Abstract
To manufacture superior-performance continuous casting mold components, high-velocity oxygen fuel spraying of a Stellite-1 coating was followed by its laser heat treatment at 1373–1473 K using a diode laser. The effects of the laser irradiation conditions on the macro- and microstructural variations along with the hardness and wear resistance within the Stellite-1 coating were evaluated. After the heat treatment, micro-voids within the sprayed coating decreased in number slightly with an increase in the heat treatment temperature. The hardness of the sprayed Stellite-1 coating increased from that of the as-sprayed coating (680 HV) after the laser heat treatment, with a hardness of 860 HV obtained at 1473 K. The cause of the increase in hardness could be the formation of nano-sized W- and Cr-based carbides such as WC, M7C3, and M23C6, as suggested by transmission electron microscopy analysis. The tribological properties of as-sprayed and laser heat-treated samples were investigated by a pin-on-disk tribometer. The laser heat treatment of Stellite-1 coating enhanced wear resistance. This resulted in a lower coefficient of friction and wear rate for the laser heat-treated sample than those for the as-sprayed sample.
Highlights
High-velocity oxygen fuel (HVOF) spraying is widely employed in the deposition of highly wear-resistant and corrosion-resistant protective coatings [1]
Stellite alloy powder has been largely employed in the HVOF spraying process [1] together with arc cladding [2,3], plasma transfer arc hardfacing [4], supersonic laser deposition [5], laser cladding [6,7,8], etc
1 coating increased from the level observed with the as-sprayed coating (680 HV) to that observed could be attributed to the laser heat treatment of the Stellite-1 coating
Summary
High-velocity oxygen fuel (HVOF) spraying is widely employed in the deposition of highly wear-resistant and corrosion-resistant protective coatings [1]. A laser heat treatment process is required in the case of HVOF sprayed coating of the continuous casting mold, as lasers bypass these issues and offer several advantages such as selective and precise control of the surface properties [21] In this regard, many researchers have investigated the laser-based surface treatment of several types of Stellite coating [14,15,21,22,23,24,25]. The HVOF coating of the Stellite alloy was employed to obtain a high-durability continuous casting mold, and the effects of the temperature-controlled laser heat treatment on the variations of the surface mechanical properties and the microstructure were investigated
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