| 摘要 |
PURPOSE:To obtain a metallic material which can effectively prevent the generation of the creep embrittleness occurring in <10>B of a metallic material for a nuclear reactor which receives thermal neutron irradiation by preliminarily adding B-contg. raw material of which the quantity ratio <11>B(<10>B+<11>B) of the isotope <11>B of B is higher than the natural existence ratio to said material and subjecting the material to de-B refining. CONSTITUTION:The cause for the creep embrittleness by the thermal neutron irradiation lies in that He is generated by the reaction of <10>B in particular among the isotopes of B, i.e., <10>B(n,alpha)<7>Li reaction. In contrast therewith, <11>B is stable and does not induce the nuclear reaction to form He. The <11>B is there upon added positively to the metallic material such as carbon steel, low Cr-Mo steel or ferrite chromium steel in the process for producing such material in this invention. The quantity ratio of the <10>B in the total B(=<10>B+<11>B) contained in the molten metal, i.e., <10>B/(<10>B+<11>B) is thereby decreased and thereafter the molten metal is subjected to the de-B refining. As a result, the generation of the creep embrittleness occurring in the <10>B of the above-mentioned metallic material is effectively prevented.
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