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Doshida, Tomoki*; Suzuki, Hiroshi*; Takai, Kenichi*; Hirade, Tetsuya; Oshima, Nagayasu*
NanotechJapan Bulletin (Internet), 8(3), 5 Pages, 2015/07
Studying the creation and time evolution of defects is an important issue for interpreting the hydrogen embrittlement mechanism of steels. We have been studied the relationship between hydrogen embrittlement of high strength steel and lattice defects associated with hydrogen by thermal desorption analysis (TDA) and positron probe microanalyzer (PPMA).
Doshida, Tomoki*; Suzuki, Hiroshi*; Takai, Kenichi*; Oshima, Nagayasu*; Hirade, Tetsuya
ISIJ International, 52(2), p.198 - 207, 2012/02
Times Cited Count：60 Percentile：92.22(Metallurgy & Metallurgical Engineering)Hydrogen behavior and hydrogen-enhanced lattice defect formation under elastic stress of tempered martensitic steel were clarified with respect to dislocations and vacancies by thermal desorption analysis (TDA) using hydrogen as a probe of defects and a positron probe microanalyzer (PPMA). The relationship between hydrogen embrittlement and lattice defects associated with hydrogen was also investigated. The amount of lattice defects increased gradually with increasing time of applied stress. The specimen fractured under elastic stress. The enhanced vacancies due to interactions between dislocations and hydrogen under elastic stress directly caused ductility loss. Even though hydrogen was completely removed by degassing the vacancies remain. Besides hydrogen content and applied stress, the time of formation and accumulation of vacancies are also concluded to be important factors causing hydrogen embrittlement.
Doshida, Tomoki*; Suzuki, Hiroshi*; Takai, Kenichi*; Hirade, Tetsuya; Oshima, Nagayasu*
no journal, ,
Hydrogen embrittlements of materials occur under elastic stress. Therefore we tried to investigate the defects in high-strength steel caused by hydrogen under elastic stress by the thermal desorption analysis of hydrogen gas and positron annihilation lifetime analysis by use of positron micro analyzer. We successfully obtained results showing the defects created by hydrogen under elastic stress cause the embrittlements.
Takai, Kenichi*; Doshida, Tomoki*; Suzuki, Hiroshi*; Oshima, Nagayasu*; Hirade, Tetsuya
no journal, ,
For high-strength steel for light weight automobile or society by use of hydrogen, we need to overcome the hydrogen brittleness right away. The hydrogen brittleness for high strength steel under constant load was investigated by thermal desorption analysis and positron annihilation lifetime measurement. We found that the hydrogen brittleness fracture was caused by the defects accumulated by existence of hydrogen under constant load.
Doshida, Tomoki*; Takai, Kenichi*; Hirade, Tetsuya; Oshima, Nagayasu*
no journal, ,
Hydrogen behavior and hydrogen-enhanced lattice defect formation under elastic stress of tempered martensitic steel were clarified with respect to dislocations and vacancies by a positron probe microanalyzer (PPMA). The relationship between hydrogen embrittlement and lattice defects associated with hydrogen was also investigated. The specimen fractured under elastic stress. The enhanced vacancies under elastic stress directly caused ductility loss. Even though hydrogen was completely removed by degassing the vacancies remain. Besides hydrogen content and applied stress, the time of formation and accumulation of vacancies are also concluded to be important factors causing hydrogen embrittlement.
Doshida, Tomoki*; Suzuki, Hiroshi*; Takai, Kenichi*; Oshima, Nagayasu*; Hirade, Tetsuya
no journal, ,
Changes in hydrogen content and lattice defect formation associated with hydrogen under elastic tensile stress of tempered martensitic steel were examined. The relationship between hydrogen embrittlement and lattice defects associated with hydrogen was also investigated. The results obtained in this study can be summarized as follows. Besides hydrogen content and applied stress, time of the formation and accumulation of vacancies was also closely involved in hydrogen embrittlement and is concluded to be an important factor causing hydrogen embrittlement.
Oshima, Nagayasu*; Doshida, Tomoki*; Suzuki, Hiroshi*; Takai, Kenichi*; Hirade, Tetsuya
no journal, ,
Studying the creation and time evolution of defects is an important issue for interpreting the hydrogen embrittlement mechanism of steels. We have been studied the relationship between hydrogen embrittlement of high strength steel and lattice defects associated with hydrogen by a positron probe microanalyzer (PPMA) which is positron lifetime measurement system with a pulsed positron microbeam. The results with the mean positron lifetime measurements indicated that vacancies or vacancy clusters were additionally formed with hydrogen embrittlement under elastic stress. We also have tried to see the detail of the change with hydrogen embrittlement by applying the multicomponent analysis of positron annihilation lifetime spectra. The results indicated a possibility that the vacancies were formed as the complex with dislocations.
Doshida, Tomoki*; Suzuki, Hiroshi*; Takai, Kenichi*; Hirade, Tetsuya; Oshima, Nagayasu*
no journal, ,
Studying the creation and time evolution of defects is an important issue for interpreting the hydrogen embrittlement mechanism of steels. We have been studied the relationship between hydrogen embrittlement of high strength steel and lattice defects associated with hydrogen by thermal desorption analysis (TDA) and positron probe microanalyzer (PPMA).
