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Microstructural Control Strategy Based on Optimizing Laser Powder Bed Fusion for Different Hastelloy X Powder Size
Jee-Eun Jang1,2, Woosung Kim1, Ji-Hyun Sung1
1Smart Manufacturing Technology R&D Group, Korea Institute of Industrial Technology, Daegu 42994, Korea.
Materials (Basel, Switzerland)
|September 23, 2022
Summary
Controlling powder size in additive manufacturing is crucial for optimizing Laser Powder Bed Fusion (LPBF) of Hastelloy X. Smaller powder sizes require significant adjustments in laser power and scan speed for desired mechanical properties at varying temperatures.
Area of Science:
- Materials Science
- Mechanical Engineering
- Additive Manufacturing
Background:
- Hastelloy X (HX) is a high-temperature alloy difficult to machine due to its hardness and ductility.
- Additive Manufacturing (AM), specifically Laser Powder Bed Fusion (LPBF), offers a viable processing route for HX.
- The interplay between powder characteristics, LPBF parameters, and mechanical properties of HX remains underexplored.
Purpose of the Study:
- To investigate the impact of Hastelloy X powder size on LPBF process parameters and resulting mechanical properties.
- To establish optimal LPBF process windows for different HX powder sizes.
- To compare the microstructure and mechanical performance of as-built LPBF HX with cast HX at room and high temperatures.
Main Methods:
- Comparison of LPBF process maps for two Hastelloy X powders with a 19.7% particle size difference.
- Analysis of optimal laser power, scan speed, and energy density variations.
- Microstructural and mechanical property evaluation (tensile strength) of as-built and cast specimens at room and high temperatures (816 °C).
Main Results:
- A small particle size difference (19.7%) necessitated substantial changes in laser power (>40 W), scan speed (>100 mm/s), and energy density (>20%) for optimal LPBF processing.
- Higher energy density led to larger molten pool sizes and influenced mechanical properties.
- As-built LPBF HX exhibited nano-dendrite structures and higher room-temperature tensile strength compared to cast HX.
- As-built LPBF HX demonstrated superior high-temperature tensile strength due to grain boundary behavior.
Conclusions:
- Powder size is a critical factor influencing LPBF process parameters and the mechanical properties of Hastelloy X.
- Tailoring powder size allows for control over microstructural features and mechanical performance at different temperatures.
- LPBF processing of Hastelloy X yields enhanced tensile strength at both room and high temperatures compared to traditional cast material.
