Crack Arrest Fracture Toughness Evaluation of Naval Construction Steels

摘要

The steels used in the fabrication of the pressure hulls of modern submarines aresubjected to rigorous testing regimes to ensure structural integrity during service. The testing to ensure structural integrity encompasses the basic property determinations such as tensile properties as well as charpy impact, dynamic tear energy and explosion bulge testing but does not include a quantitative dynamic fracture mechanics assessment Crack arrest fracture toughness, K sub la, characterizes the ability of a material to arrest rapidly propagating cracks. Although the assessment of arrest toughness does not include kinetic energy input or crack velocity dependence, it is considered appropriate for the assessment of the dynamic properties of submarine steels. This paper reports the use of a K sub la test method for the assessment of the dynamic toughness of three steels as parent plate and in the welded condition. K sub la assessment was conducted over a limited temperature range. Scanning electron microscopy of the fractured specimens was undertaken in an attempt to relate K sub la values to failure mechanisms.