Influence of the fast pulse loading at high temperature on cracking, microstructure, and mechanical property of the Stellite 6 surfacing by laser

Abstract

In the present paper, the fast pulse loading at high temperature (FPLHT) was conducted on Stellite 6 coatings with and without the interlayer, and exerted great effects on the microstructure, distribution of elements, and mechanical property of the two coatings. The evident crack occurred in the coating without the interlayer in the 400-cycle condition, which was induced by the diffusion of the Fe, the formation of reprecipitation carbides, the coarsening grain, and the formation of Laves phase. The mechanisms of the formation of the Fe–Co phase was revealed by transmission electron microscopy, binary phase diagram, and diagrammatic sketch. To specify the functions of fast pulse loading on the diffusion of Fe and the transformation of the microstructure, the Stellite 6 coating without the interlayer aged for 2880 h was employed for comparison with that in the 400-cycle condition. The softened phenomena occurred in the Stellite 6 coating without the interlayer and the Stellite 6 with the interlayer, the former resulting from the diffusion of Fe and the latter resulting from the diffusion of Ni. The Stellite 6 coating with the interlayer exhibited no crack during the FPLHT, and the disparity of deformation between Stellite 6 coatings with and without the interlayer in the 100-cycle condition was less than that in the 400-cycle condition owing to the difference of diffusion speed between Fe and Ni.