JPS6082643A - Corrosion resistant aluminum alloy having high strength and superior ductility - Google Patents

Abstract

PURPOSE:To obtain a corrosion resistant Al alloy having high strength and superior ductility by adding specified amounts of Cu, Zn, etc. to a conventional Al-Mg-Si alloy. CONSTITUTION:An Al alloy is manufactured by adding Cu and Zn to a conventional known Al-Mg-Si alloy so as to provide a composition contg. 0.5-1.5% Mg, 0.4-1.5% Si, 0.4-1.8% Cu and 1-6% Zn and by further adding one or more among 0.05-1.0% Mn, 0.05-0.35% Cr and 0.05-0.20% Zr. The alloy is a corrosion resistant Al alloy having high strength and superior ductility, and it is extremely suitable for use as the material of a body sheet for an automobile or as a material for casting or molding.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a corrosion-resistant, high-strength aluminum alloy with excellent ductility that can be suitably used, for example, in automobile body sheets, forging materials, molding materials, etc. As a high strength aluminum alloy, △
ρ-CLI series alloy, AQ-M(] series alloy, ρ-MQ-
ST alloys are well known.

Among these, ρ-CLI alloy J: and △ρ-M
(] series alloy has a tensile strength of 30'l ('J (/ mr/
+, although it has mechanical properties of elongation of 30%,〕ψ
Since it is inferior in hot workability such as rolling properties and rolling properties, it has the disadvantage of being restricted in its specific uses.

On the other hand, the Au-Mg-5+ alloy has the above-mentioned △a-
It is widely used as an extrusion material due to its superior hot workability and corrosion resistance compared to CU-based alloys and ρ-Mg-based alloys.
? It is used for lff1 purposes, but on the other hand, it has the drawback of being somewhat inferior in mechanical properties such as tensile strength and elongation. Therefore, in order to increase the strength of this alloy system, Mi
It is considered to increase the ll, 5iffi, but in this case, grain boundary cracking occurs due to the precipitation of coarse Mg2Si at the grain boundaries, resulting in a significant decrease in ductility, which may not be practical as expected. Unable to obtain alloy.

Based on the above-mentioned technical background, the present invention has developed ρ-Mg-
This was done with the intention of developing a high-strength aluminum alloy based on the 8i alloy with improved strength without sacrificing its properties.

For the above purpose, the present inventor has conducted various experiments and research, and as a result has found the following points. That is, a predetermined amount of CU is added to the conventionally known Aρ-vg-sr alloy.
By adding , intergranular cracking is reduced, so it is possible to suppress a decrease in ductility and improve strength. However, insofar as this is true, A4 with Cu added
-Mg-8i alloy A6066 alloy has been known for a long time. However, it was discovered that the addition of QU did not provide sufficient ductility, and that by adding a predetermined amount of Zll in addition to this, it was possible to further reduce intergranular cracking and improve ductility.4U7. /child .

Based on the above findings, the present invention provides a corrosion-resistant, high-strength aluminum alloy with good hot workability and excellent ductility. Contains .4-1.5% C1l: 0.4-1.8% Zn: 1.0-6.0%, Mn: 0.05-1.0% Cr: 0, 05-0, The present invention provides an aluminum alloy characterized in that it contains one or more of 35% Zr20, 05% to 0.20%, and the balance consists of aluminum and unavoidable impurities.

In this specification, all "%" are expressed on a weight basis.

The reasons for limiting the composition range of the alloy according to the present invention are as follows.

(a) MQ, Si, Cu, Zn All of these components have the effect of hardening the alloy, and by specifying their respective contents within a limited composition range, the intermediate layer mainly consisting of Mg2Si that precipitates in the matrix of the alloy can be hardened. The addition of Cu and Zn makes it possible to refine the phase precipitation and obtain a material with high strength and high ductility.

That is, M (when l is less than 0.5% and Sl is less than 0.4%,
If the predetermined strength cannot be obtained and both Mg and Si exceed 1.5%, not only the strength will not be improved, but also the hot workability will deteriorate. If 7-n is less than 4% and 7-n is less than 1.0%, a sufficient effect on the refinement of the M (12si) crystals precipitated in the 71 to lix cannot be achieved, and the improvement in ductility may be insufficient. Become.

However, when Cu exceeds 1.8% or Zn exceeds 6.0%, the corrosion resistance of the alloy deteriorates.

<11) Mn, Cr, Zr These components are used to control the alloy structure, and one or more of these components may be contained in any combination. If the content of these components is less than 0.05% of Mn, Or, and Zr, the desired effect will be poor, and conversely, if Mn exceeds 1.0% and Or is 0.35%, or Zr is 0.20
%, coarse total bending compounds are produced during casting, which deteriorates mechanical properties such as strength and ductility, as well as hot workability.

As mentioned above, the alloy according to the present invention has /'1-Mg-
Because it is based on a 5i alloy, it does not deteriorate its inherent extrudability, J1 ductility, corrosion resistance, etc., and by adding CLI and 7-n, it has high strength and excellent ductility. As a result, it can be used suitably as a material for molding and forging, even in applications that could not be processed with conventional alloys. for example,
For motorcycle fork cylinders, it has a strength comparable to that of a high-strength alloy with a tensile strength of 35 Kgf/-, which previously could not be expanded, and its improved ductility makes it possible to expand it. The alloy according to the present invention satisfies both strength and ductility at the same time as the recent trend has been to pursue higher strength and thinner walls to the maximum. It is extremely useful in that it can be used in many ways.

Next, examples of the present invention will be shown in comparison with comparative examples.

(Left below C) Alloys with the various compositions shown in Table 1 were cast into billets with a diameter of finches by die casting, and after homogenization treatment at 560°C for 8 hours, the strength was 500±5°C and the extrusion speed was 6.
It was extruded into a strip plate with a thickness of 6 mm and a width of 125 m at a rate of mm/sec. Next, this extruded material was molded to a thickness of 3 mm (Red
:50%) k cold rolled, subjected to Φ solution treatment at 530°C for 1.5 hours, water-cooled, and further subjected to aging treatment at 170°C for 7 hours to prepare a sample.

Each sample was molded into a J15-4 test piece, and its tensile strength, yield strength, and elongation were measured at a gauge pressure tlJ of 50 mm. The results are shown in Table-2.

[1 space bottom margin] Table 2 As is clear from the results in the above table, the alloy according to the present invention is superior in strength and elongation at the same time as compared to conventionally known comparative alloys.

Note that since the alloy according to the present invention is a heat-treatable alloy, elongation and strength can be controlled by aging treatment conditions.

that's all

Claims (1)

[Claims] Mo: 0.5 to 1.5% Si: O, /l to 1.5% C (1: 0.4 to 1.8% Zll: 1.0 to 6.0%) Contains at least one of the following: Mn: 0.05-1.0% Cr: O, O'5-0, 35% Zr: 0.05-0.20%, the remainder being aluminum and unavoidable impurities A corrosion-resistant, high-strength aluminum alloy with excellent ductility.