Steam Turbine Cladding Surface Smoothing After Laser Deposition
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Solution Overview
Problem
Conventional methods for producing steam turbine members with cladding layers suffer from surface unevenness, leading to reduced power generation efficiency and increased costs due to the need for post-processing machining to restore the original shape.
Innovation Solution
A method involving laser cladding with powdered materials and subsequent surface heating to a depth of 100 to 200 μm, using a semiconductor laser with a scanning speed of 400 to 600 mm/min, to form a corrosion-resistant cladding layer with a maximum height roughness of 6.3 μm or less, eliminating the need for post-processing machining.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If laser cladding is used to form a cladding layer on a steam turbine blade, then corrosion resistance and abrasion resistance are improved, but surface unevenness occurs due to bead pile-up and material powder remainder
Solution Approach 1:
The patent replaces the conventional mechanical approach (brazing with bent plates) with laser cladding technology. The laser beam melts and fuses cladding material directly onto the blade surface, forming a corrosion-resistant layer without requiring mechanical bending of pre-formed plates. This substitution enables precise control of the cladding process and achieves superior surface quality.
Solution Approach 2:
The patent optimizes multiple parameters of the laser cladding process including laser power, scanning speed, powder feed rate, and focal position to achieve the desired surface smoothness (Ra ≤ 6.3 μm). By carefully controlling these parameters, the process produces a dense, uniform cladding layer with minimal surface irregularities, eliminating the need for post-machining operations.
2Manufacturing precision
If the cladding layer is formed with greater thickness to accommodate post-machining, then surface smoothness can be restored, but the number of processes and cost increase
Solution Approach 1:
The laser cladding process inherently produces a smooth surface finish (Ra ≤ 6.3 μm) through proper parameter control, eliminating the need for separate post-machining operations. The cladding layer self-adjusts to achieve the required surface quality, making the process self-sufficient and reducing overall manufacturing complexity.
Solution Approach 2:
The patent performs surface smoothing during the cladding process itself rather than as a subsequent operation. By optimizing the laser parameters and powder delivery system, the smooth surface is created in advance during cladding, preventing the need for additional machining steps.
3Reliability
If conventional brazing with bent plates is used, then corrosion resistance is improved, but following complicated curved shapes requires technical expertise and quality consistency is difficult to maintain
Solution Approach 1:
The patent replaces the complex mechanical process of bending plates to match blade contours with laser cladding. The laser beam can be precisely positioned and moved along complex three-dimensional surfaces, automatically adapting to any blade geometry without requiring manual plate bending or specialized expertise.
Solution Approach 2:
The laser cladding system employs dynamic control of the laser beam position, scanning speed, and powder delivery to follow complicated blade shapes. The system can rapidly adapt to changing geometries, maintaining consistent cladding quality across complex curved surfaces that would be difficult to achieve with static plate bending methods.
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 produces a steam turbine member with a smooth cladding layer, enhancing power generation efficiency and reducing production costs by eliminating the need for post-processing and excess material usage.
Implementation Method 1
a surface heating step of heat-melting a surface of the cladding layer
Implementation Method 2
heat-melting a surface of the cladding layer
Data Source
AI summary
The present invention provides a method for producing a steam turbine member that is highly superior in smoothness. The present invention provides a method for producing a steam turbine member including a cladding layer forming step of forming a cladding layer from a powdered material containing a metal in a region of a base material in which corrosion easily occurs, and a surface heating step of heat-melting a surface of the cladding layer.