Effects of Pulsed Laser Irradiation on Commercially Pure Titanium: Mechanical Properties and Corrosion Resistance in a Salty Environment

Abstract

In this work, the surface oxidation of commercially pure titanium (CP-Ti grade 4) was performed by means of a Nd:YAG in a continuous wave mode in an air environment. The morphology, structure and chemical composition of the formed layers were analyzed by different characterization techniques, such as X‑ray diffraction, scanning electron microscope coupled to an electron microprobe, optical microscopy, and optical profilometry. The diffusion of light atmospheric elements (oxygen and nitrogen) was also investigated. The corrosion resistance of the treated samples was examined in 3.0 wt % NaCl solution using potentiodynamic polarization measurements. The results were compared with those obtained from untreated CP-Ti tested under the same conditions. The analysis indicates that ultra-short pulses (in a nanosecond scale) from a Nd:YAG laser effectively enhanced the corrosion resistance of the studied alloy in 3.0 wt % NaCl (simulated marine environment). An improved corrosion resistance was obtained due to the microstructural changes caused by rapid solidification after laser treatment. A notable enhancement in hardness was reached as well.