General procedure of failure analysis: Embrittlement of steels — Lesson 5

This lesson covers the topic of failure analysis and prevention, focusing on the various aspects related to failures such as the fundamental sources and investigation procedures. It delves into the unique conditions under which some components fail, even when they seem perfect in form. The lesson explains how certain environmental conditions, temperatures, and deformations can lead to changes in the mechanical properties of steel, a phenomenon known as embrittlement. It further discusses different types of embrittlements such as strain age embrittlement, quench H embrittlement, temper embrittlement, and sigma phase embrittlement, among others. The lesson also explains how these embrittlements affect the performance of steel in terms of mechanical properties.

Video Highlights

00:43 - Explanation of unique conditions under which component failures can occur.
05:09 - Explanation of the factors that lead to the embrittlement of steels.
08:56 - Explanation of the effects of these embrittlements on the performance of steel.
17:51 - Explanation of 350-degree centigrade embrittlement and 450 to 500-degree centigrade embrittlement.
22:54 - Discussion on sigma phase embrittlement.

Key Takeaways

- Embrittlement is a change in the mechanical properties of steel due to unique environmental conditions, temperatures, or deformations.
- Different types of embrittlements include strain age embrittlement, quench H embrittlement, temper embrittlement, and sigma phase embrittlement.
- Embrittlement can lead to an increase in strength, reduction in toughness, impact resistance, and ductility.
- The embrittlement process can be influenced by factors such as temperature, deformation, and the environment in which the exposure is given.
- The presence of certain gases like oxygen and nitrogen can lead to strain age embrittlement.
- The tempering process can lead to temper embrittlement, which can be reduced by high cooling rates and shorter soaking periods.