Tribological behaviour of borided H13 steel with different boriding agents

Solid boriding thermochemical treatment was carried out on AISI H13 steel. Two boriding agents were used: Ekabor 1-V2 commercial powder and a mixture of 73·26 wt-% borax, 24·06 wt-%SiC, 1·22 wt-%NH 4 Cl and 1·46 wt-%NaCl. Pin on disc wear tests were carried out to investigate tribological behaviour. After the wear tests, samples were cut in cross-section to evaluate the thickness and morphology of the boride layer by scanning electron microscopy (SEM) and Vickers microhardness. Wear mechanisms were evaluated by SEM. A large improvement in wear resistance was observed for borided samples compared with samples that had been quenched and tempered. The thickness of the borided layer was higher for samples borided with Ekabor powder than those borided with the mixture. In comparison with quenched and tempered samples, borided samples had a higher incidence of cracks, which favours spalling and reduction of grooves formed by abrasive wear.