Annealing induced recovery of long-term thermal aging embrittlement in a duplex stainless steel

After long-term thermal aging, duplex stainless steel (DSS) components suffer performance degradation and their service life is shortened. Microstructural evolution and mechanical property characterization of the Z3CN20-09M steel, thermally aged at 400 °C for up to 20,000 h and further annealed at 550 °C for 1 h were investigated. Hardening in ferrite is demonstrated to be mostly related to spinodal decomposition, and slightly related to G-phases produced. The spinodal decomposition precipitates dissolved during annealing, leading to the recovery of mechanical property of ferrite. Proper annealing is shown to be a prospective and economic approach to extending the service life of long-term working DSS components.