Effect of the powder feeding rate on the microstructure and properties of the laser-cladded titanium coating
Wei Gao, Shicheng Wang, Yuxin Tian, Hong‐Yan Lü, Hao Liu, Qi Wang, Hongying Yu, Dongbai Sun
Abstract
Laser cladding was used to deposit thin protective titanium coatings on mild steel substrates. A systematic investigation was conducted to elucidate the influence of varying powder feeding rates on the cladding quality, microstructure evolution, mechanical properties, and corrosion resistance of the coatings. The results indicate that an increase in the powder feeding rate leads to a decrease in the Fe dilution rate and a reduction in the coating cooling rate. This synergistic effect effectively suppresses crack initiation, consequently enhancing the overall cladding quality. The Fe-Ti intermetallic compounds (TiFe and Fe 2 Ti) enriched area within the coatings is the area with poor mechanical properties. Increasing the powder feeding rate to reduce the dilution rate can reduce the thickness of the Fe-Ti intermetallic compounds-rich area and improve the adhesive strength of the coatings. Moreover, the reduction in dilution rate is conducive to enhancing the corrosion resistance of the coatings. At a powder feeding rate of 6 g/min, the coating achieved a dilution rate as low as 3.3% and the lowest corrosion current density (i corr ) of 1.604 × 10 -8 A·cm -2 , with no significant corrosion observed on its surface after 1000 hours salt spray test. However, the decrease in dilution rate is accompanied by a reduction in Fe-Ti intermetallic compounds, slightly diminishing the wear resistance of the coating. Nevertheless, all laser-cladded titanium coatings exhibit superior wear resistance compared to pure titanium.