Abstract
This study provides a detailed investigation of the microstructural evolution and stress corrosion cracking (SCC) initiation of Laser Powder Bed Fusion (LPBF) Alloy 625, with a focus on the effects of hot isostatic pressing (HIP). High-resolution electron microscopy, energy-dispersive X-ray spectroscopy (EDS), thermodynamic simulation, slow strain rate tensile (SSRT) and steam oxidation testing were used to assess the relationship between processing, microstructure, and SCC initiation susceptibility. HIP treatment effectively homogenised interdendritic segregation but promoted grain boundary NbC carbides, which oxidised into brittle Nb-oxides after hydrogenated steam exposure. SSRT testing in simulated pressurised water reactor (PWR) conditions (342°C, 30 cc/kg H, 2 ppm Li) showed no intergranular SCC (IGSCC) at 5% strain, whilst some evidence of IGSCC occurred after SSRT to 26% strain. These findings suggest that SCC susceptibility of AM Alloy 625 might be associated with carbide oxidation.
| Original language | English |
|---|---|
| Title of host publication | 22nd International Conference on Environmental Degradation of Materials in Nuclear Power Systems |
| Publication status | Accepted/In press - 6 Aug 2025 |
Keywords
- additive manufacture
- stress corrosion cracking
- SCC
- oxidation
- corrosion
- nuclear
- pressurised water reactor
- PWR
- nickel
- Alloy 625
