JP4551995B2 - Aluminum alloy for casting - Google Patents

Description

The invention of this application relates to a manufacturing method that performs the control of the foundry aluminum alloys and their solidification crystal structure containing iron.

By adding a small amount of iron foundry aluminum alloy, the high-temperature strength of foundry aluminum alloys is improved are well known. Then, require strength at high temperatures from foundry aluminum alloys utilizing this method, it is also known to shape the cylinder block and an aluminum-based die-cast or the like.

However, when the iron is mixed as an impurity in the foundry aluminum alloy, when the foundry aluminum alloy not only difficult to remove the iron to solidify, acicular intermetallic compound (
Al3Fe) is mainly produced as primary crystals.

Further, in the manufacturing method of Al-Si- Fe alloy for casting, the primary crystal of the needle shaped intermetallic compounds during solidification (mainly Al3Fe) occurs it is said to be unavoidable.

  And the primary crystal of the acicular intermetallic compound produced in this way has high hardness and has a notch effect, which is considered to be a major obstacle when performing secondary processing such as rolling and extrusion. .

  In order to prevent such molding defects, conventionally, when iron (Fe) exceeds 1 wt% in an aluminum material, the aluminum material is discarded or regenerated after being diluted with a large amount of pure aluminum ingot. The method is mainly adopted.

However, since such a method wastes valuable resources, phosphorus (P) and zirconium (Zr) are prevented so that a sharp cleaved edge is not generated even when a coarse primary crystal is destroyed during molding. Or a finer such as vanadium (V) is added to make the primary crystal about 40 μm, or chromium (Cr) is added thereto to uniformly disperse the primary crystal silicon (Si). Proposed. However, the foundry aluminum alloy, a problem remains as an impurity is generated in the case of such a possible incorporation of third element reuse foundry aluminum alloy (recycling).

  A method using ultrasonic waves has been developed as a method for finely granulating primary crystals without using such a finer (see, for example, References 1 and 2).

Japanese Patent Publication No. 60-48575 However, the method described in Japanese Patent Laid-Open No. 07-278692 uses ultrasonic waves to produce an alloy, and is used to finely granulate primary crystals as in the present invention. is not. In addition, the invention described in the cited document 2 describes a method that uses ultrasonic vibration to finely pulverize and disperse acicular primary crystals made of coarse silicon (Si).

However, in the method described in the cited document 2, Si that extends in a needle shape in an Al—Si alloy having a high Si content of 20 to 40% is made to be 700 to 800 ° C.
In the molten state, ultrasonic vibration was added to form a fine lump. However, there is no description of the horn material, and a metal horn is generally used at that time. The metal horn is eroded from the molten metal, and in the case of a Ti horn of an aluminum alloy, Ti itself is a metal having a refinement effect, so the effect of ultrasonic vibration is questionable. Moreover, recycling is inhibited by adding Ti.

  When ultrasonic vibration is applied while maintaining the temperature in the melting region, the effect of miniaturization is small. Addition during solidification is important. Further, since the primary intermetallic compound at the time of solidification is hard and brittle, workability is hindered, so miniaturization is important. In this document, finely granulated Si is as coarse as 100 to 300 μm, and can be refined to 30 μm when added during solidification.

The invention of this application is to solve the limitations and problems of the prior art as described above, there is provided a foundry aluminum alloy containing a high concentration of Fe.

The invention of this application, as to solve the above problems, foundry aluminum alloy of the invention 1, Fe a 2mass% or more 20 mass% or less, or 2mass% or more 20 mass% or less Fe, 4 mass of Si % or more a 30 mass% or less for casting aluminum alloys which contain, the particle size of the Fe-Al intermetallic compound of the primary crystal is characterized in that it is a fine grained polygonal 10~80μm .

Invention 1, the high-temperature strength of foundry aluminum alloy which conventionally contains a high concentration of Fe which has been unavailable, die functionality such as abrasion resistance and sliding characteristics casting (die casting), the cylinder Applicable to blocks, connecting rods and steam turbine blades .

The invention of this application but is intended to provide a method and apparatus for controlling the solidification crystal structure foundry aluminum alloy having the features of as described above, will be described in detail embodiments thereof below.

The invention of this application mainly relates to an intermetallic compound (A
It is to finely granulate the primary crystal by applying ultrasonic vibration to the foundry aluminum alloy to generate a primary crystal l3Fe).

The fine graining of the primary crystal in this way not only improves the workability by suppressing the generation of edges having sharp cleaved surfaces caused by the destruction of the primary crystal during processing, but also stress on the edges. concentration because it is suppressed high-temperature strength of the molded article, in which an improved abrasion resistance and sliding properties or the like to expand the foundry aluminum alloy applications.

By this invention application directly applying ultrasonic vibration to the foundry aluminum alloy molten metal containing impurities such as iron dissolved by heating, intermetallic compounds (mainly Al3Fe) the primary crystal in that fine granulation It has characteristics.

Ultrasonic vibration horn for the invention of this application is to provide an ultrasonic vibration to the foundry aluminum alloy (
It is important to insert horn) into the molten metal and directly apply ultrasonic vibrations. For this reason, when the ultrasonic vibration horn (horn) is made of metal, the surface of the ultrasonic vibration horn needs to be ceramic-coated because it is eroded by the molten metal. The ultrasonic vibration horn (horn) molten metal in case of manufacturing itself with ceramic, i.e. does not react with the foundry aluminum alloy of the molten metal, excellent high-temperature strength, yet high thermal shock resistance, sialon ceramics ( It is preferable to use Si3N4 + Al2O3) or silicon nitride ceramic (Si3N4).

By applying ultrasonic vibrations directly upon the invention of application of aluminum alloys for casting the melted solidifies, intermetallic compounds (mainly Al3Fe) primary crystal to about particle diameter of several 10μm polygon of Although it is agglomerated, the primary crystal is sufficiently finely granulated by applying ultrasonic vibration around the liquidus at the time of nucleation in the initial stage of solidification when the crystal begins to solidify. For this reason, it is not necessary to apply ultrasonic vibration to the solid phase line where the crystal is completely solidified.

The foundry aluminum alloys of interest in the invention of this application, the foundry aluminum alloy which impurity iron (Fe) is contained in a large amount as scrap material (recycled molding material). For example, Al-Fe-based alloy for casting (Fe amount is 2 to 20 mass%
Containing) or foundry Al-Si-Fe-based alloy (Si content is 4 to 30 mass%, Fe weight of aluminum-based casting alloys of 2 to 20 mass% content), and the like. Of course, foundry aluminum alloy scrap material (recycled molding material), iron (Fe) than the copper also (Cu), magnesium (Mg), nickel (N
i) impurities and the like are mixed, it is naturally applicable to a method for controlling the solidification crystal structure foundry aluminum alloy containing such impurities.

Al-Si-Fe-based alloy for casting (the Si 6 mass%, the 2 to 5 mass% containing an alloy Fe) was prepared.

Pure aluminum for industrial use, Al-25 mass % Si alloy, Al-50 mass % Fe alloy, 400 g in an electric crucible in an alumina crucible (3) having an inner diameter of 40 mm and a height of 90 mm at 750 ° C.
And dissolved. This alumina crucible (3) is composed of an ultrasonic oscillator, a vibrator, a two-stage water-cooled booster (1), an ultrasonic vibration horn (2), an amplitude measuring instrument, a temperature measuring instrument having a temperature measuring thermocouple (4), and water cooling. The ultrasonic vibration was applied to the ultrasonic coagulation tissue control device composed of a copper plate.

The ultrasonic vibration of this device is such that the electrostrictive vibrator vibrates with a high-frequency current, and after the vibration is amplified by an expander, it is transmitted to the booster (1) and the ultrasonic vibration horn (2). The sonic vibration horn (2) is structured to vibrate longitudinally.

Since the ultrasonic vibration horn (2) was directly inserted into the high-temperature molten metal, a fine ceramic sialon was selected. This sialon ultrasonic vibration horn (2) is straight and has a diameter of 20m.
m was used.

FIG. 1 shows the positional relationship between the ultrasonic vibration horn and the mold. Insert the ultrasonic vibration horn (2) at a depth of 10 mm from the surface of the molten metal in the alumina crucible (3), and measure the temperature of the molten metal to which vibration is applied with a thermocouple (4) for temperature measurement. However, when the predetermined temperature was reached, the ultrasonic vibration horn (2) was pulled out.

The temperature at which the vibration is applied is preferably from the liquidus temperature to the complete solidification, and in this example, the temperature was in the range of 700 ° C. to 600 ° C. just before the complete solidification.

2 and 3 is an enlarged photograph showing the change in tissue with and without ultrasonic vibration treatment Al-6 mass% Si-5 mass% F e alloy for casting.

In general, when iron Al-Si-based alloy for casting is mixed 1.5 mass% or more of coarse acicular Al3Fe primary crystal is to occur, FIG. 2 when no ultrasonic vibration treatment FIG. 3 is a photograph when ultrasonic vibration is applied. As is apparent from the photograph in FIG. 3, the primary crystal Al3F
e is finely granular, and it has been confirmed that Al3Fe refined to 10 to 100 μm is uniformly dispersed.

  According to the present invention, a method and an apparatus for reforming a molding material such as a cylinder block, a connecting rod, or a steam turbine blade that require high functionality such as high-temperature strength, wear resistance, and sliding characteristics are provided. used.

This is an ultrasonic vibration adding device for controlling the tissue during coagulation. It shows the organization foundry Al-6 mass% Si-5 mass% F e alloy coarse HatsuAkirahari like Al3Fe when not applying ultrasonic vibration for tissue control during solidification of is crystallized. It shows the organization foundry Al-6 mass% Si-5 mass% F e Al3Fe primary crystal in the case where the ultrasonic vibration added for tissue control during solidification of the alloy is finely granulated.

1 Booster 2 Ultrasonic Vibrating Horn 3 Alumina Crucible 4 Thermocouple for Temperature Measurement

Claims (1)

An aluminum alloy for castings containing aluminum alloy scrap as a raw material and containing 2 mass% or more and 20 mass% or less of Fe , or 2 mass% or more and 20 mass% or less of Fe, and 4 mass% or more and 30 mass% or less of Si. foundry aluminum alloy grain size of the Al-based intermetallic compound is characterized in that it is a fine grained polygonal 10 to 80 [mu] m.