|About this Abstract
||Materials Science & Technology 2019
||Late News Poster Session
||P2-18: Microstructural Evolution of Austenitic Stainless Steel During Nitridation
||Alice M. Young, Milo V. Kral, Catherine M. Bishop
|On-Site Speaker (Planned)
||Alice M. Young
Formation of internal nitrides in steels has been associated with property changes such as loss of hot ductility. In petrochemical plants, where nitridation can occur in austenitic stainless steel piping in service at 800-900 °C, such property changes can lead to unexpected and costly failures. For the widely used Alloy 800H, limited existing information on microstructural evolution during nitridation restricts the ability to predict mechanical behaviour in service.
In this work, an integrated experimental and computational approach was taken. Optical and scanning electron microscopy were used to characterise Alloy 800H samples nitrided at temperatures 800-1000 °C for 50-750 hrs, where aluminium and chromium nitrides were identified. We have shown that classical models for nitride penetration do not match experiments, so a finite-difference model was developed using ThermoCalc and DICTRA to generate theoretical input data. Model predictions of precipitate penetration and matrix composition were then compared to experimental measurements.