Miniature Marciniak Setup for in-situ SEM Observation of Damage Micro-mechanisms

Abstract

The industrial and scientific interest for ductile damage and fracture has significantly increased in the last decades due to the popularity of new advanced materials, such as high strength steels and nanostructured metals [1]. To allow for detailed investigation of micro-events such as the damage micro-mechanisms, the deformation needs to be studied in real time with in-situ scanning electron microscopy, allowing for digital image correlation (DIC) of the high resolution images for local strain mapping [2], see e.g. Figure 1. These studies, however, were limited to deformation under uniaxial tension due to the constraints of in-situ SEM testing.At the same time, parallel research efforts have focused on elucidating the effect of the followed strain path on the ductile deformation micro-mechanisms, and its consequence for the resulting macroscopic forming and fracture limits in sheet metal [3]. Unfortunately, in these studies the damage micro-mechanisms were studied from post-mortem fracture analysis [4], due to the absence of a miniaturized testing setup capable of deforming sheet metal up to failure in alternative strain paths (e.g. plane strain or biaxial tension).

A Miniaturized Biaxial Deformation Rig for in Situ Mechanical Testing

“…In order to track damage evolution during deformation of sheet metal subjected to various strain paths up to the point of fracture a miniaturized Marciniak setup for in situ electron scanning microscopy (SEM) observations was developed. Combined with digital image correlation the applied strain can be followed together with deformation induced microstructural changes at the surface [11,31]. For studying thin films deposited on a polymer substrate, a miniaturized biaxial deformation rig using a polymer cruciform sample geometry can be used in situ at the DIFFABS beam line at the SOLEIL synchrotron [32,33].…”