PAPERS & REPORTS

Introduce technical papers and reports of IIT (Instrumented Indentation Technology) and correlated fields.

 

Title

Investigations on indentation size effects using a pile-up corrected hardness

Author

Y H Lee1, J H Hahn2, S H Nahm1, J I Jang3 and D Kwon4

1 Division of Metrology for Quality Life, Korea Research Institute of Standards and Science, Daejeon

305-340, Korea

2 Division of Advanced Technology, Korea Research Institute of Standards and Science, Daejeon

305-340, Korea

3 Department of Materials Science and Engineering, Hanyang University, Seoul 133-791, Korea

4 School of Materials Science and Engineering, Seoul National University, Seoul 151-742, Korea

Press and Date of publication

Received 6 August 2007, in final form 1 October 2007

Published 12 March 2008

Online at stacks.iop.org/JPhysD/41/074027

Abstract

Indentation size effects (ISEs) become severe in the nanoindentation regime because various influencing factors become active in a very shallow indentation regime. Additionally, the general analysis on the nanoindentation curve yields hardness overestimation because it cannot take into account material pile-up around contacts. Thus we tried to investigate intrinsic ISEs in monolithic materials by proposing a new hardness measurement method; the load-supporting contact boundary was approximated as the peak trajectory around an impression and analysed by a radial differentiation of the remnant indent morphology. Dependence of the new load-off hardness on the indentation depth was investigated for (1 0 0) tungsten single crystal and fused quartz. The contribution of the material pile-up to the new hardness was clearly modified but more significant hardness increase appeared at a very shallow indentation regime due to severe elastic recovery. These phenomena are discussed with the strain-gradient plasticity model.

(Some figures in this article are in colour only in the electronic version)