Development of technology for restoration and hardening of working bodies of tillage machines by laser surfacing

The article proposes a technology for restoring and strengthening the working bodies of tillage machines, including laser surfacing with a mixture of powders containing tungsten carbide to obtain a wear-resistant work surface. The purpose of the study is to determine the rational operating parameters of laser surfacing for the formation of the microstructure of wear-resistant coatings. The laser layers deposited by surfacing were examined for the resulting structure and the resulting hardness to match the modes of laser surfacing and the indicators of abrasive wear resistance. A total of 121 samples were deposited. A mixture of powders is used as a wear-resistant material, including 43…53 % of the iron base in powder form PG-C27 «Sormayt», with particle sizes of 80 microns, 45…55 % of the hardening phase in the form of tungsten carbide with particle sizes of 15 microns and 2 % aluminum oxide Al2O3 nanopowder with particle sizes of 70 nm. During the study of the microstructure, the parameters of the surfacing mode were determined, allowing to achieve the necessary dendritic-cellular structure deposited wear-resistant coating of the ledeburite type: laser radiation power 2500…2700 W, the surfacing speed is 7…9 mm/s, the content of tungsten carbide is 49…53 % of the volume powder mixtures. Theoretical studies of the laser surfacing process aimed at obtaining coatings with increased hardness have made it possible to determine the rational operating parameters for surfacing wear-resistant coatings: the deposition rate is 7 mm/s; the content of tungsten carbide in the powder mixture is 51 %; the laser radiation power is 2700 watts.