Study of the Influence of Cementation Layer Thickness on Properties of Chromium Carbide Obtained by Conversion Treatment

Abstract

Steel substrates low carbons were face-hardened by cementing in case, and then thin layers of chromium were deposited by electrolytic way on these substrates. After deposition, the samples were exposed to isothermal annealing in the temperature of 950°C. The characterization of the thin layers was made by means of optical microscopy and interferometry Vickers micro-hardness. From the obtained results, we have established the kinetics of phase shift (under effect the layer of cementing) in the thin layers of chromium which are transformed into chromium carbide while passing by metastable phases of transition. These transformations occurred by diffusion of the carbon atoms coming from layer of cementing, germination and growth in solid phase. This fact has examined according to the temperature of annealing, the evolution of the lattice parameter and the morphology of the deposited chromium layer. As regards the mechanical properties, it was established that the micro-hardness believes with the evolution of the phase shift.