To Overcome Hydrogen Embrittlement & Corrosion
Analyses of stress/strain distributions & martensitic transformation at SPring-8
u Environmentally Robust Materials, Institute for Materials Researchu Science and Technology of Functional Materials (Cooperative Lab.),
Department of Quantum Science and Energy Engineering Akiyama Laboratory
• Development of advanced steel• Microstructural control utilizing H
Prof. E. Akiyama
We are concentrating to clarify the mechanism of hydrogenembrittlement (HE) and to develop evaluation method for HEproperty of high strength steels. We also attempt to apply theinteraction between hydrogen and transformation for a novelmethod to control microstructure. In addition, we are workingon corrosion control for nuclear decommissioning.Fracture of an exposed high strength bolt
caused by hydrogen entry due to corrosion
Thermal desorption spectrometer（Codeveloped with R-DEC Co., Ltd.)
An apparatus to detect hydrogen during tensile test
HE mechanism & evaluation method
Energy dispersive X-ray diffraction (BL14B1)
a b
-1000
-500
0
500
1000incenterout
stre
ss (M
Pa)
0123456
-15 -10 -5 0 5 10 15position (mm)
heig
ht (m
m)
Mechanism of crack initiation & propagation
Hydrogen visualization techniquesa: Ag decoration techniqueb: Scanning Kelvin probe force microscope
Evaluation of HE property of high strength steel sheet simulating press forming
Hydrogen and martensitic transformation
0 1 2 3 4
10
8
6
4
2
0
Dis
tanc
e fr
om e
dge
, mm
Depth , mm
-2800
-1700
-600
500
1600
strain , 10^-6
0 1 2 3 4
10
8
6
4
2
0
Dis
tanc
e fr
om e
dge
, mm
Depth , mm
0
5
10
15
20
25
30
FWHM
ACM censor
ACM logger
constant temperature & humidity chamber
ozone meter
water trap
mass flow
air pump
Transformation induced hydrogen desorption
Cracking and microstructureStretch-formed specimen
U-bend specimen
Stress (left) and strain (right) distributions in a hole expansion
specimenStress distribution in a
stretch-formed specimen
Corrosion test under g irradiation @ QST Takasaki
Tensile test machine
Corrosion of carbon steel under g irradiation and simulating corrosion test
50 °C
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O3供給O3 supply
ACM
cur
rent
/ µA
Ozone concentration / ppm
Time / min
Acceleration of corrosion by ozone
Corrosion monitoring using an ACM sensor in a corrosion test chamber with
introduced ozone
Transformation during tensile test
Assoc. Prof. M. Koyama Assis. Prof. T. Hojo
