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To Overcome Hydrogen Embrittlement & Corrosion Analyses of stress/strain distributions & martensitic transformation at SPring-8 u Environmentally Robust Materials, Institute for Materials Research u 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 hydrogen embrittlement (HE) and to develop evaluation method for HE property of high strength steels. We also attempt to apply the interaction between hydrogen and transformation for a novel method to control microstructure. In addition, we are working on 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 in center out stress (MPa) 0 1 2 3 4 5 6 -15 -10 -5 0 5 10 15 position (mm) height (mm) Mechanism of crack initiation & propagation Hydrogen visualization techniques a: Ag decoration technique b: 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 Distance from edge , mm Depth , mm -2800 -1700 -600 500 1600 strain , 10^-6 0 1 2 3 4 10 8 6 4 2 0 Distance from edge , 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 microstructure Stretch-formed specimen U-bend specimen Stress (left) and strain (right) distributions in a hole expansion specimen Stress 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 O3 supply ACM current / 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
