Title of Invention	"A PROCESS FOR PREPARATION OF DUALLY MICROSTRUCTURED SHAPED NICKEL BASED SUPERALLOY COMPONENTS HAVING ONE STRUCTURE BYCASTING AND OTHER BY POWDER METALLURGY"
Abstract	A process for preparation of dually microstructured shaped nickel based superalloy components having one structure by casting and other by powder metallurgy wherein the process comprises steps of- (a) encapsulating both the solid and powder materials in a leak-tight capsule; (b) degassing the said capsule to a vacuum of 10° to 10° torr for 12-24 hours at a temperature of 400- 800°C followed by crimp-sealing in dynamic vacuum; (c) hot isostatic pressing of degassed capsule at a temperature of 950-1250°C and a pressure of 100 MPa for 3 hours or more; (d) skinning the capsule by machining or pickling, obtaining the desired product.

Title of Invention

"A PROCESS FOR PREPARATION OF DUALLY MICROSTRUCTURED SHAPED NICKEL BASED SUPERALLOY COMPONENTS HAVING ONE STRUCTURE BYCASTING AND OTHER BY POWDER METALLURGY"

Abstract

A process for preparation of dually microstructured shaped nickel based superalloy components having one structure by casting and other by powder metallurgy wherein the process comprises steps of- (a) encapsulating both the solid and powder materials in a leak-tight capsule; (b) degassing the said capsule to a vacuum of 10° to 10° torr for 12-24 hours at a temperature of 400- 800°C followed by crimp-sealing in dynamic vacuum; (c) hot isostatic pressing of degassed capsule at a temperature of 950-1250°C and a pressure of 100 MPa for 3 hours or more; (d) skinning the capsule by machining or pickling, obtaining the desired product.

Full Text	This invention relates to a process for preparation of dually microstructured shaped nickel based superalloys components having one structure by casting and other by powder metallurgy so that the resultant alloy has two different regions with different properties i.e. alloy has dual properties. Many turbine components used in aerospace such as turbine discs and rotors require superior high temperature creep properties at the rim region in disc or at the blades in rotors and excellent intermediate temperature tensile and low cycle fatigue properties in the hub region. One of the process by which this requirement is met is by having a gradient structure generated by controlling the heat treatment. The disadvantage of this process is that weight of the component increases thereby reducing the efficiency of engine. Another process for preparation of Nickel-base superalloys with dual properties is by brazing with a superalloy filler material. This process reduces the reliability of the component. The primary object of this invention is to propose a process for obtaining of dually microstructured shaped nickel based superalloy components by combining two structures, one cast and the other powder metallurgy structure, using hot isostatic pressing, thereby getting different properties in different areas of the same component. Another object of this invention is to propose a process for preparation of dually microstructured shaped nickel superalloy components wherein the process has a high material utilization factor and negligibly low rejection rates. Still another object of the present invention is to provide a process for preparation of dually microstructured shaped nickel superalloy components wherein the components thus obtained require no secondary operations. Further object of this invention is to propose a process for preparation of nickel based superalloy components with dual property features whereby desired properties are imparted to aerospace components like turbine disc, with reasonable reduction in weight of the component leading to an overall improvement in thermal efficiency and like of the engine. Still another object of the present invention is to propose an energy efficient process for obtaining dually microrstructred nickel based superalloy components. Still further object of the present invention is to propose a process which provides dually micro-structured alloys components with superior mechanical properties as compared to the similar alloys obtained by known processes. Yet another object of the present invention is to propose a process which provides very efficient and highly reliable components with dual properties in a more economical way. Still further object of the present invention is to provide a process which joins cast and powder metallurgy materials by hot isostatic pressing in a manner which gives uniform contact pressure. Yet further object of the present invention is to provide a process for preparation of alloys with dual properties which requires inexpensive tooling and the same process can be utilized for fabricating complex shapes which is not possible by the conventional process. Still further object of the present invention is to propose a process which alloy mitigation of casting defects such as Y- Y' eutectic nodules and cavities and homogenisation of dendritic structure, which leads to a concommitent increase in mechanical properteis ϒ-ϒ' are important safeguards in cast superalloys which are found in interdentritic or introgranular region, which effect mechanical properties of superalloy component. These are eliminated by hot isostatic pressing. Still further object of the present invention is that it provides a process which enables joining of cast and powder consolidation of powder and healing of casting defects in a single operation. According to the present invention, there is provided A process for preparation of dually microstructured shaped nickel based superalloy components having one structure by casting and other by powder metallurgy wherein the process comprises steps of encapsulating both the solid and powder materials in a leak-tight capsule; degassing the said capsule to a vacuum of 105 to 106 torr for 12-24 hours at a temperature of 400- 800°C followed by crimp sealing dynamic vacuum; hot isostatic pressing of degassed capsule at a temperature of 950-1250°C and a pressure of 100 MPa for 3 hours or more; skinning the capsule by machining or pickling, obtaining the desired product. The invention is illustrated but not limited by the following examples:- EXAMPLE Cast-IN-100 (solid) and -150/mm, P/M IN-100 (powder) materials were taken and encapsulated in leak-tight seamless AISI 304 stainless steel capsules. These capsules were degrassed at 800 degree Celsius for 16 hours to a vacuum of the order of 10~5 torr or better. The capsules were then crimp-sealed in dynamic vacuum and subjected to hot isostatic processing (HIP) at a temperature above the Y' solvus of the alloy (Y' solvus temperature : 1190 degree C, HIP temperature 1200 degree C) for 3 hours using argon gas pressure maintained at 115 Mpa. The capsule was skinned by machining to realize dual property specimen. Both metallurgical and micro-structured examination of the joints revealed that joints were sound having recrystallised grains. The undersirable casting defects such as Y' - Y' eutectic nodules and cavities were mitigated. WE CLAIM 1. A process for preparation of dually microstructured shaped nickel based superalloy components having one structure by casting and other by powder metallurgy wherein the process comprises steps of- (a) encapsulating both the solid and powder materials in a leak-tight capsule; (b) degassing the said capsule to a vacuum of 10-5 to 10-6 torr for 12-24 hours at a temperature of 400- 800°C followed by crimp-sealing in dynamic vacuum; (c) hot isostatic pressing of degassed capsule at a temperature of 950-1250°C and a pressure of 100 MPa for 3 hours or more; (d) skinning the capsule by machining or pickling, obtaining the desired product. 2. A process as claimed in claim I, wherein the material for said encapsulation has particle size less then 150 microns. 3. A process as claimed in claim 1, wherein the material for capsule used for said encapsulation is stainless steel or mild steel. 4. A process as claimed in claim 1, wherein the temperature for said hot isostatic pressing is higher than the temperature at which -precipitates dissolve into the matrix ϒ-phase. 5. A process for preparation of dually micro-structured shaped nickel based superalloys having one structure by casting and other structure by powder metallurgy as substantially described and illustrated herein.

Full Text

This invention relates to a process for preparation of dually microstructured shaped nickel based superalloys components having one structure by casting and other by powder metallurgy so that the resultant alloy has two different regions with different properties i.e. alloy has dual properties.
Many turbine components used in aerospace such as turbine discs and rotors require superior high temperature creep properties at the rim region in disc or at the blades in rotors and excellent intermediate temperature tensile and low cycle fatigue properties in the hub region. One of the process by which this requirement is met is by having a gradient structure generated by controlling the heat treatment. The disadvantage of this process is that weight of the component increases thereby reducing the efficiency of engine.
Another process for preparation of Nickel-base superalloys with dual properties is by brazing with a superalloy filler material. This process reduces the reliability of the component.
The primary object of this invention is to propose a process for obtaining of dually microstructured shaped nickel based superalloy components by combining two structures, one cast and the other powder metallurgy structure, using hot isostatic pressing, thereby getting different properties in different areas of the same component.
Another object of this invention is to propose a process for preparation of dually microstructured shaped nickel superalloy components wherein the process has a high material utilization factor and negligibly low rejection rates.
Still another object of the present invention is to provide a process for preparation of dually microstructured shaped nickel superalloy components wherein the components thus obtained require no secondary operations.
Further object of this invention is to propose a process for preparation of nickel based superalloy components with dual property features whereby desired properties are imparted to aerospace components like turbine disc, with reasonable reduction in weight of the component leading to an overall improvement in thermal efficiency and like of the engine.
Still another object of the present invention is to propose an energy efficient process for obtaining dually microrstructred nickel based superalloy components.
Still further object of the present invention is to propose a process which provides dually micro-structured alloys components with superior mechanical properties as compared to the similar alloys obtained by known processes.
Yet another object of the present invention is to propose a process which provides very efficient and highly reliable components with dual properties in a more economical way.
Still further object of the present invention is to provide a process which joins cast and powder metallurgy materials by hot isostatic pressing in a manner which gives uniform contact pressure.
Yet further object of the present invention is to provide a process for preparation of alloys with dual properties which requires inexpensive tooling and the same process can be utilized for fabricating complex shapes which is not possible by the conventional process.
Still further object of the present invention is to propose a process which alloy mitigation of casting defects such as Y- Y' eutectic nodules and cavities and homogenisation of dendritic structure, which leads to a concommitent increase in mechanical properteis ϒ-ϒ' are important safeguards in cast superalloys which are found in interdentritic or introgranular region, which effect mechanical properties of superalloy component. These are eliminated by hot isostatic pressing.
Still further object of the present invention is that it provides a process which enables joining of cast and powder consolidation of powder and healing of casting defects in a single operation.
According to the present invention, there is provided A process for preparation of dually microstructured shaped nickel based superalloy components having one structure by casting and other by powder metallurgy wherein the process comprises steps of encapsulating both the solid and powder materials in a leak-tight capsule; degassing the said capsule to a vacuum of 105 to 106 torr for 12-24 hours at a temperature of 400- 800°C followed by crimp sealing dynamic vacuum; hot isostatic pressing of degassed capsule at a temperature of 950-1250°C and a pressure of 100 MPa for 3 hours or more; skinning the capsule by machining or pickling, obtaining the desired product.
The invention is illustrated but not limited by the following examples:-
EXAMPLE
Cast-IN-100 (solid) and -150/mm, P/M IN-100 (powder) materials were taken and encapsulated in leak-tight seamless AISI 304 stainless steel capsules. These capsules were degrassed at 800 degree Celsius for 16 hours to a vacuum of the order of 10~5 torr or better. The capsules were then crimp-sealed in dynamic vacuum and subjected to hot isostatic processing (HIP) at a temperature above the Y' solvus of the alloy (Y' solvus temperature : 1190 degree C, HIP temperature 1200 degree C) for 3 hours using argon gas pressure maintained at 115 Mpa. The capsule was skinned by machining to realize dual property specimen. Both metallurgical and micro-structured examination of the joints revealed that joints were sound having recrystallised grains. The undersirable casting defects such as Y' - Y' eutectic nodules and cavities were mitigated.

WE CLAIM
1. A process for preparation of dually microstructured shaped nickel based superalloy
components having one structure by casting and other by powder metallurgy wherein the
process comprises steps of-
(a) encapsulating both the solid and powder materials in a leak-tight capsule;
(b) degassing the said capsule to a vacuum of 10-5 to 10-6 torr for 12-24 hours at a temperature of 400- 800°C followed by crimp-sealing in dynamic vacuum;
(c) hot isostatic pressing of degassed capsule at a temperature of 950-1250°C and a pressure of 100 MPa for 3 hours or more;
(d) skinning the capsule by machining or pickling, obtaining the desired product.

2. A process as claimed in claim I, wherein the material for said encapsulation has particle size less then 150 microns.
3. A process as claimed in claim 1, wherein the material for capsule used for said encapsulation is stainless steel or mild steel.
4. A process as claimed in claim 1, wherein the temperature for said hot isostatic pressing is higher than the temperature at which -precipitates dissolve into the matrix ϒ-phase.
5. A process for preparation of dually micro-structured shaped nickel based superalloys having one structure by casting and other structure by powder metallurgy as substantially described and illustrated herein.

Documents:

67-del-1996-abstract.pdf

67-del-1996-claims.pdf

67-del-1996-complete specifiction (granted).pdf

67-del-1996-correspondence-others.pdf

67-del-1996-correspondence-po.pdf

67-del-1996-description (complete).pdf

67-del-1996-form-1.pdf

67-del-1996-form-2.pdf

67-del-1996-form-4.pdf

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Patent Number

194376

Indian Patent Application Number

67/DEL/1996

PG Journal Number

44/2004

Publication Date

30-Oct-2004

Grant Date

10-Feb-2006

Date of Filing

11-Jan-1996

Name of Patentee

THE CHIEF CONTROLLER RESEARCH & DEVELOPMENT, MINISTRY OF DEFENCE GOVERNMENT OF INDIA

Applicant Address

TECHNICAL COORDINATION DTE. B-341 , SENA BHAWAN, DHQ P.O.,

Inventors:

#	Inventor's Name	Inventor's Address
1	DR. MAHESH CHANDRA SOMANI	THE DEFENCE METALLURGICAL RESEARCH LABORATORY, HYDERABAD,
2	DR. NARESH CHANDRA BIRLA	THE DEFENCE METALLURGICAL RESEARCH LABORATORY, HYDERABAD,

PCT International Classification Number

B22D 11/04

PCT International Application Number

N/A

PCT International Filing date

PCT Conventions:

#	PCT Application Number	Date of Convention	Priority Country
1			NA