The fatigue effect on En31 steel balls of microbially degraded soluble oil emulsion

Abstract The rolling four-ball machine was used to test the effect on the fatigue characteristics of En31 steel balls of (a) soluble oil emulsion (control), (b) emulsion + biocide and (c) microbially degraded emulsion. From an average of 20 tests, average (x) and standard deviations (σ) were calculated from the times to produce fatigue pits on the test balls. Compared with the control, the microbially degraded emulsion did not increase the time to produce pits, but the emulsion + biocide increased the pitting time by 18% with a concomitant doubling in the standard deviation. The Herbert corrosion test for soluble oil emulsions showed that, whereas the control emulsion, distilled water and the degraded emulsion produced moderate to severe corrosion, the emulsion + biocide showed significantly less corrosiveness.