Performance of High-Temperature Nickel-Based Alloys and Welds for Generation 3 Concentrating Solar Power (CSP) Plants

A range of Generation 3 Concentrating Solar Power (CSP) power plant designs are focused on ultimately producing heat and integrated thermal energy storage for use in a 700°C+ supercritical CO₂ power cycle (sCO₂). This necessitates the use of heat-resistant nickel-based alloys including INCONEL® alloy 740H®. Gen 3 CSP plant and component designs present some unique material product form requirements including thin wall small diameter tubing, large diameter piping, and thin sheets for heat-exchangers. To support the development of Gen 3 CSP design, EPRI and Special Metals Corporation have undertaken a collaborative project to assess the use of welded tubing and pipe and examine materials challenges specific to manufacturing and high-temperature mechanical performance. Creep and fatigue testing is being conducted to assess the mechanical response and metallurgical development in welded tubes, welded pipe, and thin-sheets to understand the complex interactions between processing, welding, microstructure, and high-temperature behavior in alloy 740H and UNS N066230 alloys. This presentation will introduce the high-temperature materials challenges associated with the application of nickel-based alloys in three different Gen 3 CSP conceptual design, highlight manufacturing studies to produce lower cost material product forms to improve the economy of these design, describe the high-temperature creep behavior of these alternatively produced products, and evaluate the microstructure of the tested materials. Debits in mechanical performance due to grain size variations and welding thermal cycles will be discussed and approaches to mitigate these effects will be examined.

This research is supported by the U.S. DOE Office of Energy Efficiency and Renewable Energy (EERE), award number DE-EE0008367

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