FRACTURE TOUGHNESS OF PRESSURE VESSEL STEELS - AWRA DOCUMENT P2-45-85, AWRA CONTRACT 93.

This report is in three parts. The first describes theoretical work to determine the hydrostatic stress in a three-point bend specimen as a function of crack depth and a relationship for the crack opening displacement that is valid for shallow cracks. The second part discusses the possibility of using machined notches instead of fatigue cracks in COD testing. In the third part the initiation crack opening displacement of AS 1405-180 as a function of hydrostatic stress is given. Work is still proceeding but it is believed that there is a definite relationship between delta //i and the hydrostatic stress. In practice, many defects in actual structures are in the form of shallow surface cracks. The hydrostatic stress at the tip of such surface cracks is much less than that obtained in the standard COD test. Consequently, it is desirable to introduce a COD test that uses a shallow crack. The first two parts of this report indicate that it is possible to introduce a standard test for shallow notches.