Pitting Corrosion of Thermally Aged Duplex Stainless Steels at Different Temperature for Long Time

Abstract

The pitting corrosion of three duplex steels (DSS), SAF2205, SAF2507, Z3CN20.09M thermally aged at 350-500 ℃ for 5500 h was investigated by the means of electrochemical techniques. The pitting potential (E p) of thermally aged Z3CN20.09M specimens decreased with increasing of ageing temperature, however, the E p of SAF2205 and SAF2507 thermally aged specimens decreased first and reached the lowest value at 450 ℃ and then increased slightly. The electrochemical impedance spectroscopy results are coincident with the potentiodynamic polarisation testing results. The variation in the charge transfer resistance of specimens coincided with the E p values. There is little influence of low temperature (below 350 ℃) on resistance to pitting of SAF2205 and SAF2507 DSS. But, the pitting resistance of them degrades drastically ageing at higher temperature above 450 ℃. The deterioration in pitting resistance of thermally aged DSS specimens mainly attributes to the precipitation of Cr-rich α′ phases which affected by temperature markedly. At the range of 350-500 ℃, the temperature the higher, the precipitation of Cr-rich α′ phases the more. The formation of G phases and the healing process during the long thermal ageing at 500 ℃ is the other reasons for the change in pitting resistance.

Análise Da Degradação Ferrítica Do Aço Inoxidável Duplex Saf 2205 Submetido a Envelhecimento Isotérmico

“…Seguem os títulos dos resumos que foram premiados: , 2013). Suas maiores aplicações incluem a indústria petroquímica, náutica e nuclear devido sua resistência à corrosão por fadiga e excelentes propriedades mecânicas (WANG et al, 2019).…”

Dilatometric Cycles in the Study of Precipitation of Intermetallic Phases in Duplex Stainless Steels

“…Duplex stainless steels (DSS) are based on Fe-Cr-Ni alloys that show a favorable combination of two phases in equal fractions, namely austenite (γ) and ferrite (δ), with chemical elements called austenitizing (Ni, N, C, Mn, Cu) and ferritizing (Cr, Mo, Si) stabilizers [1][2][3][4] , which, respectively, confer ductility and stress corrosion resistance. In general, carbide precipitation does not occur, due to the very low contents of carbon in DSS.…”