The Effects of 475 °C Embrittlement on the Mechanical Behavior of Thermally Aged 2507 and 2101 Duplex Stainless Steel Alloys

In the present work, the effects of 475 degrees C embrittlement on the tensile response of two different duplex stainless steel alloys namely 2507 SDSS and 2101 LDX aged for different times at a temperature of 475 degrees C were investigated. For this, a power law such as Hollomon's equation was applied in the plastic zone to model the true stress-strain behavior. Additionally, a difference approximation was conducted on the experimental data to obtain the strain hardening rate of the different aged specimens. The Hollomon's analysis of the experimental data shows that the 210 LDX alloy requires up to three sets of hardening exponents n and constants K to fit the model to the experimental data in the plastic region of stress-strain curves. Contrarily, the alloy 2057 SDSS exhibits a hardening transition from three to one set of n and K fitting constants as the aging time increases. Also, the strain hardening rate of the 2507 SDSS is higher than that of the 2101 LDX. SEM and EDX mapping of the microstructure indicated that in the holding time range between 100 and 1000 h, the 2507 SDSS showed the presence of precipitated particles characteristic of the G-phase whereas in the 2101 LDX no G-phase was observed in the same time range. EBSD analysis of grain material misorientation shows that the austenite phase shows higher elastic strains than the ferrite phase whereas the ferrite phase displays higher kernel average misorientation.