# US 10,370,748 B2 · Lean austenitic stainless steel > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 10,370,748 B2 - Document ID: US10370748B2 - Status: Granted - Kind: B2 - Application number: 15/427,667 - Filed: 2017-02-08 - Published: 2017-05-25 - Granted: 2019-08-06 - Earliest claimed: 2007-11-29 - Assignees: ATI Properties, Inc. - Applicants: ATI Properties LLC - Inventors: David S. Bergstrom; James M. Rakowski; Charles P. Stinner; John J. Dunn; John F. Grubb - Web page: https://patentgrep.com/patent/US10370748B2 ## CPC - C22C 38/58: with more than 1.5% by weight of manganese - C22C 38/001: {containing N} - C22C 38/002: {containing In, Mg, or other elements not provided for in one single group C22C38/001 - C22C38/60} - C22C 38/02: containing silicon - C22C 38/22: with molybdenum or tungsten - C22C 38/30: with cobalt - C22C 38/32: with boron - C22C 38/34: with more than 1.5% by weight of silicon - C22C 38/38: with more than 1.5% by weight of manganese - C22C 38/42: with copper - C22C 38/44: with molybdenum or tungsten - C22C 38/52: with cobalt - C22C 38/54: with boron - C22C: ALLOYS (treatment of alloys C21D, C22F) ## Abstract 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 MD30 value of less than 20° C. ## Claims ### Claim 1 An austenitic stainless steel comprising, in weight percentages: up to 0.20 C; greater than 2.0 to 9.0 Mn; up to 1.0 Si; 16.0 to 23.0 Cr; 1.0 to 3.0 Ni; up to 2.0 Mo; 0.1 to 0.35 N; 0.05 to 4.0 W; up to 0.01 B; up to 1.0 Co; iron; and impurities; the austenitic stainless steel having a ferrite number of at least 3 up to less than 10, and a MD30 value less than 20° C. ### Claim 2 (depends on 1) The austenitic stainless steel according to claim 1, wherein 0.5≤(Mo+W/2)≤5.0. ### Claim 3 (depends on 1) The austenitic stainless steel of claim 1, having a PREW value greater than 22. ### Claim 4 (depends on 1) The austenitic stainless steel of claim 1, having a PREW value greater than 22 and up to 30. ### Claim 5 (depends on 1) The austenitic stainless steel of claim 1, having a ferrite number of 3 up to 5. ### Claim 6 (depends on 1) The austenitic stainless steel of claim 1, having a MD30 value less than −10° C. ### Claim 7 (depends on 1) The austenitic stainless steel of claim 1, wherein C is limited to up to 0.08. ### Claim 8 (depends on 1) The austenitic stainless steel of claim 1, wherein Mn is limited to greater than 2.0 to 8.0. ### Claim 9 (depends on 1) The austenitic stainless steel of claim 1, wherein Mn is limited to 3.0 to 6.0. ### Claim 10 (depends on 1) The austenitic stainless steel of claim 1, wherein Cr is limited to 16.0 to 22.0. ### Claim 11 (depends on 1) The austenitic stainless steel of claim 1, wherein Cr is limited to 17.0 to 21.0. ### Claim 12 (depends on 1) The austenitic stainless steel of claim 1, wherein Cr is limited to 17.0 to 20.0. ### Claim 13 (depends on 1) The austenitic stainless steel of claim 1, wherein Cr is limited to 16.0 to 18.0. ### Claim 14 (depends on 1) The austenitic stainless steel of claim 1, wherein N is limited to 0.1 to 0.30. ### Claim 15 (depends on 1) The austenitic stainless steel of claim 1, wherein N is limited to 0.14 to 0.30. ### Claim 16 (depends on 1) The austenitic stainless steel of claim 1, wherein Mo is limited to 0.40 to 2.0. ### Claim 17 (depends on 1) The austenitic stainless steel of claim 1, wherein Mo is limited to 0.5 to 2.0. ### Claim 18 (depends on 1) The austenitic stainless steel of claim 1, wherein B is limited to up to 0.008. ### Claim 19 (depends on 1) The austenitic stainless steel of claim 1, wherein W is limited to 0.05 to 0.60. ### Claim 20 (depends on 1) The austenitic stainless steel of claim 1, wherein Mo is limited to 0.40 to 2.0 and having a MD30 value less than −10° C. ### Claim 21 (depends on 1) The austenitic stainless steel of claim 1, wherein Mo is limited to 0.40 to 2.0 and wherein 0.5≤(Mo+W/2)≤4.0. ### Claim 22 (depends on 21) The austenitic stainless steel of claim 21, having a MD30 value less than −10° C. ### Claim 23 An austenitic stainless steel comprising, in weight percentages: up to 0.20 C; 6.0 to 9.0 Mn; up to 1.0 Si; 16.0 to 23.0 Cr; 1.0 to 3.0 Ni; 0.40 to 2.0 Mo; 0.1 to 0.30 N; 0.05 to 4.0 W; up to 0.01 B; up to 1.0 Co; iron; and impurities; the austenitic stainless steel having a ferrite number at least 3 up to less than 10, a PREW value greater than 22 up to 30, and a MD30 value of less than 20° C. ### Claim 24 (depends on 23) The austenitic stainless steel of claim 23, wherein 0.5≤(Mo+W/2)≤4.0. ### Claim 25 An article of manufacture including an austenitic stainless steel comprising, in weight percentages: up to 0.20 C; greater than 2.0 to 9.0 Mn; up to 1.0 Si; 16.0-23.0 Cr; 1.0-3.0 Ni; up to 2.0 Mo; 0.1-0.35 N; 0.05 to 4.0 W; up to 0.01 B; up to 1.0 Co; iron; and impurities; the austenitic stainless steel having a ferrite number of at least 3 up to less than 10, and a MD30 value less than 20° C. ### Claim 26 (depends on 25) The article of manufacture of claim 25, wherein the austenitic stainless steel has a MD30 value less than −10° C. ### Claim 27 (depends on 25) The article of manufacture of claim 25, wherein in the austenitic stainless steel Mo is limited to 0.40-2.0 Mo. ### Claim 28 (depends on 25) The article of manufacture of claim 25, wherein the article is adapted for use in at least one of a low temperature environment and a cryogenic environment. ### Claim 29 (depends on 25) The article of manufacture of claim 25, wherein the article is selected from the group consisting of a corrosion resistant article, a corrosion resistant architectural panel, a flexible connector, a bellows, a tube, a pipe, a chimney liner, a flue liner, a plate frame heat exchanger part, a condenser part, a part for pharmaceutical processing equipment, a sanitary part, and a part for ethanol production or processing equipment. ### Claim 30 (depends on 1) The austenitic stainless steel of claim 1, wherein the ferrite number is calculated according to the following equation, in which elemental contents are weight percentages: Ferrite Number=[3.34×(Cr+1.5Si+Mo+2Ti+0.5Cb)]−[2.46×(Ni+30N+30C+0.5Mn+0.5Cu)]−28.6. ### Claim 31 (depends on 23) The austenitic stainless steel of claim 23, wherein the ferrite number is calculated according to the following equation, in which elemental contents are weight percentages: Ferrite Number=[3.34×(Cr+1.5Si+Mo+2Ti+0.5Cb)]−[2.46×(Ni+30N+30C+0.5Mn+0.5Cu)]−28.6. ### Claim 32 (depends on 25) The article of manufacture of claim 25, wherein the ferrite number is calculated according to the following equation, in which elemental contents are weight percentages: Ferrite Number=[3.34×(Cr+1.5Si+Mo+2Ti+0.5Cb)]−[2.46×(Ni+30N+30C+0.5Mn+0.5Cu)]−28.6.