Abstract
In this present study, the influence of isothermal aging temperature and duration on microstructural and mechanical properties of a hot-deformed UNS S32750 super duplex stainless steel (SDSS) alloy was investigated by SEM-EBSD (scanning electron microscopy-electron backscatter diffraction) and tensile testing techniques. An isothermal aging treatment, at temperatures between 400 and 600 °C and treatment duration between 3 and 120 h, was applied to a commercial UNS S32750 SDSS alloy. Microstructural characteristics of all thermomechanical (TM) processed states, such as distribution and morphology of constituent phases, grain’s modal orientation (MO), and obtained mechanical properties were analysed correlated with the TM processing conditions. The obtained experimental results show that the constituent phases, in all TM processed states, are represented by elongated γ-phase grains within the δ-phase matrix. The R-phase was observed in the case of aging treatment performed at 600 °C for 120 h. Within the δ-phase matrix, dynamically recrystallized grains were identified as a result of applying hot deformation and isothermal aging treatments. Also, it was observed that aging treatment parameters can significantly influence the mechanical behaviour exhibited by the UNS S32750 SDSS alloy, in terms of elongation to fracture and absorbed energy during impact testing.
Highlights
Super duplex stainless steels (SDSSs) are a special class of stainless steels, consisting of ferrite (δ-phase) and austenite (γ-phase), based on the iron-chromium-nickel (Fe-Cr-Ni) system.Generally, these materials contain approximately equal proportions of ferrite (δ-phase) and austenite (γ-phase) phases in their microstructure, with ferrite (δ) comprising the matrix [1,2,3]
One can observe that the phases were asS32750 follows: δ-phase in the as-received (AR)γ-phase state
One can observe that the γ-phase presents an an islands-like morphology within the δ-phase matrix
Summary
Super duplex stainless steels (SDSSs) are a special class of stainless steels, consisting of ferrite (δ-phase) and austenite (γ-phase), based on the iron-chromium-nickel (Fe-Cr-Ni) system These materials contain approximately equal proportions of ferrite (δ-phase) and austenite (γ-phase) phases in their microstructure, with ferrite (δ) comprising the matrix [1,2,3]. Metals 2020, 10, 353 in hot chlorine solutions [4,5,6] The alloying elements, such as Cr, Mo, Ni, and N, must be dissolved in the ferrite (δ-phase) and austenite (γ-phase) phases in order not to induce precipitation of deleterious secondary phases (i.e., carbides, nitrides, and intermetallic phases), owing to their negative effects on corrosion resistance, as well as on ductility, strength properties, and toughness [7,8]
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Free) 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
