About this Abstract |
| Meeting |
2025 AWS Professional Program
|
| Symposium
|
2025 AWS Professional Program
|
| Presentation Title |
Phase Transformations During Cryogenic Cooling of Additively Manufactured 17-4PH Stainless Steel Containing Nitrogen |
| Author(s) |
James Zuback, Virgil Provenzano, Fan Zhang |
| On-Site Speaker (Planned) |
James Zuback |
| Abstract Scope |
Additively manufactured 17-4PH stainless steels with nitrogen mass fractions of approximately 0.1 % retain significant amounts of austenite after solution heat treatments that are intended to produce a fully martensitic material. Interstitial nitrogen reduces the martensite transformation temperature below room temperature, leading to an incomplete transformation. Cooling steels to cryogenic temperatures to transform the remaining austenite to martensite is a common practice, but literature data for low temperature transformations in additively manufactured 17-4PH are scarce. Here, the phase transformations of nitrogen atomized 17-4PH stainless steel during cryogenic cooling are investigated by in-situ synchrotron X-ray diffraction and vibrating sample magnetometry. Alloys with variations in chemical composition are cooled from the as-built and heat-treated conditions to probe the effects of chemistry and austenite stability of phase transformation kinetics. Both the amount and rate of transformation depend on the initial alloy composition and heat treatment condition. It is shown through isochronal cooling experiments that martensite forms in a specific temperature range and the transformation depends on the rate of cooling through this range. Further, the transformation mechanism in the additively manufactured materials is shown to be partially isothermal, as opposed to the dominant athermal mechanism commonly observed in wrought 17-4PH. |
| Proceedings Inclusion? |
Undecided |