US 11,987,856 B2
Ultra-high strength maraging stainless steel with salt-water corrosion resistance
Jialong Tian, Shenyang (CN); Ke Yang, Shenyang (CN); Wei Wang, Shenyang (CN); Yiyin Shan, Shenyang (CN); and Wei Yan, Shenyang (CN)
Assigned to The Boeing Company, Arlington, VA (US); and Institute of Metal Research, Shenyang (CN)
Filed by The Boeing Company, Arlington, VA (US); and Institute of Metal Research, Liaoning (CN)
Filed on May 5, 2023, as Appl. No. 18/312,769.
Application 18/312,769 is a division of application No. 17/345,180, filed on Jun. 11, 2021, granted, now 11,680,301.
Application 17/345,180 is a continuation of application No. 16/315,475, granted, now 11,085,093, issued on Aug. 10, 2021, previously published as PCT/US2017/040660, filed on Jul. 5, 2017.
Claims priority of application No. 201610592044.7 (CN), filed on Jul. 26, 2016.
Prior Publication US 2023/0272497 A1, Aug. 31, 2023
This patent is subject to a terminal disclaimer.
Int. Cl. C21D 7/13 (2006.01); C21D 6/00 (2006.01); C22C 38/00 (2006.01); C22C 38/02 (2006.01); C22C 38/04 (2006.01); C22C 38/44 (2006.01); C22C 38/50 (2006.01); C22C 38/52 (2006.01)
CPC C21D 7/13 (2013.01) [C21D 6/004 (2013.01); C21D 6/005 (2013.01); C21D 6/007 (2013.01); C21D 6/008 (2013.01); C22C 38/002 (2013.01); C22C 38/02 (2013.01); C22C 38/04 (2013.01); C22C 38/44 (2013.01); C22C 38/50 (2013.01); C22C 38/52 (2013.01); C21D 2211/001 (2013.01); C21D 2211/008 (2013.01)] 20 Claims
OG exemplary drawing
 
1. A method for heat treatment of a stainless steel comprising:
13 to 14 wt % chromium (Cr);
5.5 to 7.0 wt % nickel (Ni);
5.5 to 7.5 wt % cobalt (Co);
3 to 5 wt % molybdenum (Mo);
1.9 to 2.5 wt % titanium (Ti); and
iron (Fe),
the method comprising:
solution treatment of the stainless steel at 1050-1150° C. for 1-2 h;
after the solution treatment, cryogenic treatment of the stainless steel in liquid nitrogen (−196° C.) for at least 5 h; and
after the cryogenic treatment, aging treatment of the stainless steel at 450-520° C. for 30 min to 16 h.