Thermal aging behaviors of duplex stainless steels used in nuclear power plant: A review

Duplex stainless steels (DSS) suffer from thermal aging embrittlement after long-term service in the temperature range of 280-320°C, leading to severe deterioration of mechanical properties and corrosion resistance. It is now well known that the typical microstructural evolutions of the thermally aged DSS are the spinodal decomposition and the G-phase precipitation in ferrite. This review provided a comprehensive analysis of the microstructure, mechanical characteristics, and corrosion resistance of the long-term thermally aged DSS. The principles for how the microstructural evolutions affect the performance of the thermally aged DSS were also highlighted. Some controversial issues such as the formation mechanism of G-phase and its role in the evolutions of material properties were discussed. In addition, a comprehensive review of the recovery behaviors of thermal aging embrittlement was also provided. At last, the limitations of present researches and future research directions of the practical engineering application requirements were summarized.