Superalloy Powder Blending to Reduce Additive Manufacturing Cracking
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Solution Overview
Problem
The challenge lies in the difficulty of additively manufacturing and welding high γ′ forming nickel-base superalloys due to solidification and grain boundary liquation cracking, as well as sensitivity to strain-age cracking, which necessitates improved processes to reduce pores and cracks without hot isostatic pressing.
Innovation Solution
A superalloy powder mixture comprising at least 51% by weight high melt superalloy powder and at least 5% by weight low melt superalloy powder, where the low melt superalloy powder has a solidus temperature lower than the high melt superalloy powder, is used to facilitate additively manufacturing or welding, thereby reducing microcracking.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If high γ′ forming nickel-base superalloy materials are used for additively manufacturing or welding, then mechanical strength and resistance to thermal fatigue, oxidation, and corrosion are improved, but solidification and grain boundary liquation cracking problems occur
Solution Approach 1:
The superalloy powder is segmented into two distinct portions: high melt superalloy powder (maintaining γ′ precipitation-strengthening properties) and low melt superalloy powder (suppressing cracking). This segmentation allows each portion to fulfill its specific function while working together to produce a reliable additively manufactured component.
Solution Approach 2:
The invention uses a composite powder mixture comprising both high melt and low melt superalloy powders. The low melt superalloy powder acts as a crack-suppressing phase that modifies the solidification behavior of the high melt superalloy, creating a composite material system that overcomes the inherent cracking problems of conventional superalloys during additive manufacturing.
2Strength
If high γ′ forming nickel-base superalloy materials are used for additively manufacturing or welding, then resistance to thermal fatigue and oxidation is improved, but grain boundary liquation cracking problems occur
Solution Approach 1:
The superalloy powder is segmented into two distinct portions: high melt superalloy powder (maintaining γ′ precipitation-strengthening properties) and low melt superalloy powder (suppressing cracking). This segmentation allows each portion to fulfill its specific function while working together to produce a reliable additively manufactured component.
Solution Approach 2:
The invention uses a composite powder mixture comprising both high melt and low melt superalloy powders. The low melt superalloy powder acts as a crack-suppressing phase that modifies the solidification behavior of the high melt superalloy, creating a composite material system that overcomes the inherent cracking problems of conventional superalloys during additive manufacturing.
3Productivity
If conventional superalloy powder is used for additively manufacturing, then component production is achieved, but pores and cracks require hot isostatic pressing to collapse
Solution Approach 1:
The low melt superalloy powder is added in advance to the high melt superalloy powder mixture before additive manufacturing. This preliminary action ensures that the crack-suppressing mechanism is already in place during the building process, preventing pore and crack formation rather than requiring subsequent hot isostatic pressing to collapse them.
Solution Approach 2:
The invention converts the typically harmful low melt superalloy powder (which would normally cause grain boundary liquation cracking) into a beneficial crack-suppressing agent. By carefully controlling the composition and ratio of low melt powder in the mixture, the harmful melting behavior is transformed into a useful mechanism that fills and seals potential crack paths during solidification.
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
The proposed solution effectively reduces microcracking and avoids the need for hot isostatic pressing, producing components suitable for high temperature applications with improved mechanical properties.
Implementation Method 1
melt the low melt superalloy powder to fill internal pores of the component
Implementation Method 2
burn out the binder
Implementation Method 3
solid state sinter the component
Implementation Method 4
form via homogenization a base alloy of which the additive portion is comprised
Data Source
AI summary
A method is provided that facilitates additive manufacturing a superalloy component using a liquid assisted additive manufacturing process. The method includes successively depositing and fusing together layers of a superalloy powder mixture comprising a high melt superalloy powder and a low melt superalloy powder to build up an additive portion of the superalloy component. The method may further include heat treating the additive portion to form a homogenized base alloy of which the additive portion is comprised, which base alloy has a chemistry defined by the superalloy powder mixture. Each of the high melt superalloy powder, the low melt superalloy powder, and the superalloy powder mixture may have a nickel content by weight greater than 40% and have an aluminum content by weight of greater than 1.5%. The low melt superalloy powder may include at least 5% by weight of tantalum, and the high melt superalloy powder may include less than half the content by weight percent of tantalum compared to the content by weight percent of tantalum in the low melt superalloy powder.