METHOD FOR MANUFACTURING A PART MADE OF AN ALUMINIUM OR MAGNESIUM-BASED ALLOY, COMPRISING THE ADDITIVE MANUFACTURING OF THE PART

Abstract

Method for manufacturing a part made of an aluminum or magnesium-based alloy, comprising the additive manufacturing of the part by melting the alloy and forming a molten bath (18) using the energy supplied by a laser beam (10) emitted along a first axis (A), characterized in that the molten bath (18) is subjected to ultrasound (22) by means of a transducer (24) which emits the ultrasound (22) along a second axis (B) inclined at an angle (α) of between 10 and 80° relative to said first axis (A). Figure for the abstract: Figure 1

Description

Title of the invention: METHOD FOR MANUFACTURING A PART MADE OF AN ALLOY BASED ON ALUMINIUM OR MAGNESIUM, INCLUDING ADDITIVE MANUFACTURING OF THE PART Technical field of the invention

[0001] The present invention relates to a method for manufacturing a part made of an aluminum or magnesium-based alloy, comprising additive manufacturing of the part. Technical background

[0002] It is known to produce a part from a metal alloy using an additive manufacturing process.

[0003] Additive manufacturing consists of producing a part layer by layer, from a filler material which can come in different forms (powder, rod, wire, etc.).

[0004] The filler material is melted, which allows a molten bath to be created. After solidification, a bead of material is formed which is formed on a previously formed bead of material and which is intended to receive another bead of material in order to build the part layer by layer.

[0005] The melting of the filler material is generally obtained by the energy supplied by a laser beam.

[0006] There are two types of laser additive manufacturing. According to a first type called SLM, which stands for Selective Laser Melting, manufacturing is carried out on a powder bed by selectively melting layers of powder. According to a second type called LMD, which stands for Laser Metal Deposition, or DED, which stands for Directed Energy Deposition, the material to be melted is supplied in powder form by a gas flow, or in the form of a rod or wire.

[0007] In the foundry field, a process called USP (Ultrasonic Melting Processing) is also known, which consists of subjecting a bath of molten metal to ultrasonic waves. However, this technology is difficult to industrialize due to the complexity of its implementation on the scale of industrial foundry baths.

[0008] The main problems encountered in additive manufacturing essentially focus on the resulting anisotropic microstructure as well as on the defects generated at the local scale during the manufacturing of a part. The present invention is more particularly concerned with improving the properties of parts produced by additive manufacturing in “light” alloys, in particular alloys based of Aluminum or Magnesium.

[0009] The present invention aims to improve the additive manufacturing of this type of part, in particular by improving the quality and homogeneity of the melted zone and by refining the microstructure of the part. Summary of the invention

[0010] The invention relates to a method for manufacturing a part made of an alloy based on Aluminum or Magnesium, comprising the additive manufacturing of the part by melting the alloy and forming a molten bath using the energy provided by a laser beam emitted along a first axis, characterized in that the molten bath is subjected to ultrasound by means of a transducer which emits the ultrasound along a second axis inclined at an angle of between 10° and 80° relative to said first axis.

[0011] Ultrasound or ultrasonic waves can act directly on the resulting microstructure during the solidification of the alloy. Ultrasound in particular allows the phases to be deagglomerated, the molten material to be degassed and the microstructure to be refined. Ultrasonic waves have a direct effect on the germination of the different phases and the air microcavities trapped in the molten pool via cavitation phenomena.

[0012] The implementation of ultrasonic waves for the additive manufacturing of parts is much more practical and efficient than for a foundry bath as a whole. Indeed, the controlled localization of the fusion zone generated by an additive manufacturing process is a key advantage for the integration of a transducer associated for example with a sonotrode.

[0013] The method according to the invention may also have one or more of the following characteristics or steps, taken alone or in combination with each other: • the angle is between 10° and 45°, and preferably between 30° and 45°; • the angle is between 45° and 80°, and preferably between 60° and 80°; • the angle is between 30° and 60°, and is preferably 45° at + / -20%; • the transducer is equipped with a sonotrode which includes a free end ultrasonic emission which is located at most 5 cm from the molten bath, preferably at most 1 cm from the molten bath and even more preferably less than 1 cm from the molten bath; • the laser for melting has a power between 100W and 1000W, and preferably 400W at + / - 10%; • ultrasound is emitted at a frequency between 10KHz and 50KHz, and preferably 20KHz at + / -10%; • the alloy comprises more than 50% by weight of Aluminum or Magnesium, and preferably more than 80% by weight of Aluminum or Magnesium; • additive manufacturing is of the SLM type and carried out on a bed of powders; • additive manufacturing is of the LMD or DED type and carried out by fusion of a powder supplied by a flow of gas or a wire or filler rod; • the gas flow is projected along a third axis, or the filler wire or rod is supplied along a third axis, the third axis being inclined at an angle of between 10° and 80° relative to said second axis; • the first, second and third axes are coplanar;

[0014] — the third axis is inclined at an angle of between 10° and 45° relative to the first axis, and for example between 20° and 30°;

[0015] — the first axis is interposed between the second and third axes;

[0016] — the third axis is inclined at an angle between 60° and 80° relative to the first axis;

[0017] — the second axis is interposed between the first and third axes. Brief description of the figures

[0018] Other characteristics and advantages of the invention will appear during the reading of the detailed description which follows for the understanding of which reference will be made to the appended drawings in which:

[0019] [Fig.l] [Fig.l] is a schematic view of an installation of the LMD or DED type for the additive manufacturing of a part, and illustrates an embodiment of a method according to the invention,

[0020] [Fig.2] [Fig.2] is a schematic view of another installation of the LMD or DED type for the additive manufacturing of a part, and illustrates another embodiment of a method according to the invention,

[0021] [Fig.3a-3b] Figures 3a and 3b are schematic views of an installation of the type SLM for additive manufacturing of a part, and illustrate another embodiment of a method according to the invention. Detailed description of the invention

[0022] The invention relates to a method for manufacturing a part made of an aluminum or magnesium-based alloy. The alloy may comprise more than 50% by weight of aluminum or magnesium, and preferably more than 80% by weight of aluminum or magnesium.

[0023] The method involves the additive manufacturing of the part by melting the alloy and forming a molten pool using the energy supplied by the laser.

[0024] [Fig.l] illustrates a first embodiment of the method in which the laser emits a laser beam 10 along a first axis A.

[0025] [Fig.l] illustrates additive manufacturing of the LMD or DED type in which the filler material is supplied in the form of a powder dispersed in a gas flow. 12 projected by a nozzle 14.

[0026] The powder is projected onto a support 16 and melted by the laser beam 10 which forms a molten bath 18. In the case of a aforementioned alloy based on Aluminum or Magnesium, the melting temperature of the alloy is greater than or equal to 620°C.

[0027] After solidification, a bead of material 20 is formed and the production of several successive and superimposed beads of material makes it possible to manufacture the part layer by layer.

[0028] According to the invention, the molten bath 18 is subjected to ultrasounds 22 or ultrasonic waves by means of a transducer 24 which emits the ultrasounds 22 along a second axis B inclined at an angle a of between 10 and 80° relative to the first axis A.

[0029] In the example shown, this angle a is between 30° and 80° and preferably between 30° and 60°. It is for example 45° at + / -20%.

[0030] The gas flow 12 can be projected along a third axis C which is inclined at an angle [3 of between 10° and 80° relative to the first axis A, preferably between 10° and 45°, and for example between 20° and 30°.

[0031] In the example shown, axes A, B and C are coplanar. Axis A is interposed between axes B and C, and the angle y formed by axes B and C is between 10° and 80°. Angle y is equal to the sum of angles a and [3.

[0032] The transducer 24 is preferably equipped with a sonotrode 26. The sonotrode 26 has an elongated shape and comprises one end connected to an output of the transducer 24 and an opposite end 28 which is free. The ultrasounds 22 are emitted from this free end 28 which is located at most 5 cm from the molten bath 18, preferably at most 1 cm from the molten bath 18 and even more preferably less than 1 cm from the molten bath 18.

[0033] [Fig. 2] illustrates additive manufacturing of the LMD or DED type in which the filler material is supplied in the form of a rod or wire 30. The principle of this additive manufacturing is similar to that of [Fig. 1]. The description of [Fig. 1] therefore applies essentially to this [Fig. 2].

[0034] The molten bath 18 is subjected to ultrasounds 22 by means of a transducer 24 which emits the ultrasounds 22 along a second axis B inclined at an angle a of between 10° and 80° relative to the first axis A.

[0035] In the example shown, this angle a is between 10° and 45°, and preferably between 30° and 45°.

[0036] The filler material extends along a third axis C which is inclined at an angle [3 of between 60° and 80° relative to the first axis A.

[0037] In the example shown, axes A, B and C are coplanar. Axis B is interposed between axes A and C.

[0038] The angle y formed by the axes B and C is between 10° and 80°, and is for example less than 45°.

[0039] Figures 3a and 3b illustrate SLM type additive manufacturing in which a powder bed 32 is deposited on a support plate 34 and is scanned by the laser beam 10 to manufacture the part 36 layer by layer.

[0040] The additive manufacturing installation comprises, in addition to the support plate 34, a scraper 38 which makes it possible to spread the powder 32 on the support plate 34.

[0041] As mentioned previously, the molten bath 18 is subjected to ultrasounds 22 by means of a transducer 24 which emits the ultrasounds 22 along a second axis B inclined at an angle α of between 10 and 80° relative to the first axis A.

[0042] In the example shown, this angle a is between 10° and 60° and preferably between 30° and 60°. It is for example 45° at + / -20%.

[0043] Advantageously:

[0044] - the laser for melting has a power between 100W and 500W, and preferably 400W at + / - 10%, and / or

[0045] - the ultrasounds are emitted at a frequency between 10KHz and 50KHz, and preferably 20KHz at + / -10%.

[0046] Applied to precipitation-hardened light alloys, the invention is particularly advantageous because it functionalizes the lasing operation, in particular it allows the cavitation of the porosities, the refining of the microstructure and the fragmentation of the intermetallics generated during solidification. The properties of the resulting alloy can be improved via the use of ultrasound by: • a reduction in the anisotropy of Young's modulus from 2%, • an increase in nanohardness of at least 5%,

[0047] a reduction in the anisotropy of the microhardness of up to 30%.

Claims

Claims

1. Method for manufacturing a part made of an alloy based on Aluminum or Magnesium, comprising the additive manufacturing of the part by melting the alloy and forming a molten bath (18) using the energy supplied by a laser beam (10) emitted along a first axis (A), characterized in that the molten bath (18) is subjected to ultrasound (22) by means of a transducer (24) which emits the ultrasound (22) along a second axis (B) inclined at an angle (a) of between 10° and 80° relative to said first axis (A).

2. A method according to claim 1, wherein the angle (a) is between 10° and 45°, and preferably between 30° and 45°.

3. A method according to claim 1, wherein the angle (a) is between 45° and 80°, and preferably between 60° and 80°.

4. A method according to claim 1, wherein the angle (a) is between 30° and 60°, and is preferably 45° at + / -20%.

5. Method according to one of the preceding claims, in which the transducer (24) is equipped with a sonotrode (26) which comprises a free end for emitting ultrasound (22) which is located at most 5 cm from the molten bath (18), preferably at most 1 cm from the molten bath (18) and even more preferably less than 1 cm from the molten bath (18).

6. Method according to one of the preceding claims, in which the laser beam (10) has a power of between 100W and 500W, and preferably 400W at + / - 10%.

7. Method according to one of the preceding claims, in which the ultrasound (22) is emitted at a frequency between 10KHz and 50KHz, and preferably from 20KHz to + / -10%.

8. A method according to any preceding claim, wherein the alloy comprises more than 50% by weight of Aluminum or Magnesium, and preferably more than 80% by weight of Aluminum or Magnesium.

9. Method according to one of claims 1 to 8, in which the additive manufacturing is of the SLM type and carried out on a powder bed.

10. Method according to one of claims 1 to 8, in which the additive manufacturing is of the LMD or DED type and carried out by melting a powder supplied by a gas flow (12) or by melting a wire (30) or a filler rod.

11. A method according to the preceding claim, wherein the gas flow (12) is projected along a third axis (C), or the wire (30) or the filler rod is fed along a third axis (C), the third axis (C) being inclined at an angle (y) of between 10 and 80° relative to said second axis (B).

12. Method according to the preceding claim, in which the first, second and third axes (A, B, C) are coplanar.

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