Al-Mg-Si alloy plate has been improved, but with the higher performance of products using aluminum alloy member materials, in addition to high electrical conductivity and workability, it has higher strength than before. Is required for the Al-Mg-Si alloy plate, whereas the Al-Mg-Si alloy plate described in Patent Document 1 has relatively high conductivity but low tensile strength. With the methods described in Document 2 and Patent Document 3, it was difficult to obtain the required strength while maintaining high conductivity and workability.

In the prior art document, focusing on an example having a relatively large plate thickness, Patent Document 1 shows an example of an Al—Mg—Si alloy rolling plate having a final plate thickness of 1 mm and 1.5 mm. The tensile strength of the example is 220 N / mm ² (MPa) is less than. On the other hand, in Cited Document 2, the tensile test strength exceeds 320 MPa in Examples with a plate thickness of around 1.0 mm, but the conductivity is low, and the conductivity improves when the temperature during aging is increased, but the tensile test strength is higher. Is decreasing.

  In view of the above technical background, the present invention has an object to provide an Al-Mg-Si alloy plate having a thickness of 0.9 mm or more, which has high electrical conductivity and good workability, and further has high strength. To do.

The above problem can be 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, Further, at least one of Ti: 0.1% by mass or less or B: 0.1% by mass or less is contained, the balance is Al and unavoidable impurities, the tensile strength is 280 MPa or more, and the conductivity is 54% IACS or more. An Al-Mg-Si alloy plate having a thickness of 0.9 mm or more.
(2) The Al-Mg-Si-based alloy plate according to the above item 1, wherein Mn, Cr, and Zn as impurities are regulated to 0.1% by mass or less, respectively.
(3) The Al-Mg-Si based alloy plate according to the above 1 or 2, wherein Ni, V, Ga, Pb, Sn, Bi and Zr as impurities are regulated to 0.05% by mass or less, respectively.
(4) The Al-Mg-Si alloy plate according to any one of the preceding items 1 to 3, in which 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 the preceding items 1 to 4, wherein the total content of rare earth elements as impurities is regulated to 0.1% by mass or less.
(6) The Al-Mg-Si alloy plate according to any one of the preceding items 1 to 5, which has a 0.2% proof stress of 230 MPa or more.
(7) The Al—Mg—Si alloy plate according to any one of the items 1 to 6, which has a tensile strength of 285 MPa or more.

  According to the invention described in the above item (1), the chemical composition is Si: 0.2 to 0.8 mass%, Mg: 0.3 to 1 mass%, Fe: 0.5 mass% or less, and Cu: 0. 0.5% by mass or less, Ti: 0.1% by mass or less or B: 0.1% by mass or less, and the balance Al and unavoidable impurities, strength, thermal conductivity, and processing. An Al-Mg-Si alloy plate having a thickness of 0.9 mm or more, which has excellent properties, can be formed.

  According to the invention described in the above item (2), Mn, Cr, and Zn as impurities are regulated to 0.1% by mass or less, respectively, so that the thickness is excellent in strength, thermal conductivity, and workability. It can be an Al-Mg-Si based alloy plate of 0.9 mm or more.

  According to the invention described in the above paragraph (3), since Ni, V, Ga, Pb, Sn, Bi and Zr as impurities are regulated to 0.05% by mass or less respectively, strength, thermal conductivity, It can be an Al-Mg-Si alloy plate having excellent workability.

  According to the invention described in the above item (4), since Ag as an impurity is regulated to 0.05% by mass or less, an Al-Mg-Si alloy plate excellent in strength, thermal conductivity and workability is obtained. You can do it.

  According to the invention described in the above paragraph (5), the total content of rare earth elements as impurities is regulated to 0.1% by mass or less, so that the Al-Mg-Si-based alloy has high strength, thermal conductivity and workability. It can be an alloy plate.

  According to the invention described in the above item (6), an Al-Mg-Si alloy plate having a high yield strength can be obtained.

  According to the invention described in the above item (7), an Al-Mg-Si alloy plate having a higher yield strength can be obtained.

  In the method for producing an Al-Mg-Si alloy sheet in which hot rolling and cold rolling are sequentially performed, the inventor of the present application sets the surface temperature of the alloy sheet just after hot rolling to a predetermined temperature or less and hot rolling. By performing a heat treatment as an aging treatment after the completion of rolling and before the completion of cold rolling, an Al-Mg-Si alloy plate having high electrical conductivity and good workability as well as higher strength can be obtained. This has led to the invention of the present application.

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

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

  Mg and Si are elements necessary for developing strength, and the respective contents are Si: 0.2 mass% or more and 0.8 mass% or less, and Mg: 0.3 mass% or more and 1 mass% or less. If the Si content is less than 0.2 mass% or the Mg content is less than 0.3 mass%, sufficient strength cannot be obtained. On the other hand, when the Si content exceeds 0.8 mass% and the Mg content exceeds 1 mass%, the rolling load in the hot rolling increases, the productivity decreases, and the formability of the obtained aluminum alloy sheet also increases. become worse. 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 mass% or more and 0.9 mass% or less, and more preferably 0.45 mass% or more and 0.55 mass% or less.

  Fe and Cu are components necessary for molding, but if they are contained in a large amount, the corrosion resistance decreases. In the present application, the Fe content and the Cu content are regulated to 0.5 mass% or less. The Fe content is preferably regulated to 0.35% by mass or less, and 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 the crystal grains and preventing solidification cracking when the alloy is cast into a slab. The above effect is obtained by adding at least one of Ti and B, and both may be added. However, when contained in a large amount, many crystallized substances having large size are generated, and thus the workability, thermal conductivity and electrical conductivity of the product are lowered. The Ti content is preferably 0.1 mass% or less, more preferably 0.005 mass% or more and 0.05 mass% or less.

  Further, the B content is preferably 0.1% by mass or less, and particularly preferably 0.06% by mass or less.

  Further, although various impurity elements are unavoidably contained in the alloy element, Mn and Cr decrease conductivity and conductivity, and Zn is less contained as the content increases, because the corrosion resistance of the alloy material decreases. preferable. The content of each of Mn, Cr, and Zn as impurities is preferably 0.1% by mass or less, and more preferably 0.05% by mass or less.

  Other impurity elements other than the above include Ni, V, Ga, Pb, Sn, Bi, Zr, Ag, and rare earth elements, but are not limited to these, and rare earth elements among these other impurity elements are included. Other than the above, the content of each element is preferably 0.05% by mass or less. Among the above-mentioned other impurity elements, the rare earth element may contain one or more kinds of elements, and may be derived from the casting raw material contained in the state of misch metal, but the total content of rare earth elements 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 based alloy material specified in the present application will be described.

  The melting 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 homogenization treatment as a step prior to heating before hot rolling.

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

  The pre-hot-rolling heating is carried out in order to form a uniform structure by solid solution of crystallized substances and Mg and Si in the Al-Mg-Si alloy ingot, but if the temperature is too high, it will partially occur in the ingot. It is preferable that the heating is performed at 450 ° C. or higher and 580 ° C. or lower, and particularly 500 ° C. or higher and 580 ° C. or lower, because the melting may occur.

  The Al-Mg-Si alloy ingot may be homogenized and then cooled, and may be heated before hot rolling, or may be continuously homogenized and heated before hot rolling. The homogenization treatment and the pre-hot rolling heating may be performed at the same temperature in a preferable temperature range of the homogenization treatment and the hot rolling pre-heating.

  After casting, before hot rolling and before heating, it is preferable to chamfer the ingot to remove an impurity layer near the surface of the ingot. The chamfering may be performed after casting and before homogenization treatment, or after homogenization treatment and before heating before hot rolling.

  Hot rolling is performed on the Al-Mg-Si alloy ingot after heating before hot rolling.

  Hot rolling consists of rough hot rolling and finish hot rolling.After performing rough hot rolling consisting of multiple passes using a rough hot rolling mill, a finish hot rolling mill different from the rough hot rolling mill is used. Is used for finish hot rolling. In the present application, when the final pass of the rough hot rolling mill is the final pass of hot rolling, finishing hot rolling can be omitted.

  In the present application, the finish hot rolling is performed once by introducing an Al—Mg—Si alloy plate from one direction using a rolling machine in which one set of upper and lower work rolls or two or more sets of work rolls are continuously installed. Will take place on the path.

  When cold rolling is performed with a coil, the Al—Mg—Si alloy plate after the finish hot rolling may be wound with a winding device to form a hot rolled coil. When omitting the finish hot rolling and making the final pass of the rough hot rolling the final pass of the hot rolling, after the rough hot rolling, the Al-Mg-Si alloy plate is wound by the winding device. It may be a hot rolled coil.

  In the rough hot rolling, after keeping the state in which Mg and Si are solid-solved in accordance with the solution heat treatment, cooling of the Al-Mg-Si alloy plate by the path of the rough hot rolling or the rough hot rolling is performed. The effect of quenching can be obtained by the temperature drop due to the forced cooling after the pass and after the pass.

  In the present application, among a plurality of passes of rough hot rolling, the surface temperature of the Al—Mg—Si alloy plate immediately before the pass is 350 ° C. or higher and 470 ° C. or lower, and the Al—Mg—Si alloy plate is cooled by the pass, or A pass having an average cooling rate of 50 ° C./minute or more by passing and forced cooling after passing is called a control pass. The surface temperature of the Al-Mg-Si alloy plate immediately before the control pass is set to 350 ° C or more and 470 ° C or less because the effect of quenching by quenching in the rough hot rolling is small below 350 ° C and the temperature is higher than 470 ° C. This is because it is difficult to rapidly cool the Al-Mg-Si alloy plate after passing.

  The above average cooling rate is an Al-Mg-Si alloy from the start to the end of the control path when the forced cooling is not performed in the control path, and from the start of the control path to the end of the forced cooling when the forced cooling is performed after the control path. The value is obtained by dividing the temperature drop (° C) of the plate by the time (minutes) required.

  The forced cooling after the control pass may be sequentially performed on the rolled portion while rolling the Al-Mg-Si alloy sheet, or may be performed after rolling the entire Al-Mg-Si alloy sheet. Good. The method of forced cooling is not limited, but water cooling or air cooling may be used, or a coolant may be used.

  The control pass is preferably performed at least once, and may be performed multiple times. When the control pass is performed a plurality of times, whether or not the forced cooling is performed after the pass can be selected for each control pass. Immediately before the pass, if the surface temperature of the Al-Mg-Si alloy plate is 470 to 350 ° C and the cooling rate is 50 ° C / min or more, the control pass can be performed plural times, but one control pass is required. By lowering the temperature of the Al-Mg-Si alloy plate to below 350 ° C, quenching can be performed efficiently and effectively.

  In the present application, when forced cooling is not performed after the final pass of the rough hot rolling, the surface temperature of the Al-Mg-Si alloy sheet immediately after the final pass of the hot rolling is set as the rough hot rolling rising temperature, and When forced cooling is performed after the final pass of rolling, the surface temperature of the Al—Mg—Si alloy plate immediately after the termination of forced cooling is taken as the rough hot rolling finish temperature.

  When finishing hot rolling is carried out in the present application, finishing hot rolling is finished, and when finishing hot rolling is not carried out, hot rolling is finished at the end of the final pass of rough hot rolling, and immediately after finishing hot rolling. The surface temperature of the Al-Mg-Si alloy plate is preferably 170 ° C or lower. By setting the temperature of the alloy sheet immediately after hot rolling to 170 ° C. or lower, an effective quenching effect can be obtained, and age hardening occurs and electrical conductivity is improved by the subsequent heat treatment.

  If the surface temperature of the Al-Mg-Si alloy plate immediately after the 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 the hot rolling and before the cold rolling. Is insufficient. The surface temperature of the aluminum plate immediately after hot rolling is more preferably 150 ° C or lower, and particularly preferably 130 ° C or lower.

  When performing finish hot rolling after rough hot rolling, the surface temperature of the Al-Mg-Si alloy plate immediately before finish hot rolling is set to obtain the quenching effect by the pass of finish hot rolling. It is preferably 280 ° C or lower.

  Similarly, when finishing hot rolling is not performed and the final pass of rough hot rolling is not the 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 lower. preferable.

  On the other hand, when the final pass of rough hot rolling is the control pass without performing finish hot rolling, the control pass is the final pass of hot rolling. Therefore, the Al--Mg--Si system immediately before the final pass of hot rolling is used. The surface temperature of the alloy plate is 470 to 350 ° C, and a control path is set so that the surface temperature of the alloy plate becomes 170 ° C or less at a cooling rate of 50 ° C / min or more by rolling or rolling and forced cooling after rolling. Carry out.

  After finishing the hot rolling and before finishing the cold rolling, the Al—Mg—Si alloy plate is heat-treated to age-harden and improve the conductivity.

  In the present application, the heat treatment of the Al—Mg—Si alloy plate after the completion of hot rolling and before the completion of cold rolling is performed at a temperature of 120 ° C. or higher and lower than 200 ° C. in order to obtain the effects of age hardening and conductivity improvement. The temperature of the heat treatment is preferably 130 ° C or higher and 190 ° C or lower, more preferably 140 ° C or higher and 180 ° C or lower.

  The time for heat treatment of the Al-Mg-Si alloy plate to be carried out at a temperature of 120 ° C or higher and lower than 200 ° C after the end of hot rolling and before the end of cold rolling is not particularly limited, but the effects of age hardening and conductivity improvement can be obtained. The time may be adjusted at a predetermined temperature so as to obtain the heat treatment, and for example, the heat treatment may be performed by adjusting the time in the range of 1 to 12 hours.

  After the heat treatment, cold rolling is performed to work-harden and further improve the strength.

  The heat treatment is preferably performed after the end of hot rolling and before the start of cold rolling in order to enhance the strength improving effect of the age-hardened Al-Mg-Si alloy plate by cold rolling.

  After the heat treatment, cold rolling is performed to obtain an Al-Mg-Si alloy plate having a predetermined thickness. Cold rolling after heat treatment is preferably carried out at a rolling rate of 50% or more in order to improve strength and workability. The rolling rate of the Al-Mg-Si alloy plate by cold rolling after the heat treatment is more preferably 60% or more, and particularly preferably 70% or more.

  The Al—Mg—Si alloy plate after cold rolling may be washed as necessary.

  When the workability of the Al-Mg-Si alloy plate is further emphasized, final annealing may be performed after cold rolling. The final annealing is preferably performed at 180 ° C. or lower, more preferably 160 ° C. or lower, and particularly preferably 140 ° C. or lower to prevent the strength of the Al—Mg—Si alloy plate from becoming too low.

  The time for the final annealing of the Al-Mg-Si alloy plate performed at a temperature of 180 ° C or lower may be adjusted so that the required workability and strength can be obtained. For example, the final annealing is performed in the range of 1 to 10 hours. It may be selected according to the temperature.

  The Al—Mg—Si alloy plate of the present invention may be manufactured using a coil or a single plate. Further, the alloy sheet may be cut in any step after the cold rolling and the step after cutting may be performed as a single sheet, or slits may be formed depending on the application.

  According to the above-mentioned manufacturing method, it is possible to improve the strength while obtaining high conductivity, and the Al-Mg-Si alloy having a thickness of 0.9 mm or more, which has high strength and excellent workability. A board is obtained.

  The Al—Mg—Si alloy plate of the present application has a conductivity of 54% IACS or more and a tensile strength of 280 MPa or more. The tensile strength is preferably 285 MPa or more, more preferably 290 MPa or more. The 0.2% proof stress of the Al-Mg-Si alloy plate of the present application is preferably 230 MPa or more, more preferably 240 MPa or more, and particularly preferably 250 MPa or more.

  Examples and comparative examples of the present invention will be shown below.

  Aluminum alloy slabs having different chemical compositions shown in Table 1 were obtained by the DC casting method.

[Example 1]
The aluminum alloy slab having the chemical composition number 1 in Table 1 was chamfered. Next, the alloy slab after the chamfering was subjected to homogenizing treatment at 570 ° C. for 3 hours in a heating furnace, and then temperature was changed in the same furnace to perform heating before hot rolling at 540 ° C. for 4 hours. After heating before hot rolling, the slab at 540 ° C. was taken out of the heating furnace, and rough hot rolling was started. After the thickness of the alloy plate during the rough hot rolling reaches 25 mm, the final pass of the 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 to perform the rough heat rolling. An alloy plate having a hot rolling finish temperature of 222 ° C. and a thickness of 12 mm was prepared. In the final pass of the rough hot rolling, the alloy plate was moved while rolling, and forced cooling was performed by water cooling, in which water was sprayed onto the alloy plate sequentially from the top and bottom of the rolled alloy plate.

  After the rough hot rolling, the alloy sheet was subjected to finish hot rolling from a temperature of 220 ° C. immediately before finish hot rolling to obtain an alloy sheet having a thickness of 7.0 mm. The temperature of the alloy sheet immediately after the finish hot rolling was 111 ° C. The alloy sheet after the finish hot rolling was heat-treated at 170 ° C. for 5 hours, and then cold rolled at a rolling rate of 87% to obtain an aluminum alloy sheet having a product sheet thickness of 0.9 mm.

[Examples 2-38, Comparative Examples 1-6]
The aluminum alloy slabs shown in Table 1 were chamfered, and then treated under the conditions shown in Tables 2 to 6 to obtain aluminum alloy plates. As in Example 1, homogenization treatment and heating before hot rolling were continuously performed in the same furnace in all Examples and Comparative Examples, and forced cooling after the final pass of rough hot rolling was performed while rolling. Either water cooling in which the alloy plate was moved and sprayed with water from the top and bottom of the alloy plate after rolling was sequentially selected, or air cooling in which air cooling was performed after completion of the final pass of the rough hot rolling was selected. Further, in some examples, final annealing was performed after cold rolling.

  In Example 13, the final pass of rough hot rolling was set as the final pass of hot rolling, and finish hot rolling was not performed.

  In Comparative Example 1 and Comparative Example 2, the solution treatment was performed by performing heat treatment at 550 ° C. for 1 minute during the cold rolling and then cooling at a rate of 5 ° C./sec or more. In Comparative Example 1 and Comparative Example 2, the cold rolling rate is the total rolling rate of the cold rolling 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 was 30%.

  The tensile strength, 0.2% proof stress, conductivity and workability of the obtained alloy plate were evaluated by the following methods.

  The tensile strength and the 0.2% proof stress of JIS No. 5 test piece were measured at room temperature by a conventional method.

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

  As for workability, a bending angle was 90 °, a bending inner radius was the thickness of each alloy plate, and a bending test was performed by the 6.3 V block method of JIS Z 2248 metal material bending test method. The sample was evaluated as ◯ and the sample with cracks was evaluated as x.

  The evaluation results of tensile strength, 0.2% proof stress, conductivity, and workability are shown in Tables 7 and 8.

The Al—Mg—Si based alloy materials described in the examples which satisfy the chemical composition, tensile strength, and conductivity specified in the present application have good workability. On the other hand, in Comparative Example 1 and Comparative Example 2 in which the solution treatment was performed during the cold rolling, the conductivity was inferior to that in the present application, and the chemical compositions did not satisfy the specified range of the present invention. Alternatively, at least one of the conductivity is inferior to that in the example, and the workability is inferior.

Claims (6)

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 mass% or less or B: 0.1 mass% or less of at least one, and the balance Al and unavoidable impurities, the tensile strength is 285 MPa or more, the conductivity is 54% IACS or more, and the thickness. Of 0.9 mm or more is an Al-Mg-Si alloy plate.   The Al-Mg-Si alloy plate according to claim 1, wherein Mn, Cr, and Zn as impurities are regulated to 0.1% by mass or less, respectively.   The Al-Mg-Si based alloy plate according to claim 1 or 2, wherein Ni, V, Ga, Pb, Sn, Bi and Zr as impurities are regulated to 0.05% by mass or less, respectively.   The Al-Mg-Si based alloy plate according to any one of claims 1 to 3, wherein Ag as an impurity is regulated to 0.05% by mass or less.   The Al-Mg-Si alloy plate according to any one of claims 1 to 4, wherein the total content of rare earth elements as impurities is regulated to 0.1% by mass or less.   The Al-Mg-Si alloy plate according to any one of claims 1 to 5, which has a 0.2% proof stress of 230 MPa or more.