実験報告書様式（一般利用課題・成果公開利用）（ ※本報告書は英語で記述してください。ただし、産業利用課題として採択されている方は日本語で記述していただいても結構です。 ）MLF Experimental Report

提出日 Date of Report
March 7th, 2013

課題番号 Project No.

装置責任者 Name of responsible person

2012B0019

Kazuya Aizawa, Stefanus Harjo

実験課題名 Title of experiment

装置名 Name of Instrument/（BL No.）

Neutron attenuation effect on strain measurement using neutron diffraction

TAKUMI/ BL19

実験責任者名 Name of principal investigator

実施日 Date of Experiment

Hiroshi Suzuki

Nov 9th – Nov 11th, 2012

所属 Affiliation
Japan Atomic Energy Agency
試料、実験方法、利用の結果得られた主なデータ、考察、結論等を、記述して下さい。（適宜、図表添付のこと）
Please report your samples, experimental method and results, discussion and conclusions. Please add figures andtables for better explanation.
1. 試料 Name of sample(s) and chemical formula, or compositions including physical form.
Annealed steel plate (JIS-SM400A*) 100mm x 100mm x 50mm

Annealed steel stick (JIS-SM400A*) 1mm x 1mm x 50mm

*JIS-SM400A: Fe, 0.2C, 0.23Si, 0.87Mn, 0.018P, 0.005S

2. 実験方法及び結果 （実験がうまくいかなかった場合、その理由を記述してください。）
Experimental method and results.

If you failed to conduct experiment as planned, please describe reasons.

In the strain measurement using time-of-flight (TOF) neutron diffraction, the average strain in the gauge
volume is weighted towards the neutron-weighted center of gravity (ncog), which takes into accountvariations in intensity within the gauge volume due to neutron attenuation and/or absence of material in thegauge volume. The difference between the ncog position and the geometric center of the gauge volume(gcog) causes an apparent peak shift, resulting in a pseudo-strain. In this study, the pseudo-strains due toneutron attenuation and surface-effects induced in the strain measurement using TOF neutron diffraction
were investigated by comparing results between a high-intensity mode (HI-mode) and a high-resolution
mode (HR-mode) of TAKUMI.
Radial collimators for 2 mm gauge width were installed in front of ±90o detector banks. The gauge
definition slit was placed 230 mm before the diffractometer center, and the slit size was selected from 2, 8and 14 mm widths (=w) with 25 mm height. Furthermore, the beam divergence slit was placed approximately
2000 mm before the diffractometer center, and the slit widths for the HR- and HI-modes were set to be 7 mm
12. 実験方法及び結果（つづき） Experimental method and results (continued)
and full-open, respectively. Figure 1 shows the0.003

variation of pseudo-strains in the plate normal

0.0025

direction of the annealed steel plate measured

0.002

distribution for the HI-mode showed similar
trend to the results obtained in the previous
experiment(2012A0043).

However,the0.0015

Pseudo-strain

for both HR- and HI-modes. The pseudo-strain

w=14 (HR)w=8 (HR)
w=2 (HR)
w=14 (HI)w=8 (HI)
w=2 (HI)

0.001
0.00050-0.0005

pseudo-strain distributions for the HR-mode-0.001

were different from those for the HI-mode. The-0.0015

D-8

pseudo-strains for w1=2mm for the HR-mode
were smaller than those for the HI-mode since-4048gcog position from surface D, mm

12Fig. 1 Variation of pseudo-strains measured bythrough-surface strain scanning for thehigh-resolution mode (HR) and the high-intensity
mode (HI).

the beam divergence is smaller for higherresolution. It was not, however, necessarily thatthe pseudo-strains for the HR-mode were always

0.003

smaller than those for the HI-mode. Especially,

0.002

the depth where the gauge volume was

0.001

completely immersed in the specimen exceeded
the values for the HI-mode by following an
increase in the size of the gauge volume. On thePseudo-strain

compressive pseudo-strains for the HR-mode atother hand, the pseudo-strain variations due tothesurface-effectthrough-surface

strainobservedscanningin

w=14 (HR)w=8 (HR)
w=2 (HR)
w=14 (HI)w=8 (HI)
w=2 (HI)0w-0.001-0.002

theY
Stick specimen-0.003

exhibited-10

different trend between the HI- and HR-modes-505Position across incident beam Y, mm

10Fig. 2 Variation of pseudo-strains measured byscanning the stick specimen across the incident
neutron beam for the HR-mode and the HI-mode.

although the trend to increase the tensile
pseudo-strain was same. Figure 2 shows thevariation of the pseudo-strains across theincident beam measured by scanning the stick specimen. The pseudo-strains were distributed linearly in thecentral region of the gauge area while the rapid change in the pseudo-strains was observed at the edge of that.
This trend was similar between the HI- and HR-modes, but the gradient of the pseudo-strain distribution for
the HR-mode was larger. This difference in the gradient would cause difference in the pseudo-strain
distributions between the HI- and HR-modes shown in Fig. 1.
As described above, the incident beam condition was important factor to determine the pseudo-strains dueto the surface-effect and the neutron attenuation effect induced in the strain measurement using TOF neutron
diffraction. Therefore, the incident divergence of the incident neutron beam must be carefully designed to
avoid pseudo-strains in time-of-flight neutron diffractometry.

2