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

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.