NACE MR0175 and the maximum allowable case depth for nitriding to 0.006″.

Question:

NACE MR0175/ISO 15156-2:2015 A.2.1.5 limits the maximum allowable case depth for nitriding to 0.006″. Case depth is not defined in NACE MR0175/ISO 15156 and there are multiple definitions of case depth that are possible. Which of the following definitions of case depth is intended here?

a) The total case depth (determined by metallographic analysis)

b) The effective case depth, based on a difference of 50 HV between core and case

c) The effective case depth, based on a difference of 10% between core and case

d) The effective case depth, based on manufacturer spec of case hardness criteria

e) Other – if so, please explain

ANSWER:

The measurement of case depth is not defined in NACE MR0175/ISO 15156. Adding a definition of the measurement criteria requires a ballot.

Reference: ISO 15156 Maintenance Panel Inquiry #2016-01

This question is in relation to NACE MR0175/ISO 15156-3 A.2.1.5

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