Specifics of the Surface Structure of Steel Products After Various Laser Alloying Methodics

Abstract

In modern conditions, volumetric alloying of steels is becoming an increasingly less economically viable process. However, the level of performance properties of unalloyed steels cannot cover the current industry needs. One of the ways to solve this problem – usage of various surface alloying methods of steels, makes it possible to obtain the required properties of the working surface of the alloyed part with minimal consumption of expensive alloying elements. Over the course of the study, combined method of laser-plasma alloying of steel surfaces was analyzed, its technological capabilities were determined, and the structural-phase state of surface layers, formed during laser and hybrid laser-plasma processing was compared. During comparative studies of samples obtained by both methods of surface alloying, it was found that in the case of laser-plasma alloying, the observed structure and carbide phases are smaller in size, with a low density and uniform distribution of dislocations in the metal of the alloyed layer. After various analysis, it was established that during both laser and laser-plasma methods of surface alloying, the crack formation tendencies was mostly attributed to various structural and concentration changes associated with the redistribution of elements, leading to the formation of sharp grain-boundary concentration gradients. An increase in the number of cracks is observed in regimes with higher heating temperatures, increased duration of exposure to high temperatures and reduced cooling rates.