Manufacturing Process, Microstructure and Physico-Mechanical Properties of W-Cr Coatings Reinforced by Cr3C2 Phase Produced on Tool Steel through Laser Processing

This paper presents study results of laser processing of W-Cr, WCr/Cr3C2 and Cr3C2 pre-coats applied on steel substrate in the form of paste. For this study, production parameters were selected to obtain the greatest possible durability of final coatings. Laser processing was carried out using a diode laser machine with a rated power of 3 kW. The laser beam scanning speed was constant at 3 m/min, but variable laser beam powers were used: 600 W, 900 W and 1200 W. Multiple laser tracks with 60% overlapping were used. After remelting the pre-coat with a steel substrate, new coatings were obtained. Following the experiment, microstructure, microhardness, wear, corrosion resistance and chemical composition were investigated. It was found that it is possible to produce W-Cr/Cr3C2 coatings through laser processing. These coatings do not have the characteristics of a composite coating; however, increasing the reinforcing phase in the pre-coat positively affects the wear resistance and microhardness. The addition of a reinforcing phase was found to lead to a microhardness of about 750–890 HV01 for 25% and 75% Cr3C2, respectively, in comparison to coating without Cr3C2. The wear resistance of coatings reinforced by chromium carbide improved more than twofold in reference to the W-Cr coating.