Effect of solution annealing on the microstructure evolution and corrosion behavior of 2205 duplex stainless steel

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 degrees 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.