Ductile fracture strength of nickel-based alloy plates with a surface flaw

• Published in: International journal of pressure vessels and piping Vol. 85; no. 9; pp. 612 - 615
• Main Authors: Nebu, Akira, Miyazaki, Katsumasa, Saito, Koichi
• Format: Journal Article Conference Proceeding
• Language: English
• Published: Oxford Elsevier Ltd 01.09.2008; Elsevier
• Subjects: Applied sciences; Ductile fracture; Energy; Energy. Thermal use of fuels; Exact sciences and technology; Fission nuclear power plants; Flow stress; Fracture mechanics (crack, fatigue, damage...); Fundamental areas of phenomenology (including applications); Installations for energy generation and conversion: thermal and electrical energy; Limit-load analysis; Nickel-based alloy; Physics; Solid mechanics; Structural and continuum mechanics; Ductile fracture; Limit-load analysis; Nickel-based alloy; Flow stress; Ductility; Ultimate limit; Load flow; Crack propagation; Welded joint; Limit state(deflection); Crack tip; Ductile material; Nickel base alloys; Carrying capacity; Weld metal; Crack width; Experimental study; Plate; Nuclear power plant; Surface defect; Plastic limit; Yield strength; Breaking test; Ultimate load; Crack
• DOI: 10.1016/j.ijpvp.2007.08.011
• ISSN: 0308-0161

Limit-load analysis is applied to fracture analyses of flawed components made of materials with high ductility in the JSME code for inservice inspection for nuclear power plant. However, the applicability of limit-load analysis to Ni-based alloys has not yet been clarified. Furthermore, flow-stress level for Ni-based alloy has not been verified by experiments. To clarify applicability of limit-load analysis and actual flow-stress level for Ni-based alloys, the ductile fracture tests were conducted. The specimens were made from both base metal and welded joint plates with a surface flaw or a through-wall flaw. In specimens with a shallow flaw, the tensile load increased with the tip of flaw blunting, and the load dropped down at the penetration of ductile crack initiated at the blunted flaw tip. In the specimens with a deep flaw, the tensile load increased due to the blunting of the flaw tip at the width direction after penetration of ductile crack. The load dropped down at the beginning of ductile crack growth in the width direction. In all cases, the net stress at the maximum tensile load was higher than 2.7 Sm and the average of yield stress and ultimate strength.