2 PARAMETERS CHARACTERIZING SUPERFICIAL MECHANICAL FEATURES

Two parameters, surface yield strength and surface work hardening expo nent, have been newly suggested in this paper to characterize the supe rficial mechanical features in engineering metallic materials. Emphasi s was placed on the method by which the two parameters are determined. X-ray stress determination and strain gage techniques were employed t o measure stress and strain. The Mises effective stresses at a sample surface under different loading conditions were then calculated with t he measured data; hence, the relationship between stress and strain wa s available. Consequently, with the data processing procedure for gene ral yield point and work hardening exponent of uniaxially loaded mater ials, the yield point and work hardening exponent at the sample surfac e can thereby be obtained. Experimental studies on a shot-peened surfa ce showed satisfactory results when the described method was used.