KR930007948B1 - Process for making grey houshold dishes of al-alloys and it's products - Google Patents

Abstract

The method comprises (1) maintaining Al alloy at 500-550 deg.C for 4-8 hours and cooling to the room temperature to be in state of alloy structure for obtaining a natural black coloring film; (2) extruding and cold rolling the Al alloy ingot heated to 380-430 deg.C; (3) annealing the rolled sheet at 560-580 deg.C; (3) annealing the rolled sheet at 560-580 deg.C for 3-8 hours and cooling to the room temperature to be in state of the natural gray coloring; (4) forming it to the designate shape; (5) anodic oxydating for obtaining the gray coloring film in the sulfate electrolytic solution. Al alloy contains (in wt.%) 1.0-2.0 Fe, below 0.05 Ti, 0.15-0.2 Si and balance Al.

Description

Manufacturing method of gray aluminum alloy base and its aluminum alloy base

The present invention is produced by a method of forming a plate by hot extrusion and cold rolling without a hot rolling process, so that the aluminum alloy substrate has a beautiful color of gray and the structure is dense and glossy good aluminum alloy base And an aluminum alloy base.

Conventionally, there has been a manufacturing method for the aluminum alloy product to have gray color.

In other words, Japanese Patent Publication No. 49-16341 and Japanese Patent Publication No. 50-145337 and Japanese Patent Publication No. 50-145338 also present methods for producing aluminum alloy products having a natural color of gray. have.

However, such a conventional Japanese invention has a problem in that a processing process for forming a plate is performed by hot rolling and cold rolling, which requires more expensive equipment than the hot extrusion and cold rolling processes.

In other words, in general, the plate production method for producing aluminum alloy materials is produced by homogeneous processing of the slab and hot rolling to produce an intermediate plate, and then cold rolled to produce a plate of the final standard. Produces plate.

On the other hand, the present invention uses a method of producing an intermediate plate by hot extrusion instead of hot rolling during the process, and this method is not only economical in compression and rolling equipment, but also has various specifications (width, thickness) of kitchen utensils. It is a method that can give a lot of advantages in production yield and productivity in small quantity production of many kinds.

Due to such differences in the hot working (extrusion or rolling) intermediate plate production method, the conditions of the conventional Japanese inventions above are not applicable to the production process of the present invention, which is a thermal change condition in the hot deformation process of the metal that occurs during hot working. Is due to the difference.

In other words, unlike hot rolling, the product production yield and quality are remarkable, such as grain growth or shaking of compressed plate, if the heat treatment conditions (homogeneity and heating) before extrusion are inadequate due to the rapid deformation of the beads and the resulting temperature rise. Because it will fall.

For example, when the material is manufactured by a method of forming a plate by the extrusion and rolling process under conditions (for example, a homogeneous temperature of 550 ° C. or more) as in the conventional Japanese invention of the above, the intermetallic compound of Al and Fe Due to the phase change, not only coarsening of particles occurs during extrusion, but also due to the phase change, the color obtained after the coating process is different from the present invention in that the occurrence rate of defective products such as milky white or mixed color stains other than gray is high. There is a problem.

In addition, Japanese Patent Publication No. 49-16341 has a gray-white color, and Japanese Patent Laid-Open Nos. 50-145337 and 50-145338 have a gray color and are for kitchen use. Since it is not a manufacturing method for producing the product, there is no suggestion of specific conditions for the annealing process, which is an essential process in the manufacture of kitchen utensils, and the alloy conditions are also mixed with zinc (Zn) or magnesium (Mg) in addition to iron (Fe), resulting in high strength and hardness. It was too high and unsuitable for the manufacture of kitchen utensils.

The present invention solves these problems by homogeneous process (500-550) to produce a good gray aluminum alloy without the above problems by the method of forming a plate by extrusion and cold rolling by a relatively inexpensive hot extruder (500-550) 4-8 hours at ℃), annealing process (3-8 hours at 56-580 ℃) and the like specifically limited.

In other words, the present invention is not only economical, but more suitable for producing small quantities of various kinds such as kitchen utensils. will be.

The present invention is described in more detail by process as follows.

[Step 1: Casting Process]

An aluminum alloy billet (Billet) consisting of 1.0-2.0% of iron (Fe), 0.05% or less of titanium (Ti), 0.15-0.2% of silicon and the remainder of aluminum (Al) is cast in a conventional manner.

In this regard, the composition and the role of each of the cast aluminum alloys is an essential element for obtaining gray anodized film.As a content less than 1%, the color development effect is not sufficient, so color uniformity is difficult to obtain. If it exceeds, it is easy to produce coarse crystals (AlmFe) during casting, which significantly reduces the extrudability and formability during the product manufacturing process, so the Fe content should be managed within 1-2%.

Ti (titanium) does not affect the formation of gray color, but it is an element that affects extrudability, rollability, formability, and final gloss of the product by making the cast structure fine, and coarseness of Ti when the content exceeds 0.05%. Ti content should be controlled below 0.05% because crystallization will result in deterioration of processability and product quality.

Si (silicone) is an auxiliary element for obtaining a gray anodized film, and has a little effect on color tone below 0.15%, and when it exceeds 0.2%, it may cause a decrease in workability due to Si crystals. It should be managed within% -0.2%.

Second Process: Homogeneous Process

The aluminum alloy ingot obtained in the first step was heated to 500-550 ° C. and held for 4-8 hours, and then cooled to room temperature at a cooling rate of 200 ° C. or more per hour by air cooling.

At this time, the aluminum alloy ingot is in a uniform alloy structure state capable of producing a black anodized spontaneous coating.

As such, heating at 500-550 ℃ for a long time is an important process to obtain high-quality products. It removes casting segregation and casting stress formed in the aluminum alloy ingot during the casting process and forms a uniform structure so that extrusion, rolling and molding processability are achieved. The homogeneous aluminum alloy ingot thus formed forms a tissue structure with a uniform black anodized film.

If the temperature is lower than 500 ℃, the above effects cannot be sufficiently obtained. If the temperature exceeds 550 ℃, defects such as color unevenness may occur due to the phase change of AlmFe crystals produced during casting. The heating conditions of 4-8 hours must be strictly observed.

[3rd process: extrusion process]

The homogenized aluminum alloy ingot is heated to about 380-430 ° C. and extruded through an extrusion die to obtain slabs of a certain thickness.

This heating temperature has a larger preheating purpose in order to suppress the phase change and grain growth of the main intermetallic compound in the aluminum alloy due to the extrusion processing temperature during extrusion in addition to the preheating purpose for facilitating the extrusion of the aluminum alloy. If it is less than 380 ℃, it is difficult to achieve the above purpose. If it exceeds 430 ℃, excessive temperature rise during extrusion may cause tissue collapse such as grain coarsening and grain boundary melting. It must be managed.

[4th process: rolling process]

The extruded slabs are cut into appropriate sizes and cold rolled to form plates of the required thickness.

[5th process: annealing process]

The rolled sheet is heated to an annealing temperature of 560-580 ° C. and maintained for about 3-8 hours, and then cooled to room temperature at a rate of 200 ° C. or more per hour by a blowing method.

This annealing process is the most important process for obtaining a uniform gray product in addition to the purpose of intermediate annealing for improving moldability. The AlmFe crystals formed through casting and homogeneous processes have Al ₆ Fe, Al ₃ Fe having a gray color structure. By the phase change to the intermediate phase, the film obtained by the subsequent anodization process becomes gray.

If it is less than 560 ℃, it will not be able to make sufficient phase change, causing color unevenness. If it exceeds 580 ℃, an additional phase change of Al ₆ Fe, Al ₃ Fe intermediate phase will proceed, resulting in color change and nonuniformity.

At this time, the aluminum alloy plate is in a uniform alloy structure state capable of producing a desired gray anodized spontaneous coating.

[Step 6: Forming Process]

The annealed sheet material is molded into a desired shape.

[7th step: rupture step]

The sulfuric acid anodized film is treated with a conventional sulfuric acid anodized film. At this time, the concentration of sulfuric acid electrolyte is 15-22%, the electrolyte temperature is 15-25 ° C, and the current density is 0.5-2.5A / dm ^{2, and the} electrolyte time is 25-40 minutes.

By the sulfuric acid anodizing film treatment, the color of the aluminum alloy base is silver white to produce a gray anodized natural color film having corrosion resistance.

The electrolysis time is different according to the current density. If the current density is high, the color is changed to dark black system. If the current density is low, the system color is changed.

In the present description, the results of the chemical composition, the homogeneous condition, and the annealing conditions were different from each other, as shown in Table 1 below.

TABLE 1

* Color: Anodized

◎: Good ○: Normal △: Bad

Specific embodiments of the present invention are as follows.

EXAMPLE

150Kg electric aluminum melting furnace and semi continuous casting make alloy ingot (diameter 178m / m) with 4 kinds of composition as shown in table (1) above, and use electric heat treatment furnace under the conditions shown in table (1). Homogenization heat treatment was performed.

The homogenized trained alloy ingot was produced using a 1650 ton direct extruder to produce a hot extruded sheet with a width of 180 mm and a thickness of 8 mm and a length of 8 m. The sheet was then produced using a two-stage cold rolling mill to produce a 2.5 mm thick rolled sheet. After cutting the plate to 350 mm, the annealing heat treatment was performed under the conditions of Table 1 using an electric heat treatment furnace.

The annealing heat-treated plate is formed into a pot-like substance by using a hydraulic press, and then subjected to surface degreasing, and subjected to a weak polarization treatment for 30 minutes by flowing a current density of 2 A / dm 2 in a 20% sulfuric acid aqueous solution (temperature 21 ° C.). Was done.

It is manufactured as described above to obtain an aluminum alloy base having a gray outer surface and a fine structure and good gloss without hot rolling.

Claims (2)

Aluminum alloy ingot containing 1.0-2.0% of iron (Fe), 0.05% (Ti) or less, and 0.15% -0.2% of silicon (Si) is heated to a homogeneous temperature of 500-550 ° C., and maintained for 4-8 hours. After cooling, the alloy structure of the aluminum alloy was formed in such a state that a black spontaneous anodized film could be formed. Then, the alloy ingot was heated to 380 ° C.-430 ° C., extruded and cold rolled to obtain a sheet material. After heating at 580 ℃ for 3-8 hours, it is cooled to room temperature to give a gray natural color. It is molded into a desired shape and the concentration of sulfuric acid electrolyte is 15-22%, electrolyte temperature is 15-25 ℃, and current density. A method for producing a gray aluminum alloy base, which is produced by producing a gray spontaneous anodized coating film by subjecting it to 0.5-2.5 A / dm 2 and an electrolysis time of 25-40 minutes. Aluminum alloy ingot containing 1.0-2.0% of iron (Fe), 0.05% of titanium (Ti) or less, and 0.15-0.2% of silicon (Si) is heated to a homogeneous temperature of 500-550 ° C. and maintained for 4-8 hours and cooled to room temperature. The alloy structure of the aluminum alloy ingot was formed in such a state that a black spontaneous anodized film could be formed, and then the alloy ingot was heated to a temperature of 380-430 ° C., extruded and cold rolled to obtain a sheet material. After heating at 580 ℃ for 3-8 hours, it is cooled to room temperature to give a uniform gray natural color. It is molded into a desired shape and the concentration of sulfuric acid electrolyte solution is 15-22%, electrolytic temperature 15-25 ℃, Natural color of gray by anodizing film with current density 0.5-2.5A / dm2, electrolysis time 25-40 minutes Gray color of natural color by anodizing film Gray natural color by anodizing film Manufactured by producing anodized film Gray aluminum alloy vessels.