API-571 Exam - Topic 1 Question 128 Discussion

Actual exam question for API's API-571 exam

Question #: 128
Topic #: 1

[All API-571 Questions]

Nitriding of steels becomes most severe at temperatures above:

A200F (95C)

B500F (260C)

C600F (315C)

D900F (480C)

Show Suggested Answer

Suggested Answer: D

API RP 571 under Nitriding (Section 4.2.16):

''Nitriding occurs at elevated temperatures and is most severe at temperatures above 900F (480C).''

''This mechanism is associated with the reaction of ammonia or other nitrogen-containing compounds with the steel surface, leading to brittle nitride formation.''

Therefore, the correct answer is D.

by Glenna at Jul 01, 2026, 08:28 PM

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Lonna

1 day ago

I’m pretty sure nitriding starts to get severe around 900F, but I’m not entirely confident about that.

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Denise

6 days ago

I practiced a similar question where the threshold was around 500F, but I feel like nitriding might be worse at 600F.

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Zachary

12 days ago

I think nitriding gets more aggressive at higher temperatures, but I can't remember if it's 600F or 900F.

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