Ati Properties, Inc.

Charles P Stinner

James M Rakowski

John J Dunn

David S Bergstrom

John F Grubb

An austenitic stainless steel having low nickel and molybdenum and exhibiting comparable corrosion resistance and formability properties to higher nickel and molybdenum alloys comprises, in weight %, up to 0.20 C, 2.0-9.0 Mn, up to 2.0 Si, 16.0-23.0 Cr, 1.0-5.0 Ni, up to 3.0 Mo, up to 3.0 Cu, 0.1-0.35 N, up to 4.0 W, up to 0.01 B, up to 1.0 Co, iron and impurities, the steel having a ferrite number of less than 10 and a MDvalue of less than 20&#xb0; C.

Lean austenitic stainless steel

An austenitic stainless steel composition having low nickel and molybdenum and exhibiting high corrosion resistance and good formability. The austenitic stainless steel includes, in weight %, up to 0.20 C, 2.0-6.0 Mn, up to 2.0 Si, 16.0-23.0 Cr, 5.0-7.0 Ni, up to 3.0 Mo, up to 3.0 Cu, 0.1-0.35 N, up to 4.0 W, up to 0.01 B, up to 1.0 Co, iron and impurities. The austenitic stainless steel has a ferrite number less than 11 and an MDvalue less than &#x2212;10&#xb0; C.

Corrosion resistant lean austenitic stainless steel

An austenitic stainless steel composition including relatively low nickel and molybdenum levels, and exhibiting corrosion resistance, resistance to elevated temperature deformation, and formability properties comparable to certain alloys including higher nickel and molybdenum levels. Embodiments of the austenitic stainless steel include, in weight %, up to 0.20 C, 2.0 to 9.0 Mn, up to 2.0 Si, 16.0 to 23.0 Cr, 1.0 to 7.0 Ni, up to 3.0 Mo, up to 3.0 Cu, 0.05 to 0.35 N, up to 4.0 W, (7.5(C))&#x2266;(Nb+Ti+V+Ta+Zr)&#x2266;1.5, up to 0.01 B, up to 1.0 Co, iron and impurities. Additionally, embodiments of the steel may include 0.5&#x2266;(Mo+W/2)&#x2266;5.0 and/or 1.0&#x2266;(Ni+Co)&#x2266;8.0.

Lean austenitic stainless steel containing stabilizing elements

An austenitic stainless steel composition including relatively low nickel and molybdenum levels, and exhibiting corrosion resistance, resistance to elevated temperature deformation, and formability properties comparable to certain alloys including higher nickel and molybdenum levels. Embodiments of the austenitic stainless steel include, in weight %, up to 0.20 C: 2.0 to 9.0 Mn, up to 2.0 Si, 16.0 to 23.0 Cr, 1.0 to 7.0 Ni, up to 3.0 Mo, up to 3.0 Cu, 0.05 to 0.35 N, up to 4.0 W, (7.5(C))&#x2266;(Nb+Ti+V+Ta+Zr)&#x2266;1.5, up to 0.01 B, up to 1.0 Co, iron and impurities. Additionally, embodiments of the steel may include 0.5&#x2266;(Mo+W/2)&#x2266;5.0 and/or 1.0&#x2266;(Ni+Co)&#x2266;8.0.

An austenitic stainless steel composition including relatively low nickel and molybdenum levels, and exhibiting corrosion resistance, resistance to elevated temperature deformation, and formability properties comparable to certain alloys including higher nickel and molybdenum levels. Embodiments of the austenitic stainless steel include, in weight %, up to 0.20 C, 2.0-9.0 Mn, up to 2.0 Si, 16.0-23.0 Cr, 1.0-7.0 Ni, up to 3.0 Mo, up to 3.0 Cu, 0.05-0.35 N, up to 4.0 W, (7.5(% C))&#x2266;(Nb+Ti+V+Ta+Zr)&#x2266;1.5, up to 0.01 B, up to 1.0 Co, iron and impurities. Additionally, embodiments of the steel may include 0.5&#x2266;(Mo+W/2)&#x2266;5.0 and/or 1.0&#x2266;(Ni+Co)&#x2266;8.0.

Various embodiments relate to interconnects for solid oxide fuel cells ('SOFCs') comprising ferritic stainless steel and having at least one via that when subjected to an oxidizing atmosphere at an elevated temperature develops a scale comprising a manganese-chromate spinel on at least a portion of a surface thereof, and at least one gas flow channel that when subjected to an oxidizing atmosphere at an elevated temperature develops an aluminum-rich oxide scale on at least a portion of a surface thereof. Other embodiments relate to interconnects comprising a ferritic stainless steel and having a fuel side comprising metallic material that resists oxidation during operation of the SOFCs, and optionally include a nickel-base superalloy on the oxidant side thereof. Still other embodiments relate to ferritic stainless steels adapted for use as interconnects comprising &#x2266;0.1 weight percent aluminum and/or silicon, and &#x3e;1 up to 2 weight percent manganese. Methods of making interconnects are also disclosed.

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Gibsonia, PA, United States of America

Charles P Stinner