The effects of solution annealing temperature and isothermal time on the phase composition evolution and corrosion behavior were investigated by employing energy dispersive spectrometry, potentiodynamic polarization measurements, electrochemical impedance spectroscopy, and Mott–Schottky analysis. The pit morphologies were observed by a digital VHX‐5000 with a visible 3D microscopy system. The highest corrosion resistance and most stable passive films were obtained for specimen solution annealing at 1075 °C. Additionally, the solution time had a significant influence on the microstructure evolution and corrosion resistance of the duplex stainless steel. The largest impedance values were exhibited, revealing the best stability with a superior corrosion resistance of the films. The depth and size of pits that occurred on austenite were smaller than those on ferrite. The phase proportion on the microstructure and redistribution of the alloying elements caused by duplex interdiffusion solution annealing simultaneously affected the density of defects and the stability of the passive film, which determined the corrosion resistance. However, the semiconductor properties of the passive films were not affected.

The effects of Ti addition on microstructure and the associated electrochemical properties of 22Cr-5Ni duplex stainless steel were evaluated using X-ray diffraction, X-ray electron probe microanalysis, electron backscattered diffraction, scanning Kelvin probe force microscopy, scanning electron microscopy-energy-dispersive X-ray spectroscopy, electrochemical techniques, and X-ray photoelectron spectroscopy. The results indicated that the addition of a minor amount of Ti refined the grains, improved the pitting potential, and lowered passive current densities remarkably. However, excessive content could cause an imbalance of phase proportion of ferrite and austenite phases and precipitation of the coarse TiN particles. The films on the base and Ti-containing alloy have a similar chemical composition, but the addition of Ti enriched the chromium in the passive film. In particular, the ratio of Cr 2 O 3 and Mo 6+ increased, which helped to form a comparatively homogeneous and stable passive film on the duplex stainless steel.

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