The effects of reversion heat treatment on the recovery of thermal aging embrittlement of CF8M cast stainless steels

Duplex Stainless Steels: Effect of Reversion Heat Treatment

“…Shamanth et al found drastic increase in tensile strength and decrease in ductility due to the embrittlement associated with the formation of α and α′ precipitates in the ferrite phase for the samples aged at 475°C for 1000 h as depicted in the Figure 5 where the mottled contrast in the ferrite matrix at nano-scale indicates the presence of Fe-rich α and Cr-rich α′ precipitates formed by the spinodal decomposition [5]. It is difficult to distinguish between α and α′ precipitate from HR-TEM results even at higher magnifications because both α and α′ precipitate had similar lattice parameter as that of Fe [9]. Also in this investigation they found that the α′ precipitate associated with the coprecipitation of Cr2N precipitates in the ferrite matrix.…”

“…However, it was not completely clear that how these microstructural changes translate on mechanical properties of DSS and vice-versa. In addition, there was a concern that the recovered DSS after the reversion heat treatment could be re-embrittled faster when it is subjected to the service temperature of nuclear power plants [9]. Therefore, understanding the re-aging behaviors of the recovered DSS is also important to determine the applicability of the reversion heat treatment.…”

Evaluation of the thermal aging of δ-ferrite in austenitic stainless steel welds by electrochemical analysis

“…The precipitation of Ni- and Si-rich G-phase and Cr-rich M 23 C 6 carbide is also reported to happen during thermal aging in welds 2 , 3 . The phase separation resists dislocation movement resulting in thermal embrittlement, while G-phase contributes to some extent based on the alloy composition and aging time 9 , 12 – 16 . A reversion heat treatment (R-HT) can be applied to recover the mechanical properties degraded due to phase separation by dissolving it, while the residual intermetallic precipitates are left in the δ-ferrite microstructure 9 , 14 – 16 .…”

Microstructural and Mechanical Characterization of Solidified Austenitic Stainless Steels

“…Among the family of stainless steels, cast austenitic stainless steels (CASSs) are preferably used in in water reactors as joints, primary circuit pipes, elbows, internals and valves due to their high mechanical properties and corrosion resistance [1][2][3][4][5][6]. These steels owe their properties to their microstructural features consisting of an austenitic matrix and δ-ferrite [3][4].…”

“…These steels owe their properties to their microstructural features consisting of an austenitic matrix and δ-ferrite [3][4]. According to the literature, obtaining delta ferrite in solidified structure improves mechanical properties and corrosion resistance and minimizes the occurrence of hot cracks [1][2][3][4]. In most austenitic stainless steels, δ-ferrite forms as primary phase during solidification according to Ferrite-Austenite (FA) solidification sequence specified by Ni/Cr equivalent.…”