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 Report2013.5.21
装置責任者 Name of responsible person

2012B0003

Kazuya AIZAWA

実験課題名 Title of experiment

装置名 Name of Instrument/（BL No.）

Martensitic transformation and carbon partitioning

TAKUMI BL19

実験責任者名 Name of principal investigator

実施日 Date of Experiment

Zengmin SHI

2013/02/18 ~ 2013/02/21

所属 Affiliation
Huazhong University of Science and Technology
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.

Martensite steel C0.22Si0.87Mn1.6
Composition: Fe-0.22C-0.87Si-1.64Mn-0.024Ti -0.0015B-0.0025N (wt. %)Physical form:

Solid, rod specimens with a dimension of 7×14 mm

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.

Experiment 1: High Temperature Deformation, Recovery and Recrystallization of Austenite.
Rod Specimens were heated up to austenitizing temperature 950 °C for 10min followed by gas cooling down
to 850°C for being performed an isothermal process, and then cooling in gas atmosphere. During the isothermal
process, specimens were applied compression or tension deformation, and then held for 90min to investigate therecovery and recrystallization behavior of the deformed austenite. The deformation amount was 15% forcompression deformation and 25% for tension deformation, where the deformation rate was 0.001s-1. The wholeexperimental time for individual process is about 4 hours. One of the performed thermo-mechanical schedule isshown in Fig.1 (a).
Experiment 2: Continue Cooling with Compression Deformation.
Rod specimens were heated up to austenitizing temperature 950 °C for 10min followed by gas cooling above
850 °C, and then cooling in gas atmosphere from 850 °C. During cooling, the specimens were simultaneously
compressed and the initial deformation temperature was 850 °C. The deformation amount was 0%, 10% and30%, respectively, which implied that the specimen temperature was 850, 769 and 699 C, respectively, at theend of deformation. The heating and cooling schedule under deformation amount of 30% is illustrated inFig.1(b).
Experiment 3: Dynamic Ferrite Transformation
12. 実験方法及び結果（つづき） Experimental method and results (continued)
Rod specimens were heated up to austenitizing temperature 950 °C for 10min followed by gas cooling down
to 690C for 100min, and then cooling in gas atmosphere. During the isothermal process at 690C, specimens
were compressed by 0% or 40% at the deformation rate of 0.0015s-1, or elongated by 20% followed by thecompression deformation of 20% at the constant deformation rate of 0.0015s-1. The performed
thermo-mechanical schedule of the last deformation schedule is shown in Fig.1(c).
Experiment 4: Tempering Behavior of Martensite.
The experiment schedule is shown in Fig.1 (d). Specimens were heated up step by step to austenitizing
temperature 950 °C and kept for 10min followed by gas cooling to room temperature. The step time was 10minand the heating speed was 5°C/s.
Experiment 5, Isothermal Transformation Behavior.
The thermo-mechanical schedule is shown in Fig.1 (e). Rod specimens were heated up to austenitizing
temperature 950 °C for 10min followed by gas cooling down to 690°C, 550, 500°C for 60min, respectively, andthen cooling in gas atmosphere to room temperature.
1000

8Disp
Temperature

1000(b)

4800
2600
4400

Disp(mm)oTemperature( C)6oTemperature( C)

800

Disp
Temperature

600
0400

Disp(mm)(a)-22200

200-4
1.2

2.4

3.6

4.800.00

6.0

1.2

2.4Time(s)5DispTemperature

4.81000(d)

350
300

600

3800
250

o

4

Temperature( C)

800

400

2200

1002468

1012Disp(mm)

o600

200
Temperature

400

100200500002Disp
Temperature

2.52.0600

1.5

600.14(f)ForceDisp

1200

800

4Time(ks)Time(ks)(e)1000150

L0.12Disp(mm)Force(MPa)o0.109000.08600

400

1.02000.5300

00.000.06
0.04
0.02

02468101214Time(ks)0246810Time(Ks)Fig.1 Thermal Schedule of the experiment (a) 1, (b) 2, (c) 3, (d) 4, (e) 5 and (f) 6.

2

0.00
12Disp.

Temperature( C)(c) 1000

Temperature( C)

3.6Time(ks)L( m)00.0

2. 実験方法及び結果（つづき） Experimental method and results (continued)
Experiment 6: Tensile Behavior of Martensite at Room Temperature.
Rod specimens were tensile deformed at room temperature, and the applied force and displacement curve isshown in Fig.1 (f).
The diffraction data were analyzed by the Rietveld method. The diffraction profiles, diffraction intensity, thepeak position and full width at a half maximum (FWHM) are used for studying the change of the phase volume
fraction, lattice strain, lattice parameter and texture. From the analysis, some interesting conclusions can bedrawn. For example, the conclusion of the experiment 2 are as follows:

The start ferrite transformation temperature detected from the neutron diffraction profile (Fig.2) increased
from 686°C, 705°C to 716°C with the increase of austenite deformation amount from 0%, 10% to 30%,respectively. The deformation of austenite influenced the carbon partitioning during the transformation. The
carbon content of retained austenite is decreased with the increase of the deformation amount, as shown inFig.3. However, the quantity of carbon partitioning into the ferrite was not sufficient to make noticeablechange of lattice parameter of ferrite. The deformation of austenite further intensified the {111} and {200}intensities in the transverse direction (RD) and gradually intensified the {220} intensity in the compression
axial direction (ND) with increasing the deformation amount, as shown in Fig.4. While the {100} and{211} ferrite intensities in the ND were strengthened by deformation.
The others are being in analysis and omitted.
_0%
_10%
_30%

Lattice parameter(A)

3.66
3.65
3.64
3.63
3.62
3.61

1000

800

600

400

200

0oTemperature( C)Fig.2 Neutron Diffraction profiles for the transverseFig.3 Change of the lattice parameter of austenite

direction (RD)with temperature
0.50

0.35

Defromation

Relative integral of intensity

Relative integral of intensity

0.450.30

Inten_RD_30%_(111)Inten_RD_30%_(200)Inten_RD_30%_(220)Inten_RD_30%_(311)0.25Transformation
0.20

0.15
900

800

700

600

500

400

300

200

0.35

Transformation

0.30
0.25
0.20
0.15
0.10

100

Inten_ND_30%_(111)Inten_ND_30%_(200)Inten_ND_30%_(220)Inten_ND_30%_(311)

Deformation

0.40

900

800

700

600

500

400

300

200

100oo

Temperature( C)

Temperature( C)Fig.4 Relative integral intensities of austenite as a function of temperature with the deformation amount of 30% in
the (a) RD and (b) ND.

3