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

課題番号 Project No.

装置責任者 Name of responsible person

2014A0140

Stefanus Harjo

実験課題名 Title of experiment

装置名 Name of Instrument/（BL No.）

Measurement of residual strain profile in front of the fatigue crack

19

after excessive loading

実施日 Date of Experiment

実験責任者名 Name of principal investigator

24 April

Kenji Kikuchi
所属 Affiliation
Ibaraki University
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.
Sample used in the experimnet is a solution-annealed austenitic stainless steel and chemical composition isplate with a size of 8x20x200mm (Fig), a small bar with10A

200.1

Fe70-Ni15-Cr-15. Specimens are a type of center-cracked
3mm in diameter, and rectangular type samples. They
M20

are to be tested for residual strain profile measurement afterloading, for acquisition of d-o value in order to define strains,and for inspecting alpha prime transformation from austenitic

88R78

Ra0.8

20205030403050200

microstructure due to cold-work process, respectively.

Center nitched specimen was preloaded in order to get fatigue crack ahead of the the notch and then over-loaded
1.3 times more than o.2% proof stress level for tension and under-loaded for compression at the same level withtension.

12. 実験方法及び結果（つづき） Experimental method and results (continued)
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.

Eperimental:
Stand-alone specimen was setup on the cylindrical bar at the center position, exposed by neutron beams through1mm collimator at the injection side, and detected by the two data banks, which were called south bank at theright hand side and north bank at the left hand side. Diffracted beams were collimated through 1mm slits. Beam
exposure time duration was designed to forty minutes for every twelve scanning points. Neutron beams wasexposde at the mid-plain of the specimen plate firstly as shown in the figure below.

Diﬀrac'on*at*mid.plain  
       2mm   εy  εx

After a completion of the first measurement the position control was fit
to the neutron measurement at surface volume as shown in the rightfigure. This measurement was done to compare the inner part and nearDiﬀrac'on*near*Surface    

 

surface one. The number of measurement volume was decdreased to ninefor time economy.

2mm 


 

Another twelve scanning points measurement followed the previous measurement but after rotating the specimen
by 90 degree as shown in the figure below. This rotation enabled to get three dimentional strain components,
εz-εx and εx-εy.

  

  

 

 
 εx  

  

2mm


  
 εZ

2 Phase transformation at the strongly deformed area wasA do measurement was done for a bar type sample.
investigated for the center notched specimen near the crack tip without using prepared rectangular samples.

A bar type specimen was used to determine d-o strain.
Results:We had data stored in the two databanks and refined by Z-Rietveld. Plot showed strain profile in the frame of
distance from the crack tip, mm, and strain, µ. Strain-x, -y and -z correspond to the direction of specimen
thickness, the specimen width and loading, respectively. Strains are defined by the next equation.

ε=d − dodo600$

strain!x(in)$strain!y(in)$strain!z(in)$400$

strain!x(surf)$

Findings are:1)
€ Sign of strains to the plate thickness
direction is tension, and absolute strain level

0$0$$

at the surface is larger than that in inner part.
2) Sign of strains to the plate width direction

strain!y(surf)$

200$

!200$

1$$

2$$

3$$

4$$

5$$

6$$



is compression. It was observed null at
y=4mm at near surface while negative strains
are still remained in mid-plate.

!400$

!600$

3) Sign of strains to the axial direction iscompression.
From the sign of the residual strains it is concluded that specimen was squeezed to the plate thickness directionand elongated to the axial and plate width directions.
The purpose of this experiment was todetermine plastic region size. It wasexpected that residual strains arealmost null at the boundary between
plastic and elastic region, area notedby ????.
Further investigation is to characterize
the 3D residual strains profile after
removing external load using FEM
calculation.
Follow up experiment was rejected
in 2014B.
Request to beam line supervisor is to do inspection alpha prime transformation from austenitic microstructure
due to cold-work process, this is originally planned in the experiment. Samples have been prepared.

3