SB-01-4(049) Basic Material Properties of Cr-Mo Steels over 1273K(Materials Performance in Nuclear Application 1)

概要

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In the steam generator (SG) of liquid metal fast breeder reactor (LMFBR), the tube may be exposed to higher temperatures higher than 1273K in sodium-water reaction caused by a single tube break accident. At this ultra high temperature, it is necessary to prevent the overheating rupture of SG tubes owing to the decrease of creep-rupture strength. In this study, the tensile and creep rupture tests at high temperatures above 1273K were carried out in order to evaluate the mechanical properties of the SG tube materials. The testing temperatures were from 973 to 1573K which cover the temperature where phase transformation of material structure from α-phase to γ-phase occurs. The tested materials were 2.25Cr-1Mo (4 heats) and Modified 9Cr-1Mo (2 heats) steels. The heat-to-heat variation was negligible in tensile and creep rupture tests at high temperature range from 1223 to 1573K. Within the overheating temperature limits of the tubes, the creep effect was dominant even when the loading time was shorter than a few seconds. Creep test data of both steels at high temperature up to 1573K could be expressed by Larson-Miller parameter method, and design allowable values for tube rupture strength were formulated based on the results.
一般社団法人日本機械学会の論文
2001-06-03