US 11,655,514 B2
Deeply-hardened-surface turnout rail with high degree of undercooling and the preparation method thereof
Jun Yuan, Panzhihua (CN); Ming Zou, Panzhihua (CN); Yong Deng, Panzhihua (CN); and Ruoxi Li, Panzhihua (CN)
Assigned to PANGANG GROUP PANZHIHUA IRON & STEEL RESEARCH INSTITUTE CO., LTD., Panzhihua (CN)
Filed by PANGANG GROUP PANZHIHUA IRON & STEEL RESEARCH INSTITUTE CO., LTD., Panzhihua (CN)
Filed on Oct. 25, 2021, as Appl. No. 17/509,375.
Claims priority of application No. 202011164327.4 (CN), filed on Oct. 27, 2020.
Prior Publication US 2022/0127689 A1, Apr. 28, 2022
Int. Cl. C21D 9/04 (2006.01); C22C 38/24 (2006.01); C22C 38/04 (2006.01); C22C 38/02 (2006.01); C22C 38/00 (2006.01); C21D 8/00 (2006.01); C21D 6/00 (2006.01)
CPC C21D 9/04 (2013.01) [C21D 6/002 (2013.01); C21D 6/005 (2013.01); C21D 6/008 (2013.01); C21D 8/005 (2013.01); C22C 38/002 (2013.01); C22C 38/02 (2013.01); C22C 38/04 (2013.01); C22C 38/24 (2013.01); C21D 2211/001 (2013.01)] 5 Claims
OG exemplary drawing
 
1. A method for preparing a hardened-surface turnout rail with a degree of undercooling, said method comprising the following sequential steps:
feeding molten iron for converter smelting;
blowing argon into the molten iron in a furnace rear argon blowing station;
LF refining;
RH vacuumization;
casting steel blanks;
cooling in a cooling pit;
austenitic homogenization;
rail rolling; and
heat treatment,
wherein: (a) 0.2-0.3 wt. % Cr, 0.04-0.06 wt % V and 0.75-0.80 wt % C are added to the molten iron during the converter smelting; (b) the heat treatment step is divided into two cooling stages; (c) the heat treatment step lasts for 110 seconds; and (d) for the first 80 seconds after a rolled rail is fed into a heat treatment unit, the rolled rail is cooled at a speed of 3-5° C./s; for the last 30 seconds, the rolled rail is cooled at a speed of 0.5-2° C./s.