IRON-BASED ALLOY POWDER CONTAINING NON-SPHERICAL PARTICLES

Abstract

The present invention relates in a first aspect to an iron-based alloy powder containing non-spherical particles and at least 40% of the total amount of particles have a non-spherical shape. The alloy mandatorily comprises the elements Fe (iron), Cr (chrome) and Mo (molybdenum). Furthermore, the alloy may comprise further elements such as C (carbon), Ni (nickel), Nb (niobium) or Si (silicon). The present invention relates, according to a second aspect, to an iron-based alloy powder wherein the alloy comprises the elements Fe, Cr and Mo and the iron-based alloy powder is produced by an ultra-high liquid atomization process comprising at least two stages as defined below.

Claims

1.-14. (canceled)

15. An iron-based alloy powder containing non-spherical particles wherein the alloy comprises the elements Fe, Cr and Mo, and at least 40% of the total amount of particles have a non-spherical shape, wherein the sphericity of the particles having a non-spherical shape is not more than 0.9 and wherein the alloy comprises in addition to the elements Fe, Cr and Mo at least three elements selected from C, Ni, Cu, Nb, Si and N.

16. The iron-based alloy powder according to claim 15, wherein said alloy comprises Fe at 82.0 wt. % to 86.0 wt. %; Cr at 10.0 wt. % to 12.0 wt. %; Ni at 1.5 wt. % to 2.5 wt. %; Cu at 0.4 wt. % to 0.7 wt. %; Mo at 1.2 wt. % to 1.8 wt. %; C at 0.14 wt. % to 0.18 wt. %; Nb at 0.02 wt. % to 0.05 wt. %; N at 0.04 to 0.07 wt. % and Si at 0 to 1.0 wt. %.

17. The iron-based alloy powder according to claim 15, wherein the alloy comprises in addition to the elements Fe, Cr and Mo at least four elements selected from C, Ni, Cu, Nb, Si and N, optionally the alloy comprises at least one element selected from O, S, P and Mn.

18. The iron-based alloy powder according to claim 15, wherein Cr is present at 14 wt. % to 19.0 wt. %, Mo is present at 2.0 wt. % to 3.0 wt. %, C is present at 0 to 0.30 wt. %, Ni is present at 8.0 wt. % to 15.0 wt. %, Mn is present at 0 to 2.0 wt. %, Si is present at 0 to 2.0 wt. % and O is present at 0 to 0.50 wt. %, the balance up to 100 wt. % is Fe.

19. The iron-based alloy powder according to claim 15, wherein i) at least 50% of the total amount of particles have a non-spherical shape, or ii) the total amount of particles having a non-spherical shape is in the range of at least 40 to 70%.

20. The iron-based alloy powder according to claim 15, wherein the particles have a diameter in the range of 1 to 200 microns.

21. A process for producing an iron-based alloy powder according to claim 15, wherein the iron-based alloy powder is provided in a molten state and an atomization step is carried out with a stream of the molten iron-based alloy powder.

22. The process according to claim 21, wherein the atomization step is carried out as an ultrahigh pressure liquid atomization by jetting at least one liquid with a pressure of at least 300 bar onto the stream of the molten iron-based alloy powder.

23. The process according to claim 21, wherein the liquid contains water, and/or the ultrahigh pressure liquid atomization is carried out by an atomization process comprising at least two stages, optionally, within a first stage of this atomization process, a stream of the molten iron-based alloy powder is fed through a nozzle into a first area located between the nozzle and a choke and a gas stream, which is preferably a nitrogen-containing gas stream and/or an inert gas stream, circulates around the molten iron-based alloy powder within this first area and, within a second stage of this atomization process, the stream of the molten iron-based alloy powder is fed to a second area located beyond the choke, where the stream of the molten iron-based alloy powder is contacted with a water-containing jet stream under a pressure of at least 300 bar, preferably of at least 600 bar causing a break up and solidification of the stream of the molten iron-based alloy powder into the respective particles, wherein at least 50% of the total amount of the particles have a non-spherical shape.

24. A use of at least one iron-based alloy powder according to claim 15 within a three-dimensional (3D) printing process.

25. A process for producing a three-dimensional (3D) object wherein the 3D object is formed layer by layer and within each layer at least one iron-based alloy powder according to claim 15 is employed.

26. The process according to claim 25 wherein in each layer the employed at least one iron-based alloy powder is molten by applying energy on the surface of the iron-based alloy powder, preferably the energy is applied by a laser beam or an electron beam.

27. The process according to claim 25, wherein the 3D object is produced by a selective laser melting (SLM) process, optionally the selective laser melting (SLM) process comprises the steps (i) to (iv): (i) applying a first layer of at least one iron-based alloy powder onto a surface, (ii) scanning the first layer of the at least one iron-based alloy powder with a focused laser beam at a temperature sufficient to melt at least part of the first layer of the at least one iron-based alloy powder throughout its layer thickness to obtain a first molten layer, (iii) solidifying the first molten layer obtained in step (ii), (iv) repeating process steps (i), (ii) and (iii) with a pattern of scanning effective to form the respective 3D object or at least a part thereof.

28. A three-dimensional (3D) object obtainable by a process according to claim 25.

Description

[0021] The invention is specified in more detail as follows.

[0022] A first subject matter according to the first aspect of the present invention is an iron-based alloy powder containing non-spherical particles wherein the alloy comprises the elements Fe, Cr and Mo, and at least 40% of the total amount of particles has a non-spherical shape.

[0023] Metal-based alloy powders as such including iron-based alloy powders are known to a person skilled in the art. This also applies to process for the production of such iron-based alloy powders as well as the specific shape of such alloy powders (for example in form of particles). The iron-based alloy powders according to the present invention comprise as mandatory (metal) elements Fe (iron), Cr (chrome) and Mo (molybdenum). Besides these three mandatory elements, the iron-based alloy powders according to the present invention may comprise further elements such as C (carbon), Ni (nickel), S (sulfur), O (oxygen), Nb (niobium), Si (silicon), Cu (copper) or N (nitrogen).

[0024] Preferably Cr is present at 10.0 wt. % to 19.0 wt. %, Mo is present at 0.5 wt. % to 3.0 wt. %, C is present at 0 to 0.35 wt. %, Ni is present at 0 to 5.0 wt. %, Cu is present at 0 to 5.0 wt. %, Nb is present at 0 to 1.0 wt. %, Si is present at 0 to 1.0 wt. %, N is present at 0 to 0.20 wt. % and the balance up to 100 wt. % is Fe.

[0025] Iron-based alloy powders according to the present invention are preferred, wherein the alloy comprises in addition to the elements Fe, Cr and Mo at least three elements selected from C, Ni, Cu, Nb, Si and N.

[0026] Preferably Cr is present at 10.0 wt. % to 19.0 wt. %, Mo is present at 0.5 wt. % to 3.0 wt. %, C is present at 0 to 0.35 wt. %, Ni is present at 0 to 5.0 wt. %, Cu is present at 0 to 5.0 wt. %, Nb is present at 0 to 1.0 wt. %, Si is present at 0 to 1.0 wt. %, N is present at 0 to 0.25 wt. % and the balance up to 100 wt. % is Fe, and preferably at least three elements selected from C, Ni, Cu, Nb, Si and N are present with at least 0.05 wt.-% each.

[0027] It is even more preferred, that the iron-based alloy powder comprises in a first embodiment the elements as follows:

Cr is present at 10.0 wt. % to 18.3 wt. %, Mo is present at 0.5 wt. % to 2.5 wt. %, C is present at 0 to 0.30 wt. %, Ni is present at 0 to 4.0 wt. %, Cu is present at 0 to 4.0 wt. %, Nb is present at 0 to 0.7 wt. %, Si is present at 0 to 0.7 wt. % and N is present at 0 to 0.25 wt. %, the balance up to 100 wt. % is Fe, and preferably at least three elements selected from C, Ni, Cu, Nb, Si and N are present with at least 0.05 wt.-% each.

[0028] Within the present invention it is also preferred that the alloy comprises in addition to the elements Fe, Cr and Mo at least four elements selected from C, Ni, Cu, Nb, Si and N, optionally the alloy may additionally comprise at least one element selected from O, S, P and Mn.

[0029] In another embodiment of the present invention it is also preferred that the iron-based alloy powder is an alloy which comprises Fe at 82.0 wt. % to 86.0 wt. %; Cr at 10.0 wt. % to 12.0 wt. %; Ni at 1.5 wt. % to 2.5 wt. %; Cu at 0.4 wt. % to 0.7 wt. %; Mo at 1.2 wt. % to 1.8 wt. %; Cat 0.14 wt. % to 0.18 wt. %; Nb at 0.02 wt. % to 0.05 wt. %; N at 0.04 to 0.07 wt. % and Si at 0 to 1.0 wt. %.

[0030] In a further embodiment of the present invention it is preferred that the iron-based alloy powder according to the present invention does not comprise Cr at 10.0 wt. % to 18.3 wt. %, Mo at 0.5 wt. % to 2.5 wt. %, C at 0 to 0.30 wt. %, Ni at 0 to 4.0 wt. %, Cu at 0 to 4.0 wt. %, Nb at 0 to 0.7 wt. %, Si at 0 to 0.7 wt. % and N at 0 to 0.25 wt. %, the balance up to 100 wt. % is Fe.

[0031] In a further preferred embodiment of the present invention, the iron-based alloy powder comprises the elements as follows:

Cr is present at 14 wt. % to 19.0 wt. %, Mo is present at 2.0 wt. % to 3.0 wt. %, C is present at 0 to 0.30 wt. %, Ni is present at 8.0 wt. % to 15.0 wt. %, Mn is present at 0 to 2.0 wt. %, Si is present at 0 to 2.0 wt. % and O is present at 0 to 0.50 wt. %, the balance up to 100 wt. % is Fe.

[0032] In a preferred embodiment, the iron-based alloy powder according to the present invention preferably comprises at most 0.3 wt. % Si and more preferably at most 0.1 wt. % Si.

[0033] It is also preferred, that the iron-based alloy powder according to the present invention is an alloy which indicates a tensile strength of at least 1000 MPa, an elongation of at least 1.0% and a hardness (HV) of at least 450.

[0034] In another embodiment, it is preferred that the iron-based alloy powder according to the present invention is an alloy which indicates a tensile strength of at least 1000 MPa, an elongation of at least 0.5% and a hardness (HV) of at least 450.

[0035] The iron-based alloy powder according to the first aspect of the present invention contains non-spherical particles. At least 40% of the total amount of particles have a non-spherical shape. Besides non-spherical particles, the iron-based alloy powder may also contain particles having a spherical shape. However, it is preferred that the iron-based alloy powder according to the present invention contains more particles having a non-spherical shape than particles having a spherical shape.

[0036] In a first embodiment of the present invention it is preferred that the iron-based powder is a powder containing particles, wherein at least 50%, preferably at least 70%, more preferably at least 95%, most preferably at least 99% of the total amount of particles have a non-spherical shape.

[0037] In another preferred embodiment of the present invention, the iron-based alloy powder contains particles, wherein the total amount of particles having a non-spherical shape is in the range of at least 40 to 70%, more preferably in the range of more than 45 to 60%, most preferably in the range of at least 50 to 55%.

[0038] In another preferred embodiment of the present invention, the iron-based alloy powder contains particles, wherein the total amount of particles having a non-spherical shape is in the range of at least 40 to 70%, more preferably in the range of more than 45 to 65%, most preferably in the range of at least 50 to 60%.

[0039] The particles of the iron-based alloy powders according to the present invention are not limited to a specific diameter. However, it is preferred that the particles have a diameter in the range of 1 to 200 microns, more preferably from 3 to 70 microns, and most preferably from 15 to 53 microns.

[0040] It is also preferred that the particles of the iron-based alloy powder according to the present invention have a particle size distribution with a d10-value of at least 15 microns and a d90-value of not more than 65 microns, preferably related on a volume based Q.sub.3-distribution.

[0041] In one embodiment of the present invention it is preferred, that the iron-based alloy powders as such are obtainable by a process, wherein the iron-based alloy powder is provided in a molten state and an atomization step is carried out with a stream of the molten iron-based alloy powder.

[0042] Within this embodiment of the present invention it is also preferred, that the atomization step is carried out as an ultrahigh pressure liquid atomization by jetting at least one liquid with a pressure of at least 300 bar, preferably of at least 600 bar onto the stream of the molten iron-based alloy powder.

[0043] Even more preferably, the liquid contains water, preferably the liquid is water, and/or the ultrahigh pressure liquid atomization is carried out by an atomization process comprising at least two stages,

preferably, within a first stage of this atomization process, a stream of the molten iron-based alloy powder is fed through a nozzle into a first area located between the nozzle and a choke and a gas stream, which is preferably a nitrogen-containing gas stream and/or an inert gas stream, circulates around the molten iron-based alloy powder within this first area and, within a second stage of this atomization process, the stream of the molten iron-based alloy powder is fed to a second area located beyond the choke, where the stream of the molten iron-based alloy powder is contacted with a water-containing jet stream under a pressure of at least 300 bar, preferably of at least 600 bar causing a break up and solidification of the stream of the molten iron-based alloy powder into the respective particles, wherein at least 40% of the total amount of the particles have a non-spherical shape.

[0044] Another subject matter of the first aspect of the present invention is a process for producing an iron-based alloy powder as described above. Processes for producing iron-based alloy powders or such are known to a person skilled in the art.

[0045] Furthermore, a person skilled in the art knows suitable measures in order to separate particles having a non-spherical shape from particles having a spherical shape. This can be done, for example, by sieving.

[0046] Preferably, the process for producing the above-described iron-based alloy powders can be carried out by a method, wherein the iron-based alloy powder is provided in a molten state and an atomization step is carried out with a stream of the molten iron-based alloy powder.

[0047] It is preferred, that the atomization step is carried out as an ultrahigh pressure liquid atomization by jetting at least one liquid with a pressure of at least 300 bar, preferably of at least 600 bar onto the stream of the molten iron-based alloy powder.

[0048] Even more preferably, the liquid contains water, preferably the liquid is water, and/or the ultrahigh pressure liquid atomization is carried out by an atomization process comprising at least two stages,

preferably, within a first stage of this atomization process, a stream of the molten iron-based alloy powder is fed through a nozzle into a first area located between the nozzle and a choke and a gas stream, which is preferably a nitrogen-containing gas stream and/or an inert gas stream, circulates around the molten iron-based alloy powder within this first area and, within a second stage of this atomization process, the stream of the molten iron-based alloy powder is fed to a second area located beyond the choke, where the stream of the molten iron-based alloy powder is contacted with a water-containing jet stream under a pressure of at least 300 bar, preferably of at least 600 bar causing a break up and solidification of the stream of the molten iron-based alloy powder into the respective particles, wherein at least 40% of the total amount of the particles have a non-spherical shape.

[0049] Another subject matter according to the first aspect of the present invention is the use of the at least one iron-based alloy powder as described above within a three-dimensional (3D) printing process and/or in a process for producing a three-dimensional (3D) object.

[0050] Three-dimensional (3D) printing process is as such as well as three-dimensional (3D) objects as such are known to a person skilled in the art. Preferably, the at least one iron-based alloy powders according to the present invention are employed within a 3D-printing process in connection of a laser beam or an electron beam technique. It is particularly preferred, that the iron-based alloy powders according to the present invention are employed of in a selective laser melting (SLM) process. As SLM-process as well as other laser beam or electron beam based 3D-printing techniques are known to a person skilled in the art.

[0051] Another subject matter according to the first aspect of the present invention is a process for producing a three-dimensional (3D) object wherein the 3D object is formed layer by layer and within each layer at least one iron-based alloy powder as described above is employed.

[0052] Within this process it is preferred that in each layer the employed at least one iron-based alloy powder is molten by applying energy on the surface of the iron-based alloy powder,

preferably the energy is applied by a laser beam or an electron beam, more preferably by a laser beam.

[0053] It is even more preferred, that the inventive process is carried out as a SLM process as described for example in WO 2019/025471.

[0054] Therefore, a process is preferred, wherein the 3D object is produced by a selective laser melting (SLM) process, preferably the selective laser melting (SLM) process comprises the steps (i) to (iv): [0055] (i) applying a first layer of at least one iron-based alloy powder onto a surface, [0056] (ii) scanning the first layer of the at least one iron-based alloy powder with a focused laser beam at a temperature sufficient to melt at least part of the first layer of the at least one iron-based alloy powder throughout its layer thickness to obtain a first molten layer, [0057] (iii) solidifying the first molten layer obtained in step (ii), [0058] (iv)) repeating process steps (i), (ii) and (iii) with a pattern of scanning effective to form the respective 3D object or at least a part thereof.

[0059] Another subject matter of the first aspect of the present invention is a three-dimensional (3D) object as such obtainable by a process according to the present invention as described above by employing at least one iron-based alloy powder according to the present invention as described above.

[0060] A further subject matter of the first aspect of the present invention is a three-dimensional (3D) printed object obtained from an iron-based alloy powder according to the invention.

[0061] A first subject matter according to the second aspect of the present invention is an iron-based alloy powder wherein the alloy comprises the elements Fe, Cr and Mo and the iron-based alloy powder is produced by an ultra-high liquid atomization process comprising at least two stages, wherein

within a first stage of this atomization process, a stream of the molten iron-based alloy powder is fed through a nozzle into a first area located between the nozzle and a choke and a gas stream circulates around the molten iron-based alloy powder within this first area and,
within a second stage of this atomization process, the stream of the molten iron-based alloy powder is fed to a second area located beyond the choke, where the stream of the molten iron-based alloy powder is contacted with a liquid jet stream under a pressure of at least 300 bar causing a break up and solidification of the stream of the molten iron-based alloy powder into individual particles of the iron-based alloy powder.

[0062] However, in another embodiment, it is also possible that within a first stage of this atomization process, instead of a stream of the molten iron-based alloy powder, a stream of respective molten iron-based alloy coins, bars and/or discs, is fed through a nozzle into a first area located between the nozzle and a choke and a gas stream circulates around the molten iron-based alloy coins, bars and/or discs within this first area.

[0063] Metal-based alloy powders as such including iron-based alloy powders are known to a person skilled in the art. This also applies to process for the production of such iron-based alloy powders as well as the specific shape of such alloy powders (for example in form of particles). The iron-based alloy powders according to the present invention comprise as mandatory (metal) elements Fe (iron), Cr (chrome) and Mo (molybdenum). Besides these three mandatory elements, the iron-based alloy powders according to the present invention may comprise further elements such as C (carbon), Ni (nickel), S (sulfur), O (oxygen), Nb (niobium), Si (silicon), Cu (copper) or N (nitrogen).

[0064] Preferably Cr is present at 10.0 wt. % to 19.0 wt. %, Mo is present at 0.5 wt. % to 3.0 wt. %, C is present at 0 to 0.35 wt. %, Ni is present at 0 to 5.0 wt. %, Cu is present at 0 to 5.0 wt. %, Nb is present at 0 to 1.0 wt. %, Si is present at 0 to 1.0 wt. %, N is present at 0 to 0.20 wt. % and the balance up to 100 wt. % is Fe.

[0065] Iron-based alloy powders according to the present invention are preferred, wherein the alloy comprises in addition to the elements Fe, Cr and Mo at least three elements selected from C, Ni, Cu, Nb, Si and N,

[0066] Preferably Cr is present at 10.0 wt. % to 19.0 wt. %, Mo is present at 0.5 wt. % to 3.0 wt. %, C is present at 0 to 0.35 wt. %, Ni is present at 0 to 5.0 wt. %, Cu is present at 0 to 5.0 wt. %, Nb is present at 0 to 1.0 wt. %, Si is present at 0 to 1.0 wt. %, N is present at 0 to 0.25 wt. % and the balance up to 100 wt. % is Fe, and preferably at least three elements selected from C, Ni, Cu, Nb, Si and N are present with at least 0.05 wt.-% each.

[0067] It is even more preferred, that the iron-based alloy powder comprises in a first embodiment the elements as follows:

[0068] Cr is present at 10.0 wt. % to 18.3 wt. %, Mo is present at 0.5 wt. % to 2.5 wt. %, C is present at 0 to 0.30 wt. %, Ni is present at 0 to 4.0 wt. %, Cu is present at 0 to 4.0 wt. %, Nb is present at 0 to 0.7 wt. %, Si is present at 0 to 0.7 wt. % and N is present at 0 to 0.25 wt. %, the balance up to 100 wt. % is Fe, and preferably at least three elements selected from C, Ni, Cu, Nb, Si and N are present with at least 0.05 wt.-% each.

[0069] Within the present invention it is also preferred that the alloy comprises in addition to the elements Fe, Cr and Mo at least four elements selected from C, Ni, Cu, Nb, Si and N, optionally the alloy may additionally comprise at least one element selected from O, S, P and Mn.

[0070] In another embodiment of the present invention it is also preferred that the iron-based alloy powder is an alloy which comprises Fe at 82.0 wt. % to 86.0 wt. %; Cr at 10.0 wt. % to 12.0 wt. %; Ni at 1.5 wt. % to 2.5 wt. %; Cu at 0.4 wt. % to 0.7 wt. %; Mo at 1.2 wt. % to 1.8 wt. %; C at 0.14 wt. % to 0.18 wt. %; Nb at 0.02 wt. % to 0.05 wt. %; N at 0.04 to 0.07 wt. % and Si at 0 to 1.0 wt. %.

[0071] In a further embodiment of the present invention it is preferred that the iron-based alloy powder according to the present invention does not comprise Cr at 10.0 wt. % to 18.3 wt. %, Mo at 0.5 wt. % to 2.5 wt. %, C at 0 to 0.30 wt. %, Ni at 0 to 4.0 wt. %, Cu at 0 to 4.0 wt. %, Nb at 0 to 0.7 wt. %, Si at 0 to 0.7 wt. % and N at 0 to 0.25 wt. %, the balance up to 100 wt. % is Fe.

[0072] In a further preferred embodiment of the present invention, the iron-based alloy powder comprises the elements as follows:

[0073] Cr is present at 14 wt. % to 19.0 wt. %, Mo is present at 2.0 wt. % to 3.0 wt. %, C is present at 0 to 0.30 wt. %, Ni is present at 8.0 wt. % to 15.0 wt. %, Mn is present at 0 to 2.0 wt. %, Si is present at 0 to 2.0 wt. % and O is present at 0 to 0.50 wt. %, the balance up to 100 wt. % is Fe.

[0074] In a preferred embodiment, the iron-based alloy powder according to the present invention preferably comprises at most 0.3 wt. % Si and more preferably at most 0.1 wt. % Si.

[0075] It is also preferred, that the iron-based alloy powder according to the present invention is an alloy which indicates a tensile strength of at least 1000 MPa, an elongation of at least 1.0% and a hardness (HV) of at least 450.

[0076] In another embodiment, it is preferred that the iron-based alloy powder according to the present invention is an alloy which indicates a tensile strength of at least 1000 MPa, an elongation of at least 0.5% and a hardness (HV) of at least 450.

[0077] The iron-based alloy powder according to the second aspect of the present invention contains individual particles of the respective iron-based alloy powder. Preferably, the iron-based alloy powder according to the second aspect of the present invention is completely present as particles. The shape of the respective particles may be both spherical and non-spherical. However, it is preferred that the iron-based alloy powder according to the second aspect of the present invention contains non-spherical particles. Preferably, at least 40% of the total amount of particles have a non-spherical shape.

[0078] In a first embodiment of the present invention it is preferred that the iron-based powder is a powder containing particles, wherein at least 50%, preferably at least 70%, more preferably at least 95%, most preferably at least 99% of the total amount of particles have a non-spherical shape.

[0079] In another preferred embodiment of the present invention, the iron-based alloy powder contains particles, wherein the total amount of particles having a non-spherical shape is in the range of at least 40 to 70%, more preferably in the range of more than 45 to 60%, most preferably in the range of at least 50 to 55%.

[0080] In another preferred embodiment of the present invention, the iron-based alloy powder contains particles, wherein the total amount of particles having a non-spherical shape is in the range of at least 40 to 70%, more preferably in the range of more than 45 to 65%, most preferably in the range of at least 50 to 60%.

[0081] The particles of the iron-based alloy powders according to the present invention are not limited to a specific diameter. However, it is preferred that the particles have a diameter in the range of 1 to 200 microns, more preferably from 3 to 70 microns, and most preferably from 15 to 53 microns.

[0082] It is also preferred that the particles of the iron-based alloy powder according to the present invention have a particle size distribution with a d10-value of at least 15 microns and a d90-value of not more than 65 microns, preferably related on a volume based Q.sub.3-distribution.

[0083] The iron-based alloy powder according to the second aspect of the present invention is preferably produced by an ultra-high liquid atomization process, wherein [0084] i) the liquid jet stream is a water-containing jet stream, preferably the liquid is pure water, and/or [0085] ii) the liquid jet stream is applied under a pressure of at least 600 bar, and/or [0086] iii) the gas stream is a nitrogen-containing gas stream and/or an inert gas stream.

[0087] Even more preferably, all three above-mentioned options i), ii) and iii) are present within said atomization process according to the second aspect of the present invention.

[0088] Another subject matter of the second aspect of the present invention is a process as such for producing an iron-based alloy powder according to the second aspect of the present invention as described above. By consequence, the present invention also relates to a process for producing an iron-based alloy powder wherein the alloy comprises the elements Fe, Cr and Mo and the iron-based alloy powder is produced by an ultra-high liquid atomization process comprising at least two stages, wherein

within a first stage of this atomization process, a stream of the molten iron-based alloy powder is fed through a nozzle into a first area located between the nozzle and a choke and a gas stream circulates around the molten iron-based alloy powder within this first area and,
within a second stage of this atomization process, the stream of the molten iron-based alloy powder is fed to a second area located beyond the choke, where the stream of the molten iron-based alloy powder is contacted with a liquid jet stream under a pressure of at least 300 bar causing a break up and solidification of the stream of the molten iron-based alloy powder into individual particles of the iron-based alloy powder.

[0089] Another subject matter according to the second aspect of the present invention is the use of the at least one iron-based alloy powder as described above within a three-dimensional (3D) printing process and/or in a process for producing a three-dimensional (3D) object.

[0090] Three-dimensional (3D) printing process is as such as well as three-dimensional (3D) objects as such are known to a person skilled in the art. Preferably, the at least one iron-based alloy powders according to the present invention are employed within a 3D-printing process in connection of a laser beam or an electron beam technique. It is particularly preferred, that the iron-based alloy powders according to the present invention are employed of in a selective laser melting (SLM) process. As SLM-process as well as other laser beam or electron beam based 3D-printing techniques are known to a person skilled in the art.

[0091] Another subject matter according to the second aspect of the present invention is a process for producing a three-dimensional (3D) object wherein the 3D object is formed layer by layer and within each layer at least one iron-based alloy powder as described above is employed.

[0092] Within this process it is preferred that in each layer the employed at least one iron-based alloy powder is molten by applying energy on the surface of the iron-based alloy powder,

preferably the energy is applied by a laser beam or an electron beam, more preferably by a laser beam.

[0093] It is even more preferred, that the inventive process is carried out as a SLM process as described for example in WO 2019/025471.

[0094] Therefore, a process is preferred, wherein the 3D object is produced by a selective laser melting (SLM) process,

preferably the selective laser melting (SLM) process comprises the steps (i) to (iv): [0095] (iv) applying a first layer of at least one iron-based alloy powder onto a surface, [0096] (v) scanning the first layer of the at least one iron-based alloy powder with a focused laser beam at a temperature sufficient to melt at least part of the first layer of the at least one iron-based alloy powder throughout its layer thickness to obtain a first molten layer, [0097] (vi) solidifying the first molten layer obtained in step (ii), [0098] (iv)) repeating process steps (i), (ii) and (iii) with a pattern of scanning effective to form the respective 3D object or at least a part thereof.

[0099] Another subject matter of the second aspect of the present invention is a three-dimensional (3D) object as such obtainable by a process according to the present invention as described above by employing at least one iron-based alloy powder according to the present invention as described above.