ON THE DESIGN OF SURFACE DURABILITY OF ROLLING-SLIDING CONTACT SURFACE.

Some 200 cases of rolling contact fatigue tests were conducted over a long period, and formation of contact surface distress was studied. The paper describes principal experimental results useful in determining a new surface durability, concerning a method of obtaining a sharply increased pitting limit of normalized soft steel by the use of work-hardening, rolling contact fatigue characteristics of cast iron, D value and pitting limit of normalized steel, spalling and case-crushing limit of case-carburized and hardened steel. Limit Hertzian stress is given as a function of D (the ratio of the magnitude of the composite surface roughness to calculated oil film thickness) and the hardness of a material. The types of failure examined are surface plastic deformation resulting from plastic flow in the inside and spalling for D less than 1, and pitting, spalling, case-crushing, etc. for D greater than equivalent to 1. The paper also refers to the effect of very thin plated copper and residual stress on the contact surface on which rolling contact fatigue failure is produced. In the last part of the paper, an outline of procedures for designing surface durability is given.