Dependency of Portevin-LeChatelier Effect and Microstructure Characteristics of 9Cr ODS Steels on Strain Rates Upon Hot Deformation

• Published in: Metals and materials international Vol. 30; no. 1; pp. 182 - 193
• Main Authors: Zhou, Xiaosheng, Zhang, Yaran, Li, Yanmo, Yuan, Meini, Li, Guodong, Chen, ZhenYa, Zhang, Huang
• Format: Journal Article
• Language: English
• Published: Seoul The Korean Institute of Metals and Materials 2024; Springer Nature B.V; 대한금속·재료학회
• Subjects: Alloying elements; Austenite; Characterization and Evaluation of Materials; Chemistry and Materials Science; Deformation; Deformation effects; Dispersion hardening alloys; Dispersion hardening steels; Engineering Thermodynamics; Heat and Mass Transfer; Heat treating; Machines; Magnetic Materials; Magnetism; Manufacturing; Martensite; Martensitic transformations; Materials Science; Metallic Materials; Microstructure; Oxide dispersion strengthening; Processes; Serrated yielding; Solid Mechanics; Strain rate; Yield strength; 재료공학; Portevin-LeChatelier effect; Oxide nanoparticles; Oxide deformation; Texture; Element distribution
• ISSN: 1598-9623; 2005-4149
• DOI: 10.1007/s12540-023-01482-y

The flow stress and microstructure evolution of 9Cr oxide dispersion strengthened (ODS) steels were investigated by isothermal compression at 1000–1150 o C with strain rates from 0.001 to 1 s − 1 . Microstructure characteristics of ODS steels under various condition were studied using the EBSD and TEM techniques. At each deformation temperature, PortevinLe--Chatelier (PLC) effect characteristics of repeated serrated stress was observed, as the strain rates were 0.01, 0.1 and 1 s − 1 . The serrations fluctuated about the mean flow curve in quick succession, and the critical strain for the PLC effect was related to both the deformation temperature and strain rates. The stress drops at strain rates of 0.01 and 0.1 s − 1 were smaller than those at 1 s − 1 . The strain rate affected the dynamic recovery and recrystallization of austenite grains, as well as the texture components of martensite transformed from austenite. Cap-shaped oxide particles in as-fabricated and hot deformed steels were characterized in detail. The cap parts of cap-shaped oxide particles were depleted of alloying elements, and the caps were crystal or amorphous. Large-sized oxide particles were easier to be deformed than small-sized ones. Despite of the oxide deformation, the PLC effect was still suggested to be related to the solute-dislocation interaction. Graphical Abstract