Influence of heat treatment conditions of Hardox 500 steel on its resistance to abrasive wear

The type, magnitude, and distribution of thermal stress arising during the hardening process of steel primarily depend – apart from the geometry of the treated component and the type of metallic material used – on the type of cooling medium employed. The difference in cooling rates between the core and the surface of the object affects the extent of deformation, particularly in large-scale components with complex shapes. Due to their high hardness, boron-alloyed steels are frequently used for components exposed to abrasive wear, and their heat treatment is typically performed on profiled structural elements such as plowshares or cultivator coulters. The critical cooling rate is primarily dependent on the chemical composition of the material and increases as its hardenability index decreases. Consequently, it is essential to investigate the feasibility of applying various heat treatment processes to medium-carbon steels, including the widely used martensitic steel Hardox 500. This study presents the results of abrasive wear tests conducted on the aforementioned steel, subjected to different heat treatment variants, which involved varying cooling rates following austenitization. For this purpose, the cooling media used included deoxygenated quenching water, mineral transformer oil, synthetic quenching oil, and air-blast cooling. For comparative purposes, equilibrium-cooled samples were also analyzed. The research findings demonstrated that the highest resistance to abrasive wear was achieved by samples quenched in water, whereas a gradual decrease in wear resistance was observed in samples cooled in media with lower cooling intensity coefficients. Furthermore, it was found that the traditionally employed roughness parameters are not suitable for evaluating the condition of surfaces subjected to abrasion. Therefore, for a comprehensive assessment of the tribological resistance of Hardox 500 steel, more advanced surface topography analysis methods must be employed.