What is the difference between brittle and ductile failure?

Brittle and ductile failures describe how materials break under mechanical stress. Brittle fractures occur suddenly without noticeable prior deformation, whereas ductile fractures exhibit visible deformation before final separation. Component characteristics like thickness and stress conditions can also influence whether a material behaves in a brittle or ductile manner.

What we know

• Brittle fractures occur without any apparent deformation before the actual fracture happens. [2]
• Ductile fractures take place after visible deformation has occurred in the material. [2]
• Thick components have plane strain conditions that increase constraint and lead to brittle failure. [5]
• Thin components have plane stress conditions that lead to ductile behavior. [5]

Where to go next

• the bigger pictureWhat is fracture mechanics?
• how it workedHow does component thickness affect fracture?
• compared withWhat is fracture toughness?
• what followedHow does fatigue cause material cracks?
• a case in pointHow do geological rock fractures form?
• an unexpected connectionWhy did people once think metal railway axles crystallized?In the nineteenth century, the sudden brittle appearance of failed metal railway axles led observers to mistakenly blame metal crystallization.

Sources

• [1]fracture (Wikidata Q5120022) · CC0 1.0
• [2]Fracture · CC BY-SA 4.0
• [3]Fatigue (material) · CC BY-SA 4.0
• [4]Fracture (geology) · CC BY-SA 4.0
• [5]Fracture toughness · CC BY-SA 4.0