The Effect of Ferrite Embrittlement in Duplex Steel on Fatigue Crack Propagation from the Low (LCF) to the Very High Cycle Fatigue (VHCF) Regime

The excellent combination of mechanical properties and corrosion resistance of duplex stainless steel is obtained from balanced amount of ferrite and austenite in the microstructure. However, this grade of steel embrittles when exposed in the temperature range of 280–500ºC limiting its application to temperatures below 280ºC. To study the effect of embrittlemnt on fatigue behavior at high strain ranges, plastic-strain- controlled LCF test and at low strain ranges, stress-controlled HCF/VHCF tests were conducted on 1.4462 duplex steel and accompanied by SEM analysis in combination with EBSD. Extensive TEM was done to study the micromechanism of fatigue crack initiation and propagation across the strain ranges.