| Article ID | Journal | Published Year | Pages | File Type |
|---|---|---|---|---|
| 1469678 | Corrosion Science | 2011 | 9 Pages |
The effects of the annealing temperature on the microstructure and the corrosion behavior of duplex stainless steel 2507 were investigated by means of magnetic force microscopy (MFM), scanning Kelvin probe force microscopy (SKPFM), atomic force microscopy (AFM) and scanning electron microscopy (SEM). The SEM results indicated that the volume fraction of the austenite phase decreased with the increased annealing temperature. SKPFM/MFM measurements conducted in air at the room temperature and an ambient relative humidity of about 25% showed a higher Volta potential of the paramagnetic austenite than that of the ferromagnetic ferrite. The in situ AFM observation in a hydrochloric acid solution provided solid evidence that corrosion preferentially occurred in the ferrite phase. The sample annealed at 1100 °C exhibited a greater Volta potential difference between the ferrite and austenite and a higher corrosion rate in the ferrite, while that annealed at 1150 °C had a smaller Volta potential difference and a lower corrosion rate. The relative nobility and microstructure change of two phases, as well as their corrosion behavior, can be explained by the effect of the composition of alloying elements.
► The volume fraction of austenite in DDS 2507 decreased as annealing temperature increased from 1050 to 1150 °C. ► The paramagnetic austenite showed a nobler Volta potential than ferromagnetic ferrite. ► The Volta potential difference between ferrite and austenite is the largest at 1100 °C and the smallest at 1150 °C. ► The preferential corrosion occurred in the ferrite phase in hydrochloric acid solution. ► The corrosion rate is highest at 1100 °C and lowest at 1150 °C.
