Abstract
The high frictional temperature and mechanical work during dry rubbing of steel produce gross structural changes of the surface layers.
Microscopical observations by the taper sectioning method and micro hardness tests have been performed on these layers.
The structural changed layers may be classified to three different types.
That is, an oxide layer, a heat transformed layer, and a ruptured grain layer.
The worn surfaces include the complex combinations of these types.
The oxide layer is very hard and brittle, and exhibits gray colour etched with an alcoholic solution of 2% nitric acid under micdoscope.
The heat transformed layer is yellow or brown etched with alcholic solution of 2% nitric acid, and often has lamina texture.
The formation processes of these layers were determined.
