METHOD FOR PRODUCING A THREE-DIMENSIONAL ARTICLE AND ARTICLE PRODUCED WITH SUCH A METHOD
The invention relates to a method for producing a three-dimensional article or at least a part of such an article made of a gamma prime (γ′) precipitation hardened nickel base superalloy with a high volume fraction (>25%) of gamma-prima phase which is a difficult to weld superalloy, or made of a cobalt base superalloy, or of a non-castable or difficult to machine metal material by means of selective laser melting (SLM), in which the article is produced by melting of layerwise deposited metal powder with a laser beam characterized in that the SLM processing parameters are selectively adjusted to locally tailor the microstructure and/or porosity of the produced article or a part of the article and therefore to optimize desired properties of the finalized article/part of the article.
1 . A method for producing a three-dimensional article or at least a part of such an article made of a gamma prime (γ′) precipitation hardened nickel base superalloy with a high volume fraction (>25%) of gamma-prima phase which is a difficult to weld superalloy, or made of a cobalt base superalloy, or of a non-castable or difficult to machine metal material by means of selective laser melting (SLM), in which the article is produced by melting of layerwise deposited metal powder with a laser beam wherein the SLM processing parameters are selectively adjusted to locally tailor the microstructure and/or porosity of the produced article or a part of the article and therefore to optimize desired properties of the finalized article/part of the article.
2 . The method according to claim 1 , wherein a subsequent heat treatment step for further adjustment of the microstructure is applied.
3 . The method according to claim 1 , wherein the processing parameters to be adjusted are at least one or a combination of laser power, scan velocity, hatch distance, powder shape, powder size distribution, processing atmosphere.
4 . The method according to claim 1 , wherein the resulted microstructure and/or porosity of the deposited layers are different.
5 . The method according to claim 1 , wherein the resulted microstructure and/or porosity is gradually changing in radial or lateral direction of the article.
6 . The method according to claim 1 , wherein the resulted porosity is a closed or opened porosity.
7 . The method according to claim 6 , wherein the selectively introduced porosity is used to adjust mass related properties, preferable the eigenfrequency or to counterbalance the effect of additionally added material on an component.
8 . The method according to claim 1 , wherein the tailored microstructure comprises in-situ generated second phase particles, preferably hard-phase particles or solid lubricants.
9 . The method according to claim 8 , wherein the elements forming the second phase particles, are supplied at least partly by a reactive gas (processing atmosphere) and/or by the SLM metal powder and/or by alloys.
10 . The method according to claim 9 , wherein the composition of the reactive gas is actively changed during the SLM process.
11 . The method according to claim 9 , wherein Re, Ti, Ni, W, Mo, B are supplied for forming highly lubricous oxides at high temperatures.
12 . The method according to claim 9 , wherein elements forming second phase particles are carbide, boride, nitride, oxide or combinations thereof forming elements, such as Al, Si, Zr, Cr, Re, Ti, Ni, W, Mo, Zn, V.
13 . The method according to claim 1 , wherein existing holes or channels in the article are filled with a polymeric substance and an inorganic filler material prior to the built-up of SLM layers and the polymeric filler is burnt out during a subsequent heat treatment step.
14 . The method according to claim 1 , wherein the method is used for producing of new or repairing of used and damaged turbine components.
15 . A three-dimensional article or at least a part of such an article produced with a method according to claim 1 wherein the article is gas turbine component or section/part of a gas turbine component.
16 . The article according to claim 15 , wherein the article has a locally tailored microstructure (material composition, layers, gradients and/or porosity).
17 . The article according to claim 15 , wherein the article comprises at least one part with an open porous structure.
18 . The article according to claim 17 , wherein the article comprises an open-porous outer layer and a fully dense inner layer including cooling channels designed for guiding a cooling medium to the open porous outer layer, which cooling channels either end at the interface to the open porous outer layer or partly or fully penetrate the open-porous outer layer.
19 . The article according to claim 17 , wherein an open porous surface thermal barrier coating layer is applied onto the open porous outer layer.
20 . The article according to claim 15 , wherein the article comprises a complex design structure, but without overhanging areas with an angle of ≧45° or with sharp concave edges.
21 . The article according to claim 15 , wherein the article is a turbine blade crown.
22 . The article according to claim 15 , wherein the article is a turbine component, on which the section built is either new or an ex-service component.