JPH0565679A - Lubricating treatment for aluminum alloy - Google Patents

Abstract

PURPOSE:To obtain the effects, e.g., of enabling forming under extremely superior lubricating conditions, mass-producing products, improving external appearance, prolonging the service life of metal mold, and relaxing the restriction on the material of a lubricant. CONSTITUTION:Etching treatment is applied to the surface of a work consisting of an aluminum alloy containing 0.5-5.0wt.% Mn to melt the surface layer of the base material by >=0.5mum thickness by etching, by which the surface is embossed with the grains of Al-Mn intermetallic compound having Al and Mn as essential constituent elements. Then, a lubricant is applied.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a surface treatment method for an aluminum alloy containing Mn, and more particularly to a surface treatment method for improving the lubricity of the alloy during forming.

2. Description of the Related Art In recent years, aluminum-based materials, particularly aluminum alloys, have been reviewed for characteristics such as high strength in spite of their light weight and good corrosion resistance, and the demand for them as members for various vehicles or containers is expanding.

The types of such aluminum-based materials are roughly classified into duralumin, which is not suitable as a structural member because of its low strength but is used as a conductive material or foil as a packaging material, or duralumin. Al-Cu- (Mn) -based, Al-M used in the body of beverage cans, etc.
n- (Mg) system, Al-Si suitable for forging and casting
Al-Mg-Mn-based for systems, can lids and structural members, Al-Mg-Si-based for building materials and vehicles, or Al-Zn- (Cu) with high strength for automobile bumpers
Classified as a system.

Such an aluminum-based material is subjected to hot, warm or cold molding in order to obtain a molded product shape according to its manufacturing process or application, but the original characteristic of aluminum is that the base material is soft. for,
It has a drawback that adhesion or seizure is likely to occur on rolls or molds during molding.

In order to suppress such adhesion or seizure, it is important to select a material having a small friction coefficient (μ) under the same lubricating condition. As such a material, the above-mentioned Al--Mn-( Mg) type (3000 series established in JIS H 4000) alloys are known.
It is said that the lubricity of this aluminum alloy is superior to that of pure aluminum or other alloys due to the hard Al-Mn intermetallic compound particles dispersed in the base material. ..

[0005]

However, as the use and demand of aluminum-based materials have expanded in recent years, the demands on the material composition and molding process have been further diversified or advanced, and due to seizure or adhesion. Problems such as deterioration of the surface quality of processed products or damage to molds often occur.

As a measure to solve such a problem, Japanese Patent Laid-Open No. 1-11026 or Japanese Patent Laid-Open No. 2-10775.
In Japanese Patent Laid-Open No. 1-63, a method of improving lubricity by transferring a roughened and roughened surface specified by using a cold rolling roll or the like to a plate material of an aluminum-based material, or JP-A-63-1
JP-A-88428 proposes a method of forming a plate surface having fine irregularities by etching. In all of these methods, the surface of the aluminum-based material is roughened to make it easier to retain the lubricant and improve the lubricity.

However, it is difficult to form large irregularities by an etching treatment with an aluminum material,
On the contrary, the roll pattern, etc. disappears and the surface tends to be smooth. On the other hand, even if the surface is roughened by a roll transfer method or the like, it is also difficult to form large irregularities, and even if the formed recesses are filled with a lubricant, the effect of improving lubricity (especially the effect of preventing seizure) is not achieved. small. Further, as the workability by the rolling roll becomes higher, the pressure applied to the apex of each convex portion becomes larger, but since the apex is also the same soft material as the base material, the effect of the lubricant that crushed and became flat and filled the concave portion was Will be reduced. Further, if the degree of processing by the rolling roll is large, it may hinder the mirror appearance of the surface appearance of the processed product, and there is a possibility that the pattern remains and the appearance is impaired. Further, there is a problem that it is difficult to apply the transfer method using a rolling roll to the deformed materials other than the plate material. Therefore, development of an aluminum material having a small friction coefficient under lubrication is strongly expected from a press working manufacturer or a cold / warm working manufacturer.

[0008]

In order to achieve the above-mentioned object, the present inventors have various lubrication properties when the surface layer of an aluminum alloy is subjected to an etching dissolution treatment to form a metal structure different from a normal aluminum surface. Was examined.
(The etching dissolution referred to in the present invention does not mean that the aluminum alloy substrate is provided with irregularities, but the substrate other than the below-mentioned "intermetallic compound" is uniformly dissolved and removed to a certain depth.) It was found that the Al-Mn-based intermetallic compound buried in the base material under the surface is raised on the surface by such an etching dissolution treatment, and then a lubricant is applied, whereby the lubricating property is significantly improved. Is what led to the construction of.

That is, in the present invention, Mn is 0.5 to 5.0.
A surface layer of a workpiece made of an aluminum alloy containing 0.5% by weight is dissolved by etching to a thickness of 0.5 μm or more, and A
This is a lubrication method for forming an aluminum alloy, characterized in that Al-Mn-based intermetallic compound particles containing l and Mn as main constituent elements are raised, and then a lubricant is applied. Hereinafter, the present invention will be described in more detail.

[0010]

First, Al-M which is an important constituent factor of the present invention
As the n-based intermetallic compound, in addition to Al ₆ Mn, Al ₆ (Fe, Mn) in which a part of Mn is replaced by Fe, or Al ₁₂ and Mn such as Al ₁₂ (Fe, Mn) ₃ Si are the main constituents. A compound that can exist in aluminum as an element is shown.

In the present invention, the Mn content is 0.5 to 5.0.
The reason for this is that the Mn content is 0.5.
If it is less than wt%, the effect of improving the lubricity is poor because the amount of Al-Mn-based intermetallic compound dispersed is small. On the other hand, if it exceeds 5.0 wt%, the effect of improving the lubricity is saturated, and the material is hardened to improve workability. Due to the decrease of. Here, an additive element other than Mn, such as Mg, Si, or Cu, may be appropriately added depending on the use and purpose from the viewpoint of corrosion resistance or material strength. A when the Mn content is within the range of the present invention
The particle size of the 1-Mn-based intermetallic compound is about 2 to 15 μm at a cooling rate such as normal annealing except when special cooling such as water cooling is performed. Usually, these intermetallic compounds are uniformly dispersed in the base material, and it is rare to look into the surface of the material after it has undergone processes such as hot / cold processing or annealing. 0.5μ even if close to
It is covered with an aluminum base material with a thickness of about m.

Therefore, if the etching amount is 3 μm, the height at which the intermetallic compound having an average particle diameter of 6 μm is exposed from the surface, that is, the embossed height is high.
It becomes 5 μm. An important feature of the present invention is that the intermetallic compound buried under the surface in this way is exposed (exposed) on the surface of the material by etching dissolution treatment, and the etching amount is 0.5 μm. The above is specified, preferably 2.0 μm or more.
If the etching amount is less than 0.5 μm, the intermetallic compound that makes the face look into the surface is extremely small, so during molding, the aluminum base, which is easily seized, and the processing jig such as the metal mold are in direct contact (lubricant oil film breakage, etc.). Because of this, the opportunity to do so increases.

On the other hand, 1/2 of the average particle diameter of the intermetallic compound
Even if an etching dissolution treatment with a thickness of a certain level or more is performed, an intermetallic compound that makes a face look anew appears on the surface, but some are missing, but the effect is saturated, but the work piece is large or has a special shape. In this case, since it is difficult to uniformly etch the entire surface, the upper limit of the etching amount is not particularly limited in the present invention.

Next, the reason why the etching amount is specified as described above will be described in more detail. FIG. 1 (A)-
(D) is the etching amount (the dissolution amount of 1 μm thick is about 1.3).
It is a drawing for explaining the change in the surface state due to 5 g / m ² ) and is a photograph of the surface after etching and dissolution by a scanning electron microscope (the sample has a Mn content of 1.2% by weight). A certain Al-Mn-based 3004 alloy, the etching dissolution treatment is immersed in a 10% NaOH aqueous solution at 20 ° C).

In FIG. 1, (A) shows the case where no etching dissolution treatment is applied (as-degreased organic solvent), (B), (C).
And (D) each have an etching dissolution thickness of 0.2.
It is the surface texture of the aluminum plate which made 5, 0.50, and 2.0 micrometers. As is clear from comparison of (A) to (D), the Al-Mn-based intermetallic compound (white particles in the figure) has a surface of which the etching thickness is 0.5 μm or more of (C). Can be raised in a large amount,
At 2.0 μm in (D) this tendency is more pronounced, while for less than 0.5 μm, eg 0.25 μm etch solution thickness in (B), the intermetallics are still buried in the aluminum matrix. It barely appears on the surface.

When FIG. 1 is viewed as a whole, the unevenness of the aluminum base material such as the roll pattern tends to become smaller as the etching dissolution amount increases, and it seems that the unevenness of the aluminum base material itself does not become large due to the etching dissolution treatment. is there. From these results, in the present invention, the etching amount is 0.5 μm or more, preferably 2.0 μm or more.

The etching treatment is carried out by immersion in an alkaline solution or an acid, preferably an alkaline solution, or electrolytic treatment. In the etching treatment according to the present invention, from the viewpoint of preventing the intermetallic compound from falling off, it should be particularly noted that the etching conditions are selected so that the surrounding aluminum base material is not selectively etched. Such preferable conditions vary depending on the material composition, production history (hot rolled material, cold rolled material, annealed material, etc.), but for example, the amount of Mn is 1.0 wt% A
20 to etch the surface layer by about 3 μm in order to raise the intermetallic compound on the surface of the cold-rolled sheet of the 1-Mn alloy.
It may be immersed in 10% NaOH at -30 ° C for about 60 seconds.

After the etching treatment, it is washed with water and immediately dried, and a lubricant or rust preventive oil is applied. The lubricant to be applied may be appropriately selected depending on the type of molding process, processing temperature, etc., mineral oil-based, beef tallow-based or synthetic oil-based stock solutions or emulsions, and water-soluble or oil-based lubricants containing various solid lubricants, etc. The material is not particularly limited as long as it functions as a liquid during molding.

The coating method may be appropriately selected according to the shape of the work to be molded such as spray coating, roll coating, dip coating or electrodeposition coating. Here, FIG. 2 is a diagram for explaining the effect of reducing the friction coefficient according to the present invention. The figure shows a load of 5 using a Bowden friction and wear tester.
It is a chart measured with a kgf, a stroke length of 20 mm, and a sliding number of 200 times (maximum), and the vertical direction (vertical axis) is a steel ball pressed with a load of 5 kg to a measured sample coated with a mineral oil-based lubricating oil. Sliding (diameter 10 mm) (reciprocating)
This is the force required to do so (ie, corresponds to the coefficient of friction), and the length (width) in the vertical direction corresponds to twice the coefficient of friction.

As measurement samples, pure aluminum materials (Mn amount; 0.05 wt% or less), Al-Mn alloys (Mn amount; 1.2 wt%) and Al-Mg alloys (M
n amount; 0.05% by weight, Mg amount; 2.5% by weight), and having a thickness of 1.0 mm that has been subjected to each process of hot rolling, cold rolling, intermediate annealing, and cold rolling. A cold rolled plate was used. The friction coefficient is a state in which these three types of plates have been degreased with an organic solvent, and a state of being subjected to an etching treatment of 3 μm (to be immersed in 10% NaOH at 20 ° C. for 1 minute) in order to raise the intermetallic compound on the surface. 6 samples in total were measured.

In the case of the Al-Mn-based alloy containing 1.2% by weight of Mn, a large amount of Al-Mn-based intermetallic compound having an average particle size of 6 μm emerges on the surface after etching treatment. It is hardly found in the system. As a result, as is clear from FIG. 2, the Al-Mn alloy produced by the method of the present invention is the same as the material which is not subjected to the etching treatment.
Compared to n-based alloys and pure aluminum-based materials, the coefficient of friction is small and it is not affected by the number of sliding times. (In the case of pure aluminum, if the number of slides exceeds about 50, the friction coefficient increases due to adhesion). During sliding, the intermetallic compound is pushed into the aluminum substrate while the projections are slightly worn, but the effect of reducing the friction coefficient does not decrease, and a good lubrication state is maintained.

As described above, the method of the present invention achieves the reduction of the coefficient of friction required for the molding process by the processing on the material side, and according to the method of the present invention, seizure, die galling,
Cold, warm or hot drawing, ironing, which has been difficult to perform in the past due to material breakage or rough surface
It contributes to improving the critical forming rate such as wire drawing, extrusion or rolling, extending the life of molds and increasing the molding speed, and also widens the selection range of lubricants, etc., so that post-treatment such as degreasing and waste liquid treatment The work load is also reduced. Hereinafter, the effects of the present invention will be described in detail in Examples.

[0023]

Example 1 Mn was 0.3, 0.8 and 1.5, respectively.
5 kinds of aluminum alloy materials containing 3.8 and 5.5% by weight (the content of elements other than Mn is Fe;
0.40, Si; 0.25, Mg; 1.05% by weight, and other unavoidable impurity elements) were hot-rolled at a finishing temperature of 320 to 400 ° C to obtain a hot-rolled sheet having a sheet thickness of 3 mm. The average particle size of the Al-Mn-based intermetallic compound in these hot-rolled sheets was in the range of 1 to 13 µm. Next, these hot-rolled sheets are immersed in a 10% NaOH solution to be subjected to etching dissolution treatment of various thicknesses, then washed with water, and sprayed with a 3% water-soluble emulsion type lubricant containing mineral oil as a base oil. While applying, cold rolling was performed to obtain a cold rolled plate having a plate thickness of 1 mm. Table 1 shows the friction coefficient of each of the 11 kinds of hot-rolled sheets and cold-rolled sheets thus prepared (Bowden formula, load 5 kg, the above-mentioned mineral oil-based stock solution was used as the lubricant), and the surface of the cold-rolled sheet. The state was evaluated by 5 levels and displayed. The evaluation method of the surface condition was 1 when seizure occurred, 2 when galling occurred, 3 or 4 with some linear flaws, and 5 when the surface was beautiful.

[0024]

[Table 1]

It can be seen from Table 1 that the hot rolled sheet treated by the method of the present invention has a small friction coefficient and excellent lubricity. Therefore, when cold-rolled, it is possible to obtain a cold-rolled sheet having excellent surface properties, and the friction coefficient of the cold-rolled sheet thus prepared is also small. It is clear that a certain effect of reducing the friction coefficient can be exhibited.

[0026]

[Example 2] Sample No. 5 prepared in Example 1
(Mn; 1.5% by weight) cold-rolled sheet having a thickness of 1 mm was subjected to etching dissolution treatment (10% N
(soaked in aOH) to emboss the Al-Mn intermetallic compound on the surface, apply a mineral oil lubricant, and press to form a cup with a drawing ratio of 1.68 and a diameter of 66.0 mm. A 20% water-soluble emulsion containing a base oil as a base oil was spray-applied to a cup, and ironing processing was performed at various ironing processing rates. The limit ironing processing rate until the material broke was 48%.

Further, sample N prepared by the method of the present invention
Regarding No. 7 (Mn amount; 1.5% by weight), no particular etching treatment was performed before pressing and the ironing ratio was determined as it was, and it was 45%. On the other hand, N for comparison
When the No. 5 iron plate was not subjected to the etching treatment, the limit was determined by the same method and the ironing rate was 40%.

From these results, sample No. 5 has an effect of improving the lubricity by the etching treatment before the press working, and sample No. 7 has the lubrication up to the press working after the cold rolling by the etching treatment on the hot rolled sheet. In any case, the effect of improving lubricity by the method of the present invention is clear, such as the effect of maintaining the lubricity.

【The invention's effect】

As described in detail above, according to the method of the present invention, it is possible to improve the lubricity of the aluminum alloy material at the time of forming, and various forming processes such as cold rolling, warm rolling and hot rolling are performed. Applying the method of the present invention to a work piece during processing, deep drawing, ironing, wire drawing or extrusion processing improves mass productivity, improves the appearance of processed products, prolongs the service life of molds, and selects lubricants. It becomes possible to relax the above restrictions,
The direct merits to the related industrial fields related to the forming and processing of aluminum materials are extremely large.

[Brief description of drawings]

FIG. 1 is a scanning micrograph of the surface of an Al—Mn-based alloy for explaining the change of the surface state depending on the etching amount.

FIG. 2 is a diagram for explaining an effect of improving lubricity (reduction of friction coefficient) when an Al—Mn-based intermetallic compound is raised on the surface by etching according to the method of the present invention.

Claims (1)

[Claims] 1. A surface of a workpiece made of an aluminum alloy containing 0.5 to 5.0% by weight of Mn is subjected to an etching treatment to dissolve a surface layer of a base material by etching to a thickness of 0.5 μm or more, and the surface is treated. Al-containing Al and Mn as main constituent elements
A method of lubrication for forming an aluminum alloy, comprising the steps of embossing Mn-based intermetallic compound particles and then applying a lubricant or rust preventive oil.