Ti—Al-based heat-resistant member

Patent metadata

Field	Value
Publication number	US-9670787-B2
Application number	US-201514665470-A
Country	US
Kind code	B2
Filing date	Mar 23, 2015
Priority date	Mar 27, 2014
Publication date	Jun 6, 2017
Grant date	Jun 6, 2017

Abstract

The present invention relates to a Ti—Al-based heat-resistant member including a Ti—Al-based alloy which includes: 28.0 mass % to 35.0 mass % of Al; 1.0 mass % to 15.0 mass % of at least one selected from the group consisting of Nb, Mo, W and Ta; 0.1 mass % to 5.0 mass % of at least one selected from the group consisting of Cr, Mn and V; and 0.1 mass % to 1.0 mass % of Si, with the balance being Ti and unavoidable impurities, in which a whole or a part of a surface of the Ti—Al-based heat-resistant member includes a hardened layer as a surface layer, the hardened layer having a higher hardness than an inside of the Ti—Al-based heat-resistant member, and the Ti—Al-based heat-resistant member has a hardness ratio (a hardness of the surface layer/a hardness of the inside) of 1.4 to 2.5.

First claim

What is claimed is:

1. A Ti—Al-based heat-resistant member comprising a Ti—Al-based alloy which comprises:
28.0 mass % to 35.0 mass % of Al;
1.0 mass % to 15.0 mass % of at least one selected from the group consisting of Nb, Mo, W and Ta;
0.1 mass % to 5.0 mass % of at least one selected from the group consisting of Cr, Mn and V; and
0.1 mass % to 1.0 mass % of Si,
with the balance being Ti and unavoidable impurities,
wherein a whole or a part of a surface of the Ti—Al-based heat-resistant member includes a hardened layer as a surface layer, said hardened layer having a higher hardness than an inside of the Ti—Al-based heat-resistant member, and
the Ti—Al-based heat-resistant member has a hardness ratio represented by the following expression (a) of 1.4 to 2.5:
Hardness ratio= HV S /HV I   (a)

in which HV S is a hardness of the surface layer and is a Vickers hardness measured at a site located at a distance of 0.02 mm±0.005 mm from the surface of the Ti—Al-based heat-resistant member (load: 0.98 N), and
HV I is a hardness of the inside of the Ti—Al-based heat-resistant member and is a Vickers hardness measured at a site located at a distance of 0.50 mm±0.10 mm from the surface of the Ti—Al-based heat-resistant member (load: 0.98 N).

2. The Ti—Al-based heat-resistant member according to claim 1 , wherein the Ti—Al-based alloy further comprises from 0.01 mass % to 0.2 mass % of C.

3. The Ti—Al-based heat-resistant member according to claim 1 , wherein the Ti—Al-based alloy further comprises from 0.005 mass % to 0.200 mass % of B.

4. The Ti—Al-based heat-resistant member according to claim 2 , wherein the Ti—Al-based alloy further comprises from 0.005 mass % to 0.200 mass % of B.

5. The Ti—Al-based heat-resistant member according to claim 1 , wherein the hardened layer has a hardened layer depth, which is a distance from the surface of the Ti—Al-based heat-resistant member to a site where the hardness is (HV S +HV I )/2, of 0.03 to 0.25 mm.

6. The Ti—Al-based heat-resistant member according to claim 2 , wherein the hardened layer has a hardened layer depth, which is a distance from the surface of the Ti—Al-based heat-resistant member to a site where the hardness is (HV S +HV I )/2, of 0.03 to 0.25 mm.

7. The Ti—Al-based heat-resistant member according to claim 3 , wherein the hardened layer has a hardened layer depth, which is a distance from the surface of the Ti—Al-based heat-resistant member to a site where the hardness is (HV S +HV I )/2, of 0.03 to 0.25 mm.

8. The Ti—Al-based heat-resistant member according to claim 4 , wherein the hardened layer has a hardened layer depth, which is a distance from the surface of the Ti—Al-based heat-resistant member to a site where the hardness is (HV S +HV I )/2, of 0.03 to 0.25 mm.

9. The Ti—Al-based heat-resistant member according to claim 1 , wherein the hardened layer has an α 2 volume ratio, which is a volume ratio of an α 2 phase measured at a site located at a distance of 0.02 mm±0.005 mm from the surface of the Ti—Al-based heat-resistant member, of 30 to 60% by volume.

10. The Ti—Al-based heat-resistant member according to claim 2 , wherein the hardened layer has an α 2 volume ratio, which is a volume ratio of an α 2 phase measured at a site located at a distance of 0.02 mm±0.005 mm from the surface of the Ti—Al-based heat-resistant member, of 30 to 60% by volume.

11. The Ti—Al-based heat-resistant member according to claim 3 , wherein the hardened layer has an α 2 volume ratio, which is a volume ratio of an α 2 phase measured at a site located at a distance of 0.02 mm±0.005 mm from the surface of the Ti—Al-based heat-resistant member, of 30 to 60% by volume.

12. The Ti—Al-based heat-resistant member according to claim 4 , wherein the hardened layer has an α 2 volume ratio, which is a volume ratio of an α 2 phase measured at a site located at a distance of 0.02 mm±0.005 mm from the surface of the Ti—Al-based heat-resistant member, of 30 to 60% by volume.

13. The Ti—Al-based heat-resistant member according to claim 5 , wherein the hardened layer has an α 2 volume ratio, which is a volume ratio of an α 2 phase measured at a site located at a distance of 0.02 mm±0.005 mm from the surface of the Ti—Al-based heat-resistant member, of 30 to 60% by volume.

14. The Ti—Al-based heat-resistant member according to claim 6 , wherein the hardened layer has an α 2 volume ratio, which is a volume ratio of an α 2 phase measured at a site located at a distance of 0.02 mm±0.005 mm from the surface of the Ti—Al-based heat-resistant member, of 30 to 60% by volume.

15. The Ti—Al-based heat-resistant member according to claim 7 , wherein the hardened layer has an α 2 volume ratio, which is a volume ratio of an α 2 phase measured at a site located at a distance of 0.02 mm±0.005 mm from the surface of the Ti—Al-based heat-resistant member, of 30 to 60% by volume.

16. The Ti—Al-based heat-resistant member according to claim 8 , wherein the hardened layer has an α 2 volume ratio, which is a volume ratio of an α 2 phase measured at a site located at a distance of 0.02 mm±0.005 mm from the surface of the Ti—Al-based heat-resistant member, of 30 to 60% by volume.

17. The Ti—Al-based heat-resistant member according to claim 1 , which is a turbine wheel.

18. The Ti—Al-based heat-resistant member according to claim 2 , which is a turbine wheel.

19. The Ti—Al-based heat-resistant member according to claim 17 , wherein a surface layer of a wing part of the turbine wheel has an average crystal grain diameter of 10 to 50 μm and has an equi-axed grain structure having random crystal orientation.

20. The Ti—Al-based heat-resistant member according to claim 18 , wherein a surface layer of a wing part of the turbine wheel has an average crystal grain diameter of 10 to 50 μm and has an equi-axed grain structure having random crystal orientation.

21. The Ti—Al-based heat-resistant member according to claim 19 , wherein an inside of the wing part of the turbine wheel has an average crystal grain diameter of 100 to 500 μm and has an equi-axed grain structure having random crystal orientation.

22. The Ti—Al-based heat-resistant member according to claim 20 , wherein an inside of the wing part of the turbine wheel has an average crystal grain diameter of 100 to 500 μm and has an equi-axed grain structure having random crystal orientation.

Assignees

• Koyanagi Yoshihiko
• Takabayashi Hiroyuki
• Sumi Yoshinori
• Daido Steel Co Ltd

Inventors

• Koyanagi Yoshihiko
• Takabayashi Hiroyuki
• Sumi Yoshinori

Classifications

• C22C14/00 Primary

  Alloys based on titanium · CPC title

• F05D2230/41

  Hardening; Annealing · CPC title

• F01D5/286

  Particular treatment of blades, e.g. to increase durability or resistance against corrosion or erosion (F01D5/288 takes precedence) · CPC title

• F05D2300/173

  Aluminium alloys, e.g. AlCuMgPb · CPC title

• C22F1/183

  of titanium or alloys based thereon · CPC title