Effects of C and N on high-temperature deformation behavior of 15Cr–15Mn–4Ni austenitic stainless steels

• Published in: Materials science & engineering. A, Structural materials : properties, microstructure and processing Structural materials : properties, microstructure and processing, 2021-07, Vol.819, p.141463, Article 141463
• Main Authors: Cho, Yeonggeun, Gwon, Hojun, Kim, Sung-Joon
• Format: Article
• Language: English
• Subjects: Activation energy; Austenitic stainless steel; Austenitic stainless steels; Carbon steels; Compression tests; Deformation effects; Dynamic recrystallization; Grain boundaries; Grain growth; Grain size; Heat resistant steels; High temperature; High-temperature deformation; Mean flow stress; Solid solutions; Solution strengthening; Stainless steel; Strain rate; Stress concentration; Temperature; Yield strength
• ISSN: 0921-5093; 1873-4936
• DOI: 10.1016/j.msea.2021.141463

The effect of interstitial C and N atoms on high-temperature deformation behavior was investigated in 15Cr–15Mn–4Ni austenitic stainless steels containing 0.1–0.3 wt% of either C or N. Single-hit compression tests were performed in the deformation temperature range 800–1100 °C and the strain rate range 0.01–1 s−1. In both C-added (+C) and N-added (+N) steels, the high-temperature strength, i.e. mean flow stress, increased as the concentration of C or N increased. At the same level of C or N concentration, the mean flow stress, activation energy for high-temperature deformation, and degree of lattice expansion were larger in +N-steels than in +C-steels, whereas the dynamically recrystallized grain size and grain growth rate were larger and faster in +C-steels than in +N-steels. The higher strength of +N-steels over + C-steels at a wide range of temperatures was attributed to the stronger solid solution hardening effect of N atoms compared to C atoms. Dynamic recrystallization was relatively retarded in the +N-steels, because N atoms interacted strongly with grain boundaries. •Direct comparison of C&N on hot deformation behavior in austenitic stainless steels.•Activation energy for hot deformation increased more rapidly by N compared to C.•N addition showed higher strength than C addition.•Grain growth and recrystallization were faster in C-added steels than N-added steels.