Computational Design of Weldable High-Cr Ferritic Steel

The U.S. Department of Energy (DOE) is actively funding research to significantly enhance the thermal efficiency of coal-fired steam boilers for power generation through the use of advanced ultra-supercritical (A-USC) steam temperatures and pressures. Since coal fired power plants are the dominant source of domestic power generation, the accelerated design, development and commercialization of efficient, reliable, next-generation coal-fired power plants can significantly increase domestic energy security and enhance the U.S. technical leadership strength. The purpose of this SBIR program is to create a new alloy for A-USC coal-fired boilers using QuesTeks computational alloy design methodology and specific experience developing and commercializing a creep-resistant ferritic superalloy with low processing cost related to welding. During the Phase I program, QuesTek Innovations collaborated with engineers from a boiler OEM as well as technical experts from the DOE to identify the elimination of post-weld heat treatment and increase in creep-resistance as two critical material objectives for the new alloys. QuesTek then designed a series of prototype alloys using computational models to target critical design parameters, fabricated prototype samples for high temperature tensile test as well as welding demonstration. In Phase I, QuesTeks new alloys show superb high temperature tensile strength and robust weld-zone microstructure unseen in incumbent alloys such as P92. Based on the results from the Phase I prototype alloys, and on input from project stakeholders, the objective of Phase II is to execute a detailed alloy design and demonstrate the performance and processing characteristics satisfying the alloy design criteria. Working with one of its suppliers, QuesTek will prototype ingots to specification at intermediate size scale (30 lb. and 1,500 lb. size). Alloy creep strength, weldability, steamside and fireside oxidation resistance will be demonstrated in the intermediate scale materials. Facilities at our OEM collaborators will be employed to simulate the actual power plant service environment. In Phase III our investigations will be expanded (in conjunction with our OEM partners) to include component level testing and qualification. Application of the alloy to additional components with similar requirements will be identified and pursued.