| About this Abstract |
| Meeting |
Materials Science & Technology 2020
|
| Symposium
|
Interfaces and Phase Transformations
|
| Presentation Title |
Phase Transformations in High-Temperature Industrial Applications: An Experimental and Computational Study of Nitridation in Commercial Austenitic Stainless Steel |
| Author(s) |
Alice Young, Milo Kral, Catherine Bishop |
| On-Site Speaker (Planned) |
Alice Young |
| Abstract Scope |
Service conditions in methanol production plants create a driving force for nitrogen uptake in austenitic stainless steel piping, resulting in formation of internal nitrogen-rich precipitates. Such precipitates severely reduce the ductility of the material, increasing the likelihood of unexpected failure. Understanding the factors influencing phase transformation during the nitridation process is a critical first step towards being able to anticipate such failures. In this work, nitridation of the widely used Alloy 800H was studied at service-relevant temperatures 800-1000°C. Both experimental and computational approaches were used. Phase identification and characterisation of precipitate-matrix interface morphology and crystallography was conducted using both scanning and transmission electron microscopy. In conjunction, a finite-difference model for nitridation of 800H was developed. All phase stability and diffusion data was calculated using Thermo-Calc and DICTRA. Experimental observations were used to inform incorporation of key thermodynamic and kinetic factors affecting transformation rates, such as precipitate morphology and nucleation barriers. |