Influence of Nanosecond Laser Processing Parameters on the Titanium Alloy Surfaces Colorization

Laser color marking experiments on titanium alloy substrates were carried out to investigate the impact of selected laser processing parameters on the resulting colors. The CIE L*a*b* color space was used to quantify these colors. The surface roughness of the marked color areas was measured by using a TR200 hand-held surface roughness instrument. The relationships between laser parameters and CIE L*a*b* values and surface roughness of the colors were obtained. Results clearly showed that different colors ranging from blue and gray to yellow were produced. Some colors can be obtained by different sets of parameters, while some colors can only be produced by a specific combination of process parameters due to the existence of different forms of heat input and thermal process. The b* value increased to the maximum which represented yellow then decreased. The surface roughness of color areas decreased with the increase of focal plane offset, scanning velocity, or hatch space.