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Performance Of Additively Manufactured Alloy 718 In Sour Service

Performance of Additively Manufactured Alloy 718 In Sour Service
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Alloy UNS N07718 (hereafter abbreviated as 718) is one of the most versatile precipitation-hardened nickel-based corrosion-resistant alloys (CRAs) used for both surface and sub-sea components in oil and gas production service. API 6ACRA1 provides heat treatment windows and acceptance criteria for 718 in these oil and gas production environments, in which the heat treatment is intended to obtain high strength and to minimize the formation of δ-phase at grain boundaries. As pointed out in NACE MR0175 Part 32 (Table 1), field failures of 718 components in sour service are primarily related to stress corrosion cracking (SCC) at elevated temperatures and hydrogen embrittlement in the lower temperature range. The latter is specifically called galvanically induced hydrogen stress cracking (GHSC or GIHSC), which is typically caused by atomic hydrogen uptake from galvanic corrosion or cathodic protection (CP) when 718 is used with steel components in a seawater environment. CP is normally used to protect steel component from corrosion in subsea environments.

Product Number: 51322-18029-SG
Author: Liu Cao, Christopher Taylor
Publication Date: 2022
Industries: Corrosion Monitoring and Control , Coatings
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$20.00
$20.00

Precipitation hardened nickel alloys are commonly used in oil and gas production equipment where materials must provide both outstanding mechanical strength and corrosion resistance. Additive manufacturing (AM) provides a new approach to the design and manufacture of components from metal powder and provides some unique advantages over traditional manufacturing. However, components produced by AM are not currently acceptable per NACE(1) MR0175/ISO(2)15156 since no AM alloys have been balloted and approved for inclusion. There are uncertainties and knowledge gaps around the performance of AM material in sour service. AM Alloy 718 (UNS N07718) test material was manufactured by laser powder bed fusion (LPBF) with final heat treatment per API(3) 6ACRA 150K designation by three suppliers. After benchmarking the basic mechanical properties in air, the AM Alloy 718 test material was evaluated by slow strain rate (SSR) testing and proof ring testing in sour environments similar to those used for the wrought Alloy 718 150K ballot for NACE MR0175/ISO 15156. The resistance to stress corrosion cracking (SCC) and galvanically induced hydrogen stress cracking (GHSC) were investigated and compared to the wrought Alloy 718 150K results. 

Precipitation hardened nickel alloys are commonly used in oil and gas production equipment where materials must provide both outstanding mechanical strength and corrosion resistance. Additive manufacturing (AM) provides a new approach to the design and manufacture of components from metal powder and provides some unique advantages over traditional manufacturing. However, components produced by AM are not currently acceptable per NACE(1) MR0175/ISO(2)15156 since no AM alloys have been balloted and approved for inclusion. There are uncertainties and knowledge gaps around the performance of AM material in sour service. AM Alloy 718 (UNS N07718) test material was manufactured by laser powder bed fusion (LPBF) with final heat treatment per API(3) 6ACRA 150K designation by three suppliers. After benchmarking the basic mechanical properties in air, the AM Alloy 718 test material was evaluated by slow strain rate (SSR) testing and proof ring testing in sour environments similar to those used for the wrought Alloy 718 150K ballot for NACE MR0175/ISO 15156. The resistance to stress corrosion cracking (SCC) and galvanically induced hydrogen stress cracking (GHSC) were investigated and compared to the wrought Alloy 718 150K results. 

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Hydrogen Embrittlement of Additively Manufactured Inconel 718

Product Number: 51319-13453-SG
Author: Liu Cao
Publication Date: 2019
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Precipitation hardenable nickel alloys are commonly used in oil and gas offshore structures where requires outstanding mechanical strength and corrosion resistance. In seawater galvanic coupling to steel or cathodic protection promotes the formation of atomic hydrogen on the surface of Inconel 718. Hydrogen atoms further dissolve into the metal matrix and cause hydrogen embrittlement. The unconventional Additive Manufacturing (AM) process generates fine microstructure and alters surface finish that affect hydrogen intake process and the subsequent hydrogen embrittlement. The effects of hydrogen embrittlement are investigated on different build orientations and surface finish of AM Inconel 718 by slow strain rate (SSR) testing in seawater environment under cathodic protection. The susceptibility of AM 718 to hydrogen embrittlement is discussed based on the SSR results and metallography analysis with respect to its wrought counterpart.
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Material Capabilities Of Additively Manufactured Alloy UNS N07718 In An H2S-Containing Environment

Product Number: 51322-17938-SG
Author: Wei Chen, Thomas Dobrowolski, Satya Ganti, Tim Haeberle, Aaron Avagliano, Anjani Achanta
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AM brings significant benefits in better performance, inventory management, and lifecycle cost reduction to the Oil & Gas industry. Both manufacturers and users are working towards AM qualification and standardization in order to realize and sustain these benefits. Starting at the product level, the goal is to ensure the product is sound in its form, fit, and function, and free from macroscopic (surface, sub-surface, internal) anomalies deleterious to its performance. Product qualification is supported by a foundational metallurgical or AM material qualification.1
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05103 Laboratory Testing of Age-Hardenable Alloys 925 and 718, in Sour Gas Environments

Product Number: 51300-05103-SG
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