Environmentally Assisted Cracking: Theory and Practice: Environmental Embrittlement, Fracture, and Fatigue
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
Thursday 8:30 AM
March 18, 2021
Room: RM 18
Location: TMS2021 Virtual
Session Chair: Jian Luo, University of California, San Diego; Stephen Raiman, Texas A&M University
8:30 AM Invited
Corrosion, Irradiation, and Cracking Studies in Support of Coating Development for SiC-based Accident Tolerant Fuel Cladding: Stephen Raiman1; Peter Doyle2; Peter Mouche3; Yutai Katoh3; 1Texas A&M University; 2University of Tennessee; 3Oak Ridge National Laboratory
SiC/SiC ceramic matrix composite (CMC) materials are attractive candidate materials for accident tolerant fuel (ATF) cladding. To improve hermiticity and compatibility with the coolant water, dual-purpose coatings are in development. To test the performance of the coating candidates during normal operating conditions, SiC and SiC/SiC composite samples were prepared with TiN, Cr, and CrN coatings. The samples were exposed to high temperature water in autoclaves to test their durability in light water reactor (LWR) conditions and irradiated in the MIT reactor to determine their radiation tolerance.Several coatings cracked during irradiation, perhaps due to differential swelling between the coatings and substrates. Some coatings that were irradiated in coolant water had higher rates of corrosion when compared to samples exposed to the same conditions without irradiation. This talk reports on the finding from the first generation of dual-purpose coatings and discusses current development efforts on second generation coatings.
9:10 AM
Modeling of Corrosion Crack Dynamics and Fracture Using a Physics-based Meshless Peridynamics Approach: Srujan Rokkam1; Masoud Behzadinasab2; Max Gunzburger3; Sachin Shanbhag3; Nam Phan4; 1Advanced Cooling Technologies Inc; 2Brown University; 3Florida State University; 4Naval Air Systems Command
Environmental assisted corrosion cracking is a major cause for structural damage in many applications. In this work, we discuss a Peridynamic (PD) approach for physics-based modeling of corrosion damage phenomena which can be applied to model crack growth and failure due to either stress corrosion cracking (SCC) or corrosion fatigue (CF). PD approach is a reformulation of classical computational mechanics that enables modeling of crack growth problem without the need to re-mesh the domain. The presentation will focus on two aspects: (i) how multiphysics aspects of corrosion damage can be modeled using nonlocal PD approach, (ii) demonstration of corrosion crack dynamics in surrogate aluminum alloys. The developed framework is able to capture ductile damage behavior as well crack path dynamics without the drawbacks of conventional theories. This work was funded by U.S. Navy/NAVAIR through STTR program, Contract N68335-15C-0032. The simulations used NSF-XSEDE allocation grants DMR180017.
9:30 AM
Humidity and Chemistry Dependent Embrittlement in the Al-Ga-In Liquid Metal Embrittlement System
: Justin Norkett1; Cameron Frampton1; Victoria Miller1; 1University of Florida
Despite over 100 years of study, liquid metal embrittlement (LME) is still poorly understood on a mechanistic level. This is in part due to the existence of multiple apparent mechanisms, sometimes competing within a single system. The aluminum gallium system is a classic example of LME, characterized by penetration of grain boundaries resulting in a near complete loss of mechanical properties. The addition of indium to the gallium liquid results in rapid oxidation and disintegration of the aluminum substrate when exposed to ambient atmosphere. By altering ambient humidity and Ga-In alloy composition, an apparent cooperative effect between corrosion and grain boundary penetration is observed. This work furthers the understanding of the role of corrosion in complex liquid metal embrittlement systems.
9:50 AM
The Effect of Additive Manufacturing Process Parameters on the Fatigue Crack Growth Rates of Alloy 718 in Elevated-pressure and Elevated temperature Hydrogen Gas: Fassett Hickey1; John Macha1; Vinicio Ynciarte2; Brendy Rincon Troconis2; 1Southwest Research Institute; 2University of Texas at San Antonio
The fatigue crack growth rates of wrought alloy 718 in the presence of high pressure hydrogen gas have been studied extensively; however, only limited studies have been performed on additively manufactured (AM) alloy 718 in hydrogen gas environments. AM process parameters and post-processing heat treatment alter the microstructure and metallurgical features, which in turn influence the susceptibility to hydrogen embrittlement. By correlating processing parameters to resultant metallurgical features and mechanical properties, optimal processing parameters, which minimize the potential for hydrogen embrittlement, can be determined. Additionally, studies are underway to investigate the effect of test temperature on the fatigue crack growth rates and failure modes by testing at various temperatures up to 500F. The objectives of this study are to measure the fatigue crack growth rates in gaseous hydrogen and understand the influence of the microstructure and metallurgical features on the hydrogen embrittlement susceptibility of wrought and AM alloy 718.
10:10 AM
Influence of Hydrogen on Softened HAZ during In-situ Slow Strain Rate Testing in YS 550 MPa Grade Steel Welds: Namhyun Kang1; Hanji Park1; Cheolho Park2; Junghoon Lee2; Stephen Liu3; Dae-Geun Nam4; 1Pusan National University; 2Chosun University; 3Colorado School of Mines; 4Korea Institute of Industrial Technology
The hydrogen-induced stress cracking (HISC) of the entire weldments needs to be evaluated because they are normally applied in various environments of stress and hydrogen. The study investigated the HISC reaction according to the microstructure and hardness distribution of the transverse welds for an ultra-high strength steel using in-situ slow-strain rate testing (SSRT). SSRT in the hydrogen-free environment resulted in the fracture of the base metal although the narrow-softened heat-affected zone (HAZ) was observed. However, during in-situ SSRT, the stress triaxiality was increased in the softened inter-critical HAZ and premature rupture was initiated by a hydrogen-promoted void and enhanced plasticity.
10:30 AM
Hydrogen Permeability for Determining Hydrogen Embrittlement Susceptibility of High Hardness Steels: William Williams1; David Salley1; Haley Doude1; David Wipf1; Daniel Field2; Krista Limmer2; Kevin Doherty2; Hongjoo Rhee1; 1Mississippi State University, CAVS; 2CCDC Army Research Laboratory
High hardness steels (HHS) are vulnerable to hydrogen embrittlement, which can lead to rapid degradation of mechanical properties. A comparison study was performed to assess the hydrogen susceptibility of select commercially available HHS alloys. Slow-strain rate tensile tests, performed with specimens charged with various levels of hydrogen, provided a macroscopic view of the onset of hydrogen embrittlement. Hydrogen permeation testing of the HHS alloys determined the uptake and diffusivity of hydrogen through the material. Quantification of hydrogen trapping sites within the HHS alloys was performed using electron microscopy. The evaluation of current HHS alloys’ susceptibility to hydrogen serves as a baseline for future hydrogen embrittlement mitigation strategies.
10:50 AM
Characterization of Hydrogen Embrittlement Sensitivity of Various High Hardness Steels: David Salley1; Will Williams1; Haley Doude1; Wilburn Whittington1; Dan Field2; Krista Limmer2; Kevin Doherty2; Hongjoo Rhee1; Shiraz Mujahid3; 1Center for Advanced Vehicular Systems, Mississippi State University; 2Metals Branch, US CCDC Army Research Laboratory; 3Mississippi State University
Multiple high hardness steel (HHS) alloys were designed and produced to evaluate the role of composition and processing on the hydrogen embrittlement (HE) susceptibility towards preventing delayed cracking. Four alloys were produced in-house to meet MIL-DTL-46100E and were compared alongside a commercially available steel. HE testing was performed using ASTM E8 specimens, electro-chemically charged with hydrogen in acid. Test results reveal correlation between material structure and properties and hydrogen embrittlement performance. The findings in this study could lead to better understanding of methodologies for reducing HE susceptibility in HHA steels.