Use of Metallography in Failure Analysis
Speaker: George F. Vander Voort
Vander Voort Consulting L.L.C. and Consultant – Struers Inc.
This course is designed to teach fundamental principles for analysis of metal failures with a strong emphasis on the use of microscopy techniques. The
following main topics will be covered:
- “How to Conduct the Failure Analysis” will discuss the following topics: why do we do failure analysis, causes of failures, examination steps for failures,
tool of the analyst, examination sequence, examination of fractures, macroscopic and microscopic methods for failure analysis, analytical tools,
typical questions to answer in the analysis program, and writing the report, making recommendations and follow up.
- “Fractography” will cover the examination of fractures and will discuss and illustrate the following topics: fracture modes and mechanisms, macroscopic
and microscopic characteristics of ductile fractures, brittle fractures (cleavage or intergranular), fatigue fractures, and corrosion-assisted
fractures. Each topic will be illustrated using macroscopic images, light optical microscope images of fracture paths and fracture surfaces and
SEM images and TEM replicas of fractures.
- “Failures Due to Materials or Manufacturing Problems” will cover and illustrate failures due to material problems, such as: initiation sites at shrinkage
cavities in castings, hydrogen blisters and hydrogen flake failures, failures due to poor formability, failures due to internal liquid metal embrittlement,
failures due to nonmetallic inclusions, grain boundary carbide films and seams and laps. Failures due to manufacturing problems included: heat
treatment problems, such as, decarburization, over- or under-austenitization, decarburization, excessive carburization, failure to temper, temper
embrittlement, quench cracks, over-heating or incipient melting, and flame impingement; plus, grinding abuse, improper electrical-discharge machining
(EDM), and welding failures.
- “Failures Due to Service Problems” will cover and illustrate failures due to corrosion problems (SCC, intergranular corrosion, sensitization and exfoliation),
creep, embrittlement phenomenon (sensitization, sigma precipitation, 700 °F embrittlement of ferrite in stainless steels, embrittlement from excessive
nitride precipitation and liquid metal embrittlement), fatigue, thermal fatigue and wear.
- “Failure Examples” provides detailed studies of specific failure case histories: A Loran C tower in Greenland that collapsed when one guy wire broke;
the derailment of an Auto- Train system in Florence, SC, when a drive axle failed due to an over-heated friction bearing; and, ASTM A490 high-strength
steel bolts that failed after being installed in structural beams in the Collins Power Plant in Morris, Illinois.
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