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The Effects of Additive Manufacturing on the Hydrogen Embrittlement of Alloy 718

Parts produced via additive manufacturing (AM) are being adopted broadly among many industries and
used in an array of applications. AM parts are attractive to these industries for several reasons. Complex
geometries that cannot be manufactured using traditional, subtractive methods can be produced
additively.

Product Number: 51323-19358-SG
Author: W. Fassett Hickey, John H. Macha, Brendy Rincon Troconis, Thomas Dobrowolski, Wei Chen
Publication Date: 2023
$0.00
$20.00
$20.00

Parts made via additive manufacturing (AM) are being adopted broadly among many industries and used
in an array of applications. AM parts are attractive to these industries for several reasons. Complex
geometries that otherwise cannot be manufactured using traditional methods can be printed. Also, the
ability to use AM to produce parts mitigates the need to maintain an inventory of replacement parts and
avoids lengthy delivery times. Alloy 718 is widely used in demanding applications due to its high strength
at high temperatures and excellent creep and corrosion resistance. Parts and components of this alloy
can be created using AM techniques. However, in hydrogen and hydrogen-producing environments, alloy
718 is susceptible to hydrogen embrittlement (HE). The overall objective of this research program was to
understand the underlying mechanisms governing the susceptibility of AM alloy 718 to HE by
investigating the mechanical performance in high-pressure gaseous hydrogen and examining the
microstructure to compare the wrought and AM materials. The fatigue crack growth rate tests showed
that the wrought and all additively manufactured specimens had very similar mechanical response.
Testing in gaseous hydrogen demonstrated that the AM and wrought materials had accelerated crack
growth rates in the hydrogen gas environment; however, the effects of hydrogen were more pronounced
in some materials than others. Metallurgical characterizations revealed differences in precipitates and
metallurgy, and the post-test fracture surface examinations showed similar fracture morphology for all
materials. No metallurgical feature or fracture morphology could be correlated with the more dramatic effects of hydrogen on the fatigue crack growth rates when comparing AM configurations and the wrought
material.

Parts made via additive manufacturing (AM) are being adopted broadly among many industries and used
in an array of applications. AM parts are attractive to these industries for several reasons. Complex
geometries that otherwise cannot be manufactured using traditional methods can be printed. Also, the
ability to use AM to produce parts mitigates the need to maintain an inventory of replacement parts and
avoids lengthy delivery times. Alloy 718 is widely used in demanding applications due to its high strength
at high temperatures and excellent creep and corrosion resistance. Parts and components of this alloy
can be created using AM techniques. However, in hydrogen and hydrogen-producing environments, alloy
718 is susceptible to hydrogen embrittlement (HE). The overall objective of this research program was to
understand the underlying mechanisms governing the susceptibility of AM alloy 718 to HE by
investigating the mechanical performance in high-pressure gaseous hydrogen and examining the
microstructure to compare the wrought and AM materials. The fatigue crack growth rate tests showed
that the wrought and all additively manufactured specimens had very similar mechanical response.
Testing in gaseous hydrogen demonstrated that the AM and wrought materials had accelerated crack
growth rates in the hydrogen gas environment; however, the effects of hydrogen were more pronounced
in some materials than others. Metallurgical characterizations revealed differences in precipitates and
metallurgy, and the post-test fracture surface examinations showed similar fracture morphology for all
materials. No metallurgical feature or fracture morphology could be correlated with the more dramatic effects of hydrogen on the fatigue crack growth rates when comparing AM configurations and the wrought
material.

Also Purchased
Picture for Statistics to Compare Alloy 718 Properties from Additive Manufactured and Newer Mill-Produced Bar Stocks
Available for download

Statistics to Compare Alloy 718 Properties from Additive Manufactured and Newer Mill-Produced Bar Stocks

Product Number: 51319-12948-SG
Author: Manuel Marya
Publication Date: 2019
$20.00

Alloy 718 is a common oilfield material for permanent and service equipment in need of high-mechanical ratings and resistance to corrosion especially environmentally-assisted cracking in sour gas wells. In past decade Alloy 718 production from traditional and newer mills has greatly increased in response to global demands; independently yet driven by similar market growth additive manufacturing (AM) has expanded beyond rapid prototyping to become an industrial production process namely in the aerospace. Today 718 bar stocks as per API6CRA are produced by over a dozen mills worldwide;similarly 718 powder products are increasingly offered by both traditional and newer mills with intents to servea multitude ofAM technologies. Due to the rise of new economic forces in the O&G there are today needs for evaluating (ultimately qualifying) newer 718 producing mills as well as 718 powders in combination with various AM technologies. Due to concerns overraw-material properties a study was conducted to analyze 718 materials from these various origins utilizing (1) mill cert big-data analyses (2) third-party recertified mechanical test data (3) a multitude of sour service test results outside the traditional NACE MR0175/ISO15156 operational service limits among others. The later raw-material test implemented in the early 2010s for screening and qualification purposes aims at quantitatively comparing 718 production heats of various origins and with additive manufacturing also generating interests since the early 2010sthe same tests have also beenextended to determine how layer-by-layer deposited materials compare to bar stock materials.