Droplet size dependent localized corrosion evolution of M50 bearing steel in salt water contaminated lubricant oil

Abstract

Corrosion of M50 steel in salt water contaminated lubricant oil (SCO) were systematically studied in combination with settling dynamics of droplet and characterization of localized corrosion area (LCA). Results show that LCA on steel surface existed in two forms: eye-like LCA and isolated outer zone. Larger outer zone was more likely to create and enlarge inner zone inside it. Outer zone actually resulted from larger droplet, because larger droplet had higher approaching velocity in oil, allowing longer duration at stabilization stage. Underlying formation mechanisms of sunken inner zone and bulging outer zone were respectively given as galvanic and uniform corrosion.