Application of a Crystal Orientation Method for Matching Surfaces Along a Fracture Line

Abstract

The overall objective of this study was to evaluate whether surface crystal orientation can be used to associate metal fracture fragments. This study examined the orientations of the fractured crystals across the fracture plane for two surfaces determined to be a matching fracture by conventional methods. This study used Electron Back-Scattered Diffraction (EBSD), sometimes known as Orientation Imaging Microscopy (OIM), to determine the crystallographic orientation of individual metal crystals along the length of the fracture on a surface perpendicular to the actual fracture surface. This investigation examined the uniqueness of crystal orientations within a metal and examined the requirements necessary for determination of crystallography using EBSD. This study also examined the crystallographic information as to whether it is sufficiently reliable characteristic from which a quantitative determination could be made that two separate pieces of metal are, in fact, from a single piece.

Physical Matching of Metals: Grain Orientation Association at Fracture Edge

“…With an angular resolution of 4°, 130,000 distinct orientations are detectable and with an angular resolution of 2°, the number increases to 4,155,000 . For an angular resolution of 4°, there are more than 130,000 distinct possible orientations for each of the grains along the sequence of grain orientation values .…”