Comparison Between J and Collapse Load Approaches Applied to Fracture Test Results on Ni Base Alloy 600 Surface Cracked Plates

The paper presents a fracture mechanics analyses of CT and surface cracked plate specimens (CCT) made from material Inconel 600. The main issue is to determine whether the plates fracture by ductile tearing or collapse with the aim of determining a simplified fracture assessment of steam generator partition plates. The paper compares J based analyses to several collapse load formulae. It is shown that estimating the tearing initiation load is almost unachievable in the present tests designed as demonstrative tests. It is also proven that most of the case collapse load formulae are very conservative. The results contribute to evidence that partition plates exhibit sufficient safety margins to failure up to the end of service life in spite of the presence of a very deep initial crack.