Session: CS-07-04 The Warren H. Bamford Memorial Symposium on Recent Developments in ASME Codes and Standards-4

Paper Number: 154356

154356 - High-Temperature Mechanical Behavior of Powder Metallurgy – Hot Isostatic Pressed 316 Stainless Steels 

Abstract: 

Powder metallurgy (PM) – hot isostatic pressing (HIP) is a manufacturing method using high temperature and pressure to consolidate metallic powders into near-net shape components. It is possible that PM-HIP can reduce post-processing fabrication steps, lower production costs, and decrease part lead time. Therefore, PM-HIP is an attractive fabrication method for high-temperature nuclear reactors. However, PM-HIP is not a manufacturing process qualified and approved for use within the American Society of Mechanical Engineers (ASME) Boiler and Pressure Vessel Code (BPVC) Section III, Division 5 for high-temperature reactor construction. This work evaluated two stainless steel alloy compositions, which were PM-HIP 316L and PM-HIP 316H. Both PM-HIP alloy compositions were within their respective American Society for Testing of Materials specification for wrought Type 316L and Type 316H stainless steels. These PM-HIP alloys were directly compared to their wrought-product counterparts, which are approved for use in ASME BPVC Sec. III, Div. 5. The PM-HIP 316H was of particular interest as it is qualified for Section III, Div. 5 Class A construction.

To evaluate the material properties, low cycle fatigue and creep-fatigue tests were performed on each alloy. These test results were combined with optical metallography and scanning electron microscopy to understand variations in failure mechanisms. Mechanical tests showed that low cycle fatigue performance between the PM-HIP and wrought 316 alloys were similar. However, the creep-fatigue testing showed that the PM-HIP material failed at less than half the number of cycles compared to the wrought-product form. Based on microstructural analysis, it is thought that the oxide particles inherent with the powder-based process may be the cause of reduced creep-fatigue performance. Because of this and published literature relating oxygen content to reduced Charpy V-notch toughness, PM-HIP material at different overall oxygen concentrations were analyzed and compared. Lowering the total oxygen to values as low as currently, commercially viable resulted in negligible changes to creep-fatigue performance.

Presenting Author: Tate Patterson Idaho National Laboratory

Presenting Author Biography: Tate Patterson is a welding engineer at Idaho National Laboratory (INL) where he joined in 2022. His areas of research include arc welding, electron beam welding, laser welding, hybrid laser arc welding, diffusion welding, powder metallurgy hot isostatic pressing, and wire arc additive manufacturing. His specific interests include in-process monitoring/sensing, process control, welding metallurgy, and material/weld properties. Patterson received his B.S. in General Engineering from Montana Technological University in 2016, and M.S. and Ph.D. degrees in Welding Engineering from the Ohio State University in 2018 and 2021, respectively. His prior work experience includes industrial manufacturing and robotic welding system design, welding system integration, robotic programming, and consulting work regarding welding process development, metallurgy, and failures. His active professional committees include the American Welding Society (AWS) C7 committee on high energy density welding, multiple committees for American Society of Mechanical Engineers (ASME) Boiler and Pressure Vessel Code (BPVC), and multiple committees with the International Institute of Welding (IIW). He is currently the Chairman for AWS C7C committee for “Laser Beam Welding, Cutting, and Associated Processes” and is actively licensed as a Professional Engineer in the State of Idaho and an AWS certified welding inspector (CWI). He is a principal reviewer for the peer-reviewed journal Welding in the World (Le Soudage Dans Le Monde) and has published on arc, diffusion, electron beam, and laser beam welding.

Authors:

Tate Patterson Idaho National Laboratory
Ryann Bass U.S. Nuclear Regulatory Commission