US 12,404,564 B2
Annealing processes for making high strength steel products
David Paul Hoydick, Pittsburgh, PA (US); Eduardo Augusto Silva, Murrysville, PA (US); and Matthew Michael McCosby, New Castle, PA (US)
Assigned to United States Steel Corporation, Pittsburgh, PA (US)
Filed by United States Steel Corporation, Pittsburgh, PA (US)
Filed on Jul. 2, 2019, as Appl. No. 16/459,757.
Application 16/459,757 is a continuation of application No. 15/591,344, filed on May 10, 2017, granted, now 10,385,419.
Claims priority of provisional application 62/396,602, filed on Sep. 19, 2016.
Claims priority of provisional application 62/334,189, filed on May 10, 2016.
Prior Publication US 2019/0390291 A1, Dec. 26, 2019
This patent is subject to a terminal disclaimer.
Int. Cl. C21D 9/46 (2006.01); B32B 15/01 (2006.01); B32B 15/04 (2006.01); B32B 15/18 (2006.01); C21D 1/18 (2006.01); C21D 1/20 (2006.01); C21D 1/22 (2006.01); C21D 1/25 (2006.01); C21D 1/26 (2006.01); C21D 1/78 (2006.01); C21D 6/00 (2006.01); C21D 8/02 (2006.01); C22C 38/00 (2006.01); C22C 38/02 (2006.01); C22C 38/04 (2006.01); C22C 38/06 (2006.01); C22C 38/08 (2006.01); C22C 38/12 (2006.01); C22C 38/14 (2006.01); C22C 38/16 (2006.01); C22C 38/18 (2006.01); C22C 38/26 (2006.01); C22C 38/28 (2006.01); C22C 38/40 (2006.01); C22C 38/54 (2006.01); C23C 2/02 (2006.01); C23C 2/06 (2006.01); C23C 2/40 (2006.01); C23C 28/02 (2006.01); C25D 3/22 (2006.01); C25D 5/36 (2006.01)
CPC C21D 9/46 (2013.01) [B32B 15/012 (2013.01); B32B 15/013 (2013.01); B32B 15/04 (2013.01); B32B 15/043 (2013.01); B32B 15/18 (2013.01); C21D 1/18 (2013.01); C21D 1/20 (2013.01); C21D 1/22 (2013.01); C21D 1/25 (2013.01); C21D 1/26 (2013.01); C21D 1/78 (2013.01); C21D 6/00 (2013.01); C21D 8/0247 (2013.01); C22C 38/001 (2013.01); C22C 38/002 (2013.01); C22C 38/008 (2013.01); C22C 38/02 (2013.01); C22C 38/04 (2013.01); C22C 38/06 (2013.01); C22C 38/08 (2013.01); C22C 38/12 (2013.01); C22C 38/14 (2013.01); C22C 38/16 (2013.01); C22C 38/18 (2013.01); C22C 38/26 (2013.01); C22C 38/28 (2013.01); C22C 38/40 (2013.01); C22C 38/54 (2013.01); C23C 2/022 (2022.08); C23C 2/0224 (2022.08); C23C 2/06 (2013.01); C23C 2/40 (2013.01); C23C 28/021 (2013.01); C23C 28/025 (2013.01); C25D 3/22 (2013.01); C25D 5/36 (2013.01); C21D 8/0236 (2013.01); C21D 8/0278 (2013.01); C21D 2211/001 (2013.01); C21D 2211/005 (2013.01); C21D 2211/008 (2013.01); Y10T 428/12757 (2015.01); Y10T 428/12799 (2015.01); Y10T 428/12958 (2015.01); Y10T 428/12965 (2015.01); Y10T 428/12972 (2015.01)] 24 Claims
OG exemplary drawing
 
1. A method of producing a high strength rolled steel sheet product comprising from 0.12 to 0.5 weight percent C, from 1 to 3 weight percent manganese, from 0.8 to 3 weight percent of a combination of Si and Al, balance Fe, the method comprising:
subjecting the steel sheet product to a first step annealing process to achieve a predominantly martensitic microstructure; and
subjecting the steel sheet product to a second step process comprising soaking the sheet product in an intercritical regime at a temperature of from 720 to 850° C., cooling the steel sheet product to a temperature above 370° C., followed by holding the sheet product at a temperature of from 370 to 430° C., wherein the steel sheet product comprises ferrite, less than 15 volume percent of fresh, untempered martensite, retained austenite grains having an average aspect ratio of less than 2.0:1, is substantially free of tempered martensite, and has a combination of ultimate tensile strength and total elongation UTS·TE of greater than 27,000 MPa % and a hole expansion ratio of at least 30 percent.