Growth Kinetics and Mechanical Properties of Rare-Earth Vanadiumizing Layer on GCr15 Steel Surface

Abstract

In this paper, rare-earth vanadiumizing layers were prepared on the surface of GCr15 steel by powder pack cementation. The tissue thicknesses of the vanadiumizing layers were characterized by metallographic microscopy, scanning electron microscopy, X-ray diffraction, electron microprobe analysis and microhardness testing at 1173, 1193, 1213 and 1223 K for 1, 3, 5 and 7 h, respectively, and the growth kinetics of the rare-earth vanadiumizing layers were investigated first. The experimental results showed that: a dense and uniform vanadiumizing layer was obtained on the surface of the substrate, and the layer mainly consisted of VCx and α-Fe; the thickness of the vanadiumizing layer increased with the increase in heating temperature and holding time, and the variation range was 4.65–12.65 µm; the microhardness of the vanadiumizing layer increased with the increase in heating temperature and holding time, and the variation range was 1892.3–2698.6 HV, compared with the substrate. The electron probe microanalysis showed that the rare earth entered the diffusion layer and affected its tissue hardness. The experimental diffusion activation energy of the GCr15 steel powder-embedded rare-earth vanadiumizing layer was 164.85 KJ/mol.