Teruo Asaoka1, Hideo Saito2, Norio Nogawa3, Naotake Morikawa3 and Yoichi lshida2
1Faculty of Science and Engineering, Tokyo Denki University, Saitama
By using electron microscopic tritium autoradiography and tritium release measurements, the hydrogen behavior in heat-treated Cr-Mo steels was analyzed.
The optimum experimental conditions for autoradiography were first determined including the tritium charging of the sample, selection of nuclear emulsions, protective films of the sample surface, sub-zero temperature exposure and development.
The autoradiographic observations by thin foil transmission electron microscopy, replica electron microscopy and electron microprobe analyser revealed that, prior austenite grain boundary, martensite-lath interfaces, precipitate-matrix interfaces and MnS inclusion-matrix were the trap sites for hydrogen in these steels. Tritium release measurement enabled us to separate quantitatively mobile and trapped hydrogen in these steels.
electron microscopic autoradiography, high voltage electron microscopy, tritium charge, tritium release measurement, hydrogen trap, chromium-molybdenum steel
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