Estimating structural integrity, using the TPFC approach, of annealed type 304 stainless steel plate and pipes containing surface defects

Test results and an evaluation of the two-parameter fracture criterion (TPFC) are presented. The tests were conducted at room temperature with annealed Type 304 stainless steel flat-plate tensile specimens containing triangular-, ellipsoidal- or rectangular-shaped surface flaws, and pressurised pipe specimens with internal or external triangular-shaped surface defects. Generally accepted analytical techniques are not available for these and other very ductile materials used in many nuclear reactor components and an accurate assessment of the influence of defects on structural component integrity is needed. The TPFC approach was used in conjunction with the initial defect size and the loads required for the initiation of subcritical crack growth, for penetration through the wall thickness and for instability. Generally, the test results obtained from the flat specimens could be used to predict, from a conservative point of view, the behaviour of pipe specimens. Since K F is thickness dependent, it is recommended that tests be conducted for the specific thickness of concern using specimens containing surface defects. The TPFC approach can provide an accurate means for predicting structural integrity.