Microstructure and Properties of Ti6Al4V Surface Processed by Continuous Wave Laser in Different Atmospheres

Abstract

Titanium alloys are considered lightweight alloys and are widely applied across various industries. However, titanium alloys are prone to wearing out or galvanic corrosion. In this paper, Ti6Al4V alloy was scanned by using a continuous laser in different atmospheres to prepare composite hardening coatings. The scanning speed was varied to adjust the heat input. When the alloy was irradiated in air, a whole coating composed of TiO2 and TiN was fabricated. With the increase in scanning speed from 10 mm/s to 20 mm/s, the melting area of the surface decreased from about 1.8 mm to 0 mm, but the thickness of the coatings underwent no significant change. When prepared under compressed oxygen with a speed of 10 mm/s, a coating with a thickness of about 60 μm was prepared. In addition, the layered phenomenon occurred, and an N-enriched layer was formed at the bottom of the coating. The coatings were composed of TiO2, TiN and Ti. With the increase in the scanning speed, the thickness of the coatings decreased obviously. The testing results show that the hardness of samples Ti-A10 and Ti-O10 increased by around 160% and 140% over that of untreated samples, respectively. The anti-corrosion performance of the samples treated via laser scanning was also improved.