Effect of Laser Scanning Speed on Microstructure and Wear Resistance of TiC-TiB2-Reinforced 316L Laser-Clad Coatings

To enhance the wear resistance of laser-clad coatings, this study investigates the underlying modulation mechanisms of scanning speed on the microstructure and properties of TiC-TiB2-reinforced 316L stainless steel composite coatings. TiC/TiB2 particle-reinforced 316L stainless steel composite coatings were fabricated on 45# steel substrates via laser cladding. Our analysis reveals that scanning speed critically governs the thermal cycle of the melt pool, thereby modulating the coating’s microstructure and properties: Lower scanning speeds prolong melt pool duration, consequently intensifying ceramic particle dissolution, coarsening, and tendencies toward agglomeration and settling. Conversely, higher scanning speeds promote rapid solidification, which both preserves ceramic particles and refines the matrix grains. With increasing scanning speed, accelerated melt pool cooling rates drive a microstructural transition from coarse dendrites to refined equiaxed grains, accompanied by dramatically enhanced uniformity in ceramic particle distribution. Coatings deposited at higher scanning speeds exhibit a 22% increase in hardness compared to those at lower speeds. Wear resistance evolution parallels this hardness trend: at 480 mm/min scanning speed, wear reduction can be expected, with the wear volume decreasing by 58.60% and the friction coefficient reducing by 42.1% relative to 120 mm/min.