1997 Fiscal Year Final Research Report Summary
Development of Heat-Resistant Displacement Sensitive Sensor and Mechanism Elucidation of Environmental Assisted Cracking at Elevated Temperature by Inverse Processing of Dissipative Elastic Wave
| Project/Area Number |
08455340
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| Research Category |
Grant-in-Aid for Scientific Research (B)
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| Allocation Type | Single-year Grants |
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| Section | 一般 |
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| Research Field |
Material processing/treatments
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| Research Institution | AOYAMA GAKUIN UNIVERSITY |
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Principal Investigator |
TAKEMOTO Mikio AOYAMA GAKUIN UNIVERSITY COLLEGE OF SCIENCE AND ENGINEERING,PROFESSOR, 理工学部, 教授 (40082838)
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| Project Period (FY) |
1996 – 1997
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| Keywords | heat resistant AE transducer / capacitive transducer / conical typc displacement trasnducer / AE source simulation / fracture dynamics / molten chloride stress corrosion cracking / fused solder embrittlement / アコースティック・エミッション |
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| Research Abstract |
Research aims to develop a out-of-plane displacement sensitive and heat resistant acoustic emission transducer which serves at temperature around 600C,and to study the mehanism and dynamics of environmentally assisted fracture. We developed two types of heat resistant transducer. One is the capacitive transducer with thin (3 micrometer) amorphous but stoichiometric alumina film which si deposited by the IR laser PVD.This sensor was demonstrated to be broad band and accurately measure the out-of-plane displacement at temperature below 600C.Disadvantage of this transducer is noise-generation due to its high bias voltage. Then we developed another conical-type transducer with a LiNbO3 element whose Curie temperature is above 1000C.Frequency band of this transducer is narrow compared withjthat of capacitive one, but it measures the out-of-plane displacement at high sensitivity below 600C.As the transducer size was minimized so as to make the multi-channel monitoring possible.
Using the transducers developed, we first measured the velocity dispersion and wave attenuation of the longitudinal wave in hot austenitic atainless steel AISI 340. we also monitored AE signals from type 304 steel subjected to molten chlorides and fused silver-based solder at 600C.A number of AE signals from fast fracture were monitored by the developed AE system. The fracture dynamics, or the fracture kinematics and kinetics, were estimated by the souce simulation to the monitored out-of-plane displacement. The source simulation developed consists of matching the displacement computed by the convolution integral of the theoretical Green's function of the second kind with the retardation function and the assumed source dynamics to the monitored one. It was first elucidated that extremely fast fracture are associated with the molten salt stress corrosion cracking and fused solder embrittlement.
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