JPS60149751A - Metal composition - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

[Detailed description of the invention] This invention relates to fine grained metal compositions.

It is known that it is advantageous to form metals in a semi-molten state (partially solid and partially liquid). US Pat. Nos. 3,948,650 and 43,954,455 disclose a method in which a metal (or alloy) in a semi-molten state is vigorously stirred and then shaped. This method involves converting the microscopic structure of the dendrites of the alloy into degenerated dendrites in a low-melting-point matrices and gas, and then subjecting this semi-molten material to forming processes such as casting and forging. be.

This semi-solid forging method is advantageous in terms of cost.

However, this has certain limits. This method
The desired non-dendritic cast rod (east ba
Create r). In this case, it is technically difficult to obtain a diameter of about 1 inch or less.

Even if this were done, the production efficiency would be extremely low. Furthermore, in many cases, this casting method does not result in the desired microscopic structure of the epidermis, and therefore the epidermis must be cut by mechanical means or the like to facilitate post-processing. Furthermore, if the diameter is non-uniform, it becomes necessary to adjust the casting cycle consisting of placement, molding preparation, running, etc. each time according to the diameter, which is troublesome and increases costs. Therefore, flexibility is reduced.

The present invention was made in view of the above circumstances, and its first purpose is to provide a metal composition with a uniform microcrystalline structure and a microstructure that cannot be obtained by conventional metal forming methods.

Another object of the present invention is to provide a metal alloy composition that can be made into a semi-molten state.

A further object of the present invention is to provide a composition that does not require vigorous stirring of the metal composition during production.

These objectives are achieved by the following metal alloy composition. That is, a solid metal alloy composition having an essentially oriented crystal structure is provided, the oriented crystal composition is heated to a temperature between the solidus and the liquidus, and at least 0.05 volume of liquid is added to the oriented crystal composition. %, the composition is strained prior to heating, and m) IJ
A mixture is prepared in which the wax composition (having a lower melting point than the spherical particles) and the middle spherical particles are uniformly dispersed, and then the heated alloy composition is solidified.

The solidified composition has a microscopic structure of uniform, fine grains with spherical particles evenly dispersed in a low melting matrix. The metal compositions obtained by these processes have a much more uniform and fine grain structure than those obtained by other known processes.

In general, heating an alloy above its homophase temperature during heat treatment or forming was considered to be extremely harmful, even by small amounts. The reason for this is that grain boundary melting occurs, causing embrittlement of the metal. This intergranular melting, also called thermal embrittlement or burning, impairs the processability of the alloy and causes a decrease in strength and elongation. Although some literature discloses methods to avoid this melting, these are just a modification of solutionization, and the heterogeneous material is dissolved in the IJ wax and removed. For example, US patent A
No. 2,249,349 attempts to improve workability by heating an aluminum alloy to initial melting. U.S. Patent A 31988.180; Ben 4.106,956:A
No. 4,019,929, the alloy is heated to a temperature slightly above the solidus and held at that temperature until the dendritic phase becomes globular. According to these prior art techniques, the inhomogeneities caused by melting are detrimental and must be removed before further processing. The present invention is metallographically independent by dispersing a homogeneous mixture of particles with sufficient uniformity.

It is something that gives rise to quality. The product obtained by the present invention is a metal composition having a uniform microscopic structure consisting of spherical particles contained in a solidified liquid phase, and the microscopic structure is more uniform and the particle size is larger than that of conventional products. Spherical shape with small particle size.

In the case of aluminum alloys and other alloys actually tested, the diameter of these spherical particles is less than 30 μm.

The method of the invention has many advantages. The starting billet material can be cast to a single desired diameter. For example, it can be 6 inches in one location and reduced to a smaller diameter as desired in the same second location. Moreover, the removal can be carried out using conventional extruders and conventional techniques. The process according to the invention makes it possible to remove the dendritic skin of the starting billet material as a normal operation before extrusion, so that the extruded billet is free of skin effects. Furthermore, the microstructure, ie, size, shape, distribution, etc., of the final product can be much finer than that of the starting material.

In the present invention, the oriented crystal structure can be extruded,
It is produced at a temperature lower than the solidus temperature by hot processing such as rolling, forging, and swaging. Hot working refers to a process in which a metal or alloy is deformed between the recrystallization temperature (generally Tsolidus Kelvin) and the solidus temperature (Tlloldug), thereby obtaining a oriented crystal structure. Formation of this oriented crystal structure is most preferably carried out by extrusion.The extrusion ratio is usually greater than 10/1 and may be as large as is economically practicable.Generally Effective extrusion ratios range from about 1971 to 60/1.

Here, before heating above the solidus temperature, it is necessary to introduce a specific bone strain into the metal or alloy, simultaneously with and integrally with this hot working, or after the hot working. If this strain is introduced integrally with hot working, it should be done by in-line linear operation, by introducing thermal strain by rapid cooling and hardening of the hot-worked material, or by extrusion at a low temperature where residual strain remains. I can do it. Extrusion or other hot working at lower temperatures produces higher residual strains in the extrudate. This is because the lower the temperature, the greater the extrusion pressure.
This is because the energy used during extrusion also increases. As a separate step, strain can also be introduced by cold working buttons. Cold working is performed by drawing, swaging, rolling, compression, upsetting, etc.

The amount of strain represents all the strain remaining in the grain after the deformation process is completed. The actual amount of strain varies depending on the specific metal or alloy, as well as the type and conditions of hot working.

For example, in the case of extruded aluminum alloys, the strain should correspond to at least 12% cold worked alloy.

In general, the amount of strain is measured experimentally to determine whether or not the IJ wax composition contains uniformly dispersed solid spherical particles after being heated to a temperature higher than the homologous temperature. You can judge and decide. A directional crystal structure is created by hot working, especially extrusion trapping, and the alloy is cold worked separately and is 4! ! It has been found that the uniformity and granular microscopic pseudostructure that can be seen in the conventional method are extremely excellent.

After completion of hot working or other predetermined cold working, the alloy is reheated to a temperature above the inphase line and below the liquidus line. The temperature in this case is a volume fraction of 0.05-0.8, preferably 0-10
~0.8, yo) is preferably chosen to form a liquid of 0.15 to 0.05. This reheated alloy is then solidified and further reheated so that it can be shaped under a semi-molten state. Note that this molding step may be performed integrally with the first reheating to bring it into a semi-molten state. The second reheating may be carried out to reach a higher in-phase fraction than the first (initial) reheating, but if the solid phase fraction is 0.2
It is preferable that the value does not exceed 0.

In a preferred embodiment of the invention, the alloy is heated to a semi-solid state and simultaneously formed by a press forging operation. In such a process, the alloy is heated to the required half-melting temperature, placed in a die cavity, and formed under pressure; the forming and solidification process times are very short and the pressure is relatively low. This press forging method has been applied for a U.S. patent.
No. 90,217 (filed August 5, 1981). Other semi-solid forming methods include casting, extrusion, etc.

FIG. 1 is a time/temperature diagram showing the method of the present invention in which the metal is melted and then solidified to form a dendritic or non-dendritic cast billet. This billet, for example an aluminum casting billet, is
Preheating for 0 minutes above the recrystallization temperature V, extrusion, and then quenching to produce a solid metal composition with oriented crystal structure. This extruded metal composition is then cold worked (at room temperature) to introduce an appropriate amount of strain. This is then reheated above the solidus temperature for about 100 seconds, for example in the case of an aluminum alloy, to a semi-solid state, and then rapidly cooled.

In the present invention, the starting materials are conventional billet-cast type dendritic metals or alloys, or U.S. Pat.
It may also be a non-dendritic metal or alloy, such as a billet made by vigorous agitation during freezing, as disclosed in US Pat. This agitation forms a so-called slurry cast structure, ie, degenerated dendritic dispersed particles in a lower melting point matrix. US Patent Application 3fi3
No. 621 (filed on March 30, 19B2) discloses a method in which the starting material is a slurry cast structure and is heated to restore it to a semi-solid state, and it can also be produced by this method. Fillets and fillets made under vigorous stirring are described in U.S. patent application A15.250 (filed February 26, 1979).
It can also be made by a continuous direct cooling casting process such as that disclosed in . In this method, molten metal is cooled in a rotating magnetic field while being vigorously stirred. This method can produce a continuous billet with a continuous, dispersed and degenerated dendritic structure. Here, billets refer to billets that are cooled and cast in a shearing environment during solidification in order to distinguish between those that have been vigorously stirred and those that have not.

The microstructures of the non-dendritic compositions described in the above-referenced U.S. Pat. or dispersed primary phase particles surrounded by a solute enriched matrix.

Hereinafter, embodiments of the present invention will be described, in which specific limitations and all parts and arcs are by weight. Note that the solid fraction is based on volume.

Example 1 An aluminum casting alloy (Aluminum Association, N'Alloy 357) was directly cold cast to a 6 inch diameter without shearing. Figure 2 is a micrograph of a cross section of this direct chill cast par, showing the dendritic structure. Note that this alloy had the following composition.

Sl −= 7. O: Cu-0,010:Mn-
=-0,004: Mg'---0.30:Z
n-...0.02: Ti-0,10:At...
...The remaining portion of this cast par was preheated to 380°C within 1/2 hour and extruded into a 0.875 inch diameter rod at a ratio of 50/1. This extrusion pressure is 67,000 ps
It was i. This rod was moved at a speed of 25 ft/min, 4
It was taken out at 60°C and then cooled with forced air. This extruded bar was stretched in a straight line, and a permanent strain of about 1% was introduced into the par as one of the integral steps of this extrusion method. Figure 3 is a micrograph of a longitudinal section of the extruded bar. be. This clearly reveals a directional crystal structure.

This extruded sample was then heated to 3J 000 Hl -6
, 75 kW (2 inch ID coil x 6 inch length) for 100±5 seconds to achieve a solid phase rest of 0.7 to 0.9 volume fraction, and then immediately quenched to 24°C. These quenched samples were metallurgically examined for particle size and shape. FIG. 4 is a micrograph of a cross section of this reheated/quenched sample.

According to FIG. 4, it is clear that the microscopic structure has become noticeably finer than that of the starting billet shown in FIG. 2. Furthermore, it has been shown that the microscopic structure of the part that has been extruded and significantly processed can be converted into a slurry microscopic structure by heating to a liquid volume fraction of 01 or more.

Example 2 An aluminum casting alloy was cast in the same manner as in Example 1,
Preheated to 380°C within 1/2 hour and extruded into a 1.250 inch diameter rod. This extrusion pressure was 14-. 000
It was psi. This extrusion was performed at 14 ft/min at 500° C. and forced air cooling was performed. This extruded par was then stretched to give it a permanent set of 1%. A portion of this lot 9 was stretched by 36% to a diameter of 1 inch. This extruded and drawn rod was reheated in the same state as in Example 1 by SK induction and press forged. In addition,
The forging in this case was made into a pot shape with a wall thickness of 0.050 inch. FIG. 5 is a micrograph of a cross-section of the final product, which shows a uniform, fine-grained, slurry-type microstructure.

Example 3 An aluminum wrought alloy (Aluminum Association Alloy 2024) was directly cold cast, homogenized (to prevent cracking during hot working and to reduce extrusion pressure), and then extruded into 1 inch diameter pars.

The composition of this alloy is as follows.

Cu...4.4:Mn...0.6;M
g...1.5: At...Remaining part of the extruded par sample was reheated in the same manner as in Example 1, another part of the sample was rolled at 29%, and then Reheated. FIG. 6 is a photomicrograph of the final reheated (but not cold worked) sample. FIG. 7 is a micrograph of a cold-worked sample. It is clear from these figures that the cold-worked sample has a much finer microscopic structure than the non-cold-worked sample.

Example 4 The same operation as in Example 3 was performed except that an aluminum wrought alloy with the following composition was used.O8 amount: 0.6: Cu:
0.28: Mg...1.0: Cr...
・0.2:kl・・・Remaining capacity (Alloy, 6061
) The resulting extrusion, reheated sample and extrusion,
A micrograph was taken of the 29% rolled and reheated sample. As a result, the same difference in microscopic structure as shown in Example 3 and FIGS. 6 and 7 was observed.

Example 5 The same operation as in Example 3 was performed except that the aluminum wrought alloy having the following composition was used.

81 =--0,6: Cu''-0,28:Mg-・
・1.0: Cr ・=・0.09: Zn・・・・
・・2.0:Pb・・・・・・06; Old・・・・・・0
．． 6: At... Residue (Alloy, 6262) As a result, the same results as Examples 3 and 4 were obtained.

Example 6 The same operation as in Example 5 was repeated except that the aluminum wrought alloy having the following composition was used.

Cu...1.6: Mg...2.5
;Cr-0,23:Zn-5,6:At...
... Residue (Alloy, 7075) As a result, Example 3~
Similar results as in case 5 were obtained.

Example 7 An aluminum alloy (Aluminum Association Alloy 357) having the composition shown below was directly cold-hard cast into a 6-inch diameter par-sized piece under a shearing environment.

S amount ・・・・・・ 7.0: Cu ・・・・・・
0010; Mn -0,004: Mg -0,30:
Zn -0,02: Ti...-0,10:A
A 22 inch long sample of this was heated to 520°C for less than 2 hours and then extruded into a 0875 inch diameter rod. This extrusion was followed by cooling with air. A 1 inch section of this was pressed axially at room temperature using two plates to a length of 5.10. and decreased to 16%. The as-extruded and pressed samples were then heated at 3>000 Hz in a 2 inch ID coil x 6 inch length heating device.
It was reheated at 6.75 kW for 100±5 seconds to a solid phase volume fraction of 0.7-0.9, and then immediately water-cooled to 24°C. The particle size and shape of these rapidly cooled samples were metallurgically examined.

Next, the extruded billet, 1 inch 35F, was compressed by 25% in the axial direction, and then
In the same manner as in step 7, a screw Okawa plug was forged in a semi-solid liquid state. Reheating time is 50 seconds, solids volume fraction is o, 8
5. Residence time is 0.5 seconds, pressure is 15y O00p s
It was ge.

Micrographs were taken at each step in this method. The 6 inch diameter starting billet had particles approximately 100 microns in diameter. The extruded billet exhibited a directional crystalline microstructure with extremely elongated grains. Center part of reheated billet (as extruded, 5,1
The grain size and shape of the grains (rolled to 16% and
It is said that when you exceed this, you will improve. Rolling 2
5% and forged into screw Otsuki plugs, the microstructure is much finer than that of the starting billet material, the shape is significantly more uniform, and the particles in the final product are less dispersed. It showed that it was going to get better. Furthermore, it was confirmed that residual strain has a large effect on the reheated crystal structure of extruded products.

Example 8 The aluminum casting alloy of Example 7 was directly cold-hard cast into 6-inch diameter fins and holes in the same manner as in Example 7. This 22
An inch section was preheated to 330°C for 2 hours (considerably lower than Example 1) and then extruded into a 1.125 inch diameter rod. The extrusion pressure of this rod is 4% 000
p s i (larger b than Example 1).

The extrusion speed of the rod was 23 ft/min and the temperature was 490°C. Next, this was cooled with air, then heated at KW in the same manner as in Example 7 so that the solid fraction was 0.7 to 0.9, and then cooled with water.

Then, as a result of metallurgically inspecting the grain size and shape, it was found to be similar to the reheated, 25% rolled, and press forged sample of Example 7. It has been found that in this extrusion, the combination of low reheating temperature (330° C.) and blast cooling results in the formation of adequate residual strain in the extrudate.

Example 9 Copper wrought alloy, C544 (4% Zn + 4% Sn, 4% p
b.

The residual copper was extruded to obtain a directional crystal structure and then cold rolled by 35% into a 1 inch diameter rod. This extruded par sample was reheated in the same manner as in Example 1, except that the heating time was 200 seconds) to obtain a semi-solid semi-liquid structure, which was then press-forged into a cam for water bombs. FIG. 8 is a microphotograph of a cross-sectional view of this final product.

Example 10 Copper forged wire alloy C360 (3% Mn, 35.5% Znr balance copper) was extruded and then cold rolled (18%) into a rod with a diameter of 1 inch. A sample of this cold worked extrusion was reheated as in Example 1. The microscopic structure of this final product was very similar to that in FIG.

Examples 11-13 Three copper alloys were hot worked into small diameters in the same manner as in the previous examples. In Example 11, hot working by extrusion was performed, followed by 50% cold working. In Example 12,
After hot working during extrusion, 29% cold working was performed. In Example 13, 20% cold working was performed after hot working by extrusion K, and further cold working was performed about 20 to 25%.

The alloy of Example 11 is a C110 alloy, which is a pure metal of 99.9% copper and the balance oxygen. The alloy of Example 12 contains Cl
87 alloy, 999% copper and 1% lead. Example 13
The alloy is C360 alloy, 60% copper, 3% lead and balance zinc. The microstructure of the alloy press-forged after final reheating or rapidly cooled after reheating is shown in Figure 9 (Example 11) and Figure 1.
0 (Example 12) and FIG. 11 (Example 13) K are shown, respectively. The alloys of these examples each have approximately 1070
℃, 980℃ and reheated to 890℃.

These microstructures showed a grain refining effect compared to the microstructure of an alloy obtained by vigorously stirring a semi-molten alloy.

Example 14 Magnesium alloy A231B (4%), 1.1% Zn
.

0.2% Mn, balance Mg) was prepared, and Examples 11 to 1 were prepared.
Hot working was performed in the same manner as in No. 3, and the rod-shaped sample was subjected to 12% compression cold working. FIG. 12 shows the microstructure of the final alloy after reheating to about 610° C. and quenching.

The grain size and shape of the microstructure were superior to those of a magnesium alloy in which a semi-molten alloy was vigorously stirred during cooling.

Example 15 Stainless steel 316 alloy (17% Nl, 12% Cr.

2.5%Mo (balance Fe) was hot-processed by hot rolling.
0% cold worked. Figure f413 shows the microscopic structure of the alloy that was reheated at about 1380°C and then rapidly cooled. The particle size was much finer and more uniform than the vigorously agitated comparison particles.

Example 16 Stainless steel 440C alloy (0,95-1,2% C11
6-18% Cr, 1% or less Mn + 1% or less sl, 75% or less Mo, balance Fe) was cast, hot worked, and 20% cold worked by cold compression. FIG. 14 shows the microscopic structure of the alloy that was reheated at about 1390° C. and then rapidly cooled.

Although the examples described above refer to aluminum, copper, magnesium, and iron alloys, the method can also be applied to other metals and alloys that can form two-phase systems with solid particles in a low-melting matrix phase. . For example, it can be used for nickel, cobalt, lead, zinc and titanium. Other cast alloys such as aluminum alloys 356 and 357, or wrought alloys such as aluminum alloys 6061, 2024 and 7075, and copper alloys C544 and C360 can be used.

[Brief explanation of drawings]

FIG. 1 is a diagram showing the method of the present invention in relation to time/temperature distribution, and FIGS. 2 to 14 are micrographs showing the state of the microscopic structure of the alloy obtained by the present invention at each stage ( (100x magnification). Applicant's agent Patent attorney Takehiko Suzue Formerly? l, a]
[ENG'IG, fl ○ FnG, IIl 1, ... Mi, 1st G, M. ■, Incident display pa1.・,,%1llBsq-"9"°8"3shi Agent January 29, 1985 Engraving of the drawings (no changes to the contents 3 G <1.. Procedural amendment to the Commissioner of the Japan Patent Office Manabu Shiga ■, Indication of the case Patent Application No. 1987-194087 2, Title of the invention Metal composition 3 Relationship with the case of the person making the amendment Patent applicant IT Industries Inc. 0 Incorporated 4, Agent 6 Supplementary iE detailed specification 7, contents of amendment and scope of claims as attached. Amended. 2 Claims (1) A magnesium, iron or copper alloy composition whose microstructure is a homogeneous and fine-grained structure with spherical particles uniformly dispersed in a low melting point matrix, the composition comprising: A solid alloy composition having a grain structure having a directionality is prepared, and the alloy composition is heated to a temperature between the solidus line and the liquidus line so that the liquid becomes at least 0.05 volumetric. A mixture of a solid and a liquid is prepared, and a predetermined amount of strain is introduced prior to heating, thereby forming uniformly dispersed spherical particles in a matrix having a lower melting point than the particles. (2) The metal composition according to claim 1, in which the alloy is a magnesium base metal. (8) The metal composition according to claim 1, in which the alloy is an iron alloy. Metal composition. (4) Claim 3 in which the iron alloy is stainless steel.
The metal composition described in . (5) The metal composition according to claim 1, wherein the base metal is a copper alloy. (6) The metal composition according to claim 1, wherein the alloy is hot worked to obtain a directional grain structure. (7) Hot processing is extrusion processing Claim 6
The metal composition described in . (8) The metal composition according to claim 6, wherein the composition is hot worked to impart directionality to the crystal grain structure and then cold worked. Applicant's agent Patent attorney Takehiko Suzue

Claims (8)

[Claims] (1) An alloy composition whose microscopic structure is a low melting point matrix) with a uniform and fine crystal grain structure in which spherical particles are uniformly dispersed in +7Tx, and is basically a solid with a crystal grain structure that has directionality. preparing an alloy composition, heating the alloy composition to a temperature between the solidus line and the liquidus line to produce a mixture of solid and liquid such that the liquid content is at least 0.05% by volume; Prior to this heating, a predetermined amount of strain is introduced, thereby forming uniformly dispersed spherical particles in a matrix having a low melting point, and solidifying this heated alloy composition. (2) The metal composition according to claim 1, wherein the alloy is a magnesium alloy. (3) The metal composition according to claim 1, wherein the alloy is an iron alloy. (4) Claim 3 in which the iron alloy is stainless steel
The metal composition described in . (5) The metal composition according to claim 1, wherein the alloy is a copper alloy. (6) The metal composition according to claim 1, wherein the alloy is hot worked to obtain a directional grain structure. (7) Hot processing is extrusion processing Claim 6
The metal composition described in . (8) The metal composition according to claim 6, wherein the composition is hot-processed to impart a crystal grain structure orientation, and then cold-processed.