実験報告書様式（一般利用課題・成果公開利用）

MLF Experimental Report
課題番号 Project No.

提出日 Date of Report
2014/10/08
装置責任者 Name of responsible person

2014A0302
実験課題名

Kazuya Aizawa, Stefanus Harjo
Title of experiment:

Role of Graphite in

装置名 Name of Instrument/（BL No.）

Deformation Behavior of Ductile Cast Irons during Cyclic

TAKUMI (BL19)

Tension-Compression Loading

実施日 Date of Experiment

実験責任者名 Name of principal investigator

2014/5/14 - 2014/5/17 (4 days)

Stefanus Harjo所属 Affiliation: J-PARC Center, JAEA
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.
A low carbon ferrite single phase steel and two ductile cast irons (FCD steels) with different morphologies
were used in this study. The chemical compositions are shown below.

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.

Dog-bone type specimen was prepared to have a parallel part with 6 mm diameter and 4 mm length. The
specimen was mounted horizontally in a loading machine which was installed at TAKUMI, in such a way thatdiffraction patterns for axial (tensile) and transversal directions could be measured simultaneously by two 90°
scattering detector banks. Neutron diffraction measurement was conducted with an incident slit size of 5 mm
× 5 mm and radial collimators viewing 5 mm wide, i.e., the average data from the parallel part was measured.
Cyclic tension-compression deformations were conducted in a continuous manner with a nominal strain rateof 5.5×10-6 s-1 in the nominal strain range of ± 1%. The nominal strain was controlled by averaging strain
values measured using two strain gauges glued on the specimen parallel part. Diffraction patterns were thensliced per 300 s, and the relevant applied macroscopic strain and stress values for each slicing interval time
were averaged over the slicing interval time. To observe intergranular strains, single peak fittings as well as amulti peak fitting using a Rietveld software were performed for data analyses.

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

Fig. 1 Macroscopic true stress strain curves of thesamples during cyclic tension-compression tests

Figure 1 shows that the tensile stresses of theferrite single phase steel are the lowest among
the three samples, while those of the FCD steel
with pearlite matrix are the highest. The tensilestresses are increased in the ferrite single phasesteel and in the FCD steel with ferrite matrix,
showing hardening due to the cyclic loading. Theferrite phase strains in the ferrite single phasesteel and in the FCD steel with ferrite matrix wereincreased with respect to the macroscopic strain(the results are not plotted here), being relevantto the increasing tensile stresses. However, thetensile stresses in the FCD steel with pearlite
matrix are almost not changed.
The phase strain responses with respect to theFig. 2 Phase strain responses with respect to themacroscopic true stress in three different samples

macroscopic true stress in three samples areshown in Fig. 2. The phase strain response in the ferrite single phase steel is linear to the macroscopic truestress even the sample is deformed plastically. In FCD steels, where different phases exist, the responses
deviate from the linearity at higher stress levels, i.e. elasto-plastic deformation stage, because load sharing
among constituent phases due to the different deformability and elastic stiffness. From comparison of theresponses in two different FCD steels, it is clear that the different matrix gives different responses in all
constituent phases, and these influence to the macroscopic stress-strain.
Note: The diffraction peaks of cementite were also recognized in the FCD steel with ferrite matrix, due tothe small amount of pearlite. Lattice strains for cementite, however, were difficult to be determined, because
those peaks were very small.

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