Effect of Solution Annealing Temperature on Pitting Behavior of Duplex Stainless Steel 2204 in Chloride Solutions

The effect of solution annealing temperature ranging from 950 to 1 200 ℃ on the microstructure and corro-sion performance of duplex stainless steel (DSS)2204 were investigated.The proportion of the ferrite phase in-creased while the austenite phase decreased and the ferrite stabilizing elements diluted in the ferrite phase with the in-crease of annealing temperature.The critical pitting temperature (CPT)of specimens annealed at 1 000 ℃ was higher than those annealed at 950 ℃,whereas further increasing the annealing temperature to 1 200 ℃ decreased the CPT. The pitting initiation sites were observed in the austenite phase,at the boundary of ferrite/austenite phase and inside the ferrite phase for specimens annealed at 950,1 000 ℃ and exceeding 1 100 ℃,respectively.The evolution trend of the CPT and the pit initiation site were analyzed by the pitting resistance equivalent number.