Determination of Precise Indentation Flow Properties of Metallic Materials Through Analyzing Contact Characteristics Beneath Indenter

The continuous indentation technique is widely used for nondestructive evaluation of the mechanical properties of devices and materials. In particular, flow properties can be obtained by using this technique with a spherical indenter. Several formulas have been suggested to determine flow properties, and they commonly require the determination of the precise contact characteristics such as the contact area or depth between material and indenter to obtain the properties accurately. In this study, contact characteristics were determined by analysis of the contact morphology from FEA (finite element analysis) using mechanical property data for several steels. The contact characteristics obtained from FE simulation were compared to an analysis of the parameters of indentation load-depth curves for the steels. The contact characteristics were shown as functions of such parameters as work-hardening exponent and indentation depth. In addition, using indentation morphology from FE simulation, the flow properties were evaluated by analysis of indentation morphology for 18 materials on the basis of the two representative preexisting definitions of stress and strain, and the definitions were verified by comparison of the flow properties with tension testing data.