Mechanical properties of nitrogen-implanted 18W4Cr1V bearing steel

Abstract

Nitrogen was implanted into 18W4Cr1V bearing steel (where the composition is in approximate weight per cent) to doses of 1014-1017 ions cm-2 at 400 keV. The specimens were analyzed using the Rutherford backscattering and the X-ray photoelectron spectroscopy techniques and then tested on a pin-on-disc wear machine. There was a thick non-metallic film on the high dose specimens which was shown by the X-ray photoelectron spectroscopy examination to be graphite. Friction and wear were significantly decreased and hardness was increased by a factor of 4. These changes were observed to depend on the nitrogen dose and the applied load. The formation of a graphite surface layer is considered to be due to vacuum carburization and the increase in wear resistance is thought to be associated with nitride precipitation hardening. © 1987.