---
name: fractography
title: Determine Failure Mode and Initiation Site From a Fracture Surface
description: Read a fracture surface systematically for initiation site, crack-growth features, and final-fracture region before attributing a cause.
keywords:
- level:L1
- characterization
---

Examine the fracture surface at multiple scales, low magnification first: locate the
initiation site (often at a surface, near-surface defect, or internal
inclusion/pore), the crack-growth region, and the final overload/fast-fracture
region, and state their relative extent — a large fatigue-growth region with a
small overload region indicates a low applied stress relative to the
material's toughness, and vice versa.

Identify features that indicate mechanism: fatigue striations and beach
marks (progressive cyclic growth), dimpled/ductile rupture (final overload
in a ductile material), cleavage or intergranular facets (brittle or
environmentally-assisted fracture) — state which features were actually
observed rather than assuming a mechanism from the loading history alone.

Connect the initiation site to a specific feature when possible: a pore or
inclusion visible at the origin (cross-reference `xct` if available), a surface roughness feature or machining mark, or a design
stress concentration — a fractographic finding that identifies WHERE and
often WHAT initiated failure is far stronger evidence than a fatigue-life
number alone.

Return the initiation site and its associated feature (defect, surface
condition, geometry), the crack-growth and final-fracture region extents,
and the failure mechanism the observed features support.