Method for post-built heat treatment of additively manufactured components made of gamma-prime strengthened superalloys

Patent metadata

Field	Value
Publication number	US-9670572-B2
Application number	US-201514705264-A
Country	US
Kind code	B2
Filing date	May 6, 2015
Priority date	May 12, 2014
Publication date	Jun 6, 2017
Grant date	Jun 6, 2017

Abstract

The invention relates to a method of post-built up heat treatment of an additively manufactured high strength component made of a gamma-prime strengthened superalloy based on Ni or Co or Fe or combinations thereof. An application of a rapid heating-up rate of 25 to 60° C./min in a specific temperature range during the first post-built heat treatment after additive manufacturing avoids or at least minimizes the gamma-prime precipitation in the component during heat-up. This results in crack-free components/articles compared to significant cracking present in conventionally heat treated components.

First claim

The invention claimed is:

1. A method for post-built up heat treatment of an additively manufactured component made of a gamma prime strengthened superalloy based on Ni or Co or Fe or combinations thereof, the method comprising:
a) providing the additively manufactured component in an as-built, then
b) heating the component from room temperature (RT) up to a first temperature T 1 at a first heating rate v 1 , wherein T 1 is 50° C. to 100° C. less than a temperature T s , at which a drop of a coefficient of thermal expansion starts, then
c) holding the component for a first time t 1 at T 1 to achieve a uniform component temperature, then
d) heating the component by applying a fast heating with a second heating rate v 2 of at least 25° C./min from T 1 to a second temperature T 2 ≧850° C. to avoid or at least to reduce precipitation of a gamma-prime phase, then
e) applying further time/temperature steps to the component depending on a purpose of the heat treatment.

2. The method according to claim 1 , wherein in step d) the second heating rate is v 2 =25° C./min to 60° C./min.

3. The method according to claim 1 , wherein in step e) an isothermal dwell time t 2 for 2 hours is done in order to reduce residual stresses.

4. The method according to claim 1 , wherein in step e) different or additional hold times at third temperatures T 3 are applied to further reduce residual stresses and/or to recrystallize a microstructure, wherein each T 3 is greater than T 2 .

5. The method according to claim 1 , wherein the method is performed under pressure during hot isostatic pressing (HIP).

6. The method according to claim 1 , wherein the following post-built heat treatment parameters for a component additively manufactured and made of IN 738LC:
T 1 =400° C.,
v 1 =5° C./min,
v 2 =35° C./min, and
T 2 =1050° C.

7. The method of claim 4 , wherein at least one additional hold time of step e) has a second time t 2 of two hours and the third temperature T 3 for that hold time is 1120° C., 1200° C. or 1250° C.

8. The method of claim 1 , wherein step e) comprises:
heating the component to a third temperature T 3 that is greater than or equal to 1120° C. for a second time t 2 that is at least two hours.

9. The method of claim 1 , wherein T 2 is ≧1050° C.

10. The method of claim 1 , wherein the as-built condition of the component is a condition of the component after the component is formed from selective laser melting (SLM) without the component undergoing any heat treatment after formation of the component via SLM.

11. The method of claim 1 , wherein the as-built condition of the component is a condition in which the component had not yet undergone heat treatment.

12. The method of claim 1 , wherein the component is a part of a gas turbine.

13. The method of claim 1 , wherein the first heating rate is at least 5° C./min and the second heating rate is greater than the first heating rate.

14. The method of claim 1 , wherein the gamma prime strengthened superalloy is IN738LC, CM247CL, or CMSX-4.

15. A method of heat treating an additively manufactured component made of a gamma prime strengthened superalloy based on Ni or Co or Fe or combinations thereof, the method comprising:
heating the component from a first temperature up to a second temperature at a first heating rate, wherein the second temperature is 50° C. to 100° C. less than a temperature at which a drop of a coefficient of thermal expansion starts for the gamma prime strengthened superalloy;
holding the component for a first time at the second temperature to achieve a uniform component temperature after heating the component from the first temperature to the second temperature via the first heating rate; and
heating the component by applying a second heating rate of at least 25° C./min from the second temperature to a third temperature to avoid precipitation of a gamma-prime phase for the gamma prime strengthened superalloy, the third temperature being greater than or equal to 850° C.

16. The method of claim 15 , comprising:
after heating of the component to the third temperature by applying the second heating rate, adjusting a temperature of the component from the third temperature to a fourth temperature.

17. The method of claim 16 , comprising:
maintaining the component at the fourth temperature for a pre-selected holding time that is two hours long; and
wherein the fourth temperature is 1120° C.

18. The method of claim 15 , wherein the component is in an as-built condition that has not undergone any heat treatment prior to the heating of the component from the first temperature to the second temperature via the first heating rate.

19. The method of claim 18 , wherein the first heating rate is lower than the second heating rate, the second heating rate being between 25° C./min and 60° C./min.

20. The method of claim 18 , wherein the second temperature is 400° C. and the third temperature is 1050° C.

Assignees

• Alstom Technology Ltd
• Ansaldo Energia Ip Uk Ltd

Inventors

• Etter Thomas
• Engeli Roman
• Kuenzler Andreas

Classifications

• B22F10/64

  by thermal means (control of energy beam parameters for post heating B22F10/364) · CPC title

• B22F10/28

  Powder bed fusion, e.g. selective laser melting [SLM] or electron beam melting [EBM] · CPC title

• B33Y40/20

  Post-treatment, e.g. curing, coating or polishing · CPC title

• B22F3/15

  Hot isostatic pressing · CPC title

• B22F3/1055

  Operations & Transport · mapped topic