Effect of Solution Treatment on Microstructure and Mechanical Properties of 2205 Duplex Stainless Steel

Abstract

Duplex stainless steels have dual phase microstructure consisting of approximately equal volume fraction of ferrite and austenite. Volume fraction of phases significantly affects mechanical properties of duplex stainless steels. In the present work, effect of solution treatment temperatures (in the range of 900-1150 °C) on microstructure (phase % of ferrite and austenite) and mechanical properties like tensile (room temperature (RT)) and Charpy impact (RT and-25 °C) of duplex stainless steel, 2205 were investigated. Analysis indicates that with increase in solution treatment temperature, % ferrite phase increases and % austenite phase decreases. 50-50% combination of both phases was obtained around 1020 °C. Tensile test results indicate that yield strength and ultimate tensile strength remains similar for all temperatures. Maximum Charpy strength was obtained at 1050 °C. A sudden drop in charpy strength was observed at 950 °C for both RT and-25 °C tests. Microstructural and SEM analysis reveals the presence of intermetallic phases like sigma (σ) and chi (χ), precipitated at ferrite/ferrite boundary and ferrite/austenite grain boundary which may cause the decrease in impact properties. Index Terms-Duplex stainless steel, chi (χ) and sigma (σ) phase.

Temperature and time effect of thermal aging treatment on microstructure and corrosion resistance of UNS S31803 duplex stainless steel

“…The mechanism of nucleation and growth occurs when the chromium content in the ferrite phase is inferior to 23% (mass) and the thermal treatment of aging is performed above 500°C. For this mechanism, the diffusion occurs with a greater reduction in the Gibbs free energy and phase α' is more roughly formed than in the spinodal decomposition, because of the formation of coherent interfaces (Cavalcanti, Muterlle & Reinke, 2019, Haupt, Silva, Falcade, Santos & Reguly, 2019, Kisasoz, Gurel & Karaaslan, 2016, Mehta, Jadhav, Shaikh, Kumar & Kirwai, 2019, Nithin, Sekar & Joseph, 2019, Ogawa & Osuki, 2020, Powar, Gujar, Manthani, Pawar & Singh, 2017, Valeriano, Correa, Mariano, Robin & Machado, 2019.…”

“…This reaction is started around the grains α/γ or α/α, and the consumption of the ferrite phase grows. Its precipitation occurs by the diffusion of the elements chromium, molybdenum and silicon, and with this, there is the formation of regions poor in these elements, leaving DSS with lower corrosion resistance, besides reducing ductility and toughness (Deng & Zheng, 2019, Dille et al, 2017, Matias, Tavares, Pardal & Ribeiro, 2017, Mehta et al, 2019, Nithin et al, 2019, Ogawa & Osuki, 2020, Xiang, Liu, Silva et al, 2016.…”