JP5586502B2 - Method for producing extruded aluminum alloy - Google Patents

Description

The present invention relates to a method of manufacturing an aluminum alloy extruded shape having both high strength and high thermal conductivity.

  Conventionally, a heat sink made of an extruded shape of an aluminum alloy has been used for heat dissipation of electronic equipment. As one means for improving the heat dissipation performance of the heat sink, it is generally performed to increase the thermal conductivity of the material. A6063, which is a typical aluminum alloy for extrusion, has excellent extrudability and a complicated cross-sectional shape, but it is difficult to stably supply an extruded shape having a thermal conductivity of 210 W / m · K or more. It was.

Patent Document 1 states that by adding B, elements other than Al, particularly Ti, V, Zr, and Cr, which lower thermal conductivity, form a crystallized product with B and are dissolved in the aluminum matrix. In addition to reducing the solid solution amount of other elements, annealing is performed in a temperature range of 300 to 400 ° C. after hot working to precipitate Mg and Si dissolved in the matrix as Mg ₂ Si. In other words, the amount of solid solution in the matrix phase is reduced to suppress the decrease in thermal conductivity.
According to the aluminum alloy described in Patent Document 1, the thermal conductivity of 210 W / m · K or more is satisfied, but impurities are reduced and annealing is performed in a temperature range of 300 to 400 ° C. after hot working. As Mg ₂ Si precipitates coarsely, the strength decreases, and the mechanical properties of A6063S-T5 defined in JISH4100 are not satisfied. Such a low-strength material is difficult to use in places subject to vibration, such as vehicles such as automobiles and trains.

JP 2004-217945 A, page 3, lines 38-47

  An object of the present invention is to provide an extruded aluminum alloy having a thermal conductivity of 210 W / m · K or more and satisfying the mechanical properties of A6063S-T5 of JISH4100.

In the method for producing an aluminum alloy extruded profile according to the first aspect of the present invention, B is added during billet casting, B and boride are formed, and impurities are settled and removed, and Si is 0.4 to 0.00. 6 mass%, Fe is 0.25 mass% or less, Mg is 0.45 to 0.6 mass%, Mn, Cr and Ti are 0.02 mass% or less, and V is 0.01 mass% or less. The adjusted aluminum alloy billet is cast, the billet is extruded, an overaging treatment is performed after the extrusion, and the thermal conductivity is 210 W / m · K or more.
When an aluminum alloy extruded shape containing Si and Mg is heated at around 200 ° C., the hardness increases with the lapse of time due to precipitation of Mg ₂ Si, the hardness reaches a peak after a certain time, and thereafter the hardness gradually increases. descend. The overaging treatment means that the aging treatment is performed until the hardness exceeds a peak.

The method for producing an aluminum alloy extruded shape according to the first aspect of the present invention reduces the thermal conductivity by adding B during billet casting, forming B and boride, and precipitating and removing impurities. Impurities such as V and Ti are reduced, and further Si and Mg dissolved in the matrix phase are appropriately precipitated as Mg ₂ Si by over-aging after extrusion, so that the thermal conductivity is 210 W / m · K. With the above, an aluminum alloy extruded profile satisfying the mechanical properties of A6063S-T5 of JISH4100 can be produced. By applying the aluminum alloy extruded profile according to the production method of the present invention to a heat sink, high heat dissipation performance is obtained, and it has high strength, so it can be damaged even when used in places subject to vibration such as automobiles. It is possible to prevent a problem such as dropping or dropping out.

Embodiments of the present invention will be described below. The aluminum alloy extruded profile of the present invention contains 0.4 to 0.6% by mass of Si, 0.25% by mass or less of Fe, and 0.45 to 0.6% by mass of Mg, Mn, Cr, Ti 0.02 mass% or less, respectively, to adjust the V below 0.01 wt%.

Si is added for precipitating Mg ₂ Si to give strength to the material, and the strength increases as the content increases, but the thermal conductivity decreases. Therefore, in order to ensure high strength and high thermal conductivity, Si is set to 0.4 to 0.6% by mass.

  If Fe is too much, the thermal conductivity is lowered, so the content was made 0.25% by mass or less.

Mg is added for precipitating Mg ₂ Si to give strength to the material, and the strength increases as the content increases, but the thermal conductivity decreases. Therefore, Mg is set to 0.45 to 0.6% by mass in order to ensure high strength and high thermal conductivity.

Since Mn and Cr are elements that lower the thermal conductivity when contained in the aluminum alloy, they are adjusted to 0.02% by mass or less, respectively .

  The aluminum ingot contains Ti and V as inevitable impurities, but since these are elements that lower the thermal conductivity when contained in the aluminum alloy, in the aluminum alloy extruded shape of the present invention, A small amount of B is added during billet casting, and B and boride are formed to settle and remove these impurities (boron treatment). Ti is 0.02% by mass or less, and V is 0.01% by mass or less. Adjust to. The amount of B added to the molten metal at the time of casting varies depending on the billet diameter and the like, but a sufficient effect can be obtained by adding 0.01% by mass, for example. The billet and the extruded profile may or may not contain B, but it is preferable that the remaining amount of B is small in order to increase the thermal conductivity.

Boron treatment is performed as described above, and Si is 0.4 to 0.6 mass%, Fe is 0.25 mass% or less, and Mg is 0.45 to 0.6 mass% by a conventional semi-continuous casting method. In order to homogenize microsegregation caused by solidification by casting a billet containing Mn, Cr and Ti of 0.02% by mass or less and adjusting V to 0.01% by mass or less, respectively , the billet is subjected to heat treatment. Perform (homogenization treatment). Thereafter, the billet is heated and extruded into a desired cross-sectional shape. The homogenization treatment and the extrusion process can be performed under the same conditions as those of a normal A6063 alloy. Thereafter, an overaging treatment is performed on the extruded profile. The overaging treatment is carried out in order to increase the strength and thermal conductivity of the profile by precipitating Si and Mg dissolved in the Al matrix after extrusion as Mg ₂ Si. Usually, in the extruded shape of A6063 alloy, an aging treatment is performed by heating at 200 ° C. for 2 hours so that the strength reaches a peak. In the present invention, however, the precipitation of Mg ₂ Si progresses further and the strength reaches a peak. It heat-processes until it will pass through the vicinity.

Specific examples of the present invention are shown below. In Example 1, boron treatment is performed at the time of billet casting, and the content of Si, Fe, Mg, Mn, Cr, Ti, V is a component having the highest strength near the upper limit of the range specified in the claims. And after the extrusion, it was over-aged by heating at 200 ° C. for 16 hours. In Example 2, boron treatment is performed at the time of billet casting, and the content of Si, Fe, Mg, Mn, Cr, Ti, V is the component having the highest thermal conductivity in the vicinity of the lower limit of the range specified in the claims. In the same manner, it was over-aged after extrusion. The amount of B added during casting is 0.01% by mass. Table 1 shows the total of Mn, Cr, Ti, and V, but individually Mn, Cr, and Ti are 0.02% by mass or less, and V is 0.01% by mass or less. Comparative Example 1 was treated with boron at the time of billet casting and had the same components as Example 1, and was subjected to normal aging treatment (heating at 200 ° C. for 2 hours) after extrusion, and Comparative Example 2 was boron at the time of billet casting. Comparative example 3 is a conventional A6063 alloy extruded shape, which is not subjected to boron treatment during casting, and is subjected to normal aging treatment after extrusion.

  For each of the extruded shapes of Examples 1 and 2 and Comparative Examples 1 to 3, mechanical properties (tensile strength, 0.2% yield strength, elongation), electrical conductivity, and thermal conductivity were tested. The results are shown in Table 2.

  As shown in Table 2, Example 1 and Example 2, which were boron-treated during billet casting and over-aged after extrusion, both have excellent mechanical properties that sufficiently satisfy the A6063S-T5 standard of JISH4100. In addition, it was confirmed that a high thermal conductivity of 210 W / m · K or more was obtained. In Comparative Example 1 in which boron treatment was performed during billet casting and normal aging treatment was performed after extrusion, the tensile strength and proof stress were higher than those in Examples 1 and 2, but the thermal conductivity was lower than 210 W / m · K. It was. In Comparative Example 2 in which the overaging treatment was performed after extrusion without performing the boron treatment, the tensile strength and the yield strength were inferior to those of Example 1, and the thermal conductivity was also lower than 210 W / m · K. In Examples 1 and 2, the tensile strength and yield strength were improved and the thermal conductivity was improved as compared with Comparative Example 3 in which boron treatment was not performed and normal aging treatment was performed after extrusion.

As is clear from the above results, boron treatment was performed during billet casting to adjust Mn, Cr, and Ti to 0.02 mass% or less and V to 0.01 mass% or less, respectively , and Si to 0.4 to 0 .6 mass%, Fe is 0.25 mass% or less, Mg is 0.45 to 0.6 mass%, and the aluminum alloy extruded profile of the present invention that has been over-aged after extrusion has reduced thermal conductivity. Impurities such as V and Ti are reduced, and Si and Mg dissolved in the matrix phase are appropriately precipitated as Mg ₂ Si by over-aging treatment after extrusion, so that the thermal conductivity is 210 W / m · K or more and satisfy the mechanical properties of A6063S-T5 of JISH4100. Therefore, by applying this aluminum alloy extruded shape to a heat sink, high heat dissipation performance is obtained and it has high strength, so it can be damaged or dropped even if it is used in a place subject to vibration such as an automobile. Can be prevented from occurring.

The present invention is not limited to the embodiments described above. The alloy component can be appropriately changed within the scope described in the claims, and may contain elements not described in the claims. If the overaging treatment is performed for an excessively long time, the strength decreases and the mechanical properties of A6063S-T5 of JISH4100 are not satisfied (for example, in the case of the alloy component of Example 2, overaging treatment at 200 ° C. for 72 hours or more) Doing, 0.2% proof stress is below 110N / mm ² specified in A6063S-T5 in JISH4100), to the extent that can be obtained, thereby satisfying the mechanical properties of A6063S-T5 of JISH4100, temperature overaging And the time can be changed as appropriate. Applications are not limited to heat sinks, but can be widely used for those requiring high thermal conductivity and high electrical conductivity.

Claims (1)

At the time of billet casting, B is added, B and boride are formed, and impurities are settled and removed. Si is 0.4 to 0.6 mass%, Fe is 0.25 mass% or less, and Mg is 0.00. containing from 45 to 0.6 wt%, Mn, Cr, and Ti 0.02 wt%, respectively less, casting the aluminum alloy billet with an adjusted V below 0.01 wt%, and extruding the billet, extrusion A method for producing an extruded aluminum alloy material, characterized in that an overaging treatment is performed later and the thermal conductivity is 210 W / m · K or more.