Failure analysis: an investigative process

The initial step to perform a failure analysis investigation begins with visually studying the failed part and asking detailed questions regarding associated parts, plant environment and operational procedure. A summary of the investigation steps includes:
• Collection of background data and selection of samples (service history and conditions)
• Preliminary examination of the failed part
• Complete metallurgical analysis of failed material (mechanical properties, chemical composition).
• A thorough examination of the failed part including macroscopic and microscopic examination and analysis (electron microscopy). This includes fractographic analysis.
• Analysis of fracture mechanics (shear, brittle or ductile).
• Evidence Interpretation, formulation of conclusions and writing of final report (Including recommendations).

Some tests may include hardness testing, weld examination, case depth, decarburisation measurement, coating/plating evaluation, surface evaluation and or grain size determination, inclusions density, morphology and type, compound analysis, microprobe analysis, etc. Typically, these tests are conducted by strictly following test methods from internationally recognised organisations such as ASTM, BS, ISO, etc.

Investigation of failures in polymeric type materials (plastics) requires tests specific to this type of material. This includes Fourier Transform Infrared (FTIR) spectrometry, Energy Dispersive X-ray spectroscopy (EDS), and thermomechanical analysis (TMA).

The main factors that relate to failure of components are material, design, manufacturing process and service condition, the last being the most common cause. the service condition factor also includes how the component was used, if it was abused or if it was just inadequate for the given task.

• The most frequent failure mechanisms observed are:
• Corrosion in its different forms (pitting, crevice, aerated cell, filiform, galvanic cell, etc).

• Fatigue
• Hydrogen embrittlement
• Stress corrosion cracking (SCC) Metallurgy is the science and technology of metals. It involves analysing the physical and mechanical properties of metals and examining how they are affected by composition, mechanical working and heat treatment.

At CARIRI’s Metallurgy Unit, our customers are our foremost concern. Our highly experienced and qualified personnel, as evidenced by our 40 years in the industry, have allowed us to treat with our clients’ most basic test requirements, as well as their more technologically advanced needs, with the same dedication and accuracy. We do this through our superior knowledge, equipment, expertise, quality certification and international accreditation.

We deliver first-class service based on excellence and expertise. We are leaders in finding solutions due to our well-established international connections and relationships, the innovations we have implemented, and our decades of experience. Our goal is to find “the best way” for our clients - not merely the easiest or quickest solution.

We work closely with our customers to provide service solutions that manage risk and reduce cost, while ensuring health and safety compliance at an internationally accredited level and quality.

We offer a wide range of tests and services that is comparable with established laboratories anywhere else in the world.

These include:
• Failure analysis of mechanical components
• Corrosion assessment and prevention of coatings and components
• Mechanical testing of material