Investigation on the effect of laser cladding parameters on the geometrical characteristics and microhardness of 17-4 steel

Laser cladding is one of the advanced surface modification techniques. In this process, a narrow layer of the material was deposited on the surface of the parts. In this research, laser cladding of 17-4 steel was performed by using 316L powder and 400 W pulsed Nd:YAG laser. Laser frequency, pulse width, and scanning speed were considered as the input variables. The geometry of the deposited beads (width, height, and clad angle), dilution ratio, and hardness were considered as the output responses. The effect of input variables on the output responses was investigated and the suitable parameters were selected for laser cladding. The results showed that by increasing the laser frequency and pulse width, the bead height and hardness decreased while the bead width, clad angle, and dilution ratio increased. By increasing the laser scanning speed, the bead height and hardness increased while the bead width, clad angle, and dilution ratio decreased. The laser frequency of 10 Hz, pulse width of 10 ms, and laser scanning speed of 5 mm/s were found to be the suitable parameters over the ranges investigated in this work. The average hardness value of the suitable sample was approximately 590 Hv, about 1.3 times the value of the substrate. The hardness value increased by increasing the distance from the substrate to the clad zone. The hardness value decreased near the clad-substrate interface. This can be attributed to a higher proportion of columnar grains formed near the clad-substrate interface.