Indentation method to measure the residual stress induced by ion implantation

A depth-sensing indentation system was used to measure the residual stress in a stainless steel plate implanted by Fe2+ ions with an energy of 3 MeV at a dose of 3 × 1016 cm−2. Unlike other measurement methods, such as substrate curvature and X-ray diffraction techniques, depth-sensing indentation provides an accurate measurement of local residual surface stresses in the thin ion-implanted layer. Micromechanical analysis was carried out based on the premise that elastic unloading responses during indentation are fully independent of any pre-existing residual stresses at the indented surface. The correctness of this premise was verified by FEM simulation. It is found that the surface stress is proportional to the load shift induced by the surface stress. By using the energy method, a formula was derived for determining the surface stress by depth-sensing indentation studies. The residual surface stress induced by ion implantation was evaluated by using this formula.