Environmentally Assisted Cracking: Theory and Practice: Poster Session
Sponsored by: TMS Structural Materials Division, TMS: Corrosion and Environmental Effects Committee
Program Organizers: Bai Cui, University of Nebraska-Lincoln; Raul Rebak, GE Global Research; Srujan Rokkam, Advanced Cooling Technologies, Inc.; Jenifer Locke, Ohio State University

Monday 5:30 PM
February 28, 2022
Room: Exhibit Hall C
Location: Anaheim Convention Center

Session Chair: Bai Cui, University of Nebraska-Lincoln

B-3: Hydrogen Embrittlement in Ni-base Superalloy 718: Hamza Khalid1; Bilal Mansoor2; 1Texas A&M University; 2Texas A&M University at Qatar
     Hydrogen embrittlement in Ni-base superalloy 718 is affected by many variables including its microstructure, hydrogen charging conditions and mechanical loading. Alloy 718 is called a precipitation-hardenable alloy; subjecting it to certain heat treatments results in the formation of precipitates which increase its strength and hardness. The alloy relies on the coherent metastable γ’ and γ” precipitates for strength whereas the incoherent but stable 𝛿-phase inhibits grain growth. Multiple studies in the last few years have shown that these precipitates also increase the alloy’s susceptibility to hydrogen embrittlement. We here explore how alloy 718 behaves in its different tempers when subjected to a range of hydrogen charging conditions. Since hydrogen can both act to trap dislocations or enhance dislocation mobility, we observe diverging results in hardness and strength based on the alloy’s microstructure. We attempt to explain these results and improve the understanding of interaction of hydrogen with complex microstructures.