Fusao Hayama

Effect of surface working on the fatigue strength and wear of a hardened 13% Cr stainless steel

Abstract The effect of surface working (grinding, lapping, barrel finishing) on the fatigue strength and wear of a hardened and tempered 13% Cr stainless steel used for compressor valves was investigated. Surface roughness, hardness, residual stress and the microstructure induced by surface working at the surface and in the surface layers were examined. The results obtained for the fatigue strength and wear are discussed in terms of these variables. It was found that the fatigue strength for lapping was similar to that for grinding whereas wear by lapping was less by a factor of about 10 than the wear by grinding. The major cause of the reduction in wear was the embedment of the harder abrasive particles in the lapped surface.

A Comparison of Wear of Annealed Carbon Steels between Reciprocating Friction and Uni-Directional Friction under a Lubricated Condition

A comparison of wear between reciprocating fricton and uni-directional friction was made on annealed low, medium and high carbon steels. Wear tests of the two sliding modes were carried out with a specially designed testing machine under similar sliding conditions in white spindle oil. The experiment indicated that a heavier wear always resulted from reciprocating friction under the sliding conditions used, and the wear differences between the two sliding modes increased with increasing normal forces and with decreasing sliding speeds. The wear differences can be explained in terms of the differences i.e., difficulty or easiness of plastic flow of sub-surfaces and the amount of abrasion by the wear debris trapped between sliding surfaces.