Examination of Some Failures in Large Thick--Wall Pressure Vessels

This paper is concerned with an analysis of a number of failures of large-size, hypervelocity light gas gun chambers and barrels. A brief description of the light gas gun principle and of the various types of guns is first given. The failures and the investigations carried out are then described in detail, with the failures divided into two groups. The first group comprises those failures caused by certain conditions to which the guns may be submitted, and includes, for example, severe local heating of the bore surface causing hardening and cracking of the steel. These conditions were accidenta! and steps were taken to prevent them. The remaining failures were due to faults in the material or in the heat-treatment, manufacturing or assembling procedures. Specifie problems, such as hydrogen embrittlement, and the use of high strength gun barrels above their ductile-brittle transition temperature by preheating prior to firing, are briefly considered. Some interesting observations are also presented on the use of surface markings, and angles of fracture of large fragments, as an indication of the origin of fractures. The use of a slow-bend notch toughness test is also suggested for assessing the fracture toughness of steel, a property which may be more easily correlated to the actual service condition than the standard notch impact test
Keywords: Failure, failures, flange, fracture, hydrogen embrittlement, light gas gun, steel, Fracture, Fractures, Materials, steel, stress, test, Tests
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