Ati Properties, Inc.

Allegheny Ludlum Corporation

John F Grubb

John J Dunn

David S Bergstrom

James M Rakowski

Charles P Stinner

James D Fritz

William A Pratt

Dominic A Sorace

Richard K Pitler

Ronald E Polinski

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.

A method of enhancing the corrosion resistance of an austenitic steel includes removing material from at least a portion of a surface of the steel such that corrosion initiation sites are eliminated or are reduced in number relative to the number resulting from processing in a conventional manner. Material may be removed from the portion by any suitable method, including, for example, grit blasting, grinding and/or acid pickling under conditions more aggressive than those used in conventional processing of the same steel.

Surface treatments to improve corrosion resistance of austenitic stainless steels

Ferritic stainless steel having high temperature creep resistance

A duplex stainless steel includes less than, in weight percent, 3 percent nickel and 1.5 percent molybdenum. In one embodiment, the duplex stainless steel includes, in weight percent, up to 0.06 percent carbon; 15 to 25 percent chromium; 1 to less than 2.5 percent nickel; greater than 2 percent up to 3.75 percent manganese; greater than 0.12 up to 0.35 percent nitrogen; up to 2 percent silicon; up to 1.5 percent molybdenum; up to 0.5 percent copper; up to 0.2 percent cobalt; up to 0.05 percent phosphorous; up to 0.005 percent sulfur; 0.001 to 0.0035 percent boron; iron and incidental impurities. The duplex stainless steel provided may be provided in the form of an article of manufacture, such as strip, bar, plate, sheet, casting, tubing or piping. A method for making the duplex stainless steel of the invention also is disclosed.

Duplex stainless steels

Method of producing stainless steels having improved corrosion resistance

A duplex stainless steel including, in weight percent, up to 0.06 percent carbon, 15 up to less than 25 percent chromium, greater than 3 up to 6 percent nickel, up to 3.75 percent manganese, 0.14 up to 0.35 percent nitrogen, up to 2 percent silicon, greater than 1.4 up to less than 2.5 percent molybdenum, up to less than 0.5 percent copper, up to less than 0.2 percent cobalt, up to 0.05 percent phosphorous, up to 0.005 percent sulfur, and 0.001 up to 0.0035 percent boron, with the remainder being iron and incidental impurities is disclosed. The duplex stainless steel may be included in an article of manufacture, such as a strip, bar, plate, sheet, casting, tubing or piping. A method for making such a duplex stainless steel is also disclosed.

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Lower Burrell, PA, United States of America

John F Grubb