Difference between carbon and nitrogen in thermal stability of metastable 18%Cr-8%Ni austenite

• Published in: Scripta materialia Vol. 154; pp. 8 - 11
• Main Authors: Masumura, Takuro, Tsuchiyama, Toshihiro, Takaki, Setsuo, Koyano, Tamotsu, Adachi, Kazuhiko
• Format: Journal Article
• Language: English
• Published: Elsevier Ltd 01.09.2018
• Subjects: Austenitic steels; Martensitic phase transformation; Stainless steels; Thermal stability; Thermodynamics; Thermodynamics; Martensitic phase transformation; Austenitic steels; Stainless steels; Thermal stability
• ISSN: 1359-6462; 1872-8456
• DOI: 10.1016/j.scriptamat.2018.05.019

The effects of carbon and nitrogen addition on the athermal α′-martensitic transformation in metastable 18%Cr-8%Ni austenite are investigated. The thermal stability of austenite in nitrogen-added steel is higher than that in carbon-added steel, and the difference between the effects of carbon and nitrogen addition becomes remarkable as the amount of both elements increases. As the two-step transformation (γ → ε → α′) always occurs in metastable 18%Cr-8%Ni austenite, the suppression of ε-martensite results in the thermal stabilization of austenite. Nitrogen is more effective than carbon for increasing the stacking fault energy, leading to a higher thermal stability of the nitrogen-bearing 18%Cr-8%Ni steels. [Display omitted]