| About this Abstract |
| Meeting |
2025 TMS Annual Meeting & Exhibition
|
| Symposium
|
High Performance Steels
|
| Presentation Title |
Dynamic Interplay of Sub-Grain Coarsening and M23C6 Precipitate Growth: Implications on Creep Behavior in Ferritic Martensitic Steels |
| Author(s) |
Amey Parnaik, Pavan A. H. V., Lakshmi Narayan Ramasubramanian |
| On-Site Speaker (Planned) |
Amey Parnaik |
| Abstract Scope |
The study examines the impact of secondary austenitization and tempering (HT condition) on the creep performance of modified 9Cr-1Mo (Grade 91) steel at 550°C, 600°C, and 650°C under stresses of 80 to 260 MPa. HT treatment generally increases creep rupture life by 2 to 10 times, depending on test conditions. Post-mortem analyses reveal mild coarsening of prior austenitic grains, slow coarsening kinetics of sub-grains and M23C6 precipitates, higher matrix dislocation density, and increased solute carbon, resulting in greater martensite tetragonality in HT compared to as-received (AR) condition. The interplay between pinning pressures from M23C6 carbides and sub-grain coarsening forces shows higher pinning pressure in HT, hindering sub-grain boundary migration. Additionally, higher solute carbon in HT reduces free dislocation motion during creep, slowing dislocation annihilation at sub-grain boundaries. These factors lead to slower damage accumulation and significantly extended creep rupture life in HT condition compared to AR condition. |
| Proceedings Inclusion? |
Planned: |
| Keywords |
Iron and Steel, Nuclear Materials, Mechanical Properties |