Abstract: Research relates to the characterization of hard chromium deposit on a steel slightly allied (42CrMo4), by electrolytic way. This characterization was carried out by Vickers indentation, where we calculated the number of hardness according to the applied load, which is generally defined like the penetration resistance of an indenter, also, an evaluation of the Young modulus under the various loads of indentation was made. A simplified approach of the calculation of tenacity for the various shapes of cracks (standard M and P) is presented, showing a progressive transition from a mode of cracking to another, according to the applied load.