Titanium Rotor Blade Weld Overlay for High-Speed Erosion Resistance
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Conventional erosion shields for steam turbine rotor blades, such as those formed by vapor deposition or surface treatments, lack sufficient thickness and strength to provide both abrasion resistance and reliability, particularly at high peripheral speeds.
Innovation Solution
A steam turbine rotor blade with a weld overlay layer composed of a parent phase of pure titanium or titanium alloy, where chromium is solid-dissolved, and a hard phase of titanium silicide is dispersed, forming a thick and robust erosion shield that enhances both hardness and adhesion, achieved through a manufacturing process involving a mixed powder of parent and inorganic compound particles melted onto the blade surface.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stability of the object's composition
If a titanium-based material is used for the erosion shield to match thermal expansion coefficient, then thermal compatibility is improved, but abrasion resistance deteriorates
Solution Approach 1:
The erosion shield is constructed as a composite material combining a titanium-based alloy matrix (for thermal compatibility) with dispersed hard particles such as chromium carbide, titanium carbide, or boron nitride (for abrasion resistance). This composite structure allows simultaneous achievement of thermal expansion compatibility and enhanced wear resistance that neither material could provide alone.
2Strength
If a hard ceramic coating film is formed by vapor deposition to improve abrasion resistance, then surface hardness is improved, but film thickness is insufficient (several tens of micrometers)
Solution Approach 1:
The coating process parameters are optimized to achieve sufficient film thickness while maintaining hardness. The erosion shield is designed with a minimum thickness of 0.5mm (500 micrometers), which is significantly thicker than conventional vapor deposition coatings (several tens of micrometers). This thickness parameter change ensures both adequate abrasion resistance and structural integrity.
3Productivity
If the steam turbine long blade length is increased to improve efficiency, then energy efficiency is improved, but peripheral speed at tip increases causing severe erosion
Solution Approach 1:
The erosion shield is applied selectively to the tip portion of the rotor blade where erosion occurs most severely due to high peripheral speed. This localized protection allows the blade to maintain its increased length for improved efficiency while the hardened tip surface resists water droplet erosion. The shield may extend partially or fully along the blade length depending on erosion severity.
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 solution provides a steam turbine rotor blade with significantly improved abrasion resistance and reliability, as demonstrated by increased hardness and reduced erosion, with the weld overlay layer thickness exceeding several millimeters and maintaining structural integrity under high-speed conditions.
Implementation Method 1
a step of forming a weld overlay layer by melting a welding raw material powder containing a raw material powder of parent phase particles and a raw material powder of inorganic compound particles by a heat source on the blade base material
Implementation Method 2
a parent phase composed of pure titanium in which a metal element being chromium is solid-dissolved or a titanium alloy in which a metal element being chromium is solid-dissolved
Data Source
Figure 1
Figure 2A~2B
Figure 3
AI summary
A steam turbine rotor blade achieving both abrasion resistance and reliability, and a method for manufacturing a steam turbine rotor blade capable of obtaining such a steam turbine rotor blade are provided. A steam turbine rotor blade according to the invention is characterized by including a blade base material and an erosion shield formed on a surface of the blade base material, wherein the blade base material is composed of a titanium alloy, and the erosion shield is composed of a weld overlay layer including a parent phase (30) composed of pure titanium in which a metal element is solid-dissolved or a titanium alloy in which a metal element is solid-dissolved, and a hard phase (31) dispersed in the parent phase.