Server maintenance is scheduled for Saturday, December 21st between 6am-10am CST.

During that time, parts of our website will be affected until maintenance is completed. Thank you for your patience.

Menu
Search
Filters
Close
Menu

51318-11478-High Strength N07718 with Improved Resistance to Cracking in H2S-Containing Environments

Picture for High Strength N07718 with Improved Resistance to Cracking in H2S-Containing Environments
Available for download

This paper describes the development of an alternative heat treatment designed to increase the strength of 718 (UNS N07718) above the current level, which is bound by the 40 HRC limit of NACE MR01751 and the heat treatment requirements of API 6ACRA.

Product Number: 51318-11478-SG
Author: Sabine Kremel / Martin Wöls / Greg Chitwood / Luciana Intiso
Publication Date: 2018
Industry: Science of Corrosion
$0.00
$20.00
$20.00

This paper describes the development of an alternative heat treatment designed to increase the strength of 718 (UNS N07718) above the current level, which is bound by the 40 HRC limit of NACE MR01751 and the heat treatment requirements of API 6ACRA.2 The investigation was triggered by hydrogen embrittlement failures reported for PH Ni-base alloys, where unfavorable microstructure was reported to be a contributing factor. Increased strength was also suspected, but this comes at a time when the industry needs to push strength higher to exploit future high-pressure/high-temperature (HP/HT) developments. Initial slow strain rate testing (SSRT) of a two-step heat treatment in a sour environment containing 28 bar H2S and 25% NaCl at 150°C revealed improvement in critical SSRT ratios (ep and RoA) over that achievable with the API heat treatment; strength increased by approximately 30 ksi and ductility and toughness were maintained. This testing was followed by more extensive sulfide stress cracking (SSC), galvanically-induced hydrogen stress cracking (GHSC), and stress corrosion cracking (SCC) to qualify the material for MR0175 at 205°C with up to 35 bar H2S. This paper documents the corrosion testing conducted to compare the alternative heat treatment with that required by API 6ACRA, and provides an explanation for the improved environmental cracking resistance through investigation of cracking morphology, microstructure, and metallurgical properties. 

Key words: 718-API, 718 high strength, SSC, GHSC, SCC, SSRT, HP/HT sour gas testing

This paper describes the development of an alternative heat treatment designed to increase the strength of 718 (UNS N07718) above the current level, which is bound by the 40 HRC limit of NACE MR01751 and the heat treatment requirements of API 6ACRA.2 The investigation was triggered by hydrogen embrittlement failures reported for PH Ni-base alloys, where unfavorable microstructure was reported to be a contributing factor. Increased strength was also suspected, but this comes at a time when the industry needs to push strength higher to exploit future high-pressure/high-temperature (HP/HT) developments. Initial slow strain rate testing (SSRT) of a two-step heat treatment in a sour environment containing 28 bar H2S and 25% NaCl at 150°C revealed improvement in critical SSRT ratios (ep and RoA) over that achievable with the API heat treatment; strength increased by approximately 30 ksi and ductility and toughness were maintained. This testing was followed by more extensive sulfide stress cracking (SSC), galvanically-induced hydrogen stress cracking (GHSC), and stress corrosion cracking (SCC) to qualify the material for MR0175 at 205°C with up to 35 bar H2S. This paper documents the corrosion testing conducted to compare the alternative heat treatment with that required by API 6ACRA, and provides an explanation for the improved environmental cracking resistance through investigation of cracking morphology, microstructure, and metallurgical properties. 

Key words: 718-API, 718 high strength, SSC, GHSC, SCC, SSRT, HP/HT sour gas testing

Product tags
Also Purchased
Picture for Hydrogen-Assisted Failure in Ni-Based Superalloy 718
Available for download

51316-7459-Hydrogen-Assisted Failure in Ni-Based Superalloy 718

Product Number: 51316-7459-SG
ISBN: 7459 2016 CP
Author: Zahra Tarzimoghadam
Publication Date: 2016
$20.00
Picture for 03126 PHYSICAL METALLURGY OF ALLOYS 718,
Available for download

03126 PHYSICAL METALLURGY OF ALLOYS 718, 725, 725HS, 925 FOR SERVICE IN AGGRESSIVE CORROSIVE ENVIRONMENTS

Product Number: 51300-03126-SG
ISBN: 03126 2003 CP
Author: Sarwan Mannan, Ed Hibner, and Brett Puckett
Publication Date: 2003
$20.00

Nickel-base alloys 718, 725, and 925 are commonly used in oil and natural gas production.  Being heavily alloyed multi-component systems; these materials require special consideration for processing and heat treatments.  This paper shows the effect of intergranular precipitates on mechanical properties and  slow strain rate (SSR) test results in sour oil patch environments.

 
Picture for 05103 Laboratory Testing of Age-Hardenable Alloys
Available for download

05103 Laboratory Testing of Age-Hardenable Alloys 925 and 718, in Sour Gas Environments

Product Number: 51300-05103-SG
ISBN: 05103 2005 CP
Author: Rainer Behrens, Krupp VDM GmbH; Dinesh C. Agarwal, ThyssenKrupp VDM USA Inc.
$20.00
Categories
Industry
Recently viewed
Popular tags
View all

Association for Materials Protection and Performance

© AMPP All Rights Reserved.
Membership Terms of Content Use
Contact Customer Support