Characterisation of duplex stainless steel subjected to long-term annealing in the sigma phase formation temperature range by the DLEPR test

The effects of long-term thermal annealing (15,000 h) between 630 and 800 °C on the duplex stainless steel (DSS) 7MoPLUS are investigated by using the double loop electrochemical potentiodynamic reactivation (DLEPR) test. The morphology of the sigma phase exerts a bigger influence on the corrosion resistance than does its composition. No healing has been observed in present DSS, although it has been found in the lean DSS 2101 by other researchers. The healing mechanism in the sigma-phase formation range has been discussed and the reason for the absence of healing in the present steel has been suggested.

► Long-term DLEPR data on duplex stainless steel.
► Morphology of the sigma phase exerts a bigger influence on the DLEPR test than does its composition.
► Effect of long-term annealing on healing has been investigated.