It is traditionally known that monocrystalline diamond tools cannot be employed to machine steels due to excessive chemical tool wear. In this study, two different materials are preprocessed by turning, grinding, and polishing, respectively, and then are nitrided to gain the compound layer for diamond turning. Tool wears are significantly reduced by two to three orders of magnitudes and the surface roughness are ranged from 4.2 to 20 nm in Ra depending on the elements and qualities of the workpieces. It is also found that Ni, Cu, Si, and Al are beneficial to improve the tool life, while Mn, Cr, and Mo play the negative role.