Mechanical Behavior and Microstructural Change of a High Nitrogen CrMn Austenitic Stainless Steel during Hot Deformation

• Published in: Metallurgical and materials transactions. A, Physical metallurgy and materials science Vol. 41; no. 4; pp. 1025 - 1032
• Main Authors: Wang, Zhenhua, Fu, Wantang, Sun, Shuhua, Li, Hui, Lv, Zhiqing, Zhao, Deli
• Format: Journal Article
• Language: English
• Published: Boston Springer US 01.04.2010; Springer; Springer Nature B.V
• Subjects: Alloys; Applied sciences; Characterization and Evaluation of Materials; Chemistry and Materials Science; Exact sciences and technology; Materials Science; Mechanical properties and methods of testing. Rheology. Fracture mechanics. Tribology; Metallic Materials; Metallurgy; Metals. Metallurgy; Microstructure; Nanotechnology; Stainless steel; Structural Materials; Surfaces and Interfaces; Thin Films; Strain Rate Range; Flow Instability; Deformation Temperature; Strain Gradient; Flow Softening; Hot deformation; Austenitic stainless steel; Austenitic steel; Stainless steel; Mechanical properties; Nitrogen; Microstructure
• ISSN: 1073-5623; 1543-1940
• DOI: 10.1007/s11661-009-0153-2

The hot deformation behavior of a high nitrogen CrMn austenitic stainless steel in the temperature range 1173 to 1473 K (900 to 1200 °C) and strain rate range 0.01 to 10 s −1 was investigated using optical microscopy, stress-strain curve analysis, processing maps, etc . The results showed that the work hardening rate and flow stress decreased with increasing deformation temperature and decreasing strain rate in 18Mn18Cr0.5N steel. The dynamic recrystallization (DRX) grain size decreased with increasing Z value; however, deformation heating has an effect on the DRX grain size under high strain rate conditions. In the processing maps, flow instability was observed at higher strain rate regions (1 to 10 s −1 ) and manifested as flow localization near the grain boundary. Early in the deformation, the flow instability region was at higher temperatures, and then the extent of this unstable region decreased with increasing strain and was restricted to lower temperatures. The hot deformation equation as well as the quantitative dependence of the critical stress for DRX and DRX grain size on Z value was obtained.