Turbine wheel of automotive turbocharger and method for producing the same

Inventors: Yoshinori Sumi (Aichi, JP); Hiroyuki Takabayashi (Aichi, JP)

Assignee: DAIDO STEEL CO., LTD.

C22C19/056 B22D18/06 F01D5/28

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Quick Facts

Patent No.: US 9,738,954
App. No.: 14/631,107
Granted: Aug 22, 2017
Kind: B2

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Abstract

The present invention relates to a turbine wheel of an automotive turbocharger, including a Ni-based alloy having a composition which contains, in terms of mass %: C: 0.08 to 0.20%; Mn: 0.25% or less; Si: 0.01 to 0.50%; Cr: 12.0 to 14.0%; Mo: 3.80 to 5.20%; Nb+Ta: 1.80 to 2.80%; Ti: 0.50 to 1.00%; Al: 5.50 to 6.50%; B: 0.005 to 0.015%; Zr: 0.05 to 0.15%; and Fe: 0.01 to 2.5%, with the remainder being Ni and unavoidable impurities, in which the turbine wheel includes a wing part and a shaft part, and a size of γ′ phase in each site of from a tip of the wing part to the shaft part is structure-controlled so as to fall within a range of from 0.4 to 0.8 μm.

Claims (46)

1. A turbine wheel of an automotive turbocharger, comprising a Ni-based alloy having a composition which contains, in terms of mass %:

C: 0.08 to 0.20%;

Mn: 0.25% or less;

Si: 0.01 to 0.50%;

Cr: 12.0 to 14.0%;

Mo: 3.80 to 5.20%;

Nb+Ta: 1.80 to 2.80%;

Ti: 0.50 to 1.00%;

Al: 5.50 to 6.50%;

B: 0.005 to 0.015%;

Zr: 0.05 to 0.15%; and

Fe: 0.01 to 2.5%,

with the remainder being Ni and unavoidable impurities,

wherein the turbine wheel comprises a wing part and a shaft part, and

a size of γ′ phase in each site of from a tip of the wing part to the shaft part is structure-controlled so as to fall within a range of from 0.4 to 0.8 μm.

2. The turbine wheel according to claim 1 , which is produced by casting the Ni-based alloy and has an as-cast structure.

3. The turbine wheel according to claim 1 , which is produced by sucking a melt of the Ni-based alloy under reduced pressure into a porous mold produced by a lost wax process, followed by casting.

4. The turbine wheel according to claim 2 , which is produced by sucking a melt of the Ni-based alloy under reduced pressure into a porous mold produced by a lost wax process, followed by casting.

5. The turbine wheel according to claim 1 , wherein, in a whole turbine wheel, a size ratio between the most fine γ′ phase and the most coarse γ′ phase is 1.5 times or less.

6. The turbine wheel according to claim 2 , wherein, in a whole turbine wheel, a size ratio between the most fine γ′ phase and the most coarse γ′ phase is 1.5 times or less.

7. The turbine wheel according to claim 3 , wherein, in a whole turbine wheel, a size ratio between the most fine γ′ phase and the most coarse γ′ phase is 1.5 times or less.

8. The turbine wheel according to claim 4 , wherein, in a whole turbine wheel, a size ratio between the most fine γ′ phase and the most coarse γ′ phase is 1.5 times or less.

9. A method for producing the turbine wheel according to claim 1 , the method comprising casting the Ni-based alloy,

wherein a ratio of a volume of a melt of the Ni-based alloy sucked and cast in a mold which is arranged inside a casting chamber to a volume of the casting chamber is set to a range of from 2 to 10%, and