Photon Factory Activity Report 2004 #22 Part B (2005)
Materials Science

3A/2002G221

Influence of Diffraction Angle on the Area Detector Type X-ray
Stress Evaluation Through Synchrotron Radiation (2nd Report)
Toshihiko SASAKI*
Department of Materials Science and Engineering, Kanazawa University,Kakuma-machi, Kanazawa, Ishikawa 920-1192, Japan.

This is our second report on a new type of the X-

Latitude=5, Sensitivity=10000, Resolution=100µm.

ray stress measurement method (the area detector typeThe diffraction profiles in radius direction wereX-ray stress evaluation method , AD/cosα method),

calculated from the diffraction image with 1° intervalin which an area detector such as an Image Plate andof the central angle. Then, 360 diffraction peakthe cosα method as a stress-converting principle arelocations were determined for each diffraction image

combined. The method has some expected advantages

using the half-value breadth method. They were thencompared with the ordinary X-ray stress measurement

converted to the lattice strains using the Bragg’s

method. The use of synchrotron radiations will enablecondition with non-strained diffraction data. Theto perform the materials evaluation for much variable

stresses within the material were obtained from eachmaterials with higher accuracy and efficiency. For
example, the measurement at the high diffraction

diffraction image with the cosα method using
Young’s modulus, Poissson’s ratio,a supplementary

angle such as 2θ > 170° will be possible. The

angle of 2θ and an incident angle of X-ray.

measurement with this range of the diffraction angle

Figure 1(a) shows an example of the diffraction

has been thought to be impossible with the ordinary

ring obtained from the experiment. Figure 1(b) shows

X-ray method up to now because the diffraction

the relation between measured and applied stresses.

beams are generally interrupted by a part of theinstrument used. However, it is known that theprecision of the X-ray stress measurement increases
with 2θ and , therefore, the range of 2θ> 170° is themost desirable condition. Since the optics for theAD/cosα method is so simple that nothing cuts
diffraction beams, we can realize the measurement inthis hopeful condition. In order to confirm these
expected possibilities, the experiment was performed(b) result of stress obtainedwith synchrotron radiations with PF at KEK. It was

After comparing the data scattering, we saw that

also investigated to elucidate the relationship between

the precision of the stress measurement is not

the precision of the AD/cosα method and theimproved with the diffraction angle as expecteddiffraction angle under some wave lengths.

before the experiment. The order of the reliability was

The experiments were made using the BL-3A of

156° , 170° and 127° in better order. This would be

the Photon Factory at KEK. A steel plate (JIS S55C)

because there are some negative factors for stress

was used as the specimen. The principal diffraction

measurement in high 2θ condition, such as theconditions were as follows; the wave length of 0.233

increase of the full width at half maximum, thenm (2θ = 170° ), 0.209nm (2θ = 156° ) and 0.209nm

decrease of the range of the orientation of the strain(2θ = 127° ) were used. The incident angle of theused for the stress determination, and low diffraction

beam onto the area detector was 30°. The applied

intensity due to the longer optical path length.

strains given to the specimens were up to 1000 × 10-6.

*sasakit@kenroku.kanazawa-u.ac.jp

The image data stored in IP were read with the IPreader (Fuji Film BAS-2000) under the condition of160(a) Debye-Scherrer ringFig.1 211 diffractions at and stresses obtained with thecondition for 2θ = 156°

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