Hydroabrasive wear of a boride-hardened austenitic Cr–Ni steel

Abstract

This study investigates a method of enhancing the hydroabrasive wear resistance of AISI 321 chromium-nickel austenitic steel. The microstructure and wear resistance of coatings deposited by electron-beam surfacing using a B–Fe powder mixture in an air atmosphere were examined. Analysis revealed that all of the surfacing materials consist of γ‑iron from the substrate, as well as a hardening phase of borides (specifically, Cr₂B, Fe₂B, and Fe_1.1Cr_0.9B). Under hydroabrasive wear conditions, surface-alloyed materials demonstrated superior resistance at 20° and 45° impingement angles, with performance 2.5 and 1.9 times higher than that of base AISI 321 steel, respectively. Abrasive particles impacted the sample surfaces, causing plastic deformation and crater formation. Fatigue cracks subsequently developed in the surface layer due to the accumulation of defects, and the coalescence of these cracks resulted in the spalling of small volumes of material. However, when the impingement angle increased to 90°, the intensified hydroabrasive action reduced the wear resistance of the surfaced coatings to the level of unmodified AISI 321 steel.