Formation of VC-composite surface layer on high C-Cr bearing tool steel by laser surface cladding

YAG fiber laser was used to clad high C-Cr bearing tool steel with VC particles. The cladding process was carried out at laser powers of 1000, 1500, and 2000W, and a fixed travelling speed of 4 mm/s. Argon gas was used as a shielding during and after laser cladding at flow rate of 151/min. VC-surface composite layers consists of VC dendrites/particles dispersed in a matrix of martensite lathes, acicular carbides and some retained austenite were formed through all the laser processing conditions. The depth of the treated zones is in direct proportion to the laser power. On the other hand, the laser power has no great effect on the treated zone width. Some of the VC particles are melted and then re-solidified in the form of fine dendrites during the laser processing. The amount of these melted and re-solidified VC particles were increased by increasing the laser power. The formed composite layers show good metallurgical bonding with the substrate without cracking, except at laser power of 1000W. The hardness values of the build-up zone in the three different power cases are almost three times as that of the base metal. Decreasing laser power was found to increase the hardness at/near the free surface of treated-zone. The wear resistance of the laser cladded surface was remarkably improved. (C) 2015 The Society of Manufacturing Engineers. Published by Elsevier Ltd. All rights reserved.