JP2013517383A - Method for producing 6xxx alloy product for vacuum chamber - Google Patents

Abstract

The present invention relates to a method of manufacturing an aluminum block having a thickness of 250 mm or more and intended for the manufacture of an element for a vacuum chamber, wherein in this method, Si: 0.5 to 1.5, Mg: 0.5 to 1.5, Fe <0.3, Cu <0.2, Mn <0.8, Cr <0.10, Ti <0.15, other elements <0 .05 and total <0.15, the balance being aluminum, cast by semi-continuous casting and solutionized directly at a temperature of 450-560 ° C. against the cast and optionally homogenized block The heat-treated block is quenched with the solution thus formed at a cooling rate of 200 ° C./h or more between the solution temperature and 200 ° C .; tempering of the block thus quenched and optionally stress-removed is performed. carry out. The blocks obtained in this way are particularly advantageous in the production of vacuum chambers for the production of semiconductor integrated electronic circuits, flat display screens and solar panels.
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Description

  The present invention relates to the manufacture of 6xxx alloy products specifically intended for use in the manufacture of vacuum chambers for the manufacture of semiconductor integrated electronic circuits, flat display screens and solar panels.

  In the production of aluminum alloy blocks for use in the fabrication of semiconductor integrated electronic circuits, flat display screens and vacuum chambers for the production of solar panels, all properties are met while limiting the cost of each operation This is very important.

In fact, the block is first of all machined into a part that exhibits the desired dimensions and rigidity, generally in such a way that at least an average vacuum (10 ⁻³ to 10 ⁻⁵ Torr) level vacuum can be achieved without deformation. It must exhibit sufficient mechanical properties to produce. Therefore, the desired breaking strength (R _m ) is generally at least 260 MPa and even higher if possible. Moreover, the residual stress in the block for machining from the mass must be low so that the desired dimensions can be easily achieved without deformation during machining. Especially in order to produce large-sized liquid crystal panels or solar cell panels, the dimensions of the vacuum chamber are constantly increasing, so it is necessary to produce aluminum alloy blocks with increasing thicknesses of at least 250 mm and even 300 mm. is there. The thicker the block, the more difficult it is to obtain sufficient mechanical properties while maintaining excellent stability during machining.

If a high vacuum (10 ⁻⁶ to 10 ⁻⁸ Torr) needs to be achieved, the block porosity level must be sufficiently low. Moreover, the gas used in the vacuum chamber is often very reactive and also due to particles or substances originating from the walls of the vacuum chamber and / or due to frequent replacement of parts or silicon wafers or liquid crystal devices It is important to protect the surface of the chamber so as to avoid the risk of contamination. From this point of view, aluminum has been found to be an advantageous material, which generally produces a hard oxide film resistant to reactive gases on the surface of the block by anodization. Because it is possible. However, the strength of the anodized film is influenced by a number of factors (crystal grain size, phase precipitation, porosity), particularly related to the microstructure of the product, and it is always desirable to improve this parameter.

  In short, it is desirable to achieve the targeted properties by an economic method, as is the case for any industrial method. Due to the large-scale development of vacuum chambers for a number of mass distribution applications (flat screens, solar panels), interest in the simplification of manufacturing methods has increased in recent years.

  U.S. Pat. No. 6,565,984 (Applied Materials Inc.) includes (by weight) Si: 0.54-0.74, Cu: 0.15-0.30, Fe: 0.05- Semiconductor manufacturing chamber having a composition of 0.20, Mn ≦ 0.14, Zn ≦ 0.15, Cr: 0.16 to 0.28, Ti ≦ 0.06, Mg: 0.9 to 1.1 It describes alloys that are suitable for manufacturing. Parts are obtained by machining or extruding to the desired shape. This composition makes it possible to control the size of the impurity particles, thus improving the performance of the anodized film.

U.S. Pat. No. 6,982,121 (Kyushu Mitsui Aluminum Co., Ltd.) describes (by weight) Mg: 2.0-3.5, Ti: 0.004-0.01%, and purity 99 An alloy that is compatible with anodization and compatible with plasma processing chambers, containing 9% residual aluminum is described. This alloy does not require heat treatment unlike an alloy that requires Mg ₂ Si precipitation. In addition, this alloy does not require the presence of Cr and Mn, which must be added to alloys 5052 and 6061 to control grain size, but at the risk of inducing heavy metal contamination of the semiconductor being processed. However, the mechanical properties of this alloy are not shown. Moreover, 99.9% pure aluminum is costly.

  U.S. Patent Application Publication No. 2009/0050485 (Kobe Steel Works, Ltd.) is anodized in such a way that the hardness of the anodized film varies within the thickness. An alloy having a composition of 1 to 2.0, Si: 0.1 to 2.0, Mn: 0.1 to 2.0, Fe, Cr, and Cu ≦ 0.03 is described. Due to the extremely low content of iron, chromium and copper, significant additional costs are incurred for the metals used.

  US Patent Application Publication No. 2001/019777 and Japanese Patent Application Laid-Open No. 2001-220737 (Kobe Steel Co., Ltd.) are (by weight percent) Si: 0.1 to 2.0, Mg: 0.1 to 3 .5, Cu: 0.02 to 4.0 and an alloy for a chamber containing impurities and having a Cr content of less than 0.04%. These documents disclose in particular products obtained by performing a hot rolling step prior to solution treatment.

  European Patent Application No. 2003219 (Kobe Steel Co., Ltd.) has Mg 0.5 to 1.25% (by weight), Si: 0.4 to 1.4%, Cu: 0.01 to 0 0.7%, Fe: 0.05 to 0.4%, Mn: 0.001 to 1.0%, Cr 0.01 to 0.35%, Ti and Zr 0.005 to 0.1% Is described. This document discloses in detail the product obtained by performing a hot forging step prior to solutionizing.

  Document “The effect of processing and Mn content on the T5 and T6 properties of AA6082 profiles”, Journal of Materials Processing Technology, 183, AA-83, A-83, A-83, A-83, A- This document discloses in detail the product obtained by performing a hot extrusion step prior to solutionization.

  The methods used in these documents lead to high costs (the purity of the aluminum used, the number of method steps). Intended for use in the fabrication of vacuum chambers that have high mechanical properties, low residual stress, and are capable of forming an anodized coating that is resistant to reactive gases after machining. There is a need for a low cost and improved manufacturing method for such aluminum alloy blocks.

The first object of the present invention is a method for producing an aluminum block having a thickness of 250 mm or more and intended for the production of an element for a vacuum chamber.
(A) By weight%, Si: 0.5 to 1.5, Mg: 0.5 to 1.5, Fe <0.3, Cu <0.2, Mn <0.8, Cr <0.10 , Ti <0.15, each other element <0.05 and the total <0.15, the balance is aluminum, cast an alloy block by semi-continuous casting,
(B) optionally, homogenizing the cast block at a temperature of 500 ° C. to 590 ° C .;
(C) performing a solution heat treatment directly at a temperature of 450 ° C. to 560 ° C. on a cast and optionally homogenized block without performing a hot or cold deformation step before solution treatment;
(D) Quenching the block thus solutionized at a cooling rate of 200 ° C./h or more between the solution temperature and 200 ° C.,
(E) Optionally, stress relieve the block thus quenched,
(F) There is a manufacturing method in which tempering of the block thus quenched and optionally subjected to stress removal is performed.

Another object of the present invention is to have a thickness of 250 mm or more, and by weight, Si: 0.5 to 1.5, Mg: 0.5 to 1.5, Fe <0.3, Cu <0. 2, Mn <0.8, Cr <0.10, Ti <0.15, each other element <0.05 and total <0.15, the balance being aluminum, and the state T6 or T652 in, in fracture strength _{R m} in 1/4 thickness than 280 MPa, a block elastic limit _{R p0.2} of at 1/4 thickness is more than 240 MPa, the block, the semi-continuous casting, 500 ° C. ~ Optional homogenization of the cast block at a temperature of 590 ° C., 450 directly on the cast and optionally homogenized block without performing a hot or cold deformation step before solutionizing Solution treatment at a temperature of from ℃ to 560 ℃, solution treatment temperature and 200 ℃ 200 ° C. / hour or more of quenching at a cooling rate between obtained by any stress relief and tempering.

  Yet another object of the invention is the use of the block according to the invention in the manufacture of a vacuum chamber for the production of semiconductor integrated electronic integrated circuits, flat display screens and / or solar panels.

FIG. 2 shows the granular structure of blocks 11 (FIG. 1a) and 21 (FIG. 1b) obtained by the method according to the invention. FIG. 3 is a diagram showing the granular structure of the reference block 31 (FIG. 2a) and the block (FIG. 2b) obtained by the method according to the prior art (deformed by forging before solution treatment).

  The names of the alloys are in accordance with the rules of the Aluminum Association (AA) which are well known to those skilled in the art. The definition of the metallurgical state is given in the European standard EN515.

  Unless otherwise stated, the static mechanical properties, in other words, the breaking strength Rm, the conventional 0.2% elongation elastic limit Rp0.2 and the breaking elongation A% are determined by a tensile test according to the EN10002-1 standard. The direction of sampling and testing is defined by the EN 485-1 standard. The hardness is measured according to the EN ISO 6506 standard.

  The elements for the vacuum chamber are in particular the body of the vacuum chamber, the gate valve body, the flange, the connecting element, the airtight element, the passage, the flexible tube.

  In the method according to the invention, 6xxx series alloys are processed into blocks that can be used for the fabrication of elements for vacuum chambers without performing a hot or cold deformation step prior to solution treatment. Thus, according to the invention, Si (by weight): 0.5-1.5, Mg: 0.5-1.5, Fe <0.3, Cu <0.2, Mn <0.8, Cr <0.10, Ti <0.15, each other element <0.05 and total <0.15, the balance is made of an alloy having a composition of aluminum with a thickness of 250 mm or more, semi-continuous casting, 500 ° C. Optional homogenization of the cast block at a temperature of ˜590 ° C., directly on the cast and optionally homogenized block without performing a hot or cold deformation step prior to solution treatment, It is obtained by solution treatment at a temperature of 450 to 560 ° C., quenching at a cooling rate of 200 ° C./h or more between the solution treatment temperature and 200 ° C., arbitrary stress removal, and tempering. Direct solution to cast blocks without performing a hot or cold deformation step prior to solution forming is within the framework of the present invention that a hot or cold deformation step is performed prior to solution forming. Although meant not to be performed, it is still possible to carry out conventional steps such as surface machining or edge cutting, in particular before or after homogenization.

  The iron content must be less than 0.3% by weight, because above this value, the anodic oxide coating obtained to protect the metal from reactive gases does not reach the desired strength. . However, the inventors have determined that it is not necessary to achieve a very high purity level in order to obtain an anodized film exhibiting the desired characteristics using the method according to the present invention. The iron content is therefore advantageously at least 0.1% by weight, which makes the process according to the invention very economical.

  The copper content must be less than 0.2% by weight because if the copper content is too high, the sensitivity to quenching is increased. However, in some cases, it is advantageous to add a limited amount of copper to improve mechanical properties, especially when the cooling rate after solutionization is greater than 800 ° C./h. In one embodiment of the invention, a copper content of 0.03 to 0.15% by weight is preferred.

  The inventors have confirmed that the desired mechanical properties, in particular the minimum mechanical strength, are not achieved when the chromium content is 0.10% by weight or more. It is generally accepted that the fabrication of wrought work piece products for vacuum chambers made of 6xxx series alloys requires the presence of chromium and / or manganese to control particle size. In contrast, the present inventors have confirmed that the absence of chromium is advantageous within the framework of the present invention. This is because the absence of chromium does not deteriorate the granular structure and is not sensitive to quenching. This is because the mechanical properties of a thick product can be improved. In an advantageous embodiment of the invention, the chromium content is less than 0.05% by weight and preferably less than 0.03% by weight. On the other hand, the manganese content must be less than 0.8% by weight, and a content of more than 0.8% by weight is particularly disadvantageous with respect to the properties of the anodized film and the contamination of the vacuum chamber. Advantageously, the manganese content is less than 0.6% by weight in order to avoid the formation of a coarse phase that can be detrimental to the properties of the anodized film. In an advantageous embodiment of the invention, the manganese content is even less than 0.05% by weight. The inventors surprisingly found that even in the absence of Cr, Mn and Zr, the granular structure obtained by the method according to the invention is controlled, in terms of mechanical properties and resistance to reactive gases. As a result, it was confirmed that sufficient characteristics could be obtained. Thus, the absence of Cr, Mn and Zr at the same time makes it possible to significantly reduce the susceptibility of the alloy to quenching and thus to improve the mechanical properties of the thick product, and for that reason granular properties. And the characteristics of the anodized film are not deteriorated. In an advantageous embodiment of the invention, the content of Cr, Mn and Zr is simultaneously less than 0.05% by weight, preferably less than 0.03% by weight.

  The content of silicon and magnesium is 0.5 to 1.5% by weight. Advantageously, a combination of 0.5-0.8% by weight silicon and 0.8-1.2% by weight magnesium, or 0.8-1.2% by weight silicon and 0.6-1. A combination with 0% by weight of magnesium is realized. In a preferred embodiment of the invention that makes it possible to achieve particularly high mechanical properties, the silicon content is 0.8 to 1% by weight, preferably 0.85 to 0.95% by weight, and the magnesium content Is 0.6 to 0.8% by weight, preferably 0.65 to 0.75% by weight.

  Alloy casting is carried out in the form of blocks by semi-continuous casting with direct cooling. Typically, a block mold having a thickness of 300 to 450 mm is used.

  The cast block may optionally be homogenized at a temperature between 500 ° C. and 590 ° C. for at least one hour. The implementation of homogenization is advantageous because it generally achieves more advantageous mechanical properties and better anodized film properties, while reducing solution time. Homogenization can be performed during another heat treatment or during a solution heat treatment.

  Before or after homogenization is performed between casting and solution heat treatment, surface machining (also called “scalping”) of at least about 5 mm per surface is generally performed, and a segregation layer on the surface To avoid the presence of cracks.

  Next, a direct solution heat treatment is performed directly on the block cast and optionally homogenized immediately at a temperature of 450-560 ° C., preferably 520-550 ° C., without prior hot or cold deformation steps. Is implemented. Conventional hot deformation of prior art methods is generally performed by rolling and / or forging and / or extrusion. Thus, the block does not undergo a significant deformation step by tempering between casting and solutionizing. Forging typically means rolling and / or forging and / or extrusion operations. Thus, according to the present invention, any of the dimensions (length, width, thickness) of the cast block will change significantly, typically at least about 10%, due to training between casting and solution treatment. It wo n’t hurt. The solution time is preferably more than one hour. The method according to the invention which makes it possible to avoid hot or cold deformation before solution treatment is very advantageous from an economic point of view because of the high cost of this deformation step. According to the prior art, this type of method has not been specifically intended for blocks intended for the fabrication of elements for vacuum chambers made of 6xxx alloy, perhaps because the elements for vacuum chambers This is because there was concern that the mechanical properties necessary for production, the strength of the anodized film and the level of porosity could not be achieved without hot deformation. Moreover, some very thick products were not available by prior art methods. Surprisingly, the inventors have not only made it possible for such a simplified method to achieve the same properties as those obtained by prior art methods, but in some cases We confirmed that we could surpass them.

  The quenching step after solution treatment is very important and must be performed at a cooling rate of 200 ° C./h or more between the solution temperature and 200 ° C. The cooling rate is calculated by the half thickness of the block. When the cooling rate is too low, the inventors have confirmed that the required mechanical properties are not achieved.

  In a first advantageous embodiment of the invention, the cooling rate is between 200 ° C./h and 400 ° C./h. In fact, surprisingly, when the cooling rate is between 200 ° C./h and 400 ° C./h, sufficient mechanical properties and low residual energy are obtained at the same time, which makes it possible to avoid the stress relief step by compression. Such a cooling rate can be obtained using watering by fog.

  In a second advantageous embodiment of the invention, the cooling rate is 800 ° C./h or more. Such a cooling rate can be obtained by watering or flooding. Preferably, water at a temperature of at least 50 ° C. is used for cooling because an excessively high cooling rate can create excessive internal stresses within the block.

  Optionally, the block thus quenched is stress relieved by cold compression, preferably with a permanent deformation rate of 1% to 5%. In the second embodiment, where the cooling rate is greater than 800 ° C./h, stress relief has been found to be very advantageous. Stress relief reduces residual stress in the metal and allows deformation during machining to be avoided.

Finally, tempering of the block thus quenched and optionally stress relieved is performed. The tempering temperature is preferably 150 to 190 ° C., more preferably 165 to 185 ° C., and the tempering time is 5 to 40 hours and preferably 8 to 20 hours. Advantageously, tempering is carried out to achieve a state T6 or T652 corresponds to the peak of the static mechanical properties _{(R m} and _{R p0.2).}

The blocks obtained by the method according to the invention are characterized by high mechanical properties. Thus, the product obtained by the process according to the present invention, in a state T6 or T652, fracture strength _{R m} in 1/4 thickness is at least 280 MPa, 1/4 elastic limit _{R p0.2} in thickness 240 MPa or more. In an advantageous embodiment, the composition is Si: 0.5-1.2, Mg: 0.6-1.0, Fe: 0.1-0.3, Cu <0.2, Mn <0. 05, Cr <0.05, Ti <0.15, each other element <0.05 and the sum <0.15 is used, and in the state T6 or T652, the thickness is ¼ of 300 MPa or more. fracture strength _{R m} is achieved, 1/4 the elastic limit _{Rp 0.2} of the thickness is at least 270 MPa, its upper silicon content 0.8-1% by weight, preferably 0.85-0.95 weight %, When the magnesium content is 0.6 to 0.8 wt%, preferably 0.65 to 0.75 wt%, the fracture strength R _m at 1/4 thickness in state T6 or T652 Is 320 MPa or more, and the elastic limit R _{p0.2 at ¼} thickness is 300 MPa or more. The

  In state T6 or T652, the product according to the invention achieves a minimum elongation of at least 0.5%. In some cases, a minimum value of elongation of at least 4% is achieved with the product according to the invention.

  The granular structure of the product according to the present invention is characterized by the absence of training prior to solutionization. Therefore, it is possible to distinguish between a product according to the prior art and a product according to the present invention in which hot or cold deformation is carried out before solutionization by a simple metallurgical inspection. Typically, the granular structure of the product according to the invention is isotropic with an average particle size of 200 μm or more.

  The blocks obtained by the method according to the invention can be used in the production of vacuum chambers for the production of electronic integrated circuits, flat display panels and / or solar panels composed of semiconductors. Thus, the block behavior for machining is advantageous, inter alia, due to high mechanical properties and low residual stress levels. Moreover, the anodic oxide coating obtained on the machined block by conventional anodizing methods is resistant to reactive gases used in the vacuum chamber.

  The blocks obtained by the method according to the invention can likewise be used advantageously for all other applications in which the properties obtained are suitable.

  In this example, the method according to the present invention was compared with the method according to the reference example. The method according to the invention was applied to two different alloys.

  Four alloy blocks having the compositions shown in Table 1 were cast by direct cooling semi-continuous casting. The block was sculpted to a thickness of 410 mm.

  The block was homogenized at a temperature of 540-590 ° C. for at least 4 hours.

  The block was then solutionized at 540 ° C. After solutionization, blocks 11, 21, and 31 were quenched with 60 ° C. water (the calculated average cooling rate between 540 ° C. and 200 ° C. was about 1500 ° C./h), while block 12 was Quenched with air, the average cooling rate between 540 ° C. and 200 ° C. was about 90 ° C./h.

  The different blocks were then subjected to 1.5-2.5% cold compression and then tempered at 165 ° C. to obtain state T652.

  The granular structure of the resulting product is shown in FIGS. 1a (block 11), 1b (block 21) and 2a (block 31). For comparison, FIG. 2b shows the granular structure of the product by the method according to the prior art (forging before solution).

  The resulting mechanical properties are provided in Table 2.

  The blocks (11 and 21) obtained by the method according to the present invention show a higher mechanical strength (Rm, Rp0.2) than that obtained with the reference ingot, and the mechanical strength obtained with the ingot 11 Is very advantageous.

  The block obtained according to the invention has a slight residual stress, so that deformation of the block during machining can be avoided. The level of porosity observed in the blocks according to the invention was very low and low enough to achieve a high vacuum.

US Pat. No. 6,565,984 US Pat. No. 6,982,121 US Patent Application Publication No. 2009/0050485 US Patent Application Publication No. 2001/019777 Japanese Patent Laid-Open No. 2001-220737 European Patent Application No. 2003219

"The effect of processing and Mn content on the T5 and T6 properties of AA6082 profiles", Journal of Materials Processing Technology, 173 (2006) 173 (2006).

Claims (15)

A method for producing an aluminum block having a thickness of 250 mm or more and intended for producing an element for a vacuum chamber,
(A) By weight%: Si: 0.5 to 1.5, Mg: 0.5 to 1.5, Fe <0.3, Cu <0.2, Mn <0.8, Cr <0.10, Casting an alloy block having a composition of Ti <0.15, each other element <0.05 and total <0.15, the balance being aluminum by semi-continuous casting,
(B) optionally, homogenizing the cast block at a temperature of 500 ° C. to 590 ° C .;
(C) performing a solution heat treatment directly at a temperature of 450-560 ° C. on the cast and optionally homogenized block without performing a hot or cold deformation step before solution treatment;
(D) Quenching the block thus solutionized at a cooling rate of 200 ° C./h or more between the solution temperature and 200 ° C.,
(E) Optionally, stress relieve the block thus quenched,
(F) A manufacturing method of performing tempering of the block thus quenched and optionally subjected to stress removal.   2. Process according to claim 1, wherein the manganese content is less than 0.6% by weight, preferably less than 0.05% by weight.   3. A process according to claim 1 or claim 2, wherein the chromium content is less than 0.05% by weight, preferably less than 0.03% by weight.   4. A method according to any one of claims 1 to 3, wherein the contents of Cr, Mn and Zr are simultaneously less than 0.05% by weight and preferably less than 0.03% by weight.   The process according to any one of claims 1 to 4, wherein the iron content is at least 0.1% by weight.   The method according to any one of claims 1 to 5, wherein the silicon content is 0.5 to 0.8 wt% and the magnesium content is 0.8 to 1.2 wt%.   The method according to claim 1, wherein the silicon content is 0.8 to 1.2% by weight and the magnesium content is 0.6 to 1.0% by weight.   The silicon content is 0.8-1% by weight, preferably 0.85-0.95% by weight, and the magnesium content is 0.6-0.8% by weight, preferably 0.65-0.75% by weight. The method of claim 7, wherein the method is%.   The method according to claim 1, wherein the cooling rate between a solution temperature and 200 ° C. is 200 ° C./h to 400 ° C./h.   The method according to claim 1, wherein the cooling rate between the solution temperature and 200 ° C. is 800 ° C./h or more.   The method according to claim 1, wherein the stress relief is performed by cold compression at a permanent deformation rate of 1% to 5%. It has a thickness of 250 mm or more, and by weight, Si: 0.5 to 1.5, Mg: 0.5 to 1.5, Fe <0.3, Cu <0.2, Mn <0.8, Cr <0.10, Ti <0.15, each other element <0.05 and total <0.15, the balance being aluminum, and destruction at 1/4 thickness in state T6 or T652 intensity _{R m} or more 280 MPa, 1/4 elastic limit _{R p0.2} in thickness a block is at least 240 MPa, semi-continuous casting, 500 ° C. to 590 any cast block at a temperature of ° C. Solution treatment temperature at 450-560 ° C. directly on cast and optionally homogenized blocks without performing a hot or cold deformation step prior to homogenization and solution treatment. Cooling rate of 200 ° C./h or more between 200 ° C. and 200 ° C. Blocks of hardening obtained by any stress relief and tempering.   13. A block according to claim 12, obtained by the method according to any one of claims 1-11. The composition was Si: 0.5 to 1.2, Mg: 0.6 to 1.0, Fe0.1 to 0.3, Cu <0.2, Mn <0.05, Cr <0. 05, Ti <0.15, the other elements <0.05 and total <it is 0.15, and in a state T6 or T652, in the fracture strength _{R m} in 1/4 thickness at least 300 MPa, 1 / The block according to claim 12 or 13, wherein the elastic limit _Rp0.2 at 4 thicknesses is 270 MPa or more.   Use of a block according to any one of claims 12 to 14 in the manufacture of a vacuum chamber for the production of semiconductor integrated electronic integrated circuits, flat display screens and / or solar panels.

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