γ, γ′ cobalt based alloys for additive manufacturing methods or soldering, welding, powder and component

Information

  • Patent Grant
  • 11180830
  • Patent Number
    11,180,830
  • Date Filed
    Wednesday, December 14, 2016
    8 years ago
  • Date Issued
    Tuesday, November 23, 2021
    3 years ago
Abstract
The invention relates to gamma, gamma'-cobalt-based alloys for additive manufacturing methods or soldering, welding, powder and component. By using a cobalt-based alloy based on Co-7W-7 Al-23Ni-2Ti-2Ta-12Cr-0.0IB-0.IC-(0-0.1Si), an alloy that is especially well-suited for additive manufacturing methods or high-temperature soldering is proposed.
Description
CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims priority to PCT Application No. PCT/EP2016/080989, having a filing date of Dec. 14, 2016, based on German Application No. 10 2016 200 135.3, having a filing date of Jan. 8, 2016, the entire contents both of which are hereby incorporated by reference.


FIELD OF TECHNOLOGY

The following relates to a γ, γ′-cobalt-based superalloy which is employed in additive manufacturing (AM) processes or in soldering or welding of high-temperature components, a powder and component.


BACKGROUND

γ′-hardened nickel-based alloys are known from high-temperature use, for example in gas turbines. Nickel-based alloys are subject to hot gas corrosion and can be repaired only with difficulty because of their brittleness. In the case of cobalt-based alloys, it is known that they have better properties in this respect. However, a disadvantage here is the poorer mechanical properties due to an unstable γ′ phase (Co, Ni)-3Ti.


A problem in respect of hot cracks is that these processes have to be carried out very carefully in the case of γ, γ′-hardened nickel-based superalloys.


New developments which lead to stabilization of the γ phase in the alloy system Co—Ni—W—Al—Ti—Ta—Cr show that the mechanical properties are comparable to those of the known γ-hardened alloy Ni738.


Additive manufacturing processes and soldering or welding are known and are also employed or developed for γ′-hardened nickel-based alloys.


SUMMARY

The aspect is achieved by a cobalt-based superalloy, for additive manufacturing processes, soldering or welding, which comprises at least, in percent by weight: 6-8% of tungsten (W), 6%-8% of aluminum (Al), 21%-25% of nickel (Ni), 1%-3% of titanium (Ti), 1%-3% of tantalum (Ta), 10%-14% of chromium (Cr), 0.005%-0.015% of boron (B), 0.05%-0.15% of carbon (C). A process for the additive manufacture of a component, wherein the alloy is used. A method for soldering or for welding, wherein an alloy is used. A powder comprising an alloy is disclosed. A component comprising at least an alloy as or produced by a process or method or by means of a powder is disclosed.


The cobalt-based superalloy, for additive manufacturing processes, soldering or welding, of is disclosed which comprises at least, in percent by weight: 7% of tungsten (W), 7% of aluminum (Al), 23% of nickel (Ni), 2% of titanium (Ti), 2% of tantalum (Ta), 12% of chromium (Cr), 0.010% of boron (B), 0.10% of carbon (C). The cobalt-based superalloy, for additive manufacturing processes, soldering or welding, can comprise at least, in percent by weight:

  • 0.05%-0.15% of silicon (Si), in particular in percent by weight:
  • 0.10% of silicon (Si).







The description presents only illustrative embodiments of the invention.


A precipitation-hardening cobalt-based alloy which can be employed in additive manufacturing and in soldering or welding is proposed.


An advantageous composition is

  • Co-7W-7Al-23Ni-2Ti-2Ta-12Cr-0.01B-0.1C-(0-0.1Si).


Owing to the alloying elements titanium (Ti), aluminum (Al), tantalum (Ta) and hafnium (Hf) in superalloys, the oxygen particle pressure has to be controlled precisely during processing.


The proportion of tungsten (W) is kept rather low because of the density.


The proportion of aluminum (Al) is kept rather low in order to reduce the weldability and oxidation susceptibility due to the γ′ content.


The proportion of nickel (Ni) is kept high in order to broaden the stability range for the γ phase in the combination with chromium (Cr).


The proportion of titanium (Ti) is kept rather low because of the oxidation susceptibility.


The proportion of tantalum (Ta) is kept in the middle range, including in order to replace the proportion of tungsten (W) in the γ′ phase and in order to strengthen the grain boundaries together with the elements boron (B) and silicon (Si).


The proportion of chromium (Cr) is kept high in order to ensure good oxidation resistance and hot gas corrosion resistance.


Boron (B), carbon (C) and/or silicon (Si) represent grain boundary strengtheners.


The alloy is preferably subjected to a two-stage heat treatment:

  • solution heat treatment at 1573° K,
  • γ′ precipitation at 1173° K and
  • then grain boundary carbide precipitation at 1073° K and
  • a concluding aging heat treatment in order to achieve the precipitation of grain boundary strengtheners such as carbides, silicides.


A further advantageous heat treatment is solution heat treatment and precipitation of γ′ in a two-stage heat treatment with temperatures of 1423° K and 1193° K.

  • These temperatures are approximate figures (+/−20° K).
  • At the end, a preferable heat treatment at 1073° K for boride precipitation is optionally conceivable but not absolutely necessary.


The alloy can be present in powder form and also be used as welding additive material. This powder can have ceramics or other admixtures as constituent.


In soldering, welding or in AM, an alloy of this type or a powder of this type is employed in order to produce components in part or in full.


Although the invention has been illustrated and described in greater detail with reference to the preferred exemplary embodiment, the invention is not limited to the examples disclosed, and further variations can be inferred by a person skilled in the art, without departing from the scope of protection of the invention.


For the sake of clarity, it is to be understood that the use of “a” or “an” throughout this application does not exclude a plurality, and “comprising” does not exclude other steps or elements.

Claims
  • 1. A cobalt-based superalloy, for additive manufacturing processes, soldering or welding,which comprises in percent by weight:7% of tungsten (W),7% of aluminum (Al),21%-23% of nickel (Ni),2.5%-3% of titanium (Ti),1%-3% of tantalum (Ta),10%-14% of chromium (Cr),0.010%-0.015% of boron (B), and0.10%-0.15% of carbon (C).
  • 2. A powder comprising the cobalt-based superalloy as claimed in claim 1.
  • 3. A component comprising at least the cobalt-based superalloy as claimed in claim 1.
  • 4. A process for heat treatment, in particular for the cobalt-based superalloy as claimed in claim 1, wherein the alloy is subjected to at least a two-stage heat treatment: solution heat treatment at 1573° K,γ′ precipitation at 1173° K andthen the grain boundary carbide precipitation at 1073° K and a concluding aging heat treatment to precipitate grain boundary strengtheners.
  • 5. A process for heat treatment, in particular for the cobalt-based superalloy as claimed in claim 1, wherein the alloy is subjected to a solution heat treatment and precipitation of γ′ in an at least a two-stage heat treatment 1423° K and 1193° Kat the end optionally a heat treatment at 1073° K for boride precipitation.
  • 6. The cobalt-based superalloy, for additive manufacturing processes, soldering or welding, of claim 1which comprises in percent by weight:7% of tungsten (W),7% of aluminum (Al),23% of nickel (Ni),2.5% of titanium (Ti),2% of tantalum (Ta),12% of chromium (Cr),0.010% of boron (B), and0.10% of carbon (C).
  • 7. The cobalt-based superalloy, for additive manufacturing processes, soldering or welding, of claim 1which comprises in percent by weight:0.05%-0.15% of silicon (Si).
  • 8. The cobalt-based superalloy, for additive manufacturing processes, soldering or welding, of claim 7which comprises in percent by weight:0.10% of silicon (Si).
Priority Claims (1)
Number Date Country Kind
10 2016 200 135.3 Jan 2016 DE national
PCT Information
Filing Document Filing Date Country Kind
PCT/EP2016/080989 12/14/2016 WO 00
Publishing Document Publishing Date Country Kind
WO2017/118547 7/13/2017 WO A
US Referenced Citations (8)
Number Name Date Kind
3898109 Shaw Aug 1975 A
5640667 Freitag et al. Jun 1997 A
20130206287 Sato et al. Aug 2013 A1
20150010428 Hardy Jan 2015 A1
20150054191 Ljungblad Feb 2015 A1
20160168662 Hardy Jun 2016 A1
20160281194 Gindorf et al. Sep 2016 A1
20170342527 Bauer Nov 2017 A1
Foreign Referenced Citations (15)
Number Date Country
103069028 Apr 2013 CN
69622581 Feb 2003 DE
112012006355 Jan 2015 DE
102013224989 Jun 2015 DE
1925683 May 2008 EP
2532762 Dec 2012 EP
2583784 Apr 2013 EP
1207979 Jun 2014 EP
2821519 Jan 2015 EP
H0432501 Feb 1992 JP
2003527480 Sep 2003 JP
2009228024 Oct 2009 JP
2009228024 Oct 2009 JP
2015082518 Jun 2015 WO
WO 2015082518 Jun 2015 WO
Non-Patent Literature Citations (3)
Entry
Osaki et al. JP2009228024A, machine-generated English language text (Year: 2020).
Japanese Office Action dated Sep. 2, 2019 for Application No. 2018-535360.
PCT International Search Report of International Searching Authority dated Mar. 21, 2017 corresponding to PCT International Application No. PCT/EP2016/080989 filed Dec. 14, 2016.
Related Publications (1)
Number Date Country
20190003017 A1 Jan 2019 US