X-RAY STRESS ANALYSIS ON SINGLE CRYSTAL BY USING IMAGING PLATE

1997 Fiscal Year Final Research Report Summary

• Project/Area Number: 08650122
• Research Category: Grant-in-Aid for Scientific Research (C)
• Allocation Type: Single-year Grants
• Section: 一般
• Research Field: Materials/Mechanics of materials
• Research Institution: Musashi Institute of Technology
• Principal Investigator: YOSHIOKA Yasuo Musashi Institute of Technology, Faculty of Engineering, Professor, 工学部, 教授 (40061501)
• Co-Investigator(Kenkyū-buntansha): MOCHIKI Koichi Musashi Institute of Technology, Faculty of Engineering, Assistant Professor, 工学部, 助教授 (80107549) ; OHYA Shin'ichi Musashi Institute of Technology Faculty of Engineering, Assistant Professor, 工学部, 助教授 (80120864)
• Project Period (FY): 1996 – 1997
• Keywords: X-ray stress measurement, / Single crystal, / Residual stress / Imaging plate, / Back reflection method, / Laue diffraction

Research Abstract

Stresses in a single crystal specimen or any individual grain of polycrystals specimen were measured by the use of imaging plate which is a two-dimensional x-ray detector. A problem is how to measure stresses experimentally because continuous Debye-Scherror (DS) diffraction ring in not measured but only just a spot from a grain is appeared on an imaginary DS circle from polycrystals specimen. Therefore, it is important to correct such spot to be measured lattice spacing and we adopted the imaging plate and a specimen oscillating because it is easy to obtain a measurable diffraction spot on an imaginary circle.
Course grained pure iron specimens were prepared and after determination of orientation (hkl) [uvw] on each grain measured by Laue method, 211 diffractions on each grain before and after plastic deformation were measured by Cr-Kalpha x-rays. A sample stage with the phi and psi rotating attachment was oscillated upon the x-ray irradiated point on the specimen surface in RX-RY directions by use of two stepping motors to convert a measurable arc from a diffraction spot. In addition, a DS ring from annealed iron powder was also diffracted on the same imaging plate for precise determination of the distance between imaging plate and specimen.
Exposure time required for a diffraction pattern was less than 3 minutes by use of the imaging plate and the lattice spacing was accurately determined by the assistance of the image processing technique. We can determine both the stress tensor from the lattice spacing before and after plastic deformation and residual stress tensor from those after plastic deformation only. Since the difference between both tensors is comparatively small, we concluded that residual stresses in a grain can be measured without the use of lattice parameters on the non-stresses condition.