JP2003136199A - Method of manufacturing half-melted molding billet of aluminum alloy for transportation machine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method of manufacturing a half-melted molding billet of an aluminum alloy for transporting machines, in which the process is simple, the cost reduction is promoted and obtained products are uniform in quality. SOLUTION: An aluminum alloy is manufactured, which contains at least one or more kinds selected from among 0.40-5.5 wt.% Cu, 10.0-25.0 wt.% Si, 1.0 wt.% or less Zn, 1.5 wt.% or less Fe, 0.65 wt.% or less Mn 0.005-0.5 wt.% Ti and 0.0001-0.5 wt.% B, and 0.40-1.8 wt.%, the balance comprises a composition of an Al substantially, primary crystal of Si has an average particle diameter of 300 μm or less and dendrite branch distance is 200 μm or less. Subsequently, work strain is introduced by cold form forging at a strain ratio of 5-50% at a work introducing rate of not more than 50 mm/s at 200 deg.C or less, and then, the temperature of the billet rises at the eutectic temperature or higher, and the billet is half-melted while being held at a temperature in which a liquid phase ratio is 20-80%.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for producing a semi-molten molded billet of an aluminum alloy used for transportation equipment.

[0002]

2. Description of the Related Art The thixocasting method using a semi-molten billet has recently attracted attention because it has advantages such as less casting segregation / defects and longer die life than the conventional die casting method. As a billet casting method used for this, a method of performing electromagnetic / mechanical stirring in the semi-melting temperature range in order to sphericalize the primary α (Al) phase in the billet stage known as the Pescine-Almax method (method) A) or a larger amount of Al-Ti- than is usually added during casting.
B was added, and the temperature was raised to the melting temperature range in the latter half and the primary crystal α (A
1) There is a method of making the phase spherical (method B). Further, a method (method C) in which the temperature is raised to spherical as in method B after introducing strain by extrusion / rolling is widely known.

[0003]

[Problems to be Solved by the Invention]
In case of method A, the process is very complicated and the manufacturing cost is high.
There was a problem of sticking. In the method B, a large amount of Al
-TiB in the melting furnace to add Ti-B _TwoFor settling
Quality instability occurs, and distortion occurs due to rolling of method C.
It is difficult to introduce uniform strain in the method of introducing
At room temperature extrusion, the work process is complicated, and the strain is uniform.
It is difficult to introduce only the product, and both strain introduction methods are product processing after processing
Is required, and mass production and cost reduction cannot be achieved.
There was a problem.

Japanese Patent No. 2976073 discloses an improved method. That is, there is a step in the first paragraph "a step of deforming a completely solidified metal or metal alloy material at a temperature lower than its recrystallization temperature, and heating the deformable material to cause recrystallization of the microstructure of the material. And partially melting the recrystallized structure to form free-standing particles in a liquid matrix that behaves thixotropically by raising the temperature of the material above its solidus temperature. A method including a step of
This method comprises heating a deformed material to cause recrystallization of the microstructure of the material, and raising the temperature of the material above its solidus temperature, so to speak 2.
The heating which should be called stepwise heating is performed. Although such a method can be said to be an improved technique as compared with the conventional technique, it still requires two steps of heating, and has a problem that the process is complicated and heating control is difficult.

The present invention solves the above-mentioned drawbacks of the prior art,
It is an object of the present invention to provide a method for manufacturing a semi-molten cast billet of an aluminum alloy for transportation equipment, which has a simple process, can promote cost reduction, and has a homogeneous product.

[0006]

In order to achieve the above object, a method for manufacturing a semi-molten cast billet of an aluminum alloy for transportation equipment according to the present invention is Cu 0.40 to 5.5 wt%, S
i13.6 to 25.0 wt%, Zn 1.0 wt% or less,
Fe 1.5 wt% or less, Mn 0.65 wt% or less, Ti
0.005-0.5 wt% and B 0.0001-0.5
wt% of at least one or more, Mg 0.40 to 1.8w
An aluminum alloy containing t%, the balance being substantially composed of Al, having an average grain size of primary crystal Si of 300 μm or less and a dendrite branch spacing (DAS) of 200 μm or less, and then having a strain rate of 5 ˜50%, processing introduction speed 50 mm / sec. Below the recrystallization temperature,
It is a method of introducing a processing strain by cold mold forging, then raising the temperature to a temperature higher than the eutectic temperature, and maintaining the liquid phase ratio at a temperature of 20 to 80% to perform semi-melt processing.

In this case, in order to homogenize the segregation of the components and release the casting stress, 450 to 450% before introducing the working strain.
It is preferable to perform the homogenization treatment at a temperature of 550 ° C. for 1 to 10 hours.

In order to achieve the above object, the method of manufacturing the semi-molten cast billet of the aluminum alloy for transportation equipment of the present invention is Cu 0.40 to 5.5 wt%, Si 10.0.
~ 25.0 wt%, Zn 1.0 wt% or less, Fe1.5
wt% or less, Mn 0.65 wt% or less, Ti 0.005
-0.5 wt% and B 0.0001-0.5 wt%, at least one or more, Mg 0.40-1.8 wt%, Ni
0.05% to 1.7% by weight, the balance substantially consisting of Al, the average grain size of primary Si is 300 μm or less, and the dendrite branch spacing (DAS) is 200 μm.
The following aluminum alloy is manufactured and then strain rate 5
˜50%, processing introduction speed 50 mm / sec. At the temperature below the recrystallization temperature, a working strain is introduced by cold mold forging, and then the temperature is raised to the eutectic temperature or higher, and the liquid phase ratio is 20 to 80.
This is a method of holding at a temperature of 10% and performing semi-melt processing.

In this case, in order to homogenize the segregation of the components and release the casting stress, 450 to 450% before introducing the working strain.
It is preferable to perform the homogenization treatment at a temperature of 550 ° C. for 1 to 10 hours.

Further, in order to achieve the above-mentioned object, the method of manufacturing the semi-molten cast billet of the aluminum alloy for transportation equipment of the present invention is the same as the alloy used in the above-mentioned method.
An aluminum alloy containing 003 to 0.150 wt% may be used.

In this case as well, in order to homogenize the segregation of the components and release the casting stress, 450 before the introduction of working strain.
It is preferable to carry out the homogenization treatment at a temperature of ˜550 ° C. for 1 to 10 hours.

[0012]

BEST MODE FOR CARRYING OUT THE INVENTION Various reasons for limiting numerical values such as limiting the numerical values of the amounts of aluminum alloy components used in the present invention will be described in detail below.

The Cu component improves not only mechanical properties but also hardness, machinability and castability, but 0.40 wt.
%, The effect is small. On the other hand, if it exceeds 5.5 wt%, the corrosion resistance is deteriorated, so 0.40 to 5.5 wt%
%.

The Si component has an effect of improving wear resistance, but if it is less than 10.0 wt%, its effect is small, while if it exceeds 25.0 wt%, elongation and toughness deteriorate and cold forgeability is poor. Therefore, it is set to 10.0 to 25.0 wt%.

The Mg component precipitates Mg ₂ Si and contributes to the improvement of mechanical properties, but if it is less than 0.40 wt%, its effect is small, while if it exceeds 1.8 wt%, cold forgeability deteriorates. Therefore, it is set to 0.40 to 1.8 wt%.

The Fe component forms an intermetallic compound with the Al component, and if it is contained in a large amount, it becomes an Al-Fe-Si compound, which adversely affects elongation, toughness and corrosion resistance.
It was set to t% or less.

The Ti component refines the structure of the ingot and prevents the occurrence of ingot cracking, but if it is less than 0.005 wt%, its effect is small, while if it exceeds 0.5 wt%, TiAl.
_{3 It} promotes the generation of huge crystallized substances, leading to cracking during cold forging and deterioration of mechanical properties of transportation equipment parts.
It was set to 0.005 to 0.5 wt%.

The B component, together with the Ti component, also refines the structure of the ingot and prevents the occurrence of ingot cracking.
If less than 0.5% by weight, the effect is small. On the other hand, if more than 0.5% by weight, cracking during cold forging and deterioration of mechanical properties of transportation equipment parts are caused, so 0.0001 to 0.5% by weight.
And

The Zn component improves the castability but deteriorates the corrosion resistance, so the content of Zn is set to 1.0 wt% or less.

The Mn component is set to 0.65 wt% or less because the toughness decreases due to the formation of coarse intermetallic compounds.

The Ni component contributes to the improvement of high temperature strength, but its effect is small when it is less than 0.05 wt%, while it deteriorates the corrosion resistance when it exceeds 1.7 wt%.
It was set to 05 to 1.7 wt%.

The P component makes primary Si of a high Si alloy finer and contributes to the improvement of mechanical properties, but 0.003 wt%
If it is less than 0.015 wt%, on the other hand, if it exceeds 0.015 wt%, the fluidity and filling property of the molten aluminum alloy are deteriorated and the castability is impaired, so 0.003 to 0.015 wt
%.

The dendrite branch spacing (DAS) is 200μ
Although the billet having a diameter of m or less is cast, if the dendrite branch spacing (DAS) exceeds 200 μm, it becomes difficult to make the primary α (Al) phase into a uniform fine spheroid when heated to a semi-melting temperature range. When the homogenization process is performed, it takes time for the homogenization process, so the dendrite branch interval (DAS) is set to 2
It was set to be not more than 00 μm. Further, the average grain size of primary Si is 30
If it exceeds 0 μm, the mechanical properties deteriorate, so 300
It was set to not more than μm.

By subjecting the billet obtained by casting to homogenization treatment, Al ₂ Cu crystallized at grain boundaries during casting,
Crystallized substances such as Mg ₂ Si dissolve in the matrix. Further, the eutectic Si and the primary crystal Si are spheroidized to reduce the deformation resistance during cold forging. When the homogenization treatment temperature is lower than 450 ° C. or the heating time does not reach 1 hour, solid solution cannot be sufficiently obtained, and eutectic Si and primary crystal Si are spheroidized and casting strain is not sufficiently removed. However, at a processing temperature exceeding 550 ° C., eutectic melting occurs and impairs workability during forging. Further, when the heating time exceeds 10 hours, the effect of homogenization corresponding to the long heating time is not increased, resulting in a loss of heating energy. Therefore, the homogenization treatment condition is 1 at a temperature of 450 to 550 ° C.
It was heated for 10 hours.

Next, the working strain is introduced by cold forging so that the process can be simplified and the strain can be effectively introduced with a small working rate, and the strain is uniformly introduced into the entire forging billet. The frame is forged so that The distortion rate is
If it is less than 5%, the introduction of strain is small, and even if the temperature is raised to the semi-melting temperature range, the primary spheroidal α (Al) phase cannot be made uniform spheroidization, while if it exceeds 50%, the primary crystal α (Al) is spheroidized. The phase size does not change, and cracks occur during cold forging, so the content was set to 5 to 50%. The strain rate here is (L ₁ −L ₂ ) / L ₁ × 100 (%) when the original length of the forging billet is L ₁ and the length of the forged billet is L _2.
Defined in.

The process introduction speed can be greatly increased by refining the crystal grains of the billet ingot, refining the eutectic Si, refining the primary Si and homogenizing treatment. From the viewpoint of productivity, it is preferable that the processing introduction speed is as fast as possible. However, 50 mm / sec. If it exceeds 50 mm / sec., Cracking will occur during forging, and strain will not be uniformly introduced into the forging dead zone. Below. When the billet temperature during cold form forging is above the recrystallization temperature, the introduction of strain is insufficient for a given processing rate, and even if the temperature is raised to the semi-melting temperature, the primary crystal α (Al) phase has a grain structure. Therefore, the temperature was lower than the recrystallization temperature.

Then, the billet is heated to a temperature higher than the eutectic temperature,
Semi-melt molding is performed by maintaining the liquid phase rate at 20-80%, but if the liquid phase rate is less than 20%, uniform spheroidization of the primary crystal α (Al) phase cannot be achieved, resulting in deformation of the semi-melt molding. The resistance is high and pressure molding becomes difficult. Further, if it exceeds 80%, a molded product having a uniform structure cannot be obtained. Therefore, the liquid phase ratio in the semi-melting temperature range above the eutectic temperature is set to 20 to 80%.

[0028]

EXAMPLES Specific examples of the present invention will be described below. FIG. 1 is a schematic view of cold formwork forging used in the method of the present invention. In the figure, reference numeral 1 is a forging die, 2 is a forging die punch, and 3 is an aluminum alloy billet.

Cu, Si, Mg, Zn, Fe, Ti,
The molten alloy was adjusted so that B, Ni and P had the compositions shown in Table 1 below, and an aluminum alloy billet was cast by continuous casting.

[0030]

[Table 1]

The aluminum alloy billets shown in Table 1 above were treated under the conditions shown in Table 2 to evaluate the formability of semi-melt molding and the shape of the primary α (Al) phase after semi-melt molding. Also described in.

[0032]

[Table 2]

The formability shown in Table 2 when the processing strain is introduced is
When the molding was performed under the molding conditions shown in Table 2, cracking did not occur and the moldability was good, the result was evaluated as ◯, and when cracking was found, the result was evaluated as x. For the moldability of semi-melt molding, the good one is ○.
Those with poor moldability were judged as x. The shape of the primary crystal α (Al) phase after semi-melt molding was judged as ◯ when spheroidization was recognized, and as x when spheroidization was insufficient. In the homogenization of the primary α (Al) phase after semi-melt molding, the primary α (A
l) A phase size of 100 μm or less is defined as ◯, and 100 μm
Those having a size exceeding 0.1 were judged as x.

FIG. 2 shows a photograph of a typical example in which the fine homogenization of the primary crystal α (Al) phase was evaluated as ◯.

[0035]

As described above, according to the present invention,
The process can be simplified and the cost can be reduced as compared with the conventional semi-molten billet. Further, the obtained structure is a uniform spheroidized structure in which the primary crystal α (Al) phase size is 100 μm or less on average and the primary crystal α (Al) phase has an area ratio of 50%. It can be used as

[Brief description of drawings]

FIG. 1 is a schematic view of cold formwork forging.

FIG. 2 is a photomicrograph of a typical example in which fine homogenization of primary crystal α (Al) phase is evaluated as ◯, and the magnification is 50 times.

[Explanation of symbols]

1 Forging die 2 Forging die punch 3 Aluminum alloy billet

─────────────────────────────────────────────────── ─── Continued Front Page (51) Int.Cl. ⁷ Identification Code FI Theme Coat (Reference) B22D 21/04 B22D 21/04 A C22C 21/02 C22C 21/02 C22F 1/043 C22F 1/043 // C22F 1/00 610 1/00 610 620 620 630 630A 630B 682 682 683 683 693 691 691B 691C 694 694A 694Z (72) Inventor Murayama Yasuyuki Fukuoka Prefecture Omuta city 80 Miyamai, Kyushu Mitsui Co., Ltd. ) Inventor Tsunaki Iwashita 80 Yoyama-cho, Omuta City, Fukuoka Prefecture F-term in Mitsui Aluminum Industry Co., Ltd. Kyushu (reference) 4E087 AA02 BA04 BA14 CB03 DB15 DB22 GA02 GA08 HB17

Claims (6)

[Claims] 1. Cu 0.40 to 5.5 wt%, Si1
0.0-25.0 wt%, Zn 1.0 wt% or less, Fe
1.5 wt% or less, Mn 0.65 wt% or less, Ti0.
005 to 0.5 wt% and B 0.0001 to 0.5 wt
%, At least one kind, Mg 0.40 to 1.8 wt%
And the balance consists essentially of Al composition.
Of aluminum having an average particle size of 300 μm or less and a dendrite branch interval of 200 μm or less, and then a strain rate of 5 to 50% and a processing introduction speed of 50 mm /
sec. At a temperature lower than the recrystallization temperature below, a working strain is introduced by cold die forging, and then the temperature is raised to the eutectic temperature or higher,
A method for producing a semi-molten molded billet of an aluminum alloy for transportation equipment, characterized by holding at a temperature at which a liquid phase ratio is 20 to 80% and performing semi-melt processing. 2. The aluminum alloy for transportation equipment according to claim 1, wherein the aluminum alloy is produced and subjected to a homogenizing treatment at a temperature of 450 to 550 ° C. for 1 to 10 hours before introducing a working strain. Method for producing semi-molten molded billet. 3. Cu 0.40 to 5.5 wt%, Si1
0.0-25.0 wt%, Zn 1.0 wt% or less, Fe
1.5 wt% or less, Mn 0.65 wt% or less, Ti0.
005 to 0.5 wt% and B 0.0001 to 0.5 wt
%, At least one kind, Mg 0.40 to 1.8 wt
%, Ni 0.05 to 1.7 wt%, and the balance substantially consisting of Al, and the average grain size of primary Si is 300 μm.
m or less and the dendrite branch spacing is 200 μm or less to produce an aluminum alloy, and then the strain rate is 5 to 5
0%, processing introduction speed 50 mm / sec. In the following, at a temperature below the recrystallization temperature, introducing processing strain by cold formwork forging,
After that, the temperature is raised to a temperature higher than the eutectic temperature, the liquid phase rate is maintained at a temperature of 20 to 80%, and semi-melt processing is performed, and a method for producing a semi-molten molded billet of an aluminum alloy for transportation equipment. 4. The aluminum alloy for transportation equipment according to claim 3, wherein the aluminum alloy is manufactured and subjected to a homogenizing treatment at a temperature of 450 to 550 ° C. for 1 to 10 hours before introducing a working strain. Method for producing semi-molten molded billet. 5. The method for producing a semi-molten molded billet of an aluminum alloy for transportation equipment according to claim 1 or 3, wherein an aluminum alloy further containing P0.003 to 0.150 wt% is used. 6. The aluminum alloy for transportation equipment according to claim 5, wherein the aluminum alloy is produced and subjected to a homogenizing treatment at a temperature of 450 to 550 ° C. for 1 to 10 hours before introducing a working strain. Method for producing semi-molten molded billet.