Strengthening mechanism and high-temperature properties of H13 + WC/Y2O3 laser-cladding coatings
Zhenzhen Yang, Hao Hao, Qian Gao, Ya-bin Cao, Rihong Han, Hai-bo Qi
Abstract
In order to meet the surface modification and repair requirements of 8407 hot extrusion die , Y 2 O 3 powder and WC powder were added as strengthening phases into an H13 powder. The coatings were strengthened through laser-cladding and then applied on the surface of 8407 steel. XRD, SEM , EDS, and Vickers high-temperature hardness tests were used to analyze the properties of the laser-cladding coating, such as its phase composition, microstructure, high-temperature hardness, and high-temperature stability. The M 7 C 3 composite strengthening phase was evenly distributed throughout the entire coating in a three-dimensional reticular shape, resulting in a uniform hardness distribution . The addition of Y 2 O 3 accelerated the decomposition of WC particles, which increased the uniformity of the laser-cladding coating. The hardness of the laser-cladding coating at room temperature was 818.7 HV, which was 48.4% higher than that of the substrate, and its hardness at 500 °C was 555.6 HV, which was 32.3% higher than that of the substrate. The hardness values of the laser-cladding coatings at different holding times were roughly the same as 8407 steel. After holding for a certain time at different high temperatures, the hardness of the laser-cladding coatings was double that of 8407 steel.