Titanium Alloy Sintering for Low Oxygen Fatigue Strength
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Solution Overview
Problem
Conventional methods for producing titanium alloy sintered parts face challenges in reducing oxygen content, which affects tensile strength and elongation properties, making it difficult to achieve low oxygen levels below 0.2% by mass and enhance fatigue strength.
Innovation Solution
A method involving metal injection molding, including a mixing process, injection molding, degreasing, and sintering at a controlled temperature of 800 to 995°C for 6 to 200 hours under vacuum conditions, using low-oxygen metal powders to produce titanium alloy sintered parts with reduced oxygen content and enhanced fatigue strength.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If conventional sintering methods are used with metal powder of average particle size less than 25 μm and sintering temperature up to 1100°C for five hours or less under reduced pressure, then production efficiency is improved, but oxygen content cannot be suppressed to 0.2% by mass or less
Solution Approach 1:
The patent changes the sintering parameters by extending the sintering time to 5-200 hours at a lower temperature range of 800-995°C under vacuum conditions (1×10^-3 Pa or less). This parameter transformation allows sufficient time for oxygen diffusion out of the powder particles while maintaining low oxygen pickup from the environment, achieving oxygen content of 0.2% by mass or less
Solution Approach 2:
The patent employs a vacuum environment (1×10^-3 Pa or less) during sintering to create an inert atmosphere that prevents oxygen pickup from the surrounding environment. This inert environment is crucial for maintaining low oxygen content in the sintered part while allowing extended sintering time for oxygen removal from the powder
2Productivity
If sintering is performed at high temperature for short duration to improve productivity, then manufacturing efficiency increases, but fatigue strength cannot be enhanced due to insufficient oxygen removal
Solution Approach 1:
The patent transforms the sintering parameters from high temperature/short time to lower temperature (800-995°C)/extended time (5-200 hours) regime. This allows complete oxygen removal from the powder particles through diffusion, achieving oxygen content of 0.2% by mass or less, which is necessary for high fatigue strength while still maintaining production efficiency
Solution Approach 2:
The extended sintering time of 5-200 hours allows continuous oxygen diffusion and removal from the powder particles throughout the sintering process. This continuous useful action ensures complete oxygen elimination, achieving the low oxygen content needed for high fatigue strength
3Ease of manufacture
If conventional sintering parameters are used to maintain production efficiency, then manufacturing cost is controlled, but tensile strength and elongation properties cannot be optimized
Solution Approach 1:
The patent changes the sintering parameters to extend time (5-200 hours) and control temperature (800-995°C) under vacuum, which achieves oxygen content of 0.2% by mass or less. This results in optimized tensile strength and elongation properties while keeping manufacturing costs controlled through efficient vacuum sintering processes
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 effectively reduces oxygen content to 0.2% or less, achieving high fatigue strength and relative density of 97.0% or more, with a mean grain size of 5.0 to 50.0 μm and an aspect ratio of 3 or less, resulting in a titanium alloy sintered part with improved mechanical properties.
Implementation Method 1
a sintering process of sintering the green part from which the binder is removed to obtain a sintered body; wherein the sintering process is performed at a sintering temperature of 800 to 995° C.
Implementation Method 2
the sintering stage is performed at a sintering temperature up to a maximum of 1100° C. for a sintering time of five hours or less in an atmosphere under a reduced pressure in comparison to normal pressure
Data Source
AI summary
There is provided a titanium alloy sintered part in which the oxygen content is reduced and the fatigue strength is enhanced, and a method for producing the titanium alloy sintered part. The method for producing a titanium alloy sintered part by a metal injection molding method includes a mixing process of producing a compound of a metal powder and a binder, an injection process of subjecting the compound to injection molding to produce a green part, a degreasing process of degreasing the green part to remove the binder, and a sintering process of sintering the green part from which the binder was removed to obtain a sintered body, and the sintering process is performed at a sintering temperature of 800 to 995° C. for a sintering time of 6 to 200 hours.