Enhancing processing capacity of precision parts via vacuum laser diffusion boron-chromizing

Authors

• Alakbar Huseynov Azerbaijan Technical University
• Farid Huseynli Azerbaijan Technical University

DOI:

https://doi.org/10.30678/fjt.162698

Keywords:

boron-chromizing, laser surface hardening, diffusion coating, microhardness, residual stress

Abstract

The study investigates the improvement of surface strength and reliability of fuel pump precision parts by forming wear-resistant boron–chromium diffusion layers using vacuum laser diffusion boron-chromizing with paste application. Plungers made of steels ХВГ, ЩХ15 and P18 were coated with boron–chromium paste and treated by vacuum laser diffusion metallization. The diffusion layer thickness and microhardness were measured using a PMT-3 tester, while the phase composition and microstructure were analysed by X-ray diffraction and metallography. The process produced boride-rich diffusion layers with thicknesses of about 0.17–0.35 mm and surface microhardness in the range of 18–21 GPa. The maximum microhardness reached 21.0 GPa for ХВГ, 18.6 GPa for ЩХ15 and 17.6 GPa for P18, with minimum values in the diffusion zone remaining above 8.8–11 GPa. X-ray analysis confirmed that complex iron–chromium borides with dominant low-boride (Fe,Cr)₂B phases are formed. A fine network of surface microcracks acts as a stress-relief mechanism, redistributing residual stresses in the coating. These results show that vacuum laser diffusion boron-chromizing with paste application is a promising technology for restoring and strengthening fuel pump precision parts and creates a solid basis for subsequent tribological testing under service-like conditions.