b'Property Improvement of ATF Wrought FeCrAlPrincipal Investigator: Yukinori Yamamoto, ORNLTeam Members/ Collaborators: Bruce A. Pint and Kenneth Kane (ORNL)Proper combinations ofD evelopment efforts forprocessability of the alloys during Accident Tolerant Fuel (ATF)tube production and the mechanical minor alloying additionswrought FeCrAl alloys haveproperties of the final tube products. in ATF wrought FeCrAlbeen pursued since fiscal year (FY)Previous efforts successfully produced alloy can improve the2013. FeCrAl alloys were selected asseamless, thin-wall FeCrAl alloy tubes processability of thean attractive candidate ATF claddingcombined with the expected fine grain seamless thin-wall tubes,material because of their excellentstructure in the final products through which significantlyoxidation resistance in high- commercially available fabrication contributes to the cost- temperature steam environments upprocess (including a vacuum effectiveness of theto 1475C, resulting from sufficientinduction melting, hot-isostatic cladding production. amounts of Cr and Al additions.pressing, extrusion, gun-drilling, After comprehensive evaluations ofdrawing and annealing). However, model Fe-Cr-Al-Y alloys (Gen. I) andbecause of a relatively narrow process engineering FeCrAl alloy series (Gen.window to balance the processability II) with a wide range of major andof C26M tube production and the minor alloy compositions, an alloyproperties in the final product, further consisting of Fe-12Cr-6Al-2Mo-0.2Si- demands appeared to increase the 0.03Y, wt.% (identified as C26M)cost-effectiveness by applying a large was down-selected for seamless,reduction in each drawing pass, wide thin-wall tube production to be usedtolerance of intermediate annealing as an ATF cladding. conditions, increased material Project Description: yield through less susceptibility of Research has been focused onunexpected crack formation during achieving a balance between high- drawing process, together with temperature performance and tubecontrolling the fine grain structure fabricability. Body-centered-cubicand sufficiently high oxidation (BCC) Fe-based materials with Crresistance at elevated temperature. and Al additions typically sufferMinor alloying additions of yttrium from poor ductility because of theirand zirconium (and some other relatively high ductile-brittle transitionelements, not shown in the report) in temperatures. Microstructural stabilityC26M base alloys have been attempted of the refined grain or subgrainto evaluate the effects on various structure at high temperatures isproperties related to the processability critical to maintaining both theand the properties.80 2019|AFC ACCOMPLISHMENTS'