Examination of the abrasive wear behaviour of boron carbide coated AISI 8620 and hardox 400 steels

In this study, hardox 400 steels and AISI 8620 cementation steels, respectively used in manufacture of excavator tips, crushers and truck trailers, and in gear manufacturing were boronized and studied. The boronizing procedure was carried out in solid state. Commercially available EKabor ® 2 powder was used as the boronizing agent. The boronizing procedure was carried out for 2, 4 and 6 hours at 850oC, 900oC and 950oC. The abrasive wear behaviour, boride layer thickness, micro structure, micro hardness and conductivity characteristics of both steel specimens boronized for different durations and under different temperatures were examined. The boride layer thickness varied between 70 µm and 280 µm depending on the duration and temperature of the boronizing procedure. The boride formation on the steel substrate was observed to have a uniform dendritic morphology after SEM and optical testing. The boride formation (FeB, Fe2B) was also verified with x-ray refraction analysis. The boride layer and alloy element distributions were studied using the energy dispersion system x-ray spectroscopy (EDS) method. The wear experiments were carried out using a pin-on disk abrasive wear testing device. 80 and 120 mesh aluminum oxide (Al2O3) abrasive materials were used during the wear tests and the specimens were tested under 10, 20 and 30 N loads at a displacement of 20 meters. The test results show that the wear resistance of materials boronized for maximum hardness was the highest. The best wear resistance was observed in the Hardox 400 steel specimen boronized for 6 hours at 850oC.Key Words: Abrasive wear, Boronizing, AISI 8620 cementation steel,Hardox 400 steel.