Design to Prevent Brittle Fracture

Susceptibility of structures to brittle fracture depends on:

1. Preexisting flaw size
2. Tensile stress level
3. Fracture toughness of the material

Flaw size and stress level are controlled by design, fabrication, and inspection in accordance with the ASME code. Toughness is controlled by material selection, also in accordance with the ASME Code.

To prevent brittle fracture, keep flaw sizes small and stress levels low, and use tough materials. Toughness is a physical property of materials that primarily characterizes their resistance to brittle fracture, depending on temperature, loading rate, and thickness.

Sufficiently tough steels are selected by one of the following:
1. Using materials selection curves, or impact exemption curves, that are in the ASME Code
2. Using steels that have been Charpy V-Notch (CVN) impact tested to Code requirements

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