Abstract
A new uniaxial creep testing apparatus is developed for miniature specimen with total length of 6mm, gauge length of 1mm and thickness of 0.5mm. This apparatus enables the creep test under the atmosphere such as vacuum or inert gases to prevent oxidation of the specimen, and noncontact measurement of elongation by image processing during the creep test. The miniature specimens are taken from base metal (BM) and fine grained heat-affected-zone (FG-HAZ) in weld of Mod.9Cr-1Mo steel, which is the material for boiler components in thermal power plants, and creep tests are carried out at 650℃ in argon gas. The creep rupture time of the BM is almost equal to that of the standard size specimen (6mm in diameter and 30mm in gage length) in air, which indicates the validity of the test result by the miniature specimen. The creep rupture time of the FG-HAZ is shorter than that of the BM, which may be one of the reasons of Type IV creep damage in FG-HAZ of the welded joint.
