Sintering and Wear Behavior of a FeCrCB Hardfacing Alloy Applied by Tape Casting: A Study of Cooling Rate Effect

Abstract

This study presents a simple process to deposit a hardfacing coating on a steel substrate, based on the sintering of metallic powder applied by tape casting (by a slurry of metallic powder suspension onto a steel substrate) thus avoiding the use of traditional welding processes and their variants. The effect of the cooling of hardfacing after the sintering process, by air at room temperature or by quenching in water, was studied. This new method ensures a good metallurgical bonding between the substrate steel and the hardfacing layer and shows mechanical property improvement on coated pieces, similar to those exhibited by hardfacing coatings produced by several kinds of welding processes. The characterization of the hardfacing coatings was made by X-ray diffraction, optical microscopy, scanning electron microscopy, microhardness and wear resistance according to the ASTM G65 standard. The characterization results show that the presented faces are: M7C3, M3C, MC, M2B and M23B6; there are three different phases in the micrograph glass phase, eutectic phase and hard phase with a volumetric fraction of 0.14, 0.20 and 0.66, respectively, for the air cooled and 0.15, 0.16 and 0.69 when quenched in water. The average microhardness value for the parts cooled in air was 832.5 HV and for that cooled in water was 958.9 HV, and the wear resistance was a mass loss of 0.219 and 0.128 g for parts cooled in air and water, respectively. These results show that the hardfacing coating could have twice the hardness and wear resistance than that observed for the boron steel used as a substrate.