Effect of laser microstructuring on change in structure and microhardness of surface layer of structural steel parts

The paper presents the results of a study of the effect of Q-switch laser microstructuring by a fiber pulsed laser on changes in the structure and properties of products made of hot-rolled structural steel sheets. It is shown that during pulsed laser treatment, the laser exposure zone is characterized by the presence of a "structureless" layer, the width and length of which depends on the number of passes. The effect of increasing the carbon content in the "structureless" layer has been revealed, which may be due to the diffusion of carbon from deep layers to surface layers and the formation of a carbide phase in the subsurface layer. The regularities of changes in the microhardness of the surface layer depending on the mode of laser microstructuring, chemical and phase composition of steel are established.