Ductile to Brittle Transition: Microscopic Aspects

Occurs as a competition between ductile tearing and cleavage fracture

• Ductile crack growth occurs via void growth
• Cleavage fracture by a stress controlled process

The method of fracture depends upon the size and geometry of the specimen

• Either may occur at a fixed temperature as seen in the figure on the next page
• Cleavage fracture usually occurs at a higher constraint than ductile fracture