Modulation and scanning-frequency effects in laser cladding process

摘要

Abstract: In the present work, the results of laser cladding by galvano scanning and modulated beam using the CO2 and Nd-YAG lasers are presented. The results are compared with the stationary beam. It is realized that the scanning frequency as well as the modulation effects were found to have significant effects on solidification and microstructural development process. The results indicate that the dendrite structure shall be fine at higher frequency or low duty modulation condition, compared to the coarse structure at lower frequency or high duty modulation condition. A shallow bead width as wide as 10 mm was obtained in a single pass. Macro- and micro- crossection, EPMA and microhardness profile have been employed to characterize the cladding. The results are correlated with the cladding quality. Microstructure, hardness, dilution etc. are discussed as a function of the processing parameter. Because of the high solidification rate a fine dendrite structure is developed in the cladding zone. A few of the actual results and EPMA analysis of the laser cladding of stellite 6 on 12 Cr-Ni turbine blade as shown in the figure are presented.!12