Laser Marking and Coloration of Ti-6Al-4V with Ultra-Short Pulses

Abstract

A routine for color marking using oxide layers and laser induced periodic surface structures is presented. Titanium and alloys thereof are marked with pixelated graphics at high resolution and tempering colors. A computational approach for the laser path calculation enables a fast-forward marking of complex designs. A color map attained from laser parameter studies enables vivid coloration. The minimal color pixel size is given by the optical setup and laser wavelength at near infrared and green radiation utilized. A pixel size of 35μm and 20μm was used within this study and no cross talk and distinctness between adjacent colors observed. Additionally, ultra-short pulsed laser systems enable the generation of laser induced periodic surface structures. These are dependent on the polarization direction and diffraction gratings with rotated spatial periodicity are generated. This allows forgery-proof marking strategies and both mechanism can be superimposed.