Which NACE MR0175 table applies to 718 (regardless of heat treated condition)?
Is UNS N07718 a Solid-Solution Alloy?
The inquiry questions whether a nickel alloy without any age/precipitation-hardening heat treatment should be categorized as a solid-solution alloy and, therefore, covered by Tables A.12 to A.16 in the NACE standard. The response discusses the heading of Tables A.31 to A.34 pertaining to precipitation-hardened Nickel-based alloys. While the heading seems to suggest that all materials listed are precipitation hardened alloys, the notes section allows for the alloys to be in other conditions. The inquiry asks if UNS N07718 alloy, when in a solution-annealed condition, should be considered a solid-solution nickel-based alloy covered by Table A.14 or still fall under the applicable Table A.32.
Understanding UNS N07718
The answer confirms that UNS N07718 is considered a precipitation hardened nickel-based alloy regardless of its heat-treated condition. Thus, it would fall under the applicable Table A.32 instead of Table A.14. This inquiry pertains to NACE MR0175/ISO 15156-3 A.9 Table A.31. Reference is made to the ISO 15156 Maintenance Panel Inquiry #2016-08.
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