The aim of this work is to evaluate the microstructural evolutions developed by mixing a corrosion-resistant and high-performance material with a high-hardness material in a coating obtained by laser-cladding technology. In this paper, five different mixtures of Inconel 625 alloy and AISI H13 steel powders have been deposited on a plate of 42CrMo4 steel using a 2.2 kW diode pumped Nd:YAG laser. The effect of adding tool steel to a Ni-based superalloy has been analyzed by the characterization of each cladded sample using optical microscopy and scanning electron microscopy (SEM). The precipitates observed in the samples have been analyzed by energy dispersive X-ray spectroscopy (EDS X-ray). SEM micrographs and EDS analysis indicate the existence of Laves phase. It has been observed that the presence of these precipitates is stabilized in a certain range of AISI H13 addition.

Copper is widely used in many industrial applications although its poor mechanical properties limit its use. Nevertheless, nickel-based alloys offer high wear resistance that applied on copper as surface coating could overcome this lack. The direct application of coatings with laser technologies on a copper substrate presents difficulties due to the poor absorption of this metal in the usual wavelengths of lasers, and this study is focused precisely on solving them. The results of the two-step laser cladding of Inconel 625 on the copper substrate are analyzed in terms of microstructure, chemical analysis, and hardness. Moreover, the metallurgical bonding of (Cu and Ni) solid solution between the direct laser cladding coating of the Ni alloy and copper is studied as well as the absence of interfacial cracks and pores under specific process parameters. This bond is assured by the high dilution and the presence of 27 wt. % of copper. The second functional Inconel 625 layer shows a dendritic microstructure with a γ-Ni matrix and Mo- and Nb-rich precipitates in the interdendritic regions with no trace of copper.

Most high-hardness tool steels comprising forming dies require expensive finish machining operations to compensate for the dimensional distortion and surface oxidation caused by the die heat treatment. Precipitation-hardening (PH) tool steels allow for soft finish machining followed by an aging treatment without major deformation or oxidation in the die, but exhibit poor wear performance owing to the lack of carbides in their structure. This drawback can be overcome by combining laser cladding technology, austenite retention, and cryogenic treatments. Hence, an alternative die manufacturing route based on laser cladding was explored. The forming surface of a modified chemistry tool steel die was subjected to cladding. The martensite finish (M_f) temperature of the steel was tuned to enhance austenite retention at room temperature. The cladded surface was then machined in a reduced-hardness condition resulting from retained austenite formation. Subsequent deep cryogenic treatment of the die favoured the retained-austenite-to-martensite transformation, thereby increasing the die hardness without major distortion or oxidation. This process combined the advantages of high-carbide-bearing tool steels and PH steels, allowing for a die with hardness exceeding 58 HRC to be finish machined at <52 HRC. Controlling the occurrence of retained austenite represents an effective strategy for achieving new manufacturing scenarios.

El objetivo de este trabajo es investigar nuevas soluciones basadas en laser cladding (aporte con láser) también llamado LMD (laser metal deposition) para el recubrimiento de discos de freno de futura generación. La aplicación de estas capas está orientada a la minimización del volumen de emisiones de partículas respirables < 10 µm a la atmósfera durante la frenada, a través de la mejora de la respuesta a la abrasión y corrosión de materiales de acero inoxidable aportados frente a la base de fundición gris laminar. El trabajo muestra resultados del proceso de laser cladding de materiales inoxidables aportados sobre fundiciones grises de alto y bajo contenido de carbono utilizando dos estrategias de laser cladding diferentes: convencional y alta velocidad. Esta última se ha utilizado con el objeto de incrementar 17 veces la productividad del proceso. Palabras clave: laser cladding, LMD, discos de freno, aceros inoxidables, fundiciones laminares The objective of this work is to investigate new solutions based on laser cladding, also called LMD (laser metal deposition) for the coating of future generation brake discs. The application of these layers is aimed at minimizing the volume of respirable emissions of particles <10 µm) into the atmosphere during braking by improving the response to abrasion and corrosion of stainless steel surfaces versus the base made of lamellar gray cast iron. The work shows results of the laser cladding process of stainless materials applied on high and low carbon gray cast irons using two different laser coating strategies: conventional and high speed. The latter has been addressed to enhance 17 times the productivity of the coating process. Keywords: laser cladding, LMD, brake discs, stainless steel, gray cast irons