Casting methods and molded articles produced therefrom

Patent metadata

Field	Value
Publication number	US-10239120-B2
Application number	US-201615271461-A
Country	US
Kind code	B2
Filing date	Sep 21, 2016
Priority date	Aug 3, 2012
Publication date	Mar 26, 2019
Grant date	Mar 26, 2019

Abstract

Molded articles and methods for forming molded articles are provided. For example, a molded article comprises a first region formed by a first casting material and a second region formed by mixing a molten or liquid portion of the first casting material and a second casting material. The first casting material is a molten, liquid, or fluid metal alloy, and the second casting material is a molten or fluid metal alloy. The first casting material has a different chemical composition than the second casting material. The first region and the second region are cast as one integral casting using directional solidification, and the first region and the second region have different microstructure patterns. The molded article has a lower concentration of impurities than were present in the first and second casting materials, and an interface between the first region and the second region is devoid of an oxidation layer.

First claim

The invention claimed is:

1. A molded article comprising:
a first region formed by a first casting material, wherein the first casting material is a molten, liquid or fluid metal alloy; and
a second region formed by mixing a molten or liquid portion of the first casting material and a second casting material wherein the second casting material is a molten or fluid metal alloy,
wherein the first casting material has a different chemical composition than the second casting material,
wherein the first region and the second region are cast as one integral casting using directional solidification,
wherein the first region and the second region have different microstructure patterns, and
wherein the molded article has a lower concentration of impurities than were present in the first casting material and the second casting material, and wherein an interface between the first region and second region is devoid of an oxidation layer.

2. The molded article of claim 1 , wherein the molded article is a component in a gas turbine engine.

3. The molded article of claim 1 , wherein the molded article is a turbine bucket in a gas turbine engine.

4. The molded article of claim 3 , wherein the second region is a squealer tip.

5. The molded article of claim 3 , wherein the second region is a tip shroud.

6. The molded article of claim 1 , wherein the first region and the second region are each single crystal, columnar, equiaxed, or a combination thereof.

7. The molded article of claim 1 , wherein the molded article further comprises a third region formed by the second casting material and a third casting material, further wherein the first region, the second region and the third region form a functionally graded, multi-layer molded article.

8. The molded article of claim 1 , wherein the second region comprises at least one improved physical property relative to the first region, the physical property being one of oxidation or corrosion resistance, wear resistance, low cycle fatigue or strain, degree of isothermal creep rupture, tensile strength, weldability, high temperature resistance, thermal cracking, or material loss.

9. The molded article of claim 1 , wherein the alloy of the second casting material comprises cobalt, chromium, molybdenum, tungsten, tantalum, aluminum, hafnium, and nickel.

10. The molded article of claim 9 , wherein the alloy comprises 1 wt % to 2 wt % hafnium, based on the total weight of the second casting material.

11. The molded article of claim 1 , wherein the alloy of the first casting material comprises about 50 wt % to about 70 wt % nickel, about 5 wt % to about 25 wt % chromium, about 5 wt % to about 15 wt % cobalt, about 0.1 wt % to about 10 wt % aluminum, about 0.1 wt % to about 10 wt % titanium, about 0.1 wt % to about 5.0 wt % molybdenum, about 0.01 wt % to about 0.50 wt % tungsten and about 0.1 wt % to about 10.0 wt % tantalum, based on the total weight of the first casting material.

12. A method comprising:
introducing the first casting material into a casting mold;
applying directional solidification to the first casting material in the casting mold;
introducing the second casting material into the casting mold, the second casting material having a different chemical composition than the first casting material;
applying directional solidification to the second casting material in the casting mold; and
forming the molded article, wherein the molded article comprises the first region formed by the first casting material and the second region formed by mixing a molten or liquid portion of the first casting material and the second casting material and the first region and the second region are cast as one integral casting,
wherein the second region has at least one improved physical property relative to the first region, the physical property being one of oxidation or corrosion resistance, wear resistance, low cycle fatigue or strain, degree of isothermal creep rupture, tensile strength, weldability, high temperature resistance, thermal cracking, or material loss, and
wherein the first region and the second region have different microstructure patterns.

13. The method of claim 12 , wherein the first casting material is introduced into the casting mold via a first inlet entry point, the second casting material is introduced into the casting mold via a second inlet entry point, and the second inlet entry point is disposed in a position below a position of a surface of the molten or liquid portion of the first casting material.

14. The method of claim 12 , wherein a withdrawal rate of the casting mold is adjusted to match a growth rate of the second casting material.

15. The method of claim 12 , wherein the second region exhibits reduced thermal cracking relative to the first region.

16. The method of claim 12 , wherein the second region exhibits improved weldability properties compared to the weldability properties of the first region.

17. The method of claim 12 , wherein the alloy of the first casting material comprises nickel, chromium, cobalt, aluminum, titanium, molybdenum, tungsten and tantalum or a combination comprising at least one of the foregoing.

18. The method of claim 12 , wherein the alloy of the second casting material comprises cobalt, chromium, molybdenum, tungsten, tantalum, aluminum, hafnium, nickel or a combination comprising at least one of the foregoing, and wherein the second casting material is substantially devoid of titanium.

19. A molded turbine bucket for use in a gas turbine engine, the turbine bucket comprising:
a hub; and
a blade, the blade including
a first region formed by a first casting material, wherein the first casting material is a molten, liquid or fluid metal alloy; and
a second region formed by mixing a molten or liquid portion of the first casting material and a second casting material, wherein the second casting material is a molten or fluid metal alloy,

wherein the first casting material has a different chemical composition than the second casting material,
wherein the first region and the second region have different microstructure patterns,
wherein the first region and the second region are cast as one integral casting using directional solidification,
wherein the molded article has a lower concentration of impurities than were present in the first casting material and the second casting material, and
wherein the second region corresponds to a tip portion of the blade and the first region corresponds to the remaining balance of the blade, and wherein an interface between the first region and second region is devoid of an oxidation layer.

Assignees

• Gen Electric

Inventors

• Cui Yan
• Bucci David Vincent
• Feng Ganjiang
• Kottilingam Srikanth Chandrudu
• Lin Dechao

Classifications

• B32B15/01

  all layers being exclusively metallic {(making layered metal workpieces by pressure cladding B23K20/22; making coatings with a metallic material characterised by its composition C23C30/00)} · CPC title

• Y10T428/12493

  Composite; i.e., plural, adjacent, spatially distinct metal components [e.g., layers, joint, etc.] · CPC title

• B22D25/06

  by its physical properties (B22D27/00 takes precedence) · CPC title

• Y10T428/12931

  Co-, Fe-, or Ni-base components, alternative to each other · CPC title

• B32B15/04

  comprising metal as the main or only constituent of a layer, {which is} next to another layer of {the same or of} a {different material (next to a bituminous or tarry layer B32B11/08; next to a water-setting substance layer B32B13/06; next to a glass layer B32B17/061; next to a cellulosic plastic layer B32B23/042)} · CPC title