Course Objectives:

• Learn to identify signs of failure in metal samples.

• Understand the contributing factors to material failure.

• Gain hands-on experience with a 19-stage investigative process.

• Develop skills in producing objective, data-driven conclusions.

The course consists of the 19 Stages of Metallurgical Investigation:

1. Collection of background data -

Gather history, ie chemical analysis and certification, specification and standards, process route history and quality tracking data.

2.   Selection of samples -

Choose representative and relevant failure samples to be investigated. Consider the number and classification of the sample sizes, their location and identification.

3. Preliminary examination of the failed part(s) -

You review visual examinations, physical measurements and record keeping, photographs, preservation and/or cleaning of critical specimens, production of label diagrams, use of non-destructive testing, planning investigation or analysis techniques.

4. Chemical composition -

Verify alloy specifications and detect anomalies linking to its data collected.

5. Non-destructive testing -

Consider appropriate method(s) of investigations and their viability to maintaining sample integrity ie using techniques like ultrasonic, radiography or dye penetrant

6. Plan of action -

Define the investigation strategy. Consider all aspects of 1 to 5 above, including internal and external outcomes, responsibilities and impact of conclusion.

7. Consolidation of Benchmarks Standards and Data -

Reference known recorded material behaviours ie refer to ASM Handbook, other reliable research data and standards, etc.

8. Visual examination -

Surface level inspection for clues and use engineering diagrams and specifications to assess samples.

9. Fracture examination -

Study fracture surfaces for failure mode ie using low power hand lens (up to x 20) if appropriate, to classify surface texture (ductile, brittle, fatigue) and also consider the colour and flow lines/direction.

10. Scanning Electron Microscopy (SEM) -

High-resolution imaging of fracture features

11. Hardness tests -

Assess material strength and consistency of surface hardness by reviewing chemical analysis and certification, specifications and standards etc.

12. Macroscopic examination -

Cut and polish sections for deeper insight. Consider the surface, review non-destructive testing external surfaces, fracture surfaces, secondary cracks etc. from the samples which have been prepared from the component in their original state. Was the correct etchant used in assessing the macroscopic examinations?

13. Longitudinal or Transverse Macro sections/others -

Review cut and polish sections for deeper insight ie sulphur priming, record keeping photographs and for comparison use unetched and etched samples.

14. Microscopic examination -

Use optical microscopy for microstructure analysis to examine longitudinal, transvers, taper sections, labelling and identification. For comparison using unetched and etched samples. To examine fracture surfaces incline sample and consider examining small sections in conjunction with possible micro hardness tests.

15. SEM (again) -

Revisit SEM for detailed microstructural or fracture analysis which is useful in a wide range of applications to examine surfaces and obtaining chemical analysis of phases.

16. Stress analysis -

Evaluate stress distribution and concentration of the failed component and consider the mode of failure ie fracture mechanics and determination of the fracture mode.

17 Mechanical Testing -

This is often considered after the metallographic examination eg tensile, impact, fatigue, fracture tests etc.

18.  Chemical analyses -

Detect contaminants or corrosion products and deposits or coatings.

19. Testing under simulated service conditions -

Replicate operating environment to confirm failure mechanisms ie hot tensile, impact testing at room temperature, hot hardness, notch tests etc.