Bladed Disc Fabrication via Diffusion Bonding and Friction Welding

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Solution Overview

Problem

Manufacturing bladed discs for gas turbine engines using dissimilar materials is challenging due to difficulties in joining materials with different crystal structures, thermal processing requirements, and the introduction of unfavorable post-weld mechanical properties, such as heat affected zones and residual stresses, which complicates the use of fusion welding and requires costly setups.

Innovation Solution

A method involving diffusion bonding and friction welding processes is used to fabricate bladed discs, where a first workpiece with different material properties is bonded to a second workpiece using diffusion bonding, and then the resulting sub-assembly is bonded to a third workpiece using friction welding, allowing for the creation of an integral assembly with improved material properties and reduced residual stress.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Ease of manufacture

If fusion welding is used to join dissimilar materials, then the bladed disc can be manufactured, but unfavorable post-weld mechanical properties occur due to heat affected zone and mixing of alloys

Engineering Contradiction:

Improvemanufacturability of bladed discVSAvoidpost-weld mechanical properties

Core Design Contradiction:

Ease of manufactureVSStrength

Solution Approach 1:

The invention changes the welding parameters by using solid state welding processes (diffusion bonding and friction welding) instead of fusion welding. These processes operate at lower temperatures that do not melt the materials, thereby avoiding the heat affected zone and alloy mixing problems while still achieving strong joints between dissimilar materials

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The invention utilizes solid state phase transitions in diffusion bonding where atoms diffuse across the interface without melting, and in friction welding where friction heat raises the temperature to a plastic state for bonding. These controlled phase transitions enable joining dissimilar materials without the detrimental effects of fusion welding

Inventive Principle:

Principle #36Phase transitions

2Ease of manufacture

If dissimilar materials are joined using solid state or melting processes, then the bladed disc can be fabricated, but large and costly setups are required

Engineering Contradiction:

Improvefabrication capabilityVSAvoidwelding setup complexity and cost

Core Design Contradiction:

Ease of manufactureVSDevice complexity

Solution Approach 1:

The invention segments the manufacturing process into two distinct stages: first diffusion bonding to create a sub-assembly, then friction welding to complete the bladed disc. This segmentation allows each process to be optimized independently and reduces the overall complexity and cost of the welding setup required

Inventive Principle:

Principle #1Segmentation

3Adaptability or versatility

If dissimilar materials with different crystal structures and thermal processing requirements are joined, then the bladed disc can be manufactured, but technical challenges arise in joining the materials

Engineering Contradiction:

Improveability to use dissimilar materialsVSAvoiddifficulty of joining process

Core Design Contradiction:

Adaptability or versatilityVSEase of manufacture

Solution Approach 1:

The invention uses an intermediary approach by first diffusion bonding the dissimilar materials at controlled temperatures and pressures to create a stable sub-assembly, then using friction welding as a second intermediary process to complete the joint. This two-step intermediary process bridges the gap between materials with different crystal structures and thermal requirements

Inventive Principle:

Principle #24Intermediary (Mediator)

Applied Scientific Principles

This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.

Function Achieved in This Case

This approach enables the efficient fabrication of bladed discs from dissimilar materials, reducing the need for expensive setups and minimizing adverse effects on material properties, while allowing for the use of simpler stress relief methods and broader applicability across various gas turbine components.

Implementation Method 1

performing a diffusion bonding process between the first surface of the first workpiece and the second surface of the second workpiece to form a sub-assembly workpiece

Methodology Applied

Scientific EffectDiffusion bonding: Diffusion Welding

Implementation Method 2

performing a friction welding process between a third surface of the sub-assembly workpiece and a fourth surface of a third workpiece to form the integral assembly

Methodology Applied

Scientific EffectFriction welding: Friction Welding

Data Source

PatentUS10738625B2Bladed disc and method of manufacturing the same

Publication Date: 2020.08.11 ROLLS ROYCE PLC

AI summary

A method (56) for fabricating an integral assembly (24) is disclosed. The method comprises providing (56) a first workpiece (26) having a first surface (46) and a second workpiece (28) having a second surface (50), performing a first bonding process between the first surface (46) of the first workpiece (26) and the second surface (50) of the second workpiece (28) to form a sub-assembly workpiece (48), and performing a second bonding process between a third surface (52) of the sub-assembly workpiece (48) and a fourth surface (54) of a third workpiece (30) to form the integral assembly (24). The material properties of the first workpiece (26) are different from material properties of the third workpiece (30).