Influence of Load, Surface Finish and Lubrication on Friction Coefficient of AISI 304 Stainless Steel

The present work aims to evaluate the friction and wear behavior of a metastable stainless steel AISI 304L against steel AISI 52100 ball. Friction tests using the "ball-on-disc" technique at constant velocity (0.03 m/s) and different loads (6 N, 15 N) with and without lubricant (liquid vaseline) were carried out. Two surface finishing conditions were considered, leading to different mixture phases of preexisting austenite and martensite in the steel. One set of samples was polished to induce martensite (PO), and another set was tested in the as-received (AR) condition. Special emphasis was placed on correlating the friction and wear behavior with microstructural analysis performed by x-ray diffraction, optical, scanning electron and transmission electron microscopy. To complete the analysis, the microhardness profile was also performed for both PO and AR samples. The PO samples showed higher microhardness and greater amount of induced martensite and work hardening in the surface in comparison with AR samples. Independently of applied load and initial surface condition, two different stages on the friction behavior can be identified in dry tests. On the contrary, a stable behavior is observed in lubricated tests. Moreover, whereas in lubricated tests wear behavior is independent of surface finishing conditions and load, it shows a pronounced influence with load in dry tests.