PLASTIC ZONE AND PILEUP AROUND LARGE INDENTATIONS

Mechanical properties of cold-worked molybdenum, grade 4 titanium, and an alpha-beta titanium alloy are measured with tensile tests and by i ndentations using conical indenters with 105, 120, and 137 deg include d angles. The extent of plastic deformation and pileup around an inden tation is measured using profilometry. Various models predicting the e xtent of plastic deformation and pileup are compared to the actual mea sured values. As inferred from indentation, the calculated yield stren gth of the material from the mean pressure does not correlate well to the yield strength measured by tensile testing. The plastic zone size surrounding an indentation can also be used to determine the yield str ength of the material, and this does correlate to the yield strength m easured by tensile tests. Furthermore, the extent of plastic deformati on is relatively independent of the included angle of the indenter for the range of materials used in this system. Models predicting the amo unt of pileup at the edges of the indentation appear to approach but o verestimate the actual amount of pileup in the materials tested.