Fractography Services

Fractography is the study of fracture surfaces of materials. Stork experts employ fractographic methods to determine the failure causes of parts, products, and engineering structures.

A fracture surface is a source of information regarding the cause of the fracture. It contains the evidence of material deficiencies, effects from the environment, and application of force. This evidence can be observed using electron fractography.

Four ways to fail
Materials fail for different reasons, but they fracture by four principal modes: fatigue, cleavage, dimple rupture, and decohesive rupture. Each of these modes has its own characteristic fracture appearance.

Fatigue fracture is the result of repetitive loading. Crack(s) initiates in Stage I, propagates in Stage II, and reaches catastrophic fracture including separation in Stage III. Fatigue striations observed generally in high cycle fatigue align perpendicular to crack propagation direction.
Cleavage is a low-energy fracture that is completely flat and featureless. River patterns, feather markings, and chevron patterns are some of the features observed in cleavage mode of fracture.
Dimple rupture is the mode of fracture when an overload is the principal cause of failure. Microvoid coalescence is the characteristic feature observed in dimple rupture.
Decohesive rupture occurs with little plastic deformation and involves weakening of the atomic bonds. Hydrogen embrittlement, stress corrosion cracking, and creep are some of the examples of decohesive rupture.

Stork locations offering Fractography Services:

Stork Materials Testing & Inspection - Huntington Beach, CA

Stork Herron Testing Laboratories, Inc. - Cleveland, OH

Stork Technimet, Inc. - New Berlin, WI

Stork Twin City Testing Corporation - St. Paul, MN

Stork Climax Research Services - Wixom, MI

Articles and case studies available for downloading for Fatigue Testing:

Technical Article: Fractography, an important tool for analyzing metal failures