Additively Manufactured Shot Peen Elements for Internal Stress Relief
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Solution Overview
Problem
Additively manufactured metal components, particularly those made from gamma prime hardened superalloys, often experience macro-cracking due to high residual surface stresses, which limits their application in complex geometries with internal features since conventional stress relief methods like shot peening are only effective on external surfaces.
Innovation Solution
Incorporating additively manufactured shot peen elements within internal openings of these components, which are designed to induce residual compressive stress upon contact, and vibrating the components at a selected frequency to distribute this stress effectively throughout the internal structures.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional shot peening is applied to external surfaces, then compressive stress is introduced to prevent macro-cracking, but internal openings cannot be treated
Solution Approach 1:
The invention transitions shot peening from external surface application to internal opening treatment by introducing treatable shot peen elements into the internal geometry of the component. This dimensional extension allows compressive stress to be applied where conventional methods cannot reach, specifically within cooling passages and internal features of additively manufactured components.
Solution Approach 2:
The shot peen elements serve as intermediaries that are temporarily placed within internal openings, perform the stress relief function, and then removed. These elements mediate between the limitation of external-only treatment and the need for internal treatment, enabling compressive stress application without requiring direct access to internal surfaces through conventional means.
2Reliability
If additively manufactured shot peen elements are used, then compressive stress can be induced in internal openings, but the elements must be detached from the component
Solution Approach 1:
The shot peen elements are designed with predetermined detachment characteristics from the outset. The elements are intentionally created with properties that allow easy removal after performing their stress relief function, such as being made from materials or with geometries that facilitate detachment through vibration or other removal mechanisms.
Solution Approach 2:
The detachment process utilizes dynamic vibrations applied to the component to dislodge the shot peen elements. This dynamic approach transforms the static attachment state into a removable state, allowing elements to be easily separated from internal openings after completing their compressive stress induction function.
3Strength
If gamma prime hardened superalloys are used, then component strength is improved, but macro-cracking occurs during stress relief heat treatment
Solution Approach 1:
The shot peen elements are applied to internal surfaces before the stress relief heat treatment process. This preliminary application of compressive stress creates a counteracting force that prevents the development of macro-cracks during subsequent heat treatment, allowing the gamma prime hardened superalloy to maintain its strength while avoiding the harmful cracking effect.
Solution Approach 2:
The shot peen elements provide a cushioning effect by introducing compressive stress that counterbalances the tensile residual stresses that would otherwise develop during heat treatment. This beforehand protection prevents macro-cracking from initiating and propagating in the high-strength gamma prime material during the vulnerable heat treatment phase.
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 method effectively converts tensile surface stresses to compressive stresses within internal openings, preventing macro-cracking and enabling the use of gamma prime hardened superalloys in complex geometries without the limitations of conventional shot peening.
Implementation Method 1
an additively manufactured shot peen element detached from a surface of the internal opening, wherein the additively manufactured shot peen element is shaped to induce a residual compressive stress upon contact with the surface of the internal opening
Implementation Method 2
vibrating the component at a selected frequency, wherein the additively manufactured shot peen element induces the compressive stress against the surface of the internal opening during the vibrating
Data Source
AI summary
The disclosure relates to inducing compressive stress with shot peen elements in an internal opening of an additively manufactured component. Methods according to the disclosure include: receiving a component made by a metal powder additive manufacturing process, the component including a body having an external surface and an internal opening passing at least partially through the body, the internal opening including an additively manufactured shot peen element detached from a surface of the internal opening, wherein the additively manufactured shot peen element is shaped to induce a residual compressive stress upon contact with the surface of the internal opening; and vibrating the component at a selected frequency, wherein the additively manufactured shot peen element induces the compressive stress against the surface of the internal opening during the vibrating.