Abstract
The present study examines the applicability of a diode laser-assisted fusing treatment and a temperature-control system to the NiWCrSiB thermal spray coating to develop the enhanced wear resistance of continuous-casting molds. As a result of the use of the lasers, the variations in the microstructure and the hardening behavior during the fusing treatment could be controlled. Fine secondary phases (approximately 0.05–10 μm in size) homogeneously present in the coating after the laser-assisted fusing were observed to be Cr-, Mo- and W-based carbides and borides. Transmission electron microscope analysis was used to characterize these fine secondary phases as M7C3 and M23C6 carbides and M5B3 boride. Because of these fine secondary phases, the hardness increased from 730 (as-sprayed status) to 1230 HV (after fusing at a temperature of 1473 K). Finally, given the formation of fine secondary phases and the occurrence of surface hardening, the laser-assisted fusing treatment was deemed to enhance the tribological performance of the thermal-sprayed coating, in that it exhibited a lower coefficient of friction and lower wear rate than the as-sprayed coating.
Highlights
Thermal spraying is a well-known and cost-effective surface-coating process
Throughout the steel production process, the production hardware is exposed to a combination of high temperatures, corrosive environments and wear
Continuous casting molds are exposed to high-temperature and abrasive environments
Summary
Thermal spraying is a well-known and cost-effective surface-coating process. It is widely used to produce wear- and corrosion-resistant coatings in the chemical and machinery industries [1]. Since a thermal-sprayed layer commonly exhibits macrostructural inhomogeneity (e.g., the macrosegregation of specific elements and voids) after spraying, subsequent treatment, such as fusing within a certain temperature range, is essential to enhance the mechanical properties of the coating [5] To this end, Otsubo et al investigated the effects of fusing on the macro- and microstructural variation behaviors of several kinds of Ni-based alloy coatings [6,7]. Several studies have addressed the fusing of thermal-sprayed Ni and Co-based powders, the fundamental applicability of temperature-controlled laser-assisted fusing and its influence on microstructural evolution and wear resistance remains still insufficient, especially for the 1276F coating. The applicability of a temperature-controlled laser-assisted fusing treatment was examined for a 1276F thermal-spray coating to develop a high-durability continuous casting mold. Microstructural evolution of a 1276F coating was characterized in detail and correlation between microstructural characteristics and wear resistance of the coating upon a laser-assisted fusing conditions was systematically studied
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Free) 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
