Effects of Ti addition on microstructure and the associated corrosion behavior of a 22Cr‐5Ni duplex stainless steel

Abstract

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.

A review on pitting corrosion and environmentally assisted cracking on duplex stainless steel

“…However, the pitting potential slightly increased when adding 8.03 wt.% in the solid solution state to duplex stainless steel [63] . Feng et al reported that manganese is detrimental when aging at 800 °C for forming precipitants [64] . Therefore, it can be concluded that manganese increases the number of pit nucleation sites when it exists in the form of precipitants (inclusions or secondary phases).…”