TY - JOUR AU - Botella, J. AU - Almagro, J. AU - Otero, E. AU - Hierro, P. AU - Merino, C. PY - 1998/05/30 Y2 - 2024/03/29 TI - High temperature behaviour of refractory austenitic stainless steels: σ-phase formation and oxidation in air JF - Revista de Metalurgia JA - Rev. metal. VL - 34 IS - Extra SE - Articles DO - 10.3989/revmetalm.1998.v34.iExtra.710 UR - https://revistademetalurgia.revistas.csic.es/index.php/revistademetalurgia/article/view/710 SP - 67-70 AB - Three stainless steels: 25Cr20Ni, 21Cr11Ni<sub>(1)</sub> and 21Cr11Ni<sub>(2)</sub> have been oxidised in air at 1,323 K for 2 h. The three materials form oxide layers 1 to 3 μm thick with MnCr<sub>2</sub>O<sub>4</sub> external crystals and Cr<sub>2</sub>O<sub>3</sub> inner ones. There are a SiO<sub>2</sub> barrier below Cr<sub>2</sub>O<sub>3</sub>, in the oxide-metal interface. SiO<sub>2</sub> also forms intra and intergranular precipitates in the metal, which are specially abundant in 21Cr11Ni materials. The theoretical predictions about σ-phase formation tendencies are confirmed after a treatment at 1,073 K for 400 h: 25Cr20Ni forms 10 % vol. σ-phase, while both 21Cr11Ni form few σ-phase or they do not form it at all. ER -