Long time expositions at high temperatures

[0707]

Significant micro structural alterations due to long time expositions at high temperatures that can result in imperfections of metallurgic origin, include:

1-Graphitisation, sigma phase, annealing embrittlement.

2-Grain growth, Graphitisation and mechanical fatigue.

3-Hardening, cavitations and embrittlement.

4-Sensitisation, graphitisation and erosion

Which would be the correct answer for the above statement?

Forum contributions would be appreciated

Luis Marques

 

[davefitz]

item 1.

Which test is this from?

 

[metengr]

Combination of 1, 2 and 4; with the exception of mechanical fatigue and erosion. Mechanical fatigue and erosion are damage mechanisms that can be affected upon prolonged exposure to elevated temperature but are not a direct consequence of this exposure.

In lieu of the term annealing embrittlement, this should be called thermal embrittlement.

 

[0707]

“Long time expositions at high temperatures”

Although interesting the subject is arguable

My question is from an American test form of a course formation action related with Heaters & Boilers. As the question is vague and the option answers are very similar the choice for the correct answer is not easy.

My option goes for the option 1 but I am not sure if it is the correct one.

Thank you for the empathy

Regards

Luis Marques