Method for additive manufacturing

• US 10,549,348 B2
• Filed: 04/24/2017
• Issued: 02/04/2020
• Est. Priority Date: 05/24/2016
• Status: Active Grant

• Current Assignee: Arcam Ab (Danaher Corporation)
• Original Assignee: Arcam Ab (Danaher Corporation)
• Inventors: Ackelid, Ulf
• Primary Examiner(s): Mayes, Melvin C.
• Assistant Examiner(s): Moody, Christopher Douglas
• Application Number:
  US15/495,225
• Publication Number:
  US 20170341142A1
• Time in Patent Office: 1,016 Days
• Field of Search: None
• CPC Class Codes: B22F 10/28 Powder bed fusion, e.g. selective laser melting [SLM] or electron beam melting [EBM]
• CPC Class Codes: B22F 10/32 of the atmosphere, e.g. composition or pressure in a building chamber
• CPC Class Codes: B22F 10/36 of energy beam parameters
• CPC Class Codes: B22F 10/64 by thermal means control of energy beam parameters for post heating B22F10/364
• CPC Class Codes: B22F 12/222 for motion along a direction orthogonal to the plane of a layer
• CPC Class Codes: B22F 12/52 Hoppers
• CPC Class Codes: B22F 12/55 Two or more means for feeding material
• CPC Class Codes: B22F 2003/241 Chemical after-treatment on the surface
• CPC Class Codes: B22F 2201/013 Hydrogen
• CPC Class Codes: B22F 2201/016 NH3
• CPC Class Codes: B22F 2201/02 Nitrogen
• CPC Class Codes: B22F 2201/10 Inert gases
• CPC Class Codes: B22F 2201/30 Carburising atmosphere
• CPC Class Codes: B22F 2998/10 Processes characterised by the sequence of their steps
• CPC Class Codes: B22F 2999/00 Aspects linked to processes or compositions used in powder metallurgy
• CPC Class Codes: B22F 3/1039 by reaction B22F3/001, B22F3/23 take precedence
• CPC Class Codes: B22F 3/15 Hot isostatic pressing
• CPC Class Codes: B22F 3/24 After-treatment of workpieces or articles B22F3/1146 takes precedence
• CPC Class Codes: B23K 15/0026 Auxiliary equipment
• CPC Class Codes: B23K 15/0086 welding for purposes other than joining, e.g. built-up welding
• CPC Class Codes: B23K 15/0093 : characterised by the properties of the materials to be welded
• CPC Class Codes: B23K 15/02 : Control circuits therefor
• CPC Class Codes: B23K 15/10 : Non-vacuum electron beam-welding or cutting
• CPC Class Codes: B23K 2103/04 : Steel or steel alloys
• CPC Class Codes: B23K 2103/08 : Non-ferrous metals or alloys
• CPC Class Codes: B23K 2103/14 : Titanium or alloys thereof
• CPC Class Codes: B23K 26/0006 : taking account of the properties of the material involved B23K26/32, B23K26/40 take precedence
• CPC Class Codes: B23K 26/126 : in an atmosphere of gases chemically reacting with the workpiece
• CPC Class Codes: B23K 26/127 : in an enclosure
• CPC Class Codes: B23K 26/342 : Build-up welding
• CPC Class Codes: B23K 26/702 : Auxiliary equipment
• CPC Class Codes: B33Y 10/00 : Processes of additive manufacturing
• CPC Class Codes: B33Y 30/00 : Apparatus for additive manufacturing; Details thereof or accessories therefor
• CPC Class Codes: B33Y 40/20 : Post-treatment, e.g. curing, coating or polishing
• CPC Class Codes: B33Y 70/00 : Materials specially adapted for additive manufacturing
• CPC Class Codes: C22C 1/0458 : Alloys based on titanium, zirconium or hafnium
• CPC Class Codes: C22C 14/00 : Alloys based on titanium
• CPC Class Codes: C23C 8/08 : only one element being applied
• CPC Class Codes: Y02P 10/25 : Process efficiency

Abstract

A method comprising the steps of: distributing a titanium alloy or pure titanium powder layer on a work table inside a vacuum chamber, directing at least one electron beam from at least one electron beam source over the work table causing the powder layer to fuse in selected locations, distributing a second powder layer on the work table of a titanium alloy or pure titanium inside the build chamber, directing the at least one electron beam over the work table causing the second powder layer to fuse in selected locations, and releasing a predefined concentration of the gas from the metal powder into the vacuum chamber when at least one of heating or fusing the metal powder layer, wherein at least one gas comprising hydrogen is absorbed into or chemically bonded to the titanium or titanium alloy powder to a concentration of 0.01-0.5% by weight of the hydrogen.

Claims

1. A method for forming a three-dimensional article through successive fusion of parts of a metal powder bed, which parts corresponds to successive cross sections of the three-dimensional article, the method comprising the steps of:

distributing a titanium alloy or pure titanium powder layer on a work table inside a vacuum chamber, where at least one gas comprising hydrogen is absorbed into or chemically bonded to the titanium or titanium alloy powder to a concentration of 0.01-0.5% by weight of the hydrogen,

directing at least one electron beam from at least one electron beam source over the work table causing the powder layer to fuse in selected locations to form a first cross section of the three-dimensional article,

distributing a second powder layer on the work table of a titanium alloy or pure titanium inside the build chamber, where at least one gas comprising hydrogen is absorbed into or chemically bonded to the titanium or titanium alloy powder to a concentration of 0.01-0.5% by weight of the hydrogen,

directing the at least one electron beam over the work table causing the second powder cross section to fuse in selected locations to form a second cross section of the three-dimensional article, wherein the second layer is bonded to the first cross section, and

releasing a predefined concentration of the at least one gas from the titanium or titanium alloy powder into the vacuum chamber when at least one of heating or fusing each powder layer,

wherein at least a portion of the released gas is configured for forming ions when being irradiated by the at least one electron beam such that ions are formed for balancing an amount of charged powder particles produced by the at least one electron beam to keep the electrical field strength below E_max.

2. The method according to claim 1, wherein the gas is pure hydrogen or deuterium or a mixture thereof.

3. The method according to claim 1, wherein the gas is a mixture of an inert gas and at least one of hydrogen or deuterium.

4. The method according to claim 1, further comprising the steps of:

introducing a first supplementary gas into the vacuum chamber, which first supplementary gas is capable of reacting chemically with or being absorbed by a finished three-dimensional article, and

releasing a predefined concentration of the gas which had reacted chemically with or been absorbed by the finished three dimensional article.

5. The method according to claim 4, wherein the first supplementary gas is one or more gases selected from the group consisting of:

hydrogen, deuterium, hydrocarbons, gaseous organic compounds, ammonia, nitrogen, oxygen, carbon monoxide, carbon dioxide, nitrous oxide, helium, argon, neon, krypton, xenon, and radon.

6. The method according to claim 4, where the first supplementary gas is introduced into the build chamber also for cooling the finished three-dimensional article.

7. The method according to claim 1, wherein a pressure in the vacuum chamber is between 1×

10<sup>−

1</sup>−

1×

10<sup>−

4</sup> mbar.

8. The method according to claim 1, wherein one or more of the steps recited therein are computer-implemented.