API 571 Certification (Corrosion & Materials) Practice Test

What is a common cause of strain aging embrittlement?

1. High temperature exposure

2. Excessive cold working

3. Corrosive environments

4. Poor welding techniques

The correct answer is: Excessive cold working

Strain aging embrittlement is primarily associated with the effects of excessive cold working on certain steel alloys, particularly those that contain elements such as carbon and aluminum. When metals are subjected to significant cold working, improvements in strength and hardness can occur. However, this process also induces dislocations within the metal's crystalline structure, which can later become stabilized by the diffusion of interstitial solute atoms, leading to an increase in brittleness over time. This phenomenon is most commonly observed in materials like low-carbon steels or certain aluminum alloys, where the cold work creates a non-homogeneous structure. If these materials are then exposed to heat, the process of strain aging can occur, making the material more susceptible to cracking and reducing its ductility. Therefore, excessive cold working is the principal cause of strain aging embrittlement, as it sets up the conditions for such a transformation to occur within the metal’s microstructure. The other causes mentioned do not directly relate to the mechanisms of strain aging embrittlement. High temperature exposure pertains more to other types of embrittlement, while corrosive environments primarily result in degradation through different electrochemical processes rather than the stabilization of dislocations. Poor welding techniques can lead to issues like lack of fusion or unwanted micro