| About this Abstract |
| Meeting |
Materials Science & Technology 2020
|
| Symposium
|
Additive Manufacturing of Metals: Complex Microstructures and Architecture Design
|
| Presentation Title |
Fabrication of High Temperature High Strength Austenitic Steels by Laser Powder-bed Fusion |
| Author(s) |
Sebastien Dryepondt, Peeyush Nandwana, Kinga Unocic, Patxi Fernandez-Zelaia, Ying Yang, Yousub Lee, Fred List |
| On-Site Speaker (Planned) |
Sebastien Dryepondt |
| Abstract Scope |
The extremely fast cooling rates during laser powder-bed fusion (LPBF) results in unique microstructural features for austenitic steels such as 316L. For example, the formation of sub-grain cellular structures with high dislocation density leads to superior tensile properties at room temperature with great ductility and yield strength. These cellular structures are, however, only stable at temperatures below ~600ºC for the LPBF 316L steel. One solution to improve the stability of the cells is to pin the cellular walls with fine precipitates. A high temperature Fe-25Cr-20Ni-1.4Nb-0.2C steel (HK30Nb) was fabricated by LPBF. Fine NbC precipitates were found at the cellular walls leading to high yield strength at temperatures up to 900ºC. The creep lifetime of the LPBF HK30Nb steel at 700-800ºC was ~3 times higher than the creep lifetime of cast HK30Nb, highlighting the alloy microstructure stability. The design of advanced high temperature austenitic steels fabricated by LPBF will be discussed. |