Research on thermal cycle characteristics and microstructure performance of TC4 laser cladding NiCrCoAlY

Numerical simulation of thermal process of laser cladding NiCrCoAlY coating on TC4 titanium alloy is studied in order to explore the influence of process parameters on thermal cycle characteristics, and laser cladding experiments are tested and verified. The results show that when the laser scanning speed is the same, the greater the laser power, the faster the cooling speed, and they are approximately linear. When the laser power is the same, as the scanning speed increases, the cooling speed increases first and then decreases, and the inflection point appears. As the laser power increases, the cooling speed of the inflection point decreases which corresponding to the scanning speed. The microstructure and properties of the coating obtained by different cooling rate are different. The increase of cooling rate will refine the grains and improve the hardness of the coating, but the excessive cooling rate will lead to defects of the coating. The best process parameters are laser power 600 W, scanning speed 3 mm/s, and suitable cooling speed 820 ℃/s.