General procedure of failure analysis: Examples of failure analysis — Lesson 4

This lesson covers the comprehensive process of failure analysis and prevention, focusing on metallic components. It provides a detailed walkthrough of how to investigate potential causes of failure, using real-world examples such as railway accidents due to rail fractures. The lesson delves into the importance of preliminary examination, non-destructive testing (NDT), mechanical property testing, macroscopy, microscopy, and chemical analysis. It also highlights the role of environmental conditions, fatigue loading, and material properties in failure analysis. For instance, it discusses how temperature conditions and hydrogen concentration can influence the failure of rail steel.

Video Highlights

01:06 - Explanation of the thermite welding process and its role in rail joint failures.
07:03 - Non-destructive testing (NDT) to identify cracks or defects near the fracture areas.
12:00 - Metallographic aspects of the failed component and chemical analysis of the rails.
21:07 - Case study of a weld joint failure and the factors contributing to it.

Key Takeaways

- Failure analysis involves a systematic investigation of potential causes of failure, including material properties, environmental conditions, and loading conditions.
- Preliminary examination, non-destructive testing, and mechanical property testing are crucial steps in failure analysis.
- The hardness, toughness, and chemical composition of a material can significantly influence its failure.
- Environmental conditions, such as temperature, can affect the material's properties and lead to failure.
- Fatigue loading, which involves repeated loading, can cause cracks to nucleate and grow, leading to failure.