抄録
In the preceding papers about the fatigue failure of a powder bed, it was reported by the authors that there is a critical repeated stress (fatigue limit or endurance limit) in terms of fatigue failure. There is also a phenomenon in which there is an increase in its tensile strength due to a cyclic tensile stress below the fatigue limit.
In this paper, in order to investigate the relationships between this phenomenon and endurance limit, the time dependent change in the tensile strength of a powder bed by loading creeping stress in ranges of from zero to static tensile strength is examined. As the results, it was found that the tensile strength of a powder bed exerted by creeping stress near the endurance limit doesn't change even after enough creeping time in which the increase in the strength is below the endurance limit. Therefore, it is concluded that the creeping stress of the endurance limit is a sort of boundary stress of increasing and decreasing strength.
