JPS6049707B2 - Manufacturing method for thin-walled extruded sections - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for producing an aluminum alloy thin-walled extruded cedar forest that improves the extrusion processability when extruding the thin-walled extruded cedar forest at high speed, particularly the surface finish of the extruded cedar forest.

Conventionally, aluminum-magnesium-silicon alloys, such as JIS6
063 alloy is generally used, but with the expansion of various uses, there is a demand for improved extrusion productivity and lighter and thinner extruded cedarwood. There is a limit. In other words, in general, in order to maintain the good surface condition required for the extruded cedar forest or the products obtained from it, an appropriate maximum extrusion speed is required when producing solid wood with a wall thickness of about 1.0 wL. is 3
Currently, the extrusion speed is 0 to 40 nL/min, and even lower extrusion speeds must be used to produce hollow materials. If higher-speed extrusion conditions are used, even if extrusion is possible temporarily, the bearing of the extrusion die will deteriorate significantly, resulting in a significant deterioration of the surface condition of the extruded cedar forest. The die must be replaced or the die bearing surface must be polished very frequently, which is disadvantageous in terms of extrusion productivity. On the other hand, 6063
An alloy that can be extruded at high speed by adding a special element to the alloy has been proposed, but it is not easy to control the concentration of the special element, and the properties and uses of the shape are limited by the added element. There are many things.

The present inventors researched the extrusion processability of 6063 alloy and various properties of extruded cedarwood obtained from it. As a result, the amount of magnesium in 6063 alloy was significantly reduced to create magnesium silicide (Mg).

By lowering the amount of silicon (Si), limiting the amount of iron as an impurity, and conversely increasing the amount of excess silicon, thin-walled extruded cedarwood can be extruded at high speed, and extrusion processability is significantly improved. At the same time, they found that the mechanical properties, surface treatment properties, and corrosion resistance of extruded cedarwood after T5 treatment are almost the same as those of 6063 alloy, making it very effective for producing thin-walled products. That is, the present invention contains 0.25 to 0.45% magnesium and 0.62 to 0.0% silicon by weight.
Using an aluminum alloy billet consisting of 80% iron as an impurity, 0.2% or less as an impurity, and the remainder aluminum and other unavoidable impurities excluding iron, the wall thickness is 1. - A method for producing a thin-walled extruded shape, which is characterized by extruding the following thin-walled extruded shape at an extrusion speed of 50 TrL,/Min or higher. The present invention will be explained in further detail. In the following description, % represents weight % unless otherwise specified. The reasons for limiting the alloy components of the aluminum alloy used in the method of the present invention will be explained.

If the amount of magnesium is less than 0.25%, the amount of magnesium silicide produced will be insufficient and the desired strength will not be obtained.

Moreover, if it is 0.45% or more, the amount of magnesium silicide produced is too large, resulting in a decrease in extrusion processability, making it difficult to make the shape thinner and to extrude at high speed. A most preferred amount of magnesium is selected from the range 0.30-0.40%. If silicon is less than 0.62%, the amount of excess silicon will be insufficient in relation to the amount of magnesium silicide produced, and no improvement in strength can be expected by T5 treatment after extrusion.

If it is 0.80% or more, although the strength is satisfactory, extrusion processability deteriorates and the intended purpose of the present invention cannot be achieved.

Most preferably, the amount of silicon is selected from the range of 0.62 to 0.70%. Iron is an impurity, and when its amount increases, it induces a large number of defects on the surface of the extruded section.
．． It needs to be 20% or less. In addition, since the surface condition of the extruded shape often deteriorates when the amount of other unavoidable impurities increases, it is preferable to limit each impurity to 0.10% or less, and the total amount to 0.15% or less.

Note that this alloy, like the normal 6063 alloy, can be refined using a master alloy or solvent containing titanium and/or boron at the stage of melting.

Since such aluminum alloys are used for extrusion processing,
It is usually formed into a built-in structure using a continuous casting method.

Next, an extrusion method using this aluminum alloy billet will be described. In carrying out the method of the present invention, the aluminum alloy billet is used to extrude a thin extruded section with a wall thickness of 1.0 mm or less into a 50rr L. Extrusion processing is performed at a high speed of /Min or higher.

The aluminum alloy billet is homogenized prior to extrusion as in the usual case, but the conditions are 480-5
It may be carried out at about 80°C for 2 to 1 hour. The build is extruded either at the homogenization temperature or, most commonly, after cooling and preheating to the appropriate extrusion temperature. The preheating temperature at this time is usually 430 to 480 degrees Celsius for solid materials and 460 to 520 degrees Celsius for hollow materials. /
Extrusion processing is performed at a high speed of Min or higher. By extruding under these conditions, the cast structure of the billet is sufficiently destroyed, and a thin-walled shape having a good structure can be obtained.
Since the aluminum alloy used in this case has a relatively low Mg addition amount, the amount of magnesium silicide produced is reduced, and extrusion processability is improved. On the other hand, the lack of strength due to the small amount of magnesium silicide is compensated for by relatively increasing the amount of excess Si, and with the aim of increasing the strength through subsequent heat treatment, we aim to achieve the desired strength and increase the strength of magnesium silicide. By controlling the amount of Si and the amount of excess Si, it is possible to obtain a product with improved surface finish through thin-walled high-speed extrusion. Depending on the combination of extrusion conditions, it is possible to extrude thin-walled shapes of 0.7 TIrm or less, or to adopt high-speed conditions of extrusion speed of 70 rrL/Min or more. The shape thus extruded was further tempered by the process 5 to have a tensile strength of 18 kg.
/i or more can be obtained.

The most effective tempering condition is heating at 180 to 220°C for 1 to 6 hours. This shape can be used as it is or with some processing to make the final product, but it is common to use surface treatments such as anodizing to make the product more resistant to corrosion and weather.

Next, examples of the present invention will be shown.

Example 1 An aluminum alloy billet (152 wrmφ x 55 d) having the chemical composition shown in Table 1 was homogenized at 530 to 580°C for 2 to 5 hours, and extruded under the conditions shown in Table 2 to obtain a billet with maximum thickness. Thickness 0.7Trr! A solid material of Rt was obtained.

The results of measuring the surface roughness of this profile are also shown in Table 2. Furthermore, the obtained shape can be used as it is, or
Their mechanical properties were investigated by subjecting them to T5 treatment for 4 hours at 0°C.

The results are shown in Table 3.

Further, the T5-treated shapes were anodized in a 15% sulfuric acid aqueous solution to form films with a thickness of about 6μ and about 9μ, and these were subjected to a cast test based on JISH868l to examine their corrosion resistance.

The results are shown in Table 4. As described above, the thin-walled extruded shape obtained by carrying out the method of the present invention has a much better surface condition than the shape obtained by extruding JIS6O63 alloy under almost the same conditions, and has better mechanical properties. No significant difference was observed in surface treatment properties and corrosion resistance.

Claims (1)

[Scope of Claims] 1. Magnesium 0.25-0.45%, silicon 0.62-0.80%, iron as an impurity 0.2% or less, the balance being aluminum and other unavoidable materials other than iron. Using an aluminum alloy billet containing impurities, a thin extruded section with a wall thickness of 1.0 mm or less was extruded at an extrusion speed of 50 m/mi.
A method for producing a thin-walled extruded shape, characterized by extruding at a high speed of n or more. 2 Magnesium in aluminum alloy is 0.3 by weight
The method according to claim 1, wherein the amount is 0 to 0.40%. 3 Silicon in aluminum alloy is 0.62 to 0 by weight
．． 70%.