Stacking fault energies in austenitic stainless steels

• Published in: Acta materialia 2016-06, Vol.111, p.39-46
• Main Authors: Lu, Jun, Hultman, Lars, Holmström, Erik, Antonsson, Karin H., Grehk, Mikael, Li, Wei, Vitos, Levente, Golpayegani, Ardeshir
• Format: Article
• Language: English
• Subjects: Accurate measurement; Austenite; Austenitic stainless steel; Austenitic stainless steels; Austenitic steel; Beams (radiation); Calculations; Concentration ranges; Dark field; Dark field imaging; Degrees of freedom; Degrees of freedom (mechanics); Density functional theory; Design optimization; Electron microscopy; First-principles calculation; Global energy minima; High resolution transmission electron microscopy; Imaging techniques; Manganese; Materials Engineering; Materialteknik; Mathematical analysis; Plasticity; Spin degrees of freedom; Stacking fault energies; Stacking fault energy; Stacking faults; Stainless steel; Steels; Transmission electron microscopy
• ISSN: 1359-6454; 1873-2453; 1873-2453
• DOI: 10.1016/j.actamat.2016.03.042

We measure the stacking fault energy of a set of 20 at% Cr-austenitic stainless steels by means of transmission electron microscopy using the weak beam dark field imaging technique and the isolated dislocations method. The measurements are analyzed together with first principles calculations. The results show that experiment and theory agree very well for the investigated concentration range of Mn (0–8%) and Ni (11–30%). The calculations show that simultaneous relaxation of atomic and spin degrees of freedom is important in order to find the global energy minimum for these materials. Our results clearly show the great potential of the weak beam dark field technique to obtain accurate measurements of the stacking fault energy of austenitic steels and that the reliable predictability of first principles calculations can be used to design new steels with optimized mechanical properties. [Display omitted]