High strain wear mechanisms in ferrous alloys

Abstract

Under slow speed lubricated wear conditions, stainless steel and mild carbon steel exhibit both subsurface high strain deformation and microextrusion. The character of the deformation and its depth appear to be significantly influenced by the effectiveness of the lubricant used. Three zones of action are seen in profile: (a) a transfer or mechanically alloyed layer on top of the surface or compressed into the surface; (2) a high strain region with heavy dislocation concentration and cell structure; (3) conventional deformation (slip lines, twins and elongated grains) below the first two zones. Flow from the second zone feeds extrusions out of the contact area and the extent of extrusion depends on the depth of the high strain zone. Break off of extrusions produces relatively large wear flakes. The size and shape of the flakes can be influenced by the effectiveness of the lubricant. The extrusion wear process is a function of the geometry, of the contact area and the relative hardness of the moving vs. the stationary parts. (Extrusion does not occur in some sliding contact systems.) The high strain mechanical properties of any metal undergoing wear are significant indicators of its wear behavior.