Investigation of thermal aging damage mechanism of the Cast Duplex Stainless Steel

Thermal ageing on the deformation and fracture mechanisms of a duplex stainless steel by quasi in-situ tensile test under OM and SEM

“…It can be easily imaged that the dislocations can be relatively easy to traverse the δ/γ coherent and semicoherent interface. In addition, It has been verified that the δ/γ angle is inferior to 10°when the δ/γ crystallographic relationship satisfies the Kurdjumov-Sachs (KS) expression: {111} γ //{110} δ and 〈011〉 γ //〈111〉 δ and in this condition, the plastic deformation of the ferrite grain is in agreement with the neighbouring austenite grains [18]. Serre et al have also reported four kinds of slip lines in the ferrite which depend on the matching degree of the δ/γ interface.…”

“…Moreover, besides the mechanical properties, the microstructures in CDSSs greatly affect the plastic deformation behavior. The deformation mode and microstructure evolution in CDSSs have been investigated by some authors by means of various techniques, like SEM, TEM, EBSD and AFM, under tensile loading and the deformation mechanisms are related to the morphology, repartition and texture of each phase [14][15][16][17][18][19]. SEM in-situ observations indicate that slip lines occur in the austenite matrix at first and slip lines in ferrite can be caused by deformation in austenite or the bulk deformation of the ferrite itself [14].…”

“…Researches show that TAE occurs in Z3CN20-09M CDSSs after long term service [4][5][6][7][8]10,[18][19][20]. However, seldom papers focus on the influence of the long thermal ageing time on the deformation behavior and fracture mechanism of Z3CN20-09M CDSSs.…”

Mechanical Properties of a Thermally-aged Cast Duplex Stainless Steel by in Situ Tensile Test at the Service Temperature

“…One use for CDSS is in coolant water pipes in the pressurized water reactor (PWR) which are designed for at least a 40-year service life and to work in service temperatures ranging from 288 • C to 327 • C [4]. Hence, such pipes experience problems of thermal aging embrittlement during service that cause degradation in mechanical properties [5][6][7][8][9][10][11][12][13][14][15]. It has been reported that the thermal aging embrittlement in CDSS was caused by the precipitation that formed in the ferrite phase after long-term thermal aging, e.g., the G-phase precipitates and the spinodal decomposition during which the ferrite phase decomposes into a Fe-rich α-phase and a Cr-rich α'-phase [10,11,[13][14][15].…”

Effect of aging temperature on phase decomposition and mechanical properties in cast duplex stainless steels

“…Previous studies have reported that long-term thermal aging at operating temperature causes hardening, loss of impact toughness, and an increase in ultimate tensile strength (UTS) in these steels [1], [2], [4]- [15].…”