Metal sheets, made of aluminium alloy, for vacuum chamber elements

Abstract

The invention relates to a method for manufacturing a metal sheet having a final thickness of between 6 and 50 mm, the method comprising the steps of: casting a rolling slab made of aluminium alloy having the following composition in % by weight: Si: 0.6-1.3; Mg: 0.6-1.2; Mn: 0.65-1.0; Fe: 0.04-0.20; Cr ≤ 0.05; Ti ≤ 0.15; Cu ≤ 0.1; other elements < 0.05 each, and < 0.15 in total, the remainder being aluminium; homogenisation; hot rolling; cold rolling; solution heat treatment; quenching; stress-relieving by controlled stretching; and tempering. The products obtained by the method according to the invention are particularly useful for producing vacuum chamber elements because they have sufficient mechanical properties, improved dimensional stability for machining steps, and also optimal suitability for creating oxide layers having high chemical resistance.

Description

[0001] Description

[0002] Title: Sheets for vacuum chamber elements made of aluminum alloy

[0003] Technical field

[0004] The invention relates to aluminum alloy products intended to be used as vacuum chamber elements, in particular for the manufacture of integrated electronic circuits based on semiconductors, flat display screens and photovoltaic panels, and their manufacturing method.

[0005] Previous art

[0006] Vacuum chamber components for the manufacture of semiconductor-based integrated electronic circuits, flat panel displays and photovoltaic panels can typically be obtained from aluminium alloy sheets.

[0007] Vacuum chamber elements are elements intended for the manufacture of vacuum chamber structures and internal vacuum chamber components, including vacuum chamber bodies, valve bodies, flanges, connection elements, sealing elements, passages, diffusers, and electrodes. They are obtained, in particular, by machining and surface treatment of aluminum alloy sheets. Excellent dimensional stability is very important for the sheets used to produce these vacuum chamber elements. It is therefore particularly important to minimize any deformation of the sheet during machining, which avoids additional pre-machining or final retouching operations.

[0008] Patent application EP2263811 relates to rolled products having a machined surface having a flatness of 0.2 mm or less. According to one embodiment of this patent application, the alloy contains 0.3 to 1.5% by mass of Mg, 0.2 to 1.6% by mass of Si, and in addition one or more elements selected from the group consisting of 0.8% by mass or less of Fe, 1.0% by mass or less of Cu, 0.6% by mass or less of Mn, 0.5% by mass or less of Cr, 0.4% by mass or less of Zn, and 0.1% by mass or less of Ti, the remainder being Al and unavoidable impurities.

[0009] Patent application WO2014 / 060660 relates to a vacuum chamber element obtained by machining and surface treatment of a sheet of thickness at least equal to 10 mm made of aluminum alloy of composition, in % by weight, Si: 0.4 - 0.7; Mg: 0.4 - 0.7; Ti 0.01 - < 0.15, Fe < 0.25; Cu < 0.04; Mn < 0.4; Cr 0.01 < 0.1; Zn < 0.04; other elements < 0.05 each and < 0.15 in total, remainder aluminum.

[0010] Patent application WO2018 / 162823 relates to a vacuum chamber element obtained by machining and surface treatment of a sheet of thickness at least equal to 10 mm made of aluminum alloy of composition, in % by weight, Si: 0.4 -0.7; Mg: 0.4 -1.0; the ratio in % by weight Mg / Si being less than 1.8; Ti: 0.01 -0.15, Fe 0.08 - 0.25; Cu < 0.35; Mn < 0.4; Cr: < 0.25; Zn < 0.04; other elements < 0.05 each and <0.15 in total, remainder aluminum, characterized in that the grain size of said sheet is such that the average linear interception length measured in the L / TC plane according to ASTM E112, is at least equal to 350 pm between surface and 1 / 2 thickness.

[0011] Patent application US2010018617 discloses an aluminum alloy for anodic oxidation treatment which comprises as alloying elements 0.1 to 2.0% of Mg, 0.1 to 2.0% of Si and 0.1 to 2.0% of Mn, each content of Fe, Cr and Cu being limited to 0.03 mass.% or less, and in which the remainder is composed of Al and unavoidable impurities. This application particularly teaches a homogenization treatment at a temperature above 550 °C and below or equal to 600 °C.

[0012] Patent application CN108239712 relates to a 6082 aluminum alloy plate for aviation and a method for manufacturing the same. The chemical components of the 6082 aluminum alloy plate include, in weight percentage, 1.0% to 1.3% Si, 0.1% to 0.3% Fe, 0.05% to 0.10% Cu, 0.5% to 0.8% Mn, 0.6% to 0.9% Mg, 0.06% to 0.12% Zn, not more than 0.05% Cr, not more than 0.05% Ti and the balance Al and unavoidable elements.

[0013] Patent application CN108239713 relates to an aluminum alloy plate for an electronic product and a method for manufacturing the aluminum alloy plate. The chemical components of the aluminum alloy plate for the appearance of the electronic product include, in weight percentage, 0.3% to 0.4% of Si, not more than 0.10% of Fe, not more than 0.05% of Cu, not more than 0.05% of Mn, 0.45% to 0.55% of Mg, not more than 0.05% of Zn, not more than 0.05% of Cr, not more than 0.05% of Ti and the balance Al and unavoidable elements. Patent application WO2021 / 064320 relates to sheets with a thickness of between 8 and 50 mm made of aluminum alloy of composition, in weight%, Si: 0.7 - 1.3; Mg: 0.6 - 1.2; Mn: 0.65 - 1.0; Fe: 0.05 - 0.35; at least one element chosen from Cr: 0.1 - 0.3 and Zr: 0.06 - 0.15; Ti < 0.15; Cu < 0.4; Zn < 0.1; other elements < 0.05 each and < 0.15 in total, remainder aluminium and their manufacturing process.The addition of Cr and / or Zr makes it possible to obtain improved dimensional stability, particularly during the machining stages, while having sufficient static mechanical properties and excellent anodizing properties. The addition of Cr and / or Zr may, however, prove unfavorable for certain applications related to vacuum chambers.

[0014] Patent application WO2021 / 250545 relates to a method of manufacturing an aluminum alloy plate for vacuum chamber elements, valves or total assemblies, the method comprising the steps of: (a) providing a rolling charge material of an Al-Mg-Si aluminum alloy having a composition comprising, by weight.%, Mg 0.80%-1.05%, Si 0.70%-1.0%, Mn 0.70%-0.90%, Fe up to 0.20%, Zn up to 0.08%, Cu up to 0.05%, Cr up to 0.03%, Ti up to 0.06%, unavoidable impurities and remainder aluminum; (b) homogenizing the rolling charge at a temperature in the range of 550 to 595°C; (c) hot rolling the homogenized rolling charge in one or more rolling stages into a hot rolled plate having a thickness of at least 10 mm; (d) solution treatment of the hot rolled plate at a temperature in the range of 540 to 590°C; (e) rapid cooling of the solution plate; (f) controlled traction by a permanent elongation of 1 to 5% of the solution-treated and cooled plate; (g) artificial aging of the stretched plate.

[0015] There is a need for aluminum alloy products for the production of vacuum chamber elements, with sufficient mechanical characteristics, improved dimensional stability for machining steps as well as optimal suitability for the creation of oxide layers with high chemical resistance.

[0016] Statement of the invention

[0017] A first subject of the invention is a method for manufacturing a sheet with a final thickness of between 6 and 50 mm in which a) a rolling plate is cast from an aluminium alloy of composition, in % by weight, Si: 0.6 - 1.3; Mg: 0.6 - 1.2; Mn: 0.65 - 1.0; Fe: 0.04 - 0.20; Cr < 0.05; Ti < 0.15; Cu < 0.1;other elements < 0.05 each and < 0.15 in total, remainder aluminum, b) said rolling plate is homogenized, c) said rolling plate is rolled with an inlet temperature of at least 500°C to obtain a sheet with a thickness of at least 8 mm, d) optionally annealing is carried out, e) cold rolling is carried out on the hot-rolled and optionally annealed sheet with a reduction of at least 20%, f) a solution treatment is carried out on the sheet thus cold-rolled and it is quenched, g) said sheet thus solution-treated and quenched is stress-relieved by controlled traction with a permanent elongation of 1 to 5%, h) a tempering heat treatment is carried out on the sheet thus stretched, i) optionally said sheet thus tempered is machined.;

[0018] Another subject of the invention is a sheet capable of being obtained by the method according to the invention. Yet another subject of the invention is the use of a sheet according to the invention for producing a vacuum chamber element.

[0019] Figures

[0020] [Fig. 1] Figure 1 illustrates the measurement of residual stresses.

[0021] Detailed description of the invention

[0022] The designation of alloys is made in accordance with the regulations of The Aluminium Association (AA), known to those skilled in the art. The definitions of metallurgical conditions are given in the European standard EN 515. Unless otherwise stated, the definitions of the standard EN12258-1 apply.

[0023] Unless otherwise stated, the compositions are expressed in % by weight.

[0024] Unless otherwise stated, the static mechanical characteristics, in other words the breaking strength R m, the conventional yield strength at 0.2% elongation R p o,2 and the elongation at break A%, are determined by a tensile test according to standard ISO 6892-1, the sampling and the direction of the test being defined by standard EN 485-1, the direction or direction L corresponds to the lengthwise direction in relation to the main rolling direction and the direction or direction TL corresponds to the cross-long direction.

[0025] In the context of the present invention, the residual stresses were determined using the bar method based on the successive removal of layers described in particular in the publication "Development of New Alloy for Distortion Free Machined Aluminum Aircraft Components", F. Heymes, B. Commet, B. Dubost, P. Lassince, P. Lequeu, GM. Raynaud, in 1st International Non-Ferrous Processing & Technology Conference, 10-12 March 1997 - Adams's Mark Hotel, St Louis, Missouri and in patent applications W02004 / 053180 or W02006 / 064113.

[0026] This method is especially applicable to tensile heavy plates, in which the stress state can be considered homogeneous in the bar sampling zone and biaxial; the two main components are located in the L and TL directions, and there is therefore no component in the TC direction. This method is based on the determination of the detections of two rectangular bars, cut in full thickness of the plate in the direction parallel to the L and TL directions. These bars are machined in the TC direction step by step. After each step, the deformation and / or the detection is measured and the thickness of the bar is recorded. In the context of the present invention, the detection was measured using a displacement sensor. Thus, it was possible to calculate the residual stress profiles in the L and TL directions.

[0027] TL. A measurement is taken after each machining pass. Typically, between 18 and 25 passes are taken to obtain a sufficient number of points to calculate the stress profile. The machining depth must not be less than 1 mm, in order to obtain good cutting quality and must be less than 4 mm (for very thick sheets, not all passes are measured). Chemical machining can also be used to remove a very small thickness of metal. The machining pitch should be the same for both samples (e.g. in the L direction and in the TL direction).

[0028] After each machining pass, the bar is detached from the vice, and the temperature is allowed to stabilize before measuring the deformation. At each step / , the thickness h(i) and the deflection (f)(i) are recorded. The diagram in Figure 1 shows how these data are collected.

[0029] These data allow the calculation of the stress profile in each bar in the form of a curve u(i)L, which corresponds to the average stress in the layer removed during the machining step / , given by the following equations:

[0030] For / = 1 to Nl where E is the Young's modulus of the thick sheet and If the length between the support points during the detection measurement. We thus obtain two profiles: u(i) L and uf / J / -which correspond to bars with rectangular section in the L and TL directions.

[0031] The stress profiles in the sheet metal are obtained by the following equations:

[0032] For / = I to Nl where v is the Poisson's ratio of the heavy plate.

[0033] We can then calculate the elastic energy stored in the sheet (W L , W L T and W to t in KJ / m3) from the equations: Wtot=W L +W LTwhere Wtot is the total elastic energy in the sheet (expressed in kJ / m 3 ) and h is the total thickness of the sheet.

[0034] According to the invention, improved sheets of aluminum alloy of the 6XXX series, in particular sheets intended for the production of vacuum chamber elements, are obtained by a process comprising steps of casting, homogenization, hot rolling, optionally annealing, cold rolling, solution treatment, quenching, stress relief, tempering and optionally machining.

[0035] In a first step, a rolling plate made of aluminum alloy of the composition according to the invention is cast.

[0036] The composition according to the invention makes it possible in particular to obtain an advantageous compromise between the mechanical properties, the dimensional stability during the machining stages and the usage properties in the construction and use of vacuum chamber elements, in particular the ability to create oxide layers with high chemical resistance.

[0037] The present inventors have found in particular that compared to a standard composition of the AA6082 alloy, the presence of a high quantity of Mn makes it possible to improve the properties, in particular by promoting a fibrous microstructure.

[0038] By fibrous microstructure is meant a microstructure whose grains have in an L / TC section an aspect ratio between the L and TC directions of at least 4, preferably at least 8 and most preferably at least 12.

[0039] Thus, the Mn content is 0.65 to 1.0% by weight. Preferably, the minimum Mn content is 0.70%, advantageously 0.75% and preferably 0.80% or even 0.85%. In one embodiment of the invention, the Mn content is 0.8 to 1.0% by weight.

[0040] The addition of Fe is also necessary. Thus, the Fe content is 0.04 to 0.20% by weight. Preferably, the minimum Fe content is 0.06%, advantageously 0.07% and preferably 0.08%. Preferably, the maximum Fe content is 0.18%, which can contribute in particular to obtaining the desired granular structure. In one embodiment of the invention, the Fe content is 0.08 to 0.18% by weight.

[0041] Mg and Si are added to achieve the desired mechanical characteristics through the formation of Mg2Si.

[0042] The Mg content is 0.6 to 1.2% by weight. Preferably, the minimum Mg content is 0.63%, advantageously 0.66% and preferably 0.70%. Preferably, the maximum Mg content is 1.1%, advantageously 1.0% and preferably 0.9% or even 0.85%. In one embodiment of the invention, the Mg content is 0.70 to 0.85% by weight. The Si content is 0.6 to 1.3% by weight. Preferably, the minimum Si content is 0.63%, advantageously 0.66% and preferably 0.70%. Preferably, the maximum Si content is 1.2% or 1.1%, advantageously 1.0% and preferably 0.9% or even 0.85%. In one embodiment of the invention, the Si content is 0.70 to 0.85% by weight.

[0043] The Mg and Si contents are balanced, as excess Si can impact anodizing performance and impair the performance in use of vacuum chamber components. Preferably, the Mg content and Si content differ by no more than 0.05% by weight.

[0044] The Ti content is a maximum of 0.15% by weight. It may be advantageous to add Ti, in particular for grain size control during casting. In one embodiment of the invention, the Ti content is 0.01 to 0.05% by weight.

[0045] The Cu content is a maximum of 0.1% by weight. Advantageously, the Cu content is a maximum of 0.07% by weight and preferably a maximum of 0.07% by weight, in particular so as not to impair the ability to create anodic oxide layers with high chemical resistance.

[0046] The Cr content is a maximum of 0.03% by weight. Advantageously, the Cr content is a maximum of 0.02% by weight and preferably a maximum of 0.01% by weight, in particular to avoid the formation of AlCr or Al(Fe,Cr) precipitates, the formation of which can harm the performance in use of the anodic layers created on vacuum chamber components.

[0047] The other elements are present as unavoidable impurities with a content of less than 0.05% by weight each and less than 0.15% by weight in total, the remainder being aluminum. Advantageously, the Zr content is at most 0.03% by weight and preferably at most 0.02% by weight in particular so as to avoid the formation of AhZr or AI(Fe,Zr) precipitates, the formation of which can harm the performance in use of anodic layers created on vacuum chamber components.

[0048] Preferably, the alloy according to the invention is cast by direct-cooling vertical semi-continuous casting. The plate thus obtained can be scalped, i.e. machined, before the subsequent steps. The rolling plate is then homogenized. Preferably, the homogenization temperature is less than 580°C. In an advantageous embodiment of the invention, the homogenization temperature is from 520°C to 570°C. Hot rolling is then carried out to obtain a sheet with a thickness of at least 8 mm. The hot rolling inlet temperature is at least 500°C, preferably at least 520°C and preferentially at least 530°C. An intermediate heat treatment, in particular to restore the sheet thus hot-rolled, can optionally be carried out subsequently, advantageously at a temperature of between 300°C and 400°C.

[0049] Cold rolling, with a reduction rate of at least 20%, is carried out following hot rolling or intermediate heat treatment if it is carried out. The present inventors have found that the presence of a cold rolling step before solution treatment and quenching makes it possible to improve the dimensional stability properties during machining. Advantageously, the reduction rate by cold rolling is 25% to 35%.

[0050] The cold-rolled sheet then undergoes solution treatment followed by quenching. Solution treatment is preferably carried out at a temperature of 510°C to 570°C. Quenching is typically carried out by immersion or spraying with cold water. The solution-treated and quenched sheet is then stress-relieved by controlled traction with a permanent elongation of 1 to 5%, preferably 1.5 to 3%. Stress-relieving is preferably carried out in the longitudinal and transverse directions.

[0051] Finally, tempering is carried out, typically at a temperature between 150°C and 210°C, to preferably obtain a TX51 state.

[0052] Optionally, the returned sheet metal is machined to its final thickness.

[0053] The sheets that can be obtained by the process according to the invention have particularly advantageous properties.

[0054] The mechanical properties of the sheets according to the invention are particularly advantageous. Preferably, the sheets according to the invention have an elastic limit R p o,2(TL) of at least 230 MPa, preferably at least 240 MPa and more preferably at least 250 MPa, and / or a breaking strength R m (TL) of at least 255 MPa, preferably at least 265 MPa and preferably at least 275 MPa and / or an elongation at break A% of at least 10%, preferably at least 12% and preferably at least 14%.

[0055] The sheets according to the invention have a low level of internal stresses. Thus the total elastic energy Wtot is less than 0.5 kJ / m 3 , preferably less than 0.4 kJ / m 3 , preferably less than 0.3 kJ / m 3 , and preferably less than 0.2 kJ / m 3 .

[0056] Preferably, the sheets according to the invention have a fibrous microstructure.

[0057] According to the invention, sheets according to the invention are used to produce a vacuum chamber element. Thus, the sheets according to the invention are machined and anodized to produce vacuum chamber elements, such as vacuum chamber bodies, valve bodies, flanges, connection elements, sealing elements, passages, diffusers, electrodes. Indeed, the sheets according to the invention have improved dimensional stability, particularly during the machining steps, while having sufficient static mechanical properties, and an optimal ability to create oxide layers with high chemical resistance.

[0058] Example

[0059] In this example, rolling plates were prepared from alloy whose composition is given in Table 1.

[0060] [Table 1]

[0061] Composition of alloys in percentage by weight

[0062] The plates were homogenized at 540 °C. The plates were hot rolled to a thickness of 14 to 32 mm depending on the case. The hot rolling inlet temperature was between 530 and 550 °C. In a reference process A, the final thickness was obtained by hot rolling. In a process B, according to the invention, a 30% cold rolling was carried out after hot rolling to obtain the final thickness. The sheets thus obtained were solution-treated at 540 °C, quenched, held by controlled traction in the longitudinal and transverse directions with a permanent elongation of 2% and heat treated to obtain an over-tempered state.

[0063] The static mechanical characteristics in tension, in other words the breaking strength R m , the conventional yield strength at 0.2% elongation R po,2 and the elongation at break A%, were determined by a tensile test according to standard NF EN ISO 6892-1 (2016) in the long transverse direction (TL), the sampling and the direction of the test being defined by standard EN 485 (2016). The characterizations were carried out in the long transverse direction.

[0064] The results are given in Table 2

[0065] [Table 2]

[0066] Static mechanical properties

[0067] Elastic energy was measured using the rod method already described.

[0068] [Table 3]

[0069] Average elastic energies determined by the bar method (3 measurements per part, 6 measurements in the case where 2 parts are concerned)

[0070] The parts obtained with the process according to the invention have a significantly lower elastic energy than that obtained with the reference process, while having more advantageous mechanical characteristics.

Claims

Demands 1. Process for manufacturing a sheet of final thickness between 6 and 50 mm in which a) a rolling plate of aluminium alloy of composition, in % by weight, Si: 0.6 - 1.3; Mg: 0.6- 1.2; Mn: 0.65- 1.0; Fe: 0.04-0.20; Cr < 0.05; Ti < 0.15; Cu < 0.1; is castother elements < 0.05 each and < 0.15 in total, remaining aluminum, b) said rolling plate is homogenized, c) said rolling plate is rolled with an inlet temperature of at least 500°C to obtain a sheet of thickness at least equal to 8 mm, d) optionally an intermediate heat treatment is carried out, e) the hot-rolled and optionally heat-treated sheet is cold-rolled with a reduction of at least 20%, f) the cold-rolled sheet is solution-treated and quenched, g) the solution-treated and quenched sheet is stress-relieved by controlled tensile stress-relief with a permanent elongation of 1 to 5%, h) the tensile-treated sheet is tempered, i) optionally the tempered sheet is machined.

2. A method according to claim 1 wherein the Mn content is 0.8 to 1.0% by weight.

3. A method according to claim 1 or claim 2 wherein the Fe content is from 0.08 to 0.18% by weight.

4. A process according to any one of claims 1 to 3 wherein the cold rolling reduction rate is 25% to 35%.

5. Sheet metal that can be obtained by the process according to any one of claims 1 to 4.

6. Sheet metal according to claim 5 having a yield strength R p o,2(TL) of at least 230 MPa, preferably at least 240 MPa and preferably at least 250 MPa, and / or a tensile strength R m (TL) of at least 255 MPa, preferably of at least 265 MPa and preferably of at least 275 MPa and / or an elongation at break A% of at least 10%, preferably of at least 12% and preferably of at least 14%.

7. Sheet metal according to claim 5 or claim 6 such that the total elastic energy Wtot is less than 0.5 kJ / m 3, preferably less than 0.4 kJ / m 3 , preferably less than 0.3 kJ / m 3 , and preferably less than 0.2 kJ / m 3 . Sheet metal according to any one of claims 5 to 7 having a fibrous microstructure. Use of sheet metal according to any one of claims 5 to 8 for producing a vacuum chamber element. Use according to claim 9 wherein the sheets according to the invention are machined and anodized to produce vacuum chamber elements, such as vacuum chamber bodies, valve bodies, flanges, connecting elements, sealing elements, passages, diffusers, and electrodes.

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