Investigation of powder fed laser cladding of NiCr-chromium carbides single-tracks on titanium aluminide substrate

Abstract

In the present study, a Cr3C2NiCr powder mixture was used to fabricate laser claddings on a titanium aluminide (TiAl) substrate. The effect of processing parameters, such as laser power (P), powder feeding rate (F) and scanning speed (S), were studied on the geometrical properties (height, width, dilution and wetting angle) of single-line claddings and their systematic correlation were predicted using the regression analysis method. The results indicated that the clad height showed a linear dependency on the P1.S−1.F0.85 parameter. Similarly, the width, wetting angle and penetration depth depicted a linear dependency on the P1.S−1.F−0.7, P0.8.S−0.7.F1 and P0.75.S0.5.F−1 parameters, respectively, while the dependency on dilution was S0.8.F−0.8. High values of the correlation coefficient were observed for all empirical dependencies. Finally, a processing window was developed for the laser cladding of the Cr3C2NiCr powder mixture on the TiAl substrate. The microstructure analysis of the optimal cladding showed that the microstructure was covered with different chromium carbides (Cr3C2, Cr7C3 and Cr23C6), together with the Ni(Cr) solid solution. The microhardness of the optimal clad was found to be around 820 HV, which was higher than that of the titanium aluminide substrate (320 HV).