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What are the NACE MR0175 material requirements for Inconel 625 (UNS N06625)?

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Sour service material manufactured with Inconel 625 (UNS N06625) has to comply with ANSI/NACE MR0175/ISO 15156. NACE MR0175 provides the metallurgical requirements for Inconel 625. Metallurgical condition and hardness are two of those requirements discussed in this article.

NACE MR0175 requires alloy 625 to be in the annealed condition. Some suppliers offer alloy 625 quenched off the hammer. This question was raised to the maintenance panel.

Question: Is Alloy N06625 (Name – Alloy 625) material meet NACE MR0175/ISO 15156-3, Table A.13 if forged material is quenched off the hammer as opposed to performing a separate annealing?


It is up to the Manufacturer to determine if alloy 625 is annealed under these conditions. It is not the role of the MP to answer metallurgical questions. If alloy 625 is annealed then it meets requirements of Table A.13.


What is the NACE MR0175 hardness requirement for Inconel 625 (UNS N06625)?


NACE MR0175 / ISO 15156 Part 3 Clause A.4 provides details of material requirements for solid solution nickel alloys. 

At Oil & Gas Corrosion we help manufacturers determine the optimal route for forging and annealing Alloy 625. We also help users review material test reports (MTRs) and manufacture documentation to confirm compliance with NACE MR0175 and other regulatory requirements.

UPDATE 2018-06-04: A recent Technical Circular brings relevant updates on NACE MR0175 and 625 weld overlays: https://oilandgascorrosion.com/nace-mr0175-iso-15156-technical-circulars-for-part-2-and-3-published-2018-06-01/

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