title: Deformation field heterogeneity in punch indentation.
abstract: Plastic heterogeneity in indentation is fundamental for understanding mechanics of hardness testing and impression-based deformation processing methods. The heterogeneous deformation underlying plane-strain indentation was investigated in plastic loading of copper by a flat punch. Deformation parameters were measured,in situ, by tracking the motion of asperities in high-speed optical imaging. These measurements were coupled with multi-scale analyses of strength, microstructure and crystallographic texture in the vicinity of the indentation. Self-consistency is demonstrated in description of the deformation field using thein situmechanics-based measurements and post-mortem materials characterization. Salient features of the punch indentation process elucidated include, among others, the presence of a dead-metal zone underneath the indenter, regions of intense strain rate (e.g. slip lines) and extent of the plastic flow field. Perhaps more intriguing are the transitions between shear-type and compression-type deformation modes over the indentation region that were quantified by the high-resolution crystallographic texture measurements. The evolution of the field concomitant to the progress of indentation is discussed and primary differences between the mechanics of indentation for a rigid perfectly plastic material and a strain-hardening material are described.
authors.affiliation: Department of Civil Engineering , Indian Institute of Science , Bangalore 560012, India.
authors.forename: Tejas G
authors.initials: TG
authors.lastname: Murthy
authors.affiliation: Harold and Inge Marcus Department of Industrial and Manufacturing Engineering , Pennsylvania State University , University Park, PA 16802, USA.
authors.forename: Christopher
authors.initials: C
authors.lastname: Saldana
authors.affiliation: School of Aeronautics and Astronautics , Purdue University , West Lafayette, IN 47907, USA.
authors.forename: Matthew
authors.initials: M
authors.lastname: Hudspeth
authors.affiliation: R&D Materials and Technology Development , Seco Tools AB , Fagersta 73782, Sweden.
authors.forename: Rachid
authors.initials: R
authors.lastname: M'Saoubi
keywords: deformation; indentation; particle image velocimetry