Effect of Abrasive Soil Mass Grain Size on the Steel Wear Process

This article analyses the effect of the size of abrasive soil mass grains on the steel wearing process. The study examined Hardox 500 steel used for working parts exposed to abrasive wear. Wear tests were performed under laboratory conditions using the “spinning bowl” method. The study was carried out using natural soil abrasive mass, in which three grain size fractions were distinguished: 0.05-2 mm – sand, 2-16 mm – gravel, 0.05-16 mm – sandy gravel. Steel wearing tests were completed for each fraction as well as for their mixes. The mixes were prepared using one additional fraction with a grain size below 0.05 mm described as dust and loam. The highest wear impact was recorded for the abrasive mass of a gravel (75 %) and dust-loam (25 %) mix. The wear was higher than that obtained for 100 % gravel. The addition of dust and loam had a different effect on the wear impact of sand. A 25 % addition of dust and loam to sand significantly reduced the abrasive wear of samples in comparison to the application of 100 % sand. The abrasive mass of dust and loam resulted in the lowest mass loss of the examined steel. Based on the results obtained from the wearing process in natural abrasive masses, three types of phenomena of steel wear in soil mass could be distinguished, i.e. by micro-cutting, fatigue wear and ploughing. The type of prevailing wear for different mixes of soil fractions depends on the volumetric content of a given fraction in the composition of soil mass. The wear intensity of the experimental steel is higher in mixes of soil fractions than for the particular soil fractions.