Investigating the effect of laser cladding parameters on the microstructure, geometry and temperature changes of Inconel 718 superalloy using the numerical and experimental procedures

چکیده مقاله

In this paper, a novel numerical model was used to simulate the laser cladding process using the finite element technique in order to assess the influence of scanning rate and laser power on the microstructure, geometry and temperature changes of Inconel 718. The laser cladding process was also performed experimentally to show the capability of the applied model for prediction of the results. The results showed that a maximum temperature of 2942 °C was obtained at the end of cladding layer for scanning rate of 4 mm/s and laser power of 250 W. With the increase of scanning rate and the decrease of laser power the height and length of cladded sample decreased, because the heat transfer to the sample was faster than its temperature rise. The microstructure analysis demonstrated that a columnar grain structure was formed when the scanning rate and laser power reached to 4 mm/s and 200 W respectively, due to the increase of cooling rate. However, the increase of laser power up to 250 W led to formation of an equiaxed microstructure, which was owing to the reduction of thermal gradient and consequently the reduction of G/R ratio. An elevation of the laser power from 200 to 250 W resulted in a reduction in the cooling rate and thus an increase in the primary and secondary dendrite arm spacings by about 27 % and 31.5 % respectively. Moreover, a rise of scanning rate from 4 to 5 mm/s led to a decrease in the primary and secondary dendrite arm spacings by about 14 % and 17 % respectively.