Influence of cooling rate on microstructure evolution and pitting corrosion resistance in the simulated heat-affected zone of 2304 duplex stainless steels

Pitting corrosion resistance of 2304 duplex stainless steel heat-affected zone with different cooling rates has been studied by potentiostatic critical pitting temperature (CPT) in 1.0 M NaCl. The results showed that, as cooling rate decreased from 100 to 10 °C/s in the temperature range of 1350–800 °C, the austenite fraction increased from 27.8% to 35.7%, and the CPT value increased from 14 to 19 °C. The morphologies after the CPT tests showed pitting occurred preferentially in the ferrite phase for all specimens. Moreover, relationship between pitting corrosion resistance and microstructure evolution was further discussed.

► Effect of cooling rate on microstructure evolution was studied.
► Effect of cooling rate on pitting corrosion resistance was studied.
► Using CPT to evaluate the pitting corrosion resistance after thermal cycle of welding is studied.
► The weaker region of DSS HAZ was determined, which can be explained by PREN.