Effect of laser cladding parameters in NbC reinforced 316L austenitic stainless steel composite depositions on a mild steel

The cladding process aims to improve mechanical, chemical, and physical features in metal surfaces. The laser cladding process is frequently used to promote such alterations through deposition of metals/alloys with superior mechanical behavior on the substrate. In this contribution, an ASTM A36 mild steel was covered with AISI 316L reinforced with niobium carbide (NbC) powder as a filler metal using multiple laser deposition steps. The effect of the studied parameters on the geometry, surface appearance, dilution, and macrostructural features was evaluated. The laser power, scanning speed, and powder mixing ratios were altered, while the other parameters were kept constant. Increases in power and scanning speed resulted in increased dilution region, whereas the coating reinforcement material rising led to decreased dilution. The scanning speed and the powder flow strongly influence the penetration in the bead-on-plate deposits. This behavior was attributed to the beam's interaction with the substrate due to the named shadow effect. The metal flow in the deposit is governed by the Marangoni effect, which in the case of the laser process presents a single upward flow direction in the center and descending from the surface and the sides, which determines the location of the particles and pores when used 10% of NbC reinforcing particles. For 30% NbC, particle distribution and porosities are homogeneous inside the pool, due to the more significant agitation produced by the NbC. The porosities are associated with the particles' dragging of gas towards the pool and NbC precipitate dissolution.