A STUDY OF THE BEHAVIOR OF SMALL PRESSURE VESSELS UNDER BIAXIAL STRESS CONDITIONS AND IN THE PRESENCE OF SURFACE CRACKS.
MELLON INST PITTSBURGH PA
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Results are presented of a study of small, seamless, thin-wall pressure vessels of several ultrahigh strength steels tested under biaxial stress conditions and also in the presence of surface fatigue cracks of predetermined sizes inserted on the exterior sidewall of the vessels, perpendicular to the hoop direction. Behavior of the test vessels under biaxial stress conditions is correlated to that of flat sheet specimens, containing approximately same size fatigue cracks, but tested under uniaxial stress. Flaws appeared to affect the performance of the medium carbon 0.30 to 0.35 constructional steels, AISI 4130, AMS 6434, MX-2 to a lesser degree than higher carbon 0.40 and higher and higher alloy constructional steels. Under biaxial stress conditions cracks have a more potent influence in reducing the stress capability than under uniaxial stress for all materials, except the Maraging 18Ni steels which exhibited low crack sensitivity. Fracture control mode in the presence of flaws in all except the Maraging 18Ni steel pressure vessels was K sub Ic initiated. Author