Abstract：The duplex stainless steels are widely used in the oil and gas industry. When the duplex stainless steel is subjected to a thermal gradient, such as welding and thermal treatment, the precipitation of some intermetallic phases usually occurs. Among these precipitated phases, the σ phase is dominant. Since σ phase is hard and brittle, even a small quantity of σ phase can reduce the mechanical and corrosion resistance properties of material drastically. Therefore, the detection and characterization of σ phase is very important. Based on the composition, structure, morphology, quantity and distribution of σ phase, several characterization methods of σ phase in duplex stainless steel were summarized, including X-ray diffractometry (XRD), scanning electron microscope (SEM), transmission electron microscope (TEM), X-ray energy dispersive spectrometry (EDS), electron backscatter diffraction (EBSD), color metallography, chemical extraction, magnetic measurement and hardness measurement.
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2023, Vol. 41 
