Determination of elastic and plastic material properties using indentation: Development of method and application to a thin surface coating

The objective of this work is to develop a combined computational-experimental indentation based method to determine the elastic-plastic stress-strain behaviour of a material. Both ultra-micro and nano-indentation is considered and a power-law material strain hardening behaviour is assumed. This paper reports on the results obtained for indentation into AISI 01 heat-treated steel and a MoST™ coating on an AISI 01 steel substrate. In developing the method, the percentage plastic work (PPW) at maximum indentation load and the plastic zone size surrounding an indentation are investigated to ascertain if either can be used in conjunction with a force-indentation depth curve in determining the material properties. It is shown that it is possible to identify the material properties using the plastic zone size but not the PPW. The method is validated experimentally for the AISI 01 steel. It is then used to determine the material properties of the MoST™ coating.