Mechanical and Tribological Performance of a Ni-Based Alloy Coating Deposited by Laser Directed Energy Deposition on Gray Cast Iron Substrate

Gray Cast Iron (GCI) is widely utilized for its favorable balance between cost and performance, particularly in large diesel engine blocks that can be effectively repaired using Laser Cladding (LC) with Ni-based alloys. This study aims to optimize the LC process for depositing Ni-1031 alloy coatings on GCI substrates derived from used diesel engines while investigating the coatings' hardness and tribological performance. A design of experiments methodology was employed to parameterize the laser cladding process, analyzing various parameters including laser power, travel speed, hatch spacing, and layer height during single bead, single layer, and multilayer applications. The adjustments made addressed the challenges posed by the brittle nature of the GCI and its microstructural characteristics. Findings reveal that the coating microstructure exhibited refined dendritic grains, while the hardness surpassed that of GCI attributed to solid-solution strengthening and precipitates enriched with B and Cr. Furthermore, tribological performance assessments indicated that the coated samples demonstrated superior wear resistance due to the lubricating effect of graphite, which contributed to a lower friction coefficient, reduced wear rate, and mitigated wear mechanisms. This research underscores the effectiveness of LC processes in enhancing the durability of critical automotive components.