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Vývoj poškození u protlačovacích zkoušek na miniaturních discích při konstantní rychlosti deformace
Dymáček, Petr ; Milička, Karel ; Hrubý, V.
In this contribution a set of three steels of various ductility has been selected and tested using small punch technique. The set of specimens was loaded in incremental way, in order to determine at which load level the crack initiates. The location of crack initiation was evaluated and compared with the equivalent plastic strain distributions in the FEM model of the specimen. The findings should help for better comprehension of the fracture mechanisms that can occur in SP testing and recognizing the main differences between the conventional and SP testing.
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APPLICATION OF SMALL PUNCH TECHNIQUE FOR EVALUATION OF MECHANICAL PROPERTIES OF ADVANCED METALLIC MATERIALS
Milička, Karel ; Dobeš, Ferdinand
Results of an application of small punch tests on non-steel advanced materials are presented with the aim to show several possibilities of this techique. As representative, three materials were selected: an aluminium alloy 2124Al reinforced with 20 vol.% SiC particulates, a composite of alloy AZ91 with Saffil fibres and an intermetallic alloy based on Fe3Al compound. It is shown that there are some close relationships between the results of the small punch technique and results of creep tests using massive specimens. Advantages of the small punch tests under specific conditions, e.g., if a small amount of testing materials is at disposal, are discussed.
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Study of local creep properties of power-plant pipe after long-term service
Milička, Karel ; Dobeš, Ferdinand
A distribution of creep properties in the wall of exposed pipe bend was studied by means of small punch creep. The method consists in a deformation of miniaturized disc specimen by spherical punch under an influence of constant force at elevated temperature. The thickness of the disc applied in the present study was 0.5 mm. The technique is illustrated using results of the tests of pipe bend manufactured from low alloy steel of Czech designation 15128 (DIN equivalent 14MoV 6 3) after service at 540 0C and 17.1 MPa for 104,000 hours. The procedures for estimating creep rupture strength and creep ductility from small punch tests are given.
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