Ati Properties, Inc.

James M Rakowski

David S Bergstrom

Charles P Stinner

John J Dunn

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 Ni and Mo levels, and exhibiting corrosion resistance, resistance to elevated temperature deformation, and formability properties comparable to certain alloys including higher Ni and Mo levels. Embodiments of the austenitic stainless steel include, in weight percentages, up to 0.20 C, 2.0-9.0 Mn, up to 2.0 Si, 15.0-23.0 Cr, 1.0-9.5 Ni, up to 3.0 Mo, up to 3.0 Cu, 0.05-0.35 N, (7.5(C))&#x2266;(Nb+Ti+V+Ta+Zr)&#x2266;1.5, Fe, and incidental impurities.

A method of reducing the formation of electrically resistive scale on a an article comprising a silicon-containing ferritic stainless subjected to oxidizing conditions in service includes, prior to placing the article in service, subjecting the article to conditions under which silica, which includes silicon derived from the steel, forms on a surface of the steel. Optionally, at least a portion of the silica is removed from the surface to placing the article in service. A ferritic stainless steel alloy having a reduced tendency to form silica on at least a surface thereof also is provided. The steel includes a near-surface region that has been depleted of silicon relative to a remainder of the steel.

Method for reducing formation of electrically resistive layer on ferritic stainless steels

An article of manufacture comprises a ferritic stainless steel that includes a near-surface region depleted of silicon relative to a remainder of the ferritic stainless steel. The article has a reduced tendency to form an electrically resistive silica layer including silicon derived from the steel when the article is subjected to high temperature oxidizing conditions. The ferritic stainless steel is selected from the group comprising AISI Type 430 stainless steel, AISI Type 439 stainless steel, AISI Type 441 stainless steel, AISI Type 444 stainless steel, and E-BRITE&#xae; alloy, also known as UNS 44627 stainless steel. In certain embodiments, the article of manufacture is a fuel cell interconnect for a solid oxide fuel cell.

Articles comprising ferritic stainless steels

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.

A method of reducing defect heights of iron mound defects on a mill glass coated electrical steel, comprises contacting at least a portion of a surface of a mill glass coated electrical steel with an acidic solution for a contacting time sufficient to reduce an average height of iron defects on the surface to a an average height in a range of 0 percent to 150 percent of the thickness of the mill glass coating, without effectively removing the mill glass coating. After contacting, the acid contacted mill glass coated electrical steel is rinsed with water and dried.

Chemical removal of surface defects from grain oriented electrical steel

An austenitic stainless steel composition including relatively low Ni and Mo levels, and exhibiting corrosion resistance, resistance to elevated temperature deformation, and formability properties comparable to certain alloys including higher Ni and Mo levels. Embodiments of the austenitic stainless steel include, in weight percentages, up to 0.20 C, 2.0-9.0 Mn, up to 2.0 Si, 15.0-23.0 Cr, 1.0-9.5 Ni, up to 3.0 Mo, up to 3.0 Cu, 0.05-0.35 N, (7.5(% C))&#x2266;(% Nb+% Ti+% V+% Ta+% Zr)&#x2266;1.5, Fe, and incidental impurities.

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Allison Park, PA, United States of America

James M Rakowski