Effect of oblique angle on the formability, crystal growth behavior and microstructure in laser direct energy deposited thin-wall structure of single-crystal superalloy
- Resource Type
- article
- Authors
- Zhaoyang Liu; Xiaochu Liu; Tao Zou; Yafei Wang; Jinrui Xiao; Zhongwei Liang
- Source
- Journal of Materials Research and Technology, Vol 29, Iss , Pp 4406-4417 (2024)
- Subject
- Single-crystal superalloy
Crystal growth
Microstructure
Laser direct energy deposition
Mining engineering. Metallurgy
TN1-997
- Language
- English
- ISSN
- 2238-7854
Laser directed energy deposition process shows a tremendous potential to additively repair and manufacture single-crystal components in a near-net shape. For the specific non-vertical structure such as the tilted and torsional sidewalls of single-crystal components, achieving complete monocrystalline nature in the manufactured zone is still a great challenge and hazy. In this study, oblique thin-wall structures of single-crystal superalloy were fabricated by coaxial laser directed energy deposition process. The effect of oblique angle on the formability, crystal growth behavior and microstructure formation in thin-wall structures of single-crystal superalloy was discussed. The results showed that the critical oblique angle for good formability of thin-wall structure is 30°. A poor-quality and shapeless deposited bead forms once the oblique angle researches 40°. The thin-wall structure inherits the [001]/ crystalline orientation from parent single-crystal substrate through the continuous epitaxial growth of ultrafine columnar dendrites. The competition and alternate development of primary trunks-secondary arms-tertiary arms achieve the multiplication and reproduction of ideal columnar dendrites along the [001]/ crystalline orientation in the overhanging region of the thin-wall structure. Periodic segregation forms among the columnar dendrites. Epitaxial-growth continuity of the columnar dendrites with consistent crystalline orientation of substrate can be successfully achieved in large-scale tilted and torsional thin-wall structures of single-crystal superalloy with proper processing parameters. These findings are of great importance in the microstructure control for additively manufacturing complex single-crystal components by laser directed energy deposition process.