Titanium Alloy Peening and Plating Adhesion
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Solution Overview
Problem
Existing methods for enhancing fatigue and wear resistance in titanium alloy components are incompatible, as heat treatment processes required for improved adhesion of plating materials negate the beneficial residual compressive stresses induced by peening for fatigue resistance.
Innovation Solution
A method involving mechanical working, such as peening, rolling, or burnishing, to establish a residual stress region in titanium alloy components, followed by diffusion of a metallic layer to enhance adhesion and fatigue resistance, while controlling the depth and intensity of the mechanical working to maintain compressive stress and prevent detachment of the plating.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If heat treating is used to improve adhesion between titanium alloy and plating material, then adhesion is improved, but residual compressive stress from peening is relieved and fatigue resistance deteriorates
Solution Approach 1:
The patent applies peening treatment before plating to establish residual compressive stress in the titanium alloy substrate. This preliminary action creates a stress state that improves fatigue resistance before the plating process begins, allowing the beneficial compressive stress to be present during service even after plating is applied.
Solution Approach 2:
The patent creates a gradient in residual stress distribution through controlled peening, where the compressive stress is concentrated in specific regions (particularly at the surface and near-surface zones) rather than being uniformly distributed. This local concentration of compressive stress provides targeted fatigue resistance where it is most needed, while the plating layer provides adhesion and wear resistance.
2Reliability
If peening is used to improve fatigue resistance, then fatigue resistance is improved, but wear resistance deteriorates due to lack of hard plating
Solution Approach 1:
The patent combines two different surface treatment processes - peening and plating - into a single integrated solution. The peening process provides fatigue resistance through residual compressive stress, while the subsequent plating process provides wear resistance through a hard surface layer. By merging these two processes in a specific sequence and with controlled parameters, the patent achieves both fatigue and wear resistance simultaneously.
3Reliability
If mechanical working intensity is increased to improve fatigue resistance, then fatigue resistance is improved, but adhesion of plating deteriorates due to stress relief
Solution Approach 1:
The patent carefully controls the parameters of the peening process, including the intensity, duration, and distribution of mechanical working. By optimizing these parameters, the patent achieves sufficient residual compressive stress for fatigue resistance while avoiding excessive stress that would be relieved during plating heat treatment. The mechanical working is controlled to create an appropriate stress gradient that maintains adhesion.
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 method improves adhesion and fatigue resistance of titanium alloy components by creating a residual stress region that extends through the metallic layer and into the substrate, effectively combining fatigue and wear resistance without compromising the benefits of peening.
Implementation Method 1
diffusion of a metallic layer to enhance adhesion and fatigue resistance
Implementation Method 2
peened to provide a residual compressive surface zone that offsets applied fatigue tensile stresses
Data Source
Figure 1~2
Figure 3~4
AI summary
A method (12) of processing an article includes mechanically working (20) an article having a metallic layer disposed on a titanium substrate and establishing (22) a residual stress region that extends through the metallic layer and at least partially into the titanium substrate.