Titanium Alloy AM Powder Composition to Avoid HIP for Fatigue Strength
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Solution Overview
Problem
Titanium alloy additive manufacturing products made using gas atomized powder exhibit low fatigue strength due to internal defects, and while HIP treatment can improve this, it is costly and not always feasible.
Innovation Solution
Developing a titanium alloy additive manufacturing product with a composition of 5.50 to 6.75 wt% Al, 3.50 to 4.50 wt% V, and minimal impurities, produced using a rotating electrode method to minimize pore content and particle size, thereby enhancing tensile and fatigue strength without requiring HIP treatment.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If gas atomized powder is used as raw material for additive manufacturing, then the manufacturing process is simple and cost-effective, but the fatigue strength is low due to internal pores and defects
Solution Approach 1:
The invention changes the particle size parameter of the raw material powder to 250 μm or less, which fundamentally alters the powder characteristics and enables production of additive manufacturing products with 500 MPa or higher fatigue strength without HIP treatment, resolving the contradiction between manufacturing simplicity and fatigue strength
Solution Approach 2:
The invention takes preliminary action by controlling and minimizing pore content in the raw material powder before the additive manufacturing process, thereby preventing the formation of defects that would otherwise reduce fatigue strength, achieving high reliability without requiring subsequent HIP treatment
2Reliability
If HIP treatment is applied to improve fatigue strength, then the fatigue strength increases to 600 MPa, but the treatment cost and process complexity increase significantly
Solution Approach 1:
The invention performs preliminary action by producing raw material powder with 250 μm or less particle size and controlled pore content before additive manufacturing, which pre-prevents defect formation and eliminates the need for subsequent HIP treatment, achieving high fatigue strength with simpler processes
Solution Approach 2:
The invention replaces the expensive and complex HIP treatment process with a simpler approach using finely controlled raw material powder (250 μm or less), achieving comparable or superior fatigue strength without requiring additional expensive equipment and processing steps
3Productivity
If larger powder particle size is used, then the powder production efficiency increases, but the pore volume ratio and argon gas content in particles increase, reducing fatigue strength
Solution Approach 1:
The invention optimizes the particle size parameter to 250 μm or less, which balances powder production efficiency with fatigue strength requirements, achieving the desired contradiction resolution by finding the optimal parameter value that satisfies both productivity and reliability
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 achieves a tensile strength comparable to or exceeding that of HIP-treated materials and a fatigue strength of 80% or more of HIP-treated materials, while reducing production costs by eliminating the need for HIP treatment.
Implementation Method 1
a metal powder obtained by a gas atomization method (hereinafter, referred to as a gas atomized powder)
Implementation Method 2
irradiating the metal powder with a laser or an electron beam, and heating, dissolving, and solidifying only a specific part
Implementation Method 3
the fatigue strength (107 cycles) is improved and increased up to 600 MPa by subjecting such a material as additive manufactured (as built) to a HIP treatment
Data Source
AI summary
A titanium alloy additive manufacturing product contains 5.50 to 6.75 wt % of Al, 3.50 to 4.50 wt % of V, 0.20 wt % or less of O, 0.40 wt % or less of Fe, 0.015 wt % or less of H, 0.08 wt % or less of C, 0.05 wt % or less of N, and inevitable impurities, in which a pore content is 0.05 number/mm2 or less, and a tensile strength is 855 MPa or more.