| 摘要 |
PURPOSE:To understand quantitatively the lamellar tear of a steel material, by forming a annular cut at the edge part of a test piece cut from the thickness direction of a steel plate, generating a fatigue crack at the bottom part of the annular cut and applying the upper tensile strength of bead welding to a supporting member. CONSTITUTION:A test piece 4 is cut out of a basic material 1 from its thickness direction, and a annular cut 5 is formed at an area several millimeters apart from the surface of the material 1 by a mechanical process. Then a rod-shaped auxiliary member is joined to the tip of the piece 4 by a press-contact process, etc., and the tensile strength of a low cycle is applied to the piece 4 to produce a annular fatigue crack 5 at the bottom area of the cut 5. Then the auxiliary member is removed, and the piece 4 is inserted to a supporting plate 8. Then a welding bead 2 is welded at the upper end of the piece 4, and the piece 4 is joined to the plate 8. The tensile strength is applied immediately after welding to perform an implant type test. The measurement of a crack length is consecutively recorded by a potential difference method. Then the transmitting action is rearranged by a breakdown dynamic method for generation of lamellar tear due to the fatigue crack. |
