Tensile Properties of 21-6-9 Austenitic Stainless Steel Built Using Laser Powder-Bed Fusion

Area of Science:

• Materials Science
• Metallurgical Engineering
• Additive Manufacturing

Background:

• Alloy 21-6-9 is a high-strength austenitic stainless steel utilized in aerospace.
• Traditional manufacturing methods have been used for decades.
• Limited research exists on Alloy 21-6-9 produced via laser powder-bed fusion (LPBF).

Purpose of the Study:

• Optimize LPBF process parameters for Alloy 21-6-9 to minimize porosity.
• Investigate mechanical properties and anisotropy of LPBF-manufactured Alloy 21-6-9.
• Evaluate the effect of elevated temperatures on tensile properties.

Main Methods:

• Design of Experiments (DOE) to determine optimal LPBF parameters.
• Building horizontal and vertical samples for mechanical testing.
• Tensile testing at room temperature and 750 °C.

Main Results:

• Optimized LPBF parameters achieved 99.7% relative density.
• Ultimate tensile strength of 825 MPa and elongation of 41% were recorded.
• No significant anisotropic behavior was observed, with consistent properties across orientations and temperatures.

Conclusions:

• Alloy 21-6-9 can be successfully manufactured using LPBF with excellent properties.
• The LPBF process yields a dense material with high strength and ductility.
• The alloy exhibits minimal anisotropy and maintains good tensile properties at elevated temperatures, making it suitable for demanding applications.