Identifying and suppressing Cr3Ni2 σ-phase via transition layer design for reliable titanium–steel bimetal fabrication in laser directed energy deposition
Titanium–steel bimetal combines the low density of titanium and the excellent formability of steel, providing an ideal solution for applications requiring concurrent weight reduction and wear resistance. However, research on high-reliability titanium–steel bimetal fabrication via additive manufactur...
Saved in:
| Main Authors: | , , , , , |
|---|---|
| Format: | Article |
| Language: | English |
| Published: |
Elsevier
2025-08-01
|
| Series: | Materials & Design |
| Subjects: | |
| Online Access: | http://www.sciencedirect.com/science/article/pii/S0264127525006082 |
| Tags: |
Add Tag
No Tags, Be the first to tag this record!
|
| Summary: | Titanium–steel bimetal combines the low density of titanium and the excellent formability of steel, providing an ideal solution for applications requiring concurrent weight reduction and wear resistance. However, research on high-reliability titanium–steel bimetal fabrication via additive manufacturing remains limited. This study achieved crack-free titanium–steel bimetal via laser directed energy deposition using V/Cr/Ni transition layers. A functional bond was established between Ti6Al4V and M50 steel along the path Ti6Al4V/V/Cr/Ni/M50 steel. Crack-free fabrication requires transition layers with a total thickness of 2.5 mm, composed of at least two layers of V, one layer of Cr, and one layer of Ni. A Cr3Ni2 σ-phase was identified in the Cr/Ni transition region, which appears to be the first observation in additive manufacturing and is not documented in existing phase diagrams. The high-hardness Cr3Ni2 σ-phase (1043 HV) may cause stress concentration during mechanical loading. To suppress Cr3Ni2 σ-phase formation, the Ni layer was replaced with Ni–30Cr. This modification eliminated brittle phase generation and induced grain refinement in transition layers, enhancing structural reliability. |
|---|---|
| ISSN: | 0264-1275 |