About this Abstract |
Meeting |
2023 TMS Annual Meeting & Exhibition
|
Symposium
|
Environmentally Assisted Cracking: Theory and Practice
|
Presentation Title |
A Combined Micromechanics/Materials Science Approach to Understanding High Temperature Hydrogen Attack |
Author(s) |
Kshitij Vijayvargia, Mohsen Dadfarnia, Petros Sofronis, Masanobu Kubota, Aleksandar Staykov, Kentarou Wada, John Pugh, Tom Eason |
On-Site Speaker (Planned) |
Kshitij Vijayvargia |
Abstract Scope |
High temperature hydrogen attack (HTHA) is degradation of carbon steels whereby internal hydrogen reacting with carbides forms methane gas bubbles typically on grain boundaries which grow and coalesce, leading to loss of strength and toughness. Current design practice against HTHA is based on Nelson curves which define the conditions for safe operation in a temperature/hydrogen-partial-pressure diagram. Nelson curves are phenomenological and do not account for the underlying failure mechanism(s), microstructure, carbide stability, and applied stresses. To this end, we present a micromechanical model for predicting void growth and coalescence in carbon steels due to methane pressure and external loads. The methane gas pressure was calculated by combining kinetics-based modeling with density functional theory. The effect of hydrogen on the constitutive response was quantified by determining the activation parameters that govern the deformation during HTHA. The micromechanical model is used to construct physically-based Nelson-type curves indicating lifetime under given applied stresses. |
Proceedings Inclusion? |
Planned: |
Keywords |
Modeling and Simulation, Environmental Effects, |