General procedure of failure analysis: Metallography of failed components — Lesson 4

This lesson covers the significance of metallography in failure analysis. It delves into the general procedure of failure analysis, focusing on the study of the microstructure of failed components using optical microscopy or scanning electron microscopy. The lesson explains how metallography helps identify the class of the failed metal, estimate its chemical composition, and determine the effect of service conditions. It also discusses how metallography can reveal manufacturing methods, detect oxidation, corrosion, and work hardening, and identify the characteristics of cracks. The lesson uses examples such as the study of a failed steel component to illustrate these points.

Video Highlights

01:03 - Explanation of the use of optical microscopy or scanning electron microscopy for microstructure study.
05:23 - Explanation of the estimation of the chemical composition of metallic components using phase diagrams and lever rule.
10:34 - Explanation of the method of manufacturing identification through metallography.
17:24 - Explanation of the targets of metallography, including microstructure study and compositional estimation.
19:24 - Discussion on the use of image analysis in metallography.

Key Takeaways

- Metallography is crucial in failure analysis as it helps identify the class of the failed metal and estimate its chemical composition.
- It can reveal the effect of service conditions on the failed component, such as load, environment, and deformation.
- Metallography can detect manufacturing methods, oxidation, corrosion, and work hardening in the failed component.
- It can also identify the characteristics of cracks and their propagation during fracture.