Superalloy Seamless Tube Composition for Corrosion-Resistant Precision Rolling
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Solution Overview
Problem
Current research on iron-nickel-based precipitation hardened and wrought superalloys primarily focuses on physical and chemical properties, with limited industrialized production of seamless tubes, particularly for aerospace engines, where enhanced high-temperature resistance, corrosion resistance, and mechanical strength are required.
Innovation Solution
A superalloy seamless tube composition with specific weight percentages of C, Si, Mn, P, S, Cr, Ni, Al, Ce, Ti, and N, combined with a multi-step heat treatment and cold rolling process, results in a tube with improved intergranular corrosion resistance, high tensile and yield strength, and precise dimensional accuracy and surface quality.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional GH2747 superalloy is used with standard composition, then basic high-temperature strength is achieved, but intergranular corrosion resistance is insufficient and industrialized production of seamless tubes with precise dimensional accuracy is difficult
Solution Approach 1:
The patent modifies the chemical composition parameters of the superalloy by reducing carbon content to 0.01-0.05% (lower than conventional GH2747) and optimizing alloying elements (Ni: 44-46%, Cr: 15-17%, Al: 2.9-3.9%, Ti: 0.1-0.3%, N: 0.03-0.08%). These parameter changes improve intergranular corrosion resistance while maintaining high-temperature strength, enabling successful industrialized production of seamless tubes with precise dimensional accuracy (outer diameter deviation ≤0.05mm, wall thickness deviation ≤0.05mm).
Solution Approach 2:
The patent creates a composite microstructure through controlled precipitation hardening, forming a matrix with gamma prime (γ') precipitates and gamma (γ) solid solution, enhanced by Ti-N carbides and intermetallic compounds. This composite structure at the micro level provides both corrosion resistance and mechanical strength, while the optimized composition enables uniform precipitation distribution that facilitates precise dimensional control during manufacturing.
2Reliability
If carbon content is reduced to improve corrosion resistance, then intergranular corrosion resistance increases, but high-temperature strength may decrease
Solution Approach 1:
The patent reduces carbon content to 0.01-0.05% to eliminate carbon-rich precipitates that cause intergranular corrosion, while compensating for potential strength loss by optimizing nickel (44-46%) and aluminum (2.9-3.9%) content to enhance gamma prime precipitate formation. The addition of titanium (0.1-0.3%) and nitrogen (0.03-0.08%) creates alternative strengthening mechanisms through Ti-N carbides and intermetallic compounds, maintaining high-temperature strength despite low carbon content.
Solution Approach 2:
The patent introduces nickel and aluminum as intermediary elements that form gamma prime (γ') precipitates, which serve as the primary strengthening phase. These precipitates compensate for the reduced carbon content by providing alternative precipitation hardening mechanisms. The titanium-nitrogen combination acts as another intermediary, forming carbides and intermetallic compounds that further contribute to strength while not compromising corrosion resistance.
3Manufacturing precision
If multi-step heat treatment and cold rolling process is implemented to achieve precise dimensional accuracy and surface quality, then manufacturing complexity increases, but production efficiency improves
Solution Approach 1:
The patent divides the manufacturing process into distinct sequential stages: solution treatment (1000-1100°C for 1-4 hours) to dissolve precipitates and homogenize structure, followed by controlled cooling, then cold rolling to achieve precise dimensional accuracy (outer diameter ±0.05mm, wall thickness ±0.05mm), and finally aging treatment (700-750°C for 4-8 hours) to precipitate gamma prime phases for strength. Each stage is optimized independently, making the complex process manageable and repeatable for industrialized production.
Solution Approach 2:
The solution treatment step performs preliminary action by dissolving existing precipitates and homogenizing the alloy structure before cold rolling. This preliminary homogenization ensures uniform material properties throughout the tube, which facilitates subsequent precise dimensional control during cold rolling and prevents defects during aging treatment. The preliminary structure preparation enables the final product to achieve both high precision and high strength.
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 superalloy seamless tube with enhanced high-temperature resistance, oxidation corrosion resistance, high tensile strength, and high yield strength, meeting the mechanical performance requirements for aerospace engines while ensuring good dimensional accuracy and surface quality, facilitating industrialized production.
Implementation Method 1
high-temperature oxidation resistance, and corrosion resistance
Implementation Method 2
subjecting the tube blank to a hot piercing, to obtain a crude tube; subjecting the crude tube to a first solution heat treatment and a cold rolling in sequence
Implementation Method 3
Iron-nickel-based precipitation hardened and wrought superalloys
Data Source
AI summary
A superalloy seamless pipe and a preparation method thereof are provided. The superalloy seamless pipe comprises the following components in percentages by weight: C: 0.01-0.06%, Si: 0.40-1.00%, Mn: 0.30-1.00%, P≤0.025%, S≤0.020%, Cr: 15.00-17.00%, Ni: 44.00-46.00%, Al: 2.90-3.90%, Ce: 0.01-0.03%, Ti: 0.10-0.30%, N: 0.03-0.08%, and the balance of Fe and inevitable impurities.