Tribological Properties Analysis on Nitrided AISI 3161 Stainless Steel

AISI 3161 stainless steel have been treated by surface hardening technique, which is
low temperature nitriding gas treatment in horizontal tnbe furnace. The environment gas
for this treatment is ammonia, which become the source of nitrogen gas that purged into
the furnace where the steel is located. The temperature of this treatment is at 450 ac with
the variable of 2, 5 and 8 hours nitriding time. The purpose of this investigation is to
improve the wear resistance and surface hardness of the stainless steel as the element of
tribological properties analysis. Theoretically, the low temperature treatment is to avoid
the formation of nitride and carbide precipitation because it can reduce the corrosion
resistance of stainless steel. Pin-on disc wear test at dry sliding condition become the
standard test to analyze the wear resistance of this nitrided steel according to the ASTM
G99-95a standard. The further analysis on tribological properties of nitrided steel are
conducting microhardness assessment by Vickers hardness test on the surface of treated
steel to identizy the improvement of surface hardness by the formation of nitrided layer.
This investigation also strongly support by conducting nitrided layer morphology by
utilizing Field Emission Scanning Electron Microscope (FESEM) instrument which is to
measure the thickness of nitrided layer. Surface morphology of worn region by FESEM
also investigated to understand the wear mechanism characteristics of nitrided steel. The
results showed that the nitrided layer become more thicker through the extending of time
treatments and relatively improved the surface hardness. The nitrided layer characteristic
that support the protection oxide layer and resist the wear mechanism is confirmed
where the wear resistance improved from the result of coefficient of friction by the pinon
disc wear test with the value obtained become lower as the time of treatment is
extended. Surface morphology by FESEM investigation on worn region after wear test
for untreated and nitrided steels indicates how the wear mechanism influenced the
improvement of wear resistance. Untreated samples experienced severe wear while
nitrided steel presented only slight abrasion with shallow and narrower wear track.