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

Abstract

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 NbC powder as a ller metal using multiple laser deposition steps. The effect of the studied parameters on the geometry, surface appearance, dilution, and macrostructural features were evaluated. The laser power, deposition speed, and powder ux were altered, while the other parameters were kept constant. Increases in power and scanning speed resulted in increased dilution region, whereas the coating material rising led to decreased dilution. The welding speed and the powder ow strongly in uence 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 ow in the deposit is governed by the Marangoni effect, which in the case of the laser process presents a single upward ow 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 signi cant agitation produced by the NbC. The porosities are associated with the particles' dragging of gas towards the pool and NbC precipitate dissolution. IntroductionComponents and equipment need to be reliable and suitable for their applications in face of severe environmental conditions, such as elevated temperatures and pressures, corrosive atmosphere, and high mechanical loads [1, 2] Rigorous procedures and materials are selected in many situations in order to maintain safety and reliability during the operations [3, 4]. In this context, the development of material and the optimization process are required to achieve a such high demanding application.Concerning the increasing demand for the materials and the necessity of reducing the costs from industry, it's frequently unsuitable to use unique material to accomplish all the requirements. Thus, an application of a higher performance coating, as those applied by laser cladding, could be a solution for these demands [5, 6]. Laser cladding creates a metallurgical bonding with substrate and, compared to conventional coating processes, produces low porosity, minimal dilution, little distortion of the base metal, and a small heat affected zone [7][8][9][10][11].The coating, compared with the substrate material, should present some improved features, which allow complementing the properties of the substrate, forming combined and synergetic properties that, together, present greater performance against different mechanical and environmental stresses [5,12]. Many studies with the employment of composite coatings have been conducted [13][14][15][16][17], which the abrasive wear, highly re...