US 12,227,813 B2
Degassing method for manufacturing steel
Yun Li, Murrysville, PA (US); David L. Runner, Louisville, KY (US); Jonathan D. Youngblood, Southaven, MS (US); and Scott R. Story, Pittsburgh, PA (US)
Assigned to United States Steel Corporation, Pittsburgh, PA (US)
Filed by United States Steel Corporation, Pittsburgh, PA (US)
Filed on Apr. 10, 2023, as Appl. No. 18/132,521.
Application 18/132,521 is a continuation in part of application No. 17/897,824, filed on Aug. 29, 2022.
Claims priority of provisional application 63/237,636, filed on Aug. 27, 2021.
Prior Publication US 2023/0323492 A1, Oct. 12, 2023
Int. Cl. C21C 7/068 (2006.01); C21C 5/52 (2006.01); C21C 7/00 (2006.01); C21C 7/06 (2006.01); C21C 7/064 (2006.01); C22C 38/00 (2006.01)
CPC C21C 7/068 (2013.01) [C21C 5/52 (2013.01); C21C 7/0075 (2013.01); C21C 7/06 (2013.01); C21C 7/064 (2013.01); C22C 38/004 (2013.01)] 11 Claims
OG exemplary drawing
 
1. A method of making non-grain oriented (NGO) steel, comprising:
tapping the liquid steel out of an electric arc furnace;
deoxidizing the liquid steel before or after transferring the liquid steel to a ladle metallurgy furnace producing killed deoxidized liquid steel;
removing sulfur at the ladle metallurgy furnace (LMF) producing desulfurized liquid steel;
skimming off ladle slag and/or adding fluxes to the ladle slag at the LMF to prevent sulfur reversion;
transferring the desulfurized and killed deoxidized liquid steel from the LMF to a RH degasser;
removing nitrogen from the desulfurized and killed deoxidized liquid steel at the RH degasser with fast vacuum pump down;
adding fluxes into the RH degasser to fortify a bottom layer of ladle slag transferred from the LMF to the RH degasser against sulfur reversion;
removing carbon by oxygen blowing into the liquid steel at the RH degasser to produce decarburized liquid steel comprising 0.003 weight percent or less carbon; and
recirculating the steel at the RH degasser to remove inclusions.