Texture Evolution Behavior and Its Triggered Mechanical Anisotropy of CP Ti During Severe Cold Rolling and Subsequent Annealing

The texture evolution behavior and its triggered mechanical anisotropy of commercially pure titanium(CP Ti) during severe cold rolling and subsequent annealing are discussed based on the optical microscopy and the electron backscattered diffraction analyses. Some enlightening results are found. It is shown that planar textures exist under all treatments, namely the {11–29}<10–10> under rolling state, the {11–27}<10–10> under 300 °C annealing state and the {11–24}<10–10> under 500 °C annealing state. This indicates that the crystal plane indices of planar texture change toward {-12–10} with increasing annealing temperature, which is a result of crystal lattice rotation. Planar texture triggers anisotropy of the mechanical properties for CP Ti sheets under all treatments. In particular, CP Ti sheets exhibit severe and similar anisotropy behavior under rolling and 300 °C annealing states. Generally speaking, the rolling direction(RD) specimens get relatively low yield strength, high ultimate tensile strength and good plasticity, and RD + 45° specimens show relatively high yield strength, low ultimate tensile strength and good plasticity. The transverse direction specimens, however, usually exhibit high yield strength and low plasticity. It is proved that the above anisotropy behavior is mainly determined by the Schmid factor distribution of the(10–10)[11–20] prismatic slip system in different directions. Due to the non-negligible influence exerted by the(0001)[11–20] basal slip system after 500 °C annealing, the anisotropy behavior under this state is obviously different.

Enhanced localized and uniform corrosion resistances of bulk nanocrystalline 304 stainless steel in high-concentration hydrochloric acid solutions at room temperature

The localized and uniform corrosion resistances of bulk nanocrystalline 304 stainless steel（NC-304 SS）produced by severe rolling technique, and its conventional polycrystalline 304 stainless steel（CC-304 SS）counterpart, were investigated in high-concentration hydrochloric acid solutions at room temperature.NC-304 SS can scarcely suffer from localized corrosion in 4 mol/L and 5 mol/L HCl solutions during 5-day immersion tests, and in 1-3 mol/L HCl solutions during thirty-five-day immersion tests. The corrosion rate of NC-304 SS was also less than that of CC-304 SS during these immersion tests. The improved localized and uniform corrosion resistances of NC-304 SS were explained in terms of the adsorption and chemical activity of Cl;on NC-304 SS and CC-304 SS characterized by X-ray photoelectron spectroscopy,and the valence electron configurations of NC-304 SS and CC-304 SS were characterized by ultra-violet photoelectron spectroscopy rather than conventional electrochemical results.