Yield-Before-Break Fracture Mechanics Analysis of High-Strength Steel Pressure Vessels

Abstract

Case study examples of fracture mechanics testing and analysis of Ni-Cr-Mo high strength steel cannon tubes are presented. The testing and analysis include the situation of significant plastic deformation accompanying fracture, which often occurs when high pressure is applied to high-toughness steel pressure vessels. analysis is based on a comparison of the size of the Irwin crack-tip plastic zone the remaining ligament of the tube in the area of the critical fatigue crack which causes final failure. The results of the study show that the type of final failure can be predicted—as either a relatively safe, yield-before-break failure or a less safe running-crack type of failure—for a variety of material, configuration, and loading conditions.