Classifications

• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B33—ADDITIVE MANUFACTURING TECHNOLOGY
  • B33Y—ADDITIVE MANUFACTURING, i.e. MANUFACTURING OF THREE-DIMENSIONAL [3-D] OBJECTS BY ADDITIVE DEPOSITION, ADDITIVE AGGLOMERATION OR ADDITIVE LAYERING, e.g. BY 3-D PRINTING, STEREOLITHOGRAPHY OR SELECTIVE LASER SINTERING
  • B33Y10/00—Processes of additive manufacturing
• • C—CHEMISTRY; METALLURGY
  • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
  • C22C—ALLOYS
  • C22C38/00—Ferrous alloys, e.g. steel alloys
  • C22C38/06—Ferrous alloys, e.g. steel alloys containing aluminium
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B22—CASTING; POWDER METALLURGY
  • B22F—WORKING METALLIC POWDER; MANUFACTURE OF ARTICLES FROM METALLIC POWDER; MAKING METALLIC POWDER; APPARATUS OR DEVICES SPECIALLY ADAPTED FOR METALLIC POWDER
  • B22F1/00—Metallic powder; Treatment of metallic powder, e.g. to facilitate working or to improve properties
  • B22F1/05—Metallic powder characterised by the size or surface area of the particles
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B22—CASTING; POWDER METALLURGY
  • B22F—WORKING METALLIC POWDER; MANUFACTURE OF ARTICLES FROM METALLIC POWDER; MAKING METALLIC POWDER; APPARATUS OR DEVICES SPECIALLY ADAPTED FOR METALLIC POWDER
  • B22F10/00—Additive manufacturing of workpieces or articles from metallic powder
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B22—CASTING; POWDER METALLURGY
  • B22F—WORKING METALLIC POWDER; MANUFACTURE OF ARTICLES FROM METALLIC POWDER; MAKING METALLIC POWDER; APPARATUS OR DEVICES SPECIALLY ADAPTED FOR METALLIC POWDER
  • B22F10/00—Additive manufacturing of workpieces or articles from metallic powder
  • B22F10/10—Formation of a green body
  • B22F10/12—Formation of a green body by photopolymerisation, e.g. stereolithography [SLA] or digital light processing [DLP]
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B22—CASTING; POWDER METALLURGY
  • B22F—WORKING METALLIC POWDER; MANUFACTURE OF ARTICLES FROM METALLIC POWDER; MAKING METALLIC POWDER; APPARATUS OR DEVICES SPECIALLY ADAPTED FOR METALLIC POWDER
  • B22F10/00—Additive manufacturing of workpieces or articles from metallic powder
  • B22F10/20—Direct sintering or melting
  • B22F10/25—Direct deposition of metal particles, e.g. direct metal deposition [DMD] or laser engineered net shaping [LENS]
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B22—CASTING; POWDER METALLURGY
  • B22F—WORKING METALLIC POWDER; MANUFACTURE OF ARTICLES FROM METALLIC POWDER; MAKING METALLIC POWDER; APPARATUS OR DEVICES SPECIALLY ADAPTED FOR METALLIC POWDER
  • B22F10/00—Additive manufacturing of workpieces or articles from metallic powder
  • B22F10/20—Direct sintering or melting
  • B22F10/28—Powder bed fusion, e.g. selective laser melting [SLM] or electron beam melting [EBM]
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B33—ADDITIVE MANUFACTURING TECHNOLOGY
  • B33Y—ADDITIVE MANUFACTURING, i.e. MANUFACTURING OF THREE-DIMENSIONAL [3-D] OBJECTS BY ADDITIVE DEPOSITION, ADDITIVE AGGLOMERATION OR ADDITIVE LAYERING, e.g. BY 3-D PRINTING, STEREOLITHOGRAPHY OR SELECTIVE LASER SINTERING
  • B33Y70/00—Materials specially adapted for additive manufacturing
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B33—ADDITIVE MANUFACTURING TECHNOLOGY
  • B33Y—ADDITIVE MANUFACTURING, i.e. MANUFACTURING OF THREE-DIMENSIONAL [3-D] OBJECTS BY ADDITIVE DEPOSITION, ADDITIVE AGGLOMERATION OR ADDITIVE LAYERING, e.g. BY 3-D PRINTING, STEREOLITHOGRAPHY OR SELECTIVE LASER SINTERING
  • B33Y80/00—Products made by additive manufacturing
• • C—CHEMISTRY; METALLURGY
  • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
  • C22C—ALLOYS
  • C22C1/00—Making non-ferrous alloys
  • C22C1/02—Making non-ferrous alloys by melting
• • C—CHEMISTRY; METALLURGY
  • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
  • C22C—ALLOYS
  • C22C33/00—Making ferrous alloys
  • C22C33/02—Making ferrous alloys by powder metallurgy
  • C22C33/0257—Making ferrous alloys by powder metallurgy characterised by the range of the alloying elements
  • C22C33/0278—Making ferrous alloys by powder metallurgy characterised by the range of the alloying elements with at least one alloying element having a minimum content above 5%
  • C22C33/0285—Making ferrous alloys by powder metallurgy characterised by the range of the alloying elements with at least one alloying element having a minimum content above 5% with Cr, Co, or Ni having a minimum content higher than 5%
• • C—CHEMISTRY; METALLURGY
  • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
  • C22C—ALLOYS
  • C22C38/00—Ferrous alloys, e.g. steel alloys
  • C22C38/001—Ferrous alloys, e.g. steel alloys containing N
• • C—CHEMISTRY; METALLURGY
  • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
  • C22C—ALLOYS
  • C22C38/00—Ferrous alloys, e.g. steel alloys
  • C22C38/002—Ferrous alloys, e.g. steel alloys containing In, Mg, or other elements not provided for in one single group C22C38/001 - C22C38/60
• • C—CHEMISTRY; METALLURGY
  • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
  • C22C—ALLOYS
  • C22C38/00—Ferrous alloys, e.g. steel alloys
  • C22C38/005—Ferrous alloys, e.g. steel alloys containing rare earths, i.e. Sc, Y, Lanthanides
• • C—CHEMISTRY; METALLURGY
  • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
  • C22C—ALLOYS
  • C22C38/00—Ferrous alloys, e.g. steel alloys
  • C22C38/02—Ferrous alloys, e.g. steel alloys containing silicon
• • C—CHEMISTRY; METALLURGY
  • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
  • C22C—ALLOYS
  • C22C38/00—Ferrous alloys, e.g. steel alloys
  • C22C38/04—Ferrous alloys, e.g. steel alloys containing manganese
• • C—CHEMISTRY; METALLURGY
  • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
  • C22C—ALLOYS
  • C22C38/00—Ferrous alloys, e.g. steel alloys
  • C22C38/18—Ferrous alloys, e.g. steel alloys containing chromium
• • C—CHEMISTRY; METALLURGY
  • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
  • C22C—ALLOYS
  • C22C38/00—Ferrous alloys, e.g. steel alloys
  • C22C38/18—Ferrous alloys, e.g. steel alloys containing chromium
  • C22C38/22—Ferrous alloys, e.g. steel alloys containing chromium with molybdenum or tungsten
• • C—CHEMISTRY; METALLURGY
  • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
  • C22C—ALLOYS
  • C22C38/00—Ferrous alloys, e.g. steel alloys
  • C22C38/18—Ferrous alloys, e.g. steel alloys containing chromium
  • C22C38/24—Ferrous alloys, e.g. steel alloys containing chromium with vanadium
• • C—CHEMISTRY; METALLURGY
  • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
  • C22C—ALLOYS
  • C22C38/00—Ferrous alloys, e.g. steel alloys
  • C22C38/18—Ferrous alloys, e.g. steel alloys containing chromium
  • C22C38/26—Ferrous alloys, e.g. steel alloys containing chromium with niobium or tantalum
• • C—CHEMISTRY; METALLURGY
  • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
  • C22C—ALLOYS
  • C22C38/00—Ferrous alloys, e.g. steel alloys
  • C22C38/18—Ferrous alloys, e.g. steel alloys containing chromium
  • C22C38/28—Ferrous alloys, e.g. steel alloys containing chromium with titanium or zirconium
• • C—CHEMISTRY; METALLURGY
  • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
  • C22C—ALLOYS
  • C22C38/00—Ferrous alloys, e.g. steel alloys
  • C22C38/18—Ferrous alloys, e.g. steel alloys containing chromium
  • C22C38/34—Ferrous alloys, e.g. steel alloys containing chromium with more than 1.5% by weight of silicon
• • C—CHEMISTRY; METALLURGY
  • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
  • C22C—ALLOYS
  • C22C38/00—Ferrous alloys, e.g. steel alloys
  • C22C38/18—Ferrous alloys, e.g. steel alloys containing chromium
  • C22C38/40—Ferrous alloys, e.g. steel alloys containing chromium with nickel
  • C22C38/44—Ferrous alloys, e.g. steel alloys containing chromium with nickel with molybdenum or tungsten
• • C—CHEMISTRY; METALLURGY
  • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
  • C22C—ALLOYS
  • C22C38/00—Ferrous alloys, e.g. steel alloys
  • C22C38/18—Ferrous alloys, e.g. steel alloys containing chromium
  • C22C38/40—Ferrous alloys, e.g. steel alloys containing chromium with nickel
  • C22C38/46—Ferrous alloys, e.g. steel alloys containing chromium with nickel with vanadium
• • C—CHEMISTRY; METALLURGY
  • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
  • C22C—ALLOYS
  • C22C38/00—Ferrous alloys, e.g. steel alloys
  • C22C38/18—Ferrous alloys, e.g. steel alloys containing chromium
  • C22C38/40—Ferrous alloys, e.g. steel alloys containing chromium with nickel
  • C22C38/48—Ferrous alloys, e.g. steel alloys containing chromium with nickel with niobium or tantalum
• • C—CHEMISTRY; METALLURGY
  • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
  • C22C—ALLOYS
  • C22C38/00—Ferrous alloys, e.g. steel alloys
  • C22C38/18—Ferrous alloys, e.g. steel alloys containing chromium
  • C22C38/40—Ferrous alloys, e.g. steel alloys containing chromium with nickel
  • C22C38/50—Ferrous alloys, e.g. steel alloys containing chromium with nickel with titanium or zirconium
• • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
  • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
  • Y02P—CLIMATE CHANGE MITIGATION TECHNOLOGIES IN THE PRODUCTION OR PROCESSING OF GOODS
  • Y02P10/00—Technologies related to metal processing
  • Y02P10/25—Process efficiency

Definitions

• the present disclosure relates to a new printable powder material for additive manufacturing and an additive manufactured object and the uses thereof.
• the present disclosure also relates to an additive manufacturing process for producing the object.
• Additive manufacturing has become a more and more attractive solution for the manufacturing of metallic functional prototypes and components, especially those with complicated design.
• Ferritic alloys containing aluminum are attractive to use in electrical heating and high temperature applications.
• one of the problems with these alloys is that they are difficult to weld due to their brittle nature.
• these alloys may also be difficult to machine.
• it may be both difficult and complicated to manufacture complex structures in these alloys.
• the present disclosure aims at solving or at least reducing the above-mentioned problems.
• An aspect of the present disclosure is therefore to provide a printable ferritic iron- chromium-aluminum (FeCrAl) metal powder composition to be used in additive manufacturing.
• the present disclosure therefore relates to a printable ferritic FeCrAl powder composition, wherein the FeCrAl powder composition consists in weight%:
• the FeCrAl powder composition has a powder size distribution between 4 to 200 pm, such as 10 and 120 pm.
• the present powder will have good flowability, good packing density and good spreadability thus it will be excellent to print.
• the printable powder composition is also a gas atomized ferritic iron-chromium-aluminum (FeCrAl) powder composition meaning that the powder has been obtained by a gas atomizing process.
• the printable ferritic FeCrAl powder composition is advantageous for obtaining 3D shaped objects which will essentially be fully dense and will have excellent high temperature oxidation properties and will have excellent high temperature creep properties. Additionally, the powder may also be sieved to the specific desired particle size distribution.
• the present disclosure also relates to an additive manufactured object comprising the alloying element in the ranges as the FeCrAl powder as defined hereinabove as hereinafter and manufactured from said FeCrAl powder.
• the 3D shape of the additive manufactured object will depend on the final use.
• the inventors have surprisingly found that an additive manufactured object manufactured from the FeCrAl powder as defined hereinabove or hereinafter and thereby comprising an alloy consisting the same elements in the same ranges of the powder as defined hereinabove or hereinafter will have excellent mechanical properties in high temperature, more specifically it will have excellent creep resistance at high temperature and additionally high oxidation resistance.
• the additive manufactured object is especially useful in as an electrical heating element or a component in high temperature applications (in applications operating between 400 to 1350 °C) or as a component in electrical heating applications.
• the object may also be used for protecting another object against high temperature wear and corrosion.
• the present object may be used in both electrical heating and high temperature applications.
• Another aspect of the present disclosure is to provide an additive manufacturing process.
• the present disclosure relates to an additive manufacturing process for manufacturing an object as defined hereinabove or hereinafter of the powder as defined hereinabove or hereinafter, wherein the additive manufacturing process is selected from a powder bed fusion additive manufacturing process or from Direct Energy Deposition (DED).
• DED Direct Energy Deposition
• Figure 1 shows the difference in creep properties at 900 °C and 1100 °C and
• Figure 2 shows the difference in mass gain at 1100 °C between a printed sample and a conventional manufactured alloy.
• Figure 3 shows a micrograph of an object manufactured from the powder as defined hereinabove or hereinafter by using DED.
• the present disclosure relates to a printable ferritic FeCrAl powder composition, wherein the FeCrAl powder composition consists in weight% (wt%):
• the FeCrAl powder composition has a powder size distribution between 4 to 200 pm, such as 10 to 120 pm. Further, it is accordingly an aspect of the present disclosure to provide a printable ferritic FeCrAl powder composition which may be used in an additive manufacturing process for obtaining an object superior in complex structure and mechanical properties.
• printable is meant that the powder can be used in at least one additive manufacturing process.
• Chromium will promote the formation of an AI2O3 layer on the alloy as defined hereinabove or hereinafter through the so-called third element effect, i.e. by formation of chromium oxide in the transient oxidation stage. Chromium shall be present in the alloy as defined hereinabove or hereinafter in an amount of at least 9 wt%.
• An increased Cr content will provide for an increased solid solutioning hardening effect on the ferritic structure. From around 11 wt% Cr and above, the ferritic structure will become instable in the temperature range 300-500°C. The ferrite may then be decomposed into one low Cr ferrite phase and one high Cr ferrite phase. When this occur, the material becomes harder and more brittle.
• the maximum Cr is set to 25 wt%.
• the content of Cr is therefore of from 18 to 24 wt%, such as 19 to 23.5 wt%.
• the content of Cr is therefore of from 9 to 11 wt%, and according to yet another embodiment, the content of Cr is therefore from 9 to 15 wt%.
• Aluminum is an important element in the powder as defined hereinabove or hereinafter as aluminum, when exposed to oxygen at high temperature, will form the dense and thin oxide AI2O3, which will protect the underlying alloy surface from further oxidation.
• the amount of aluminum should be at least 2.5 wt% to ensure that an AI2O3 layer is formed and that sufficient aluminum is present to heal the AI2O3 layer if damaged.
• aluminum has a negative impact on the formability of the object obtained from the present powder composition and the amount of aluminum should not exceed 8 wt% in the present powder as defined hereinabove or hereinafter.
• A1 is between 3 - 7 wt%.
• A1 is between 3 - 6 wt%, such as 3.5 - 6 wt%, such as 4 to 6 wt%.
• silicon is often present in levels of up to about 0.5 wt%.
• Si is present in a level up to 0.5 wt%.
• Si may play an important role for improving oxidation and corrosion resistance.
• Si may be present above 0.5 to 3 wt%, such as 1 to 3 wt%, such as 1 to 2.5 wt%, such as 1.5 to 2.5 wt%.
• the upper limit of Si is by the increasing susceptibility to formation of brittle CnSi and s phase during long term exposure. Additions of Si therefore have to be done by taken into consideration the content of A1 and Cr.
• Manganese may be present as an impurity in the powder as defined hereinabove or hereinafter. Manganese may also have a negative impact on the oxidation life above 1 100 °C.
• the maximum content of Mn is therefore up to 1.0 wt%. According to one embodiment, the content of Mn is ⁇ 0.5 weight%.
• Molybdenum may be an impurity or may be added as an alloying element.
• the maximum level is less than or equal to 0.5 wt%.
• the minimum level is more than 0.5 wt%, such as more than 1.0 wt% such as between 1.0 to 4.0 wt%.
• Carbon may be included to increase strength. At too high levels, carbon may result in difficulties to form the material and have a negative effect on the corrosion resistance. Hence, C is therefore limited to ⁇ 0.1 wt%, such as ⁇ 0.05 wt%. According to one embodiment, the C content is from 0.001 to 0.1 wt%.
• Nitrogen may be included to increase strength. Nitrogen may also be present as an unavoidable impurity resulting from the production process. At too high levels, nitrogen may result in difficulties to form the material and may have a negative effect on the corrosion resistance. Hence, N is therefore limited to ⁇ 0.1 wt%. According to one embodiment, the N content is from 0.001 to 0.1 wt%.
• Oxygen may exist as an impurity resulting from the production process. Hence, O is therefore limited to ⁇ 0.2 wt%, such as ⁇ 0.1 wt%.
• the reactive elements are highly reactive with carbon, nitrogen and oxygen.
• Yttrium (Y), Titanium (Ti), Zirconium (Zr), Niobium (Nb), Vanadium (V), Hafnium (Hf), Tantalum (Ta), Lanthanum (La) and Ce (Cerium) and these elements may be added in order to improve the oxidation properties.
• these elements have the following content in the present powder and thereby in the object made from the powder Ti ⁇ 1.7 wt%;
• the FeCrAl powder as defined hereinabove or hereinafter may have these elements in the following weight (wt%):
• the printable FeCrAl powder composition consists in weight%:
• the printable FeCrAl powder composition consists in weight%:
• Iron (Fe) and unavoidable impurities make up the balance in the powder or the object both as defined hereinabove or hereinafter.
• Example but not limiting of unavoidable impurities are metals which will form low melting phases as these low melting phases have shown to have an impact on the crack resistance properties.
• alloying elements include Cobalt, Copper, Zinc and Magnesium.
• the powder size distribution may be selected from 4 to 200 pm, 10 to 120 pm, 10 to 90 pm.
• An additive manufactured object manufactured by using the ferritic FeCrAl powder as defined hereinabove or hereinafter will perform well in operating temperatures up to 1350°C. Furthermore, the present object will have significant high-temperature corrosion resistance and a high resistance against oxidation, sulphidization and carburization. Additionally, the additive manufactured object will have significant high- temperature creep strength and high form stability and high electrical resistivity compared to conventionally manufactured objects.
• the additive manufacturing processes described hereinabove or hereinafter use a computer aided design of the 3D shaped object to be printed, which is resolved into 2D thin slices by using software which also will link the generated data to the hardware.
• a powder bed fusion additive manufacturing process is used.
• the powder bed fusion manufacturing process is selected from selective laser melting (SLM) or electron beam melting (EBM).
• SLM selective laser melting
• EBM electron beam melting
• a powder bed is used in both these processes.
• the powder layer will be exposed to an energy source and thereby melted or at least partially melted.
• a new powder layer will be provided and, this will continue until the desired object is obtained.
• the energy source is one or more laser beams, such as energy source continuous laser beam or a pulsed laser beam and in EBM the energy source is an electron beam.
• SLM is carried out in an inert atmosphere, such as argon or nitrogen atmosphere. Additionally, the process may use a support when needed for example to reinforce small angles and the support will be removed afterwards. Additionally, SLM printing is performed directly on the loose powder layer.
• each powder layer may be preheated before they are locally melted by the electron beam.
• the process is performed in vacuum and high temperatures.
• each new powder layer is first pre-sintered with the electron beam before the actual printing of the powder layer starts.
• the powder layer thickness is between 10 - 250 pm.
• the layer thickness may be from 10 to 80 pm and in EBM the layer thickness may be from 10 pm to 250 pm.
• the power of the energy source when printing is, when laser beam is used between 80 - 400 W, and when electron beam is used 300 - 1000 W.
• more than one laser beam may be used, each beam has then the power mentioned herein.
• the energy density for the energy source is in the range of 1 - 6 J/mm 2 .
• the energy density is the energy delivered by the energy source per unit area in the powder layer during printing.
• the additive manufacturing process used is direct energy deposition (DED).
• DED direct energy deposition
• an energy source is used to create a local melt pool. Metal powder is feed into this melt pool as filler material. The position of the melt pool is constantly shifting so that a 3-dimensional body is created by the solidifying material.
• the energy source may either be laser beam or a plasma arc.
• the power of the laser source can be between 50 - 2000 W.
• the DED process is performed with an inert shielding gas atmosphere protecting the melt pool.
• the material feed angle may be altered depending on what is the predetermined shaped object.
• an object manufactured by DED may be stress-relieved.
• the stress relieve temperature will range from 650 - 1200 °C and will depend on volume of the manufactured object.
• the stress relieve time will vary from very short, such as from 15 min, to longer times, such as several hours.
• pre-oxidation may be performed at the same time as the stress relive after printing.
• the purpose of pre oxidation is to form an aluminium oxide surface layer.
• said aluminium oxide layer has a thickness of at least 0.5 pm.
• Powder 1 to 3 Three powders (Powder 1 to 3) with the chemical composition in wt% according to Table 1 were produced using gas atomization and then sieved to suitable fraction so that Powder 1 and Powder 3 and Power 4 had a particle size within 10 - 45 pm, Powder 2 had a particle size within 1 - 45 pm. .
• the powders as described above were provided to a SLM machine by addition to the powder delivery system. During the printing process, the powder was provided from the powder delivery system in the machine and a scraper spread a layer of powder on the building plate. The laser then passed over the layer of powder according to a provided 3D drawing, whereby the powder layer was exposed to the laser beam and therefore melted. After the layer of powder was melted, a new layer was provided until the desired sample(s) were formed according to the 3D drawing.
• the thickness of the powder layers was between 20 and 30 pm.
• the printing was performed in an inert atmosphere using argon.
• the scan speed was between 500 to 800 mm/s.
• the power of the energy source was between 80 - 200 W.
• the samples were allowed to cool to room temperature in the inert atmosphere.
• the printed samples were de-powdered and then the building plate comprising the samples was removed from the machine.
• the building plate with the samples was heat treated in 650 to 1200 °C for 0.5 to 3 hours.
• the building plate and the samples were then cooled to room temperature and then machined (cut) in order to remove the samples from the building plate.
• a laser source was used to create a local melt pool.
• the powder was feed into the melt pool and was rapidly solidified.
• the powder was added to the pool by using a focused powder stream.
• the laser was moved along a pre-designed path, creating a layer of solidified substrate (X-Y plane).
• the laser was then moved up (Z axis) and started to create melt pool on the surface of the previous substrate, creating a new layer following the specific path. Thus, a 3 -dimensional body was created.
• the powder layer height was between 0.3 to 2 mm.
• the printing was performed with or without using argon atmosphere.
• the deposition speed was between 1000 mm/min - 2500 mm/min.
• Powder feed was between 4 g/min to 25 g/min.
• the power of the laser source was between 50 - 2000 W.
• FIG 3 a micrograph of a DED printed structure of Powder 5 is disclosed.
• the structure is very dense, not showing any indications of cracking, defects or porosity.
• a Leica stereo microscope was used.
• Figure 1 presents a comparison of the creep strength of samples containing conventionally produced FeCrAl (CP 1) alloys and samples which have been manufactured by additive manufacturing by using SLM (SLM 1) and samples which has have been manufactured by additive manufacturing by using (SLM 2).
• the conventional samples were produced by casting and rolling and-prepared according to S.S. EN ISO 6892-2:2018, “Cylindrical test pieces with threaded gripping ends”, with diameter, do, 4 mm and original gauge length, Lo, 20 mm.
• the conventional samples had a composition according to the following specification:
• the additive manufacturing samples were, after printing, machined to standard S.S. EN ISO 6892-2:2018, with gripped (turned) ends, diameter, do 4 mm and original gauge length, Lo, 20 mm.
• the additive manufacturing samples (SLM 1 and SLM2) had a composition according to the following specification:
• the samples were loaded with dead load.
• the creep rate was calculated as percentage change in length of the samples over time at constant loading and temperatures.
• the testing of the printed samples was performed at 1100 °C and 1200 °C.
• the conventional produced samples (CP 1) were tested 900 °C and 1100 °C.
• the printed material is found to be anisotropic.
• the creep results shown in Figure 1 are for the stronger direction of the material where samples were loaded parallel to printing direction. Further, as can be seen from Figure 1, the additive manufactured samples have much lower creep rate compared to the conventionally produced sample. Even though the conventionally produced samples were tested at lower temperature, the creep strength of the printed samples was still higher as the creep rate was lower. In addition, the printed samples had a long time to rupture which means that the lifetime of such product will be longer.
• Figure 2 shows mass gain curves vs time at 1100 °C for an additive manufactured sample made from Powder 4 of Table 1 and a conventional manufactured sample having a similar composition as Powder 4.
• the mass gain weight was checked at 100 h intervals.
• the mass gain curves show that the additive manufactured sample have better oxidation properties than the conventional manufactured sample thus meaning that it will be excellent in high temperature applications and will have a longer service life.

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