Development and evaluation of middle scale CBB test method with notched specimen

摘要

A modified middle scaled CBB test method with a notched specimen is developed and its stress conditions are evaluated, in order to investigate stress corrosion cracking behavior around fusion boundary between nickel base alloy (Alloy 182) and low alloy steel (LAS) under high stress condition. Stress conditions of crack tips are evaluated by a newly developed 'equivalent stress intensity factor, KJ', which is defined by J integral considered plastic deformation behavior around a crack tip. Stress analyses revel that KJ value of the notched specimen is greater than that of a smooth specimen with multi cracks. By adequately changing a configuration of notch, including its depth and radius of curvature, a CBB test could be carried out under a stress condition at arbitrary KJ value. In addition, multi notched specimens with various notch configuration are useful for investigation of crack propagation under different stress conditions at the same time.