JPH0313537A - Wheel rim made of aluminum alloy having excellent corrosion resistance and brightness and its manufacture - Google Patents

Abstract

PURPOSE:To manufacture the rim having excellent corrosion resistance and brightness by grinding an automobile wheel rim manufactured by an Al alloy having specified compsn., thereafter subjecting it to anodic oxidation treatment and executing sealing treatment in a water soln. contg. dyes. CONSTITUTION:An automobile wheel rim is manufactured by an Al alloy having the compsn. contg., by weight, 2.5 to 6.0% Mg, 0.05 to 0.5% Mn, 0.05 to 0.5% Cu, 0.05 to 0.4% Si, contg. one or more kinds among 0.05 to 0.30% Cr, 0.05 to 0.30% Zr, 0.001 to 0.1% Ti and 0.0001 to 0.002% B, in which Fe content is regulated to <=0.15% and the balance Al. The rim is subjected to mechanical grinding such as buffing or chemical grinding by phosphoric acid, sulfuric acid or the like and an anodically oxidized film having 0.1 to 3.0mum thickness is thereafter formed. The rim is successively immersed into a water soln. in which black dyes or black dyes with yellow dyes are dissolved for 1 to 40min to execute sealing treatment to pinholes in the anodically oxidized film, by which the bright rim having corrosion resistance and having a color tone similar to a Cr plating color can be manufactured.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to an automobile wheel rim made of an aluminum alloy that is excellent in both corrosion resistance and brightness, and a method for manufacturing the same.

[Conventional technology]

Conventional aluminum alloy for wheel rims is Ao-
Mg-Mn based JIS 5454 material, Al-Mg based J
IS 5052 material or Al2-Mg, -3i based JI
Materials such as S6061 have been put into practical use.

Among these alloys, JIS 5454 material and JES 505
After both of the two materials are hot-rolled, they are numerically subjected to zero-material treatment (processing to soften them by annealing) before use. The reason why zero material is treated in this way is that appropriate ductility is required when forming into a wheel rim. Furthermore, when used as a wheel rim, plating or alumite treatment is required.

[Problem to be solved by the invention]

Conventional aluminum alloys for wheel rims are assembled into wheels and then plated as described above to maintain a beautiful appearance. However, since plating increases the price of the wheel, cheaper and lighter aluminum alloy wheels are used instead. This is one obstacle in providing this service. Furthermore, in the plating process, the plating may peel off, and fatigue cracks may occur starting from the peeled parts, which poses a problem in the durability of the wheel.

Furthermore, as a surface treatment, anodic oxidation treatment is sometimes performed instead of plating treatment, but conventional aluminum alloys do not have good brightness, so there is no gloss after anodization treatment, and compared to wheels that are plated. However, it was still a problem as it was inferior in appearance and luxury.

[Means to solve the problem]

In view of this, as a result of various studies, the present invention has found that glitter is influenced by the alloy components, the surface finish before anodizing treatment, and the thickness of the anodized film. That is, Mn, Mg,
It has been found that Si influences the brightness of aluminum alloys for the following reasons.

First, when the Mn content increases beyond the specified amount, A(2-
When a Mn--Fe compound is formed and subjected to chemical polishing, the area around the compound is preferentially etched, resulting in the formation of minute irregularities and loss of brightness. Similarly, when the Mf content increases beyond the specified amount, the coarse β phase of the A12-Mg compound is formed and preferentially etched, resulting in loss of brightness. However, even when adding a large amount of Mg necessary for strengthening, by adding St at the same time, M[hSl, which is a compound of Mg and St.
was precipitated, the growth of the β phase was suppressed, and the brightness was not impaired.

Furthermore, even if the same alloy is used, the smoothness of the surface before anodizing is important in order to obtain brightness, and if the anodic oxide coating is too thick, it will not be possible to obtain luster, and it will be difficult to maintain corrosion resistance. It was also found that there is an appropriate value in terms of balance.

It was also found that dyeing with black dye is necessary to obtain a hue similar to that of chrome plating, and that sealing treatment is necessary to prevent decolorization over time.

As a result of further study, we solved the problems of conventional products, and produced an aluminum alloy wheel rim that was inexpensive and easy to process to achieve brightness, and was stronger and more reliable than conventional products. It provides law.

That is, one of the present invention is that Mg 2.5 to 6 wt%, Mn
0.05-0.5wt%, Cu 0.05-0.5
wtL Contains Sl 0.05~0.4wt%, Cr
0.05-0.3wt%, Zr 0.05-0.
3wtL Tl 0.001~0.1wtL B
Contains one or more selected from 0.0001 to 0.002 wt%, and further contains Fe at 0.15 wt%
It is characterized by being regulated as follows and consisting of the remainder A(2), unavoidable impurities, and Al.

Another aspect of the present invention is that Mg2.5 to 6wt%, Mn
0.05-0.5wt%, Cu 0.05-0.5
Contains wtL Si 0.05-0.4wt%, Cr
0.05-0.3wt%, Zr0.05-0.3wt
%, Ti 0.001-0.1wt%, B 0
．． One or two selected from 0001 to 0,002wt%
After mechanically and/or chemically polishing the alloy, which contains more than 100% of the Fe content and the Fe content is regulated to 0.15 wL% or less, and the remainder consists of Al, inevitable impurities, and AO, the alloy has a thickness of 0.
．． 1-3. Olm is anodized, and then 1 to 4
It is characterized by being immersed for 0 minutes and then subjected to a sealing treatment.

[Effect]

Next, the reason for limiting the content of the alloy components as described above will be explained.

Mn contributes to improving strength and stress corrosion cracking resistance, but its content is 0.05wtX (hereinafter referred to as W1%).
If the amount is less than 0.5%, this effect will not be obtained, and if it exceeds 0.5%, the glitter will be lost for the above-mentioned reason.

Mg is one of the elements that harden the base material, and if its content is less than 2.5%, it will not contribute to strengthening, and if it exceeds 6%, stress corrosion cracking susceptibility will increase.

Cu is also a hardening element for the base material, and if its content is less than 0.05%, it will not have this effect, and if it exceeds 0.5%, corrosion resistance will deteriorate.

If Sl is less than 0.05%, the formation of Mg and 3i is insufficient and there is no effect of improving glitter, and if it exceeds 0.4%, coarse MIhSi will precipitate unevenly and reduce the strength of the base material. .

Cr contributes to stress corrosion cracking resistance, but if it is less than 0.05%, the effect is small, and if it exceeds 0.3%, it will cause coarse A(
! - Forms a Cr-based compound and reduces ductility.

Zr also has the same effect as C, but its content is 0.
If it is less than 0.05%, the effect is small, and if it exceeds 0.3%, coarse A12-Zr compounds are formed and the ductility is reduced.

Ti and B are effective in refining grains, but they have no effect when their content is less than 0.001%, o, and oooi%, respectively, and when they exceed 0.1% and 0.002%, respectively, the ductility decreases. descend.

Addition of Fe has a slight effect on improving the glitter, but if its content exceeds 0.15%, 〇-Mn-Fe-based compounds are likely to be formed, impairing the glitter.

Also, the purpose of mechanically or chemically polishing the surface of such an aluminum alloy is to make the surface smooth and to obtain brightness, and the average roughness Ra after treatment is 0.005.
~0.1p is desirable.

As a mechanical treatment, for example, puff polishing or cutting with a lathe can be used, and as a chemical treatment, there is a method of treatment in a liquid containing phosphoric acid, sulfuric acid, nitric acid, etc. It is more efficient to use them together because the finishing time is shortened. For chemical polishing, use phosphoric acid or sulfuric acid.

Preferably, the treatment is performed at 90 to 120° C. for 0.5 to 4 minutes in a solution containing nitric acid or the like.

Furthermore, the purpose of anodizing is to obtain corrosion resistance; if the thickness is less than 0.1, it has no effect, and if the thickness exceeds 3, the gloss will be lost, and when a load is applied, it will become microscopic. This causes fatigue cracks to develop and lead to wheel failure.

Also black dye. The reason why it is dyed in a mixed aqueous solution of black dye and yellow dye is to obtain a hue similar to that of chrome plating or a deep blackish hue. In this case, it is preferable to use the black dye as an aqueous solution with a concentration of 1 -15 g/l, and the yellow dye as an aqueous solution with a concentration of 0.05 to 5 g/l. If the immersion time is less than 1 minute, the desired color cannot be obtained, and if the immersion time exceeds 40 minutes, the color becomes dark with no transparency.

The sealing treatment is performed to prevent discoloration, and it is sufficient to perform the sealing treatment at 70° C. or higher for 1 to 30 minutes.

〔Example〕

Next, examples of the present invention will be described.

Aluminum alloy No., A~No. with the composition shown in Table 1
, H were melted in a conventional manner to obtain an ingot with a thickness of 500 mm, which was soaked and then hot rolled to a thickness of 51 mm.
II11 board, then 20 o III width Xl10
It was finished to a size of 0 length, treated with 0 material, and then roll formed into a rim shape. Furthermore, after polishing this with a puff to remove surface scratches, phosphoric acid 75. Sulfuric acid 14, nitric acid 12. Boric acid8. A chemical polishing solution mixed with a volume ratio of 8 parts copper nitrate to 10 parts
Polished at 0°C for 2 minutes to obtain the surface roughness Ra shown in Table 2.
Further, test specimens were prepared by performing anodizing treatment, dyeing, and sealing treatment shown in Table 2.

Thereafter, these test specimens were examined for corrosion resistance, brightness, fatigue strength, and color as follows, and the results are also listed in Table 2.

Corrosion resistance: 90% in a 5% aqueous solution of NaC (2)
After being immersed for a day, those with corrosion holes are marked with an X mark, and those without are marked with an O mark. Brightness: The surface is irradiated with light, and the amount of reflected light relative to the incident light is measured. Display ratio as % Fatigue strength: 2000c for surface-treated plate material
A plane bending test is performed to' times at a speed of 100 pm, and the fatigue strength at that time is displayed as follows: --- If the color is similar to chrome plating, the color is ○.
As is clear from Table 2, the methods of the present invention are No. 1 to 3.
No. 5 has a brightness of 47% or more, excellent corrosion resistance, and a good coloration, even at 1 degree fatigue.
2kgf/ma+" high and stable.

On the other hand, comparative methods No. 6 to No. 12 are inferior to at least one of these special methods.

4 Bright Effects] As described above, according to the present invention, it is possible to provide bright rims that are cheaper, more reliable, and lighter than conventional chrome-treated wheel rims. Fuo that has a remarkable effect on

Claims (2)

[Claims] (1) Mg2.5-6wt%, Mn0.05-0.5w
t%, Cu0.05-0.5wt%, Si0.05-0
．． Contains 4wt%, Cr0.05-0.3wt%, Zr
0.05-0.3wt%, Ti0.001-0.1wt
%, B1 selected from 0.0001 to 0.002wt%
species or two or more species, and further contains Fe content of 0.15
An aluminum alloy wheel rim with excellent corrosion resistance and brightness, which is regulated to less than wt% and the remainder consists of Al and unavoidable impurities. (2) Mg2.5-6wt%, Mn0.05-0.5w
t%, Cu0.05-0.5wt%, Si0.05-0
．． Contains 4wt%, Cr0.05-0.3wt%, Zr
0.05-0.3wt%, Ti0.001-0.1wt
%, B1 selected from 0.0001 to 0.002wt%
species or two or more species, and further contains Fe content of 0.15
After mechanically and/or chemically polishing the alloy consisting of the balance Al and unavoidable impurities below wt%, it is anodized to a thickness of 0.1 to 3.0 μm, and then black dye is applied. Or 1 in a mixed aqueous solution of black dye and yellow dye.
A method for producing an aluminum alloy wheel rim with excellent corrosion resistance and brightness, which comprises soaking the rim for ~40 minutes and then sealing the rim.