Abstract
This study discusses the result of creep-fatigue tests of a high-chromium steel, F82H which was designed as blanket structural materials of nuclear fusion reactor, carried out at room temperature to 823K in air. Strain paths applied were a push-pull loading and a circle loading in which normal and shear strain have 90 degree phase difference. The holding times used were 180 s and 600 s. Moreover, an evaluation of failure life by taking into account intensities of creep and non-proportionality is discussed based on both the life evaluation proposed by Itoh, et al and method of modified universal slopes. Availability of the equation for the life evaluation was confirmed by comparison with conventional universal slope method.
Highlights
Nuclear fusion reactor is used as a kind of large scale power generation around the world1), and diversified researches are performed toward implementation of the power generation by nuclear fusion reactor
The materials used under high temperature environment has been subjected to the thermal loading in addition to the mechanical loading resulting in the non-proportional loading in which principal directions of stress and strain are changed in a cycle
Regardless of different test temperatures, the fatigue data of F82H steel can be evaluated by the method of modified universal slopes to 823K in air, and it is confirmed that fatigue life of F82H steel did not largely decrease
Summary
Nuclear fusion reactor is used as a kind of large scale power generation around the world1), and diversified researches are performed toward implementation of the power generation by nuclear fusion reactor. High chromium steel, F82H steel, was applied as a first wall of nuclear fusion reactor. This material is similar to Mod.9Cr-1Mo steel which was used as fast breeder reactor2) (FBR). Creep-fatigue tests of high chromium steel at ambient and high temperatures under non-proportional loading were conducted. Those data were evaluated by means of both the parameter concerning creep damage and non-proportionality proposed by Itoh, et al and method of modified universal slopes. Whether the equation has more validity in comparison with usual universal slope method was discussed to investigate the suitability of the modified equation as a design standard under non-proportional loading
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