JP2005298871A - Aluminum alloy for plastic working, and its manufacturing method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an aluminum alloy for plastic working, which are useful for high performance members, such as automotive parts, fishing gears, golf clubs and snow boards, and has high tensile strength, high Young's modulus and high ductility, and to provide its manufacturing method. <P>SOLUTION: A powder mixture is prepared by mixing 10 to 25wt.% alumina with an aluminum alloy powder having a composition consisting of, by weight, 0.4 to 2.0% Si, 0.4 to 2.0% Mg, 0.5 to 2.0%, in total, of one or more elements selected from among Fe, Mn and Cr, and the balance Al with inevitable impurities. The powder mixture is compacted at room temperature, and the resultant green compact is vacuum degassed at 200 to 450°C and further sintered at a high temperature of 500 to 600°C. The resultant sintered compact is pressure sintered and then forged. By this method, a structural member as a finished product having ≥80 GPa Young's modulus at room temperature, ≥300 MPa tensile strength at room temperature after water quenching treatment and ≥5% elongation can be obtained. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a high tensile strength, high Young's modulus and high ductility aluminum alloy for plastic working, which is useful as a high-functional member such as bicycle parts, fishing gear, golf clubs and snowboards, and a method for producing the same.

  In recent years, attempts have been made to improve the characteristics, particularly the rigidity, by adding and dispersing ceramics to an aluminum alloy powder obtained by a rapid solidification method. For example, Al-high Si-based, Al-Fe-Mo-based, Al-Cu-based, Al-Si-Mg-based, or Al-Zn-Mg-based compositions have been studied (for example, see Patent Document 1).

Also, when hot forming processing such as extrusion or forging of aluminum alloy, hydrates and air are contained in the inside and surface of the powder compact that has been cold compacted prior to it, so When hot working is performed, defects such as blistering (blowing) may occur during hot working or in a subsequent heat treatment process. Therefore, degassing is generally performed before hot working so as not to cause defects.
Japanese Patent No. 2546660 (Claims)

  However, conventional aluminum alloys have a problem that high tensile strength, high Young's modulus, and high ductility, which are useful as high-functional members such as bicycle parts, fishing gear, golf clubs and snowboards, cannot be obtained sufficiently.

  The present invention has been made in view of the above circumstances, and has a high tensile strength, a high Young's modulus and a high ductility that are useful as high-functional members such as bicycle parts, fishing gear, golf clubs and snowboards, and a plastic working aluminum alloy and It is an object to provide a manufacturing method thereof.

  In order to solve the above problems, the invention according to claim 1 is selected from Si: 0.4 to 2.0 wt%, Mg: 0.4 to 2.0 wt%, and further Fe, Mn, and Cr. Further, it is a solidified molding material obtained by mixing aluminum alloy powder composed of Al containing 0.5 to 2.0% by weight in total with the remainder containing inevitable impurities and 10 to 25% by weight of alumina. The Young's modulus at room temperature is 80 GPa or more, the room temperature tensile strength after water quenching treatment is 300 MPa or more, and the elongation is 5% or more.

  The invention according to claim 2 is the aluminum alloy for plastic working according to claim 1, wherein the aluminum alloy powder is Si: 0.4 to 2.0 wt%, Mg: 0.4 to 2.0 wt%, Fe: 0.10 to 0.3 wt%, Mn: 0.05 to 0.6 wt%, Cr: alloy powder made of Al containing 0.05 to 0.6 wt% To do.

Here, the addition amount of Si is set to 0.4 to 2.0% by weight because the addition of Si forms Mg and the compound Mg ₂ Si to increase the strength of the aluminum matrix after heat treatment to 300 MPa or more. This is because the addition of at least 0.4% by weight is necessary, and if the addition amount of Si exceeds 2.0% by weight, an elongation of 5% or more cannot be obtained, which hinders forging.

Further, the amount of Mg added is set to 0.4 to 2.0% by weight because the addition of Mg is necessary for forming the compound Mg ₂ Si with Si in order to increase the strength after the heat treatment, and the tensile strength of 300 MPa or more. This is because, in order to obtain the strength, the addition of at least 0.4% by weight is necessary, and if the amount of Mg exceeds 2.0% by weight, the plastic workability deteriorates.

  Fe forms a compound of Si and Al—Fe—Si to reduce the decrease in elongation, which is an adverse effect of excess Si. The addition amount of Fe was set to 0.10 to 0.3% by weight. When the addition amount was less than 0.10% by weight, the effect of refining the structure of the atomized powder was lost, and when the addition amount exceeded 0.3% by weight. This is because the elongation decreases.

  By adding appropriate amounts of Mn and Cr, there is an effect of suppressing the coarsening of the structure due to hot working. The reason why the amount of Mn and Cr added is 0.05 to 0.6% by weight is that, if the amount is less than 0.05% by weight, the above effect is not obtained, and if the amount added exceeds 0.6% by weight, the ductility is lowered. It is.

  The reason why the amount of alumina added is 10 to 25% by weight is to improve the Young's modulus and wear resistance. When the amount added is less than 10% by weight, the Young's modulus decreases and exceeds 25% by weight. This is because the elongation decreases.

  The invention according to claim 3 is the aluminum alloy for plastic working according to claim 1 or 2, wherein the average particle size of the aluminum alloy powder is 10 to 150 μm, and the average particle size of alumina is 5 to 20 μm. And

  Here, the average particle diameter of the aluminum alloy powder is set to 10 to 150 μm. When the average particle diameter is less than 10 μm, aggregation occurs between the aluminum alloy powders, and it becomes difficult to uniformly mix with alumina, resulting in large variations in strength and elongation. This is because the plastic workability is hindered, and if it exceeds 150 μm, the number of coarse particles increases, and it becomes difficult to uniformly disperse alumina, resulting in large variations in strength and elongation, thereby hindering plastic workability.

  The average particle size of alumina is set to 5 to 20 μm in order to improve the Young's modulus and wear resistance of alumina. When the average particle size is less than 5 μm, uniform mixing cannot be performed. This is because a large amount of alumina reduces the elongation and plastic workability.

  Invention of Claim 4 is the manufacturing method of the said aluminum alloy for plastic working, Comprising: Si: 0.4-2.0 weight%, Mg: 0.4-2.0 weight%, Furthermore, Fe, Mn 1 or more selected from Cr, a total of 0.5 to 2.0% by weight of aluminum alloy powder composed of Al containing inevitable impurities in the balance, and 10 to 25% by weight of alumina mixed The powder is pressure-molded at room temperature, the compact is vacuum degassed at 200 to 450 ° C., and further, the compact that is sintered at a high temperature of 500 to 600 ° C. is pressure-sintered, and then forged. Then, the Young's modulus at room temperature is 80 GPa or more, the room temperature tensile strength after water quenching treatment is 300 MPa or more, and the elongation is 5% or more to obtain a finished structural member free from blistering. It is characterized by that.

  According to the present invention, high tensile strength and high Young's modulus are useful as high-functional members such as bicycle parts, fishing gear, golf clubs and snowboards, and the conventional product has an alumina content of 10% by weight. However, in the present invention, even if the content of alumina is 10% by weight or more, it reaches 8%, which is excellent in ductility and suitable for plastic workability. In addition, it is possible to obtain an aluminum alloy for plastic working that suppresses gas re-adsorption even after degassing and does not cause processing defects such as blistering (blowing).

  Below, the best embodiment of the manufacturing method of the aluminum alloy for plastic working which concerns on this invention is described in detail with reference to FIG.

  First, by weight% (hereinafter simply expressed as%), Si: 0.4 to 2.0% (for example, 0.8%), Mg: 0.4 to 2.0% (for example, 1.0) %) And at least one selected from Fe, Mn, and Cr in a total of 0.5 to 2.0% (for example, Fe: 015%, Mn: 0.05%, Cr: 0.3%) Aluminum alloy rapidly solidified powder made of Al containing the inevitable impurities in the balance {step 1-1, aluminum alloy powder production step}. As a method for producing the rapidly solidified powder, a known manufacturing method such as an atomizing method, a melt spinning method, a rotating disk method, or a rotating electrode method may be used. In this invention, the atomizing method is suitable because it is suitable for industrial production. The method (particularly the gas atomization method) is suitable. In preparation of the aluminum alloy powder, the average particle size of the aluminum alloy powder is preferably 10 to 150 μm in consideration of uniform mixing and variations in strength and elongation. The reason is that if the average particle size of the aluminum alloy powder is less than 10 μm, the aluminum alloy powders aggregate together, making it difficult to mix uniformly with alumina, and the average particle size of the aluminum alloy powder is 150 μm. This is because if the average particle size is exceeded, the number of coarse particles increases, making it difficult to uniformly disperse alumina, resulting in large variations in strength and elongation, which hinders plastic workability.

Next, alumina (Al ₂ O ₃ ) having an average particle diameter of 5 to 20 μm (for example, 15 μm) is mixed and dispersed in the aluminum alloy rapidly solidified powder in a pot mill by 10 to 25% (for example, 15%). The obtained mixed powder is cold isostatically pressed (CIP) and temporarily formed {step 1-2, pressure forming step}. Here, the reason why the average particle size of Al ₂ O ₃ is 5 to 20 μm is that uniform mixing cannot be performed when the average particle size is less than 5 μm, and when the average particle size exceeds 20 μm, coarse Al ₂ O ₃ increases and elongation occurs. This is because the plastic workability is lowered.

  Next, degassing treatment is performed on the temporarily formed mixed powder by vacuum suction {step 1-3, degassing treatment step}. When the degassing treatment is performed while heating, the gas is easily released and partial sintering also proceeds, so vacuum degassing is performed at 200 to 450 ° C. When the furnace temperature exceeds 200 ° C, air and moisture absorbed by the temporary molded body are removed, and when the furnace temperature exceeds 300 ° C, hydrates are decomposed and removed. These phenomena occur even at 450 ° C. or higher, but when the temperature of the temporary molded body exceeds 450 ° C., sintering gradually occurs, and the gaps between the powders inside the temporary molded body from which air and moisture are released begin to close. Therefore, in the present invention, the molded body is held for 1 to 6 hours (for example, 1.5 hours) in a furnace having a furnace temperature of 400 ° C. in order to sufficiently perform degassing before the sintering starts.

  Subsequently, the sintered compact which has been further sintered at a high temperature of 500 to 600 ° C. (for example, 550 ° C.) for 1 to 6 hours (for example, 4 hours) is subjected to pressure sintering by hot extrusion or hot rolling { Step 1-4, Pressure Sintering Step}. In this pressure sintering process, if the temperature is less than 500 ° C., the oxide covering the powder surface is obstructed, the sintering speed is slow and the sintering does not proceed so much. It is preferable to heat the above. If it becomes this temperature (550 degreeC) or more, powder itself will become soft and a part of surface will fuse | melt. The molten metal that has melted oozes out from breaks such as oxide covering the powder surface, fills the gaps between the powders, and sintering proceeds rapidly. In addition, when it hold | maintains at the temperature exceeding 600 degreeC, melting of alloy powder will occur and the mechanical characteristic of a hot work material will fall remarkably. Further, if the holding time is shorter than 1 hour, sintering does not proceed sufficiently, so the holding time needs to be 1 hour or longer. On the other hand, if the holding time is longer than 6 hours, the crystals / precipitates in the alloy powder become coarse and the mechanical properties of the hot-worked material deteriorate. Therefore, the holding time is preferably 1 to 6 hours.

  After pressure sintering, forging is performed to obtain a finished structural member {step 1-5, forging process}.

  Hereinafter, characteristics of the aluminum alloy for plastic working, which is a structural member of the finished product obtained through the above steps, and an experiment for surface observation will be described.

First, an aluminum alloy rapidly solidified powder containing the elements shown in Table 1 and Al ₂ O ₃ is produced (produced) by a gas atomization method. The obtained aluminum alloy powder is formed into a billet having a diameter of 325 mm by cold isostatic pressing. The obtained billet was kept in a vacuum furnace at a temperature of 380 ° C. for 1 hour, degassed, and then baked at a high temperature of 560 ° C. (only No. 20 and No. 21 in Table 1 were 480 ° C.) for 2 hours. After cooling the formed compact to room temperature, it is heated to 500 ° C. by induction heating, extruded and pressed onto a round bar, and water-quenched (T6) treatment, that is, held at 540 ° C. for 2 hours, then water-cooled, and at 180 ° C. for 6 hours. When artificial aging was performed, the results shown in Table 2 were obtained.

As a result of the above experiments, the inventive alloys (No. 1 to No. 4) have a tensile strength of 305 to 367 MPa, a Young's modulus of 80 to 87 GPa, and an elongation of 5.2 to 8.5%, which is sufficient. It showed high tensile strength, Young's modulus and elongation. Furthermore, the re-adsorption of gas was suppressed even after degassing, and an aluminum alloy for plastic working that did not cause processing defects such as blisters could be obtained. On the other hand, the comparative alloys (No. 5 to No. 23) are insufficient in tensile strength, Young's modulus, and elongation because the component amounts, average particle diameter, and sintering temperature of the aluminum alloy powder and Al ₂ O ₃ are not appropriate. It was found that there was large variation or blistering.

Therefore, by weight% (hereinafter the same), Si: 0.4-2.0%, Mg: 0.4-2.0%, and at least one selected from Fe, Mn, Cr in total 0.5 to 2.0% (specifically, Fe: 0.10 to 0.3%, Mn: 0.05 to 0.6%, Cr: 0.05 to 0.6%), By dispersing Al ₂ O ₃ in an aluminum alloy powder composed of Al containing the inevitable impurities in the balance, 10 to 25%, the Young's modulus at room temperature is 80 GPa or more, and the room temperature tensile strength after water quenching treatment is An aluminum alloy for plastic working that is 300 MPa or more and has an elongation of 5% or more and does not generate blisters can be obtained.

It is a flowchart which shows the process of the manufacturing method of the aluminum alloy for plastic working which concerns on this invention.

Claims (4)

  Si: 0.4 to 2.0% by weight, Mg: 0.4 to 2.0% by weight, and at least one selected from Fe, Mn, and Cr in total 0.5 to 2.0% by weight Is a solidified molding material in which the balance is aluminum alloy powder composed of Al containing inevitable impurities and alumina in an amount of 10 to 25% by weight, and has a Young's modulus of 80 GPa or more at room temperature and is water-quenched. An aluminum alloy for plastic working, which has a later room temperature tensile strength of 300 MPa or more and an elongation of 5% or more. In the aluminum alloy for plastic working according to claim 1,
The said aluminum alloy powder is Si: 0.4-2.0 weight%, Mg: 0.4-2.0 weight%, Fe: 0.10-0.3 weight%, Mn: 0.05-0. An aluminum alloy for plastic working, which is an alloy powder made of Al containing 6% by weight and Cr: 0.05 to 0.6% by weight. In the aluminum alloy for plastic working according to claim 1 or 2,
An aluminum alloy for plastic working, wherein the aluminum alloy powder has an average particle size of 10 to 150 μm and alumina has an average particle size of 5 to 20 μm. Si: 0.4 to 2.0% by weight, Mg: 0.4 to 2.0% by weight, and at least one selected from Fe, Mn, and Cr in total 0.5 to 2.0% by weight A mixed powder obtained by mixing 10 to 25% by weight of alumina into an aluminum alloy powder containing Al, the balance of which contains inevitable impurities, is pressure-molded at room temperature, and the compact is vacuum degassed at 200 to 450 ° C. Gas, and then press-sinter the molded body sintered at a high temperature of 500 to 600 ° C., then forging, the Young's modulus at room temperature is 80 GPa or more, and room temperature tensile after water quenching treatment A method for producing an aluminum alloy for plastic working, comprising obtaining a finished structural member having a strength of 300 MPa or more and an elongation of 5% or more.

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