Influence of laser scanning speed on the microstructure and wear resistance properties of Inconel 718 coating

Laser process parameters directly impact the quality of cladding, and selecting appropriate parameters can yield optimal microstructure and properties. To enhance the wear resistance of 316L stainless steel, an Inconel 718 coating was applied to the steel surface. The effects of different laser scanning speeds on the structure of the coating were examined. The phase composition, element distribution, microstructure, hardness, and wear resistance of the coating were also analyzed. The results showed that at different laser scanning speeds, the coating phases consisted of γ-(Fe, Ni) solid solution, Ni₃Nb, (Nb_0.03Ti_0.97) Ni₃, and MC_X (M = Cr, Nb, Mo). At scanning speeds of 1.5, 2, and 2.5 mm/s, the average microhardness of the coating was 530.4, 604.6, and 593.2 HV_0.2, and the wear rates were 5.85 × 10⁻⁵, 2.97 × 10⁻⁵, and 8.53 × 10⁻⁵ mm³∙N⁻¹∙m⁻¹, respectively. The coating exhibits the best performance at the laser scanning speed of 2 mm/s. The coating transitions from equiaxed crystals at the upper part to dendritic, cellular, columnar, and planar crystals near the bonding zone. The wear mechanisms observed are abrasive wear and adhesive wear.