NiCrAlY/YSZ Double Layer Laser Cladding onto Inconel 713LC Superalloy
A. Khorram and M. Nicknia
Double layer cladding of Inconel 713LC superalloy was carried out using a 700 W pulsed Nd:YAG laser. PAC 131 powder was used as the bond coat and Metco 204NS ceramic powder as the topcoat. The effect of process parameters (laser scanning speed and focal length) was investigated on the crack formation, microstructure, and hardness. The results show that increasing the laser scanning speed leads to crack formation in the samples. Changing the focal point position reduces the dilution ratio and the formation of cracks. The clad zone has a hypereutectic microstructure and is mainly composed of chromium carbides (Cr7C3) surrounded by a eutectic structure (γ + Cr7C3). Samples containing more and coarser Cr7C3 chromium carbides are more prone to the formation and growth of cracks. Increasing the laser scanning speed from 80 to 120 mm/min raises the hardness value of the clad zone from 940 to 1040 Vickers. Another factor that increases the hardness of the clad zone is changing the focal point position. The optimal parameters for the process are as follows: a pulse width of 7.5 ms, a laser frequency of 18 Hz, a laser scanning speed of 120 mm/min, and a focal point position of 4.5 mm. The average hardness in the optimal sample is approximately 1130 Hv, which is approximately 2.6 times the hardness of the substrate.
Keywords: Nd:YAG laser, Inconel 713LC, PAC 131