FIFTH CANADIAN CONFERENCE ON NONDESTRUCTIVE ... - IAEA

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DEVELOPMENTS IN X"RAY STRESS MEASUREMENT
THE CANMET PORTABLE STRESS DIFFRACTOMETER
R.A. Holt
Enzfigy, H-Lne.i> and Rz&ou.fic.Q.i, Canada
Ottawa, Ontaftlo
ABSTRACT
The measurement of stress in a surface with X-rays makes use of
the Bragg law for the diffraction of monochromatic X-rays from a crystal
to measure precisely the small changes in lattice parameter corresponding
to elastic distortion, until recently, accurate stress measurements
using this technique have been confined to the laboratory.
The recent development of compact position sensitive proportional
counters, solid state high voltage supplies and compact X-ray
tubes and the availability of powerful, inexpensive computers make it
possible to design a diffractometer to measure stress in engineering
structures and components in the field under clement conditions.
The CANMET Portable Stress Diffractometer has been designed to
make accurate stress measurements in the field while retaining adequate
versatility for dedicated laboratory use. It has several unique features
including the precisely controlled angular alignment of the incident
X-ray beam relative to the specimen surface which allows the measurement
of stress in coarse grained materials and those with pronounced gradients
in crystallographic texture. A commercial prototype of the instrument
is currently being built.