Effect of Laser Cladding Process Parameters on Crack Rate and Wear Performance of Gray Cast Iron Substrate Coatings

This study investigated the deposition of Fe-Cr-Ni-B-Si iron-based alloy powder onto gray cast iron substrates. Four process parameters—laser power (2300-3300 W), scanning speed (20-30 mm/s), powder feed rate (21.6-29.6 g/min), and overlap ratio (40-60%)—were systematically varied to evaluate their effects on crack susceptibility, coating thickness, interfacial metallurgical quality, and friction-wear performance. Contrary to conventional expectations, the transition zone width decreased from 42.2 to 12.7 μm with increasing laser power, attributed to Marangoni convection reversal and graphite flake dissolution. Results indicated that laser power and overlap ratio predominantly controlled coating thickness, while powder feed rate linearly regulated deposition volume. The parameter combination of 2300 W, 20 mm/s, 25.6 g/min, and 60% overlap yielded optimal performance: 1161 μm coating thickness without through-thickness cracks, a friction coefficient of 0.3 (closest to the substrate), and wear mass loss of only 0.3 mg (95% reduction), resulting from an optimized dual-phase microstructure of 65.3% martensite and 34.7% austenite. Conversely, excessive laser power (3300 W) induced severe cracking due to steep elemental gradients and residual stress concentration, while excessive scanning speed (30 mm/s) caused single-phase martensite embrittlement and dendritic segregation. This process optimization system balances crack resistance, coating thickness, and tribological properties, providing a feasible technical solution for green remanufacturing of brake drums.