Additive manufacturing of metals: a brief review of the characteristic microstructures and properties of steels, Ti-6Al-4V and high-entropy alloys

Abstract

We present a brief review of the microstructures and mechanical properties of selected metallic alloys processed by additive manufacturing (AM). Three different alloys, covering a large range of technology readiness levels, are selected to illustrate particular microstructural features developed by AM and clarify the engineering paradigm relating process–microstructure–property. With Ti-6Al-4V the emphasis is placed on the formation of metallurgical defects and microstructures induced by AM and their role on mechanical properties. The effects of the large in-built dislocation density, surface roughness and build atmosphere on mechanical and damage properties are discussed using steels. The impact of rapid solidification inherent to AM on phase selection is highlighted for high-entropy alloys. Using property maps, published mechanical properties of additive manufactured alloys are graphically summarized and compared to conventionally processed counterparts.

KEYWORDS:

• Additive manufacturing
• 3D printing
• microstructure
• Ti alloys
• steels, high entropy alloys

Classification:

• 10 Engineering and Structural materials
• 106 Metallic materials

Acknowledgements

C.H. greatly acknowledges the support of the Woodside Innovation Centre Director, Professor Nick Birbilis. The help of Drs Sam Gao and Wenwen Sun in obtaining the images shown in Figures 9, 10 and 12 is greatly appreciated. R. B. thanks S.A. Mantri for literature survey and discussion regarding additive manufacturing.