Appreciable Increase in Pitting Limit of Contact Surfaces Under Rolling and Sliding Conditions

Abstract

This work was conducted to discover the highest pitting limits of the contact surfaces under combined rolling/sliding conditions. Appreciable increases in pitting limits were obtained in rollers with hardnesses in the range 190 to 335 HB using an improved testing machine made by the authors. The allowable contact forces corresponding to the new pitting limits were about four times greater than those corresponding to the earlier pitting limits. Some factors which might prevent appreciable increases in pitting limits were examined and a new experiment was conducted using rollers with a pit-producing ability limited to a small area of less than 0.1 percent of whole contact surface of the rollers. It was found that the local metallic contacts which cause only a slight increase in the friction coefficient can bring about severe pitting failure before 107 rotations.