Microstructural evolution and coarsening behavior of the precipitates in 2205 duplex stainless steel aged at 850 °C

Abstract

The formation of the secondary phases in the 2205 duplex stainless steel (DSS) influences greatly its mechanical properties. Studies on the microstructural evolution and coarsening behavior of the precipitates in the 2205 DSS have both scientific and technological significance. In the present work, the evolution of the composition and morphology of the precipitates in the 2205 DSS aged at 850 °C for periods up to 200 h are systematically investigated by SEM/EDS (Scanning Electron Microscope/Energy Dispersive Spectrometer) and TEM (Transmission Electron Microscope). In addition, the size statistics for intermetallic precipitates, especially for the σ phase, are carried out based on the SEM images by using deep learning and digital image processing technique. Based on the above, the average interphase energy between the σ and γ phases is reasonably estimated according to the Ostwald coarsening mechanism. This work provides a comprehensive understanding of the microstructural evolution and coarsening behavior of the precipitates in 2205 DSS.