Environmental Degradation of Additively Manufactured Alloys: Material Degradation in Irradiated Environments, Environmental Assisted Cracking
Sponsored by: TMS Structural Materials Division, TMS: Corrosion and Environmental Effects Committee, TMS: Additive Manufacturing Committee
Program Organizers: Kinga Unocic, Oak Ridge National Laboratory; Jenifer Locke, Ohio State University; Sebastien Dryepondt, Oak Ridge National Laboratory; Michael Kirka, Oak Ridge National Laboratory; Xiaoyuan Lou, Purdue University; Brendy Rincon Troconis, University of Texas at San Antonio; Luke Brewer, University of Alabama
Thursday 2:00 PM
March 18, 2021
Room: RM 20
Location: TMS2021 Virtual
Session Chair: Kinga Unocic, Oak Ridge National Laboratory; Sebastien Dryepondt, Oak Ridge National Laboratory; Michael Kirka, Oak Ridge National Laboratory
2:00 PM Invited
Additively Manufactured 316L Stainless Steel for Nuclear Applications: Gary Was1; Miao Song1; 1University of Michigan
Irradiation induced microstructure and irradiation-assisted stress corrosion cracking (IASCC) of additively manufactured (AM) 316L stainless steel were evaluated for application as a core structural material. Both stress-relieving (SR) and hot-isotropic pressing (HIP) were performed on AM 316L SS for comparison with the wrought condition. The HIP AM 316L showed better radiation tolerance than SR AM 316L after a 2.5 dpa proton irradiation at 360℃, with fewer dislocation loops and cavities. Irradiation to 30 dpa with 5 MeV Fe2+ ions at 500 - 600 ℃ revealed less void swelling in HIP AM 316L than in SR AM 316L. SR AM 316L had a higher cracking susceptibility when loaded perpendicular to the build direction, though large interlayer cracks were observed in the parallel direction loading, and fewest cracks were found in the HIP AM 316L SS. The post-printed HIP condition eliminated anisotropic behavior, enhanced radiation tolerance, and exhibited greatest IASCC resistance.
2:30 PM
Comparison of Oxidation Behavior of Ultrasonic Additively Manufactured and Conventional Zircaloy-4: Cory Parker1; Kenneth Kane1; Stephen Raiman1; Bruce Pint1; Caleb Massey1; Andrew Nelson1; 1Oak Ridge National Laboratory
Ultrasonic additive manufacturing (UAM) is a promising solid state joining technique for producing planar geometries. While established for other materials, use of UAM to fabricate composite structure using zirconium alloys for nuclear reactor applications is in early development. Development of more complex geometries and structures must be preceded by studies that establish UAM can produce materials of acceptable properties. The corrosion behavior of Zry-4 during exposure to water coolants and the oxidation of Zry-4 in high temperature steam and oxygen are critical performance metrics. Residual voids formed between layers of Zry-4 tape used in the UAM process and other heterogeneities are not present in conventional Zry-4 processing, and their impact must be understood. The oxidation behavior of Zry-4 is studied here alongside conventionally manufactured Zry-4 using exposures in TGA furnaces at temperatures 600-1200°C for up to 100 h. Hydrothermal corrosion is also compared using continuously refreshing autoclave exposures for ≥1,000h.
2:50 PM
Performance of Additively Manufactured FeCrAl Alloy Accident Tolerant Fuel Cladding in Nuclear Power Reactor Environments: Vipul Gupta1; Andrew Hoffman1; Raul Rebak1; 1GE Research
FeCrAl alloys are currently being develop by General Electric Company [(GE) including GE Research, GE-Hitachi Nuclear Energy, and Global Nuclear Fuel (GNF)] as one of the promising concepts for Accident Tolerant Fuel (ATF) cladding in nuclear power reactors. Because the manufacturing of FeCrAl alloys involves a powder metallurgy process, subtractive machining of parts (such as fuel cladding end caps) can result in significant waste. Near net shape additive manufacturing can therefore provide the possibility of significant cost savings. The performance of additively manufactured parts, however, must show performance that is comparable to other manufacturing methods. We will discuss the effects of processing parameters on microstructure. The impact of this microstructure on performance testing of additively manufactured FeCrAl alloys during high temperature water autoclave testing and high temperature steam testing will also be discussed when compared to other manufacturing methods including wrought cast and forged FeCrAl alloys and Zr alloys.
3:10 PM
Sensitization and Stress Corrosion Cracking of Alloy 800H by Laser Powder Bed Fusion: Jingfan Yang1; Xiang Liu2; Miao Song3; Lingfeng He2; Xiaoyuan Lou1; 1Auburn University; 2Idaho National Laboratory; 3University of Michigan
Alloy 800H (UNS No. N08810), also known as Incoloy 800H, has been widely used in many high-temperature water systems due to its excellent corrosion resistance and creep resistance. However, as some types of austenitic stainless steels and nickel-base alloys, this material was found susceptible to intergranular stress corrosion cracking (IGSCC) within the sensitization temperature range. This study explored the sensitization susceptibility of the additively manufactured (AM) Alloy 800H and related stress corrosion cracking (SCC) performance. With a particular interest in the carbide formation kinetics in the laser fused non-equilibrium AM structure, the study covers a wide range of heat treatment conditions. The special roles of high-angle grain boundary and unique cellular/columnar sub-grain structure to the sensitization susceptibility of AM Alloy 800H are discussed. The correlated SCC tests are also conducted on specimens with the representative heats to understand the relationship between sensitization and IGSCC susceptibility.