Micro-abrasive wear of boride layers on AISI D2 tool steel produced by the thermoreactive process

Boride layers were formed on AISI D2 steel by the thermoreactive deposition/diffusion (TRD) process in borax baths, containing ferroniobium and aluminium, at 1000?C/4h. They were characterised by optical microscopy, Vickers microhardness, X-ray Diffraction (XRD), Glow Discharge Optical Spectroscopy (GDOS) and micro-abrasive wear tests. Depending on the bath composition, Fe2B or FeB was the predominant phase in the borided layers. The layers exhibited a lenticular morphology with thicknesses varying from 60 to 120 mm, and hardnesses in the range of 1596 to 1744 HV. Wear resistance of the borided samples was superior to the hardened, uncoated AISI D2 steel. The wear mechanism observed was abrasive wear.