Preparation, Microstructure Evolution and Performance of Laser-Cladded Titanium Alloy Coating on Mild Steel

Almost all types of steels are vulnerable when serving long-termly in a corrosive marine environment. Coating steels with titanium alloys is an effective way to improve the anti-corrosion performance. Herein, high-performance titanium alloy coatings were successfully prepared from Ti6Al4V powder via a laser cladding technology. The key technological and structural factors were systematically studied and discussed. The correlation between interdiffusion behavior of titanium and iron and microstructure characteristics of the coatings was established. It is demonstrated that the well-controlled heat input and thermal diffusion can ensure the high performance. Due to the effect of thermal diffusion, there exists a critical coating thickness that highly determines the coating structure and performance. Thin coating is mainly composed of Fe-rich intermetallic compounds, leading to defective brittle structure and poor corrosion resistance in 3.5% NaCl solution. While thicker coatings prepared under higher powder feed rate mainly consist of titanium-rich phases, leading to much better corrosion resistance and higher bonding strength. Moreover, owing to the high hardness, the wear loss of a coating is about one-seventh of a Ti6Al4V alloy block in wear tests. The high-performance titanium alloy coating prepared via a low-cost and short-flow laser cladding technology is promising for applications in marine engineering