Abstract
Laser powder bed fusion additive manufacturing (LPBF-AM) of a low-alloy, high-performance AF-9628 steel results in exceptionally high strength and good ductility. The reasons for such mechanical properties are investigated through detailed microscopy performed at several length scales. Thus, the characterization of melt pool, porosity, grain morphology, phases, and dislocations is performed in the as-printed material. The as-printed material consists of only 0.004 vol% of uniformly distributed porosity, single-phase martensitic laths with an average lath size of ≈2.5 μm, the absence of carbides indicating interstitial trapping of C atom, and high dislocation density in the martensitic laths. Experimental data through microscopy are then fed in analytical models for calculating strengthening contributions from various strengthening mechanisms. Calculated yield strength agrees well with experimentally determined value, and therefore, activation of various strengthening mechanisms is established in as-printed AF-9628.
| Original language | English |
|---|---|
| Article number | 2000845 |
| Journal | Advanced Engineering Materials |
| Volume | 23 |
| Issue number | 1 |
| DOIs | |
| State | Published - Jan 2021 |
| Externally published | Yes |
Funding
This study was performed under a cooperation agreement between the Army Research Laboratory and the University of North Texas (W911NF1920011). The authors thank the Materials Research Facility (MRF) at the University of North Texas for access to the microscopy facilities.
Keywords
- X-ray microscopy
- additive manufacturing
- high-strength steels
- mechanical properties
- microstructures
- strengthening mechanisms
