US 12,276,003 B2
Method of heat treating a high strength steel and a product obtained therefrom
Hongliang Yi, Liaoning (CN); Shu Zhou, Shanghai (CN); Dapeng Yang, Liaoning (CN); Huajie Qin, Liaoning (CN); Xiaochuan Xiong, Jiangsu (CN); and Guodong Wang, Liaoning (CN)
Assigned to IRONOVATION MATERIALS TECHNOLOGY CO., LTD., Jiangsu (CN)
Appl. No. 17/617,681
Filed by IRONOVATION MATERIALS TECHNOLOGY CO., LTD., Jiangsu (CN)
PCT Filed Oct. 18, 2019, PCT No. PCT/CN2019/111796
§ 371(c)(1), (2) Date Dec. 9, 2021,
PCT Pub. No. WO2020/248459, PCT Pub. Date Dec. 17, 2020.
Claims priority of application No. 201910496707.9 (CN), filed on Jun. 10, 2019.
Prior Publication US 2022/0251673 A1, Aug. 11, 2022
Int. Cl. C21D 1/26 (2006.01); C21D 1/18 (2006.01); C21D 6/00 (2006.01); C22C 38/02 (2006.01); C22C 38/04 (2006.01); C22C 38/22 (2006.01); C22C 38/24 (2006.01); C22C 38/26 (2006.01); C22C 38/28 (2006.01); C22C 38/38 (2006.01); C22C 38/44 (2006.01); C22C 38/46 (2006.01); C22C 38/48 (2006.01)
CPC C21D 1/26 (2013.01) [C21D 1/18 (2013.01); C21D 6/002 (2013.01); C21D 6/005 (2013.01); C21D 6/008 (2013.01); C22C 38/02 (2013.01); C22C 38/04 (2013.01); C22C 38/22 (2013.01); C22C 38/24 (2013.01); C22C 38/26 (2013.01); C22C 38/28 (2013.01); C22C 38/38 (2013.01); C22C 38/44 (2013.01); C22C 38/46 (2013.01); C22C 38/48 (2013.01)] 11 Claims
OG exemplary drawing
 
1. A method of heat treating a high-strength steel, wherein the high-strength steel comprises, by weight: 0.30-0.45% C, 1.0% or less Si, 0.20-2.5% Mn, 0.20-2.0% Cr, 0.15-0.50% Mo, 0.10-0.40% V, 0.2% or less Ti, 0.2% or less Nb, and a balance of Fe and other alloy elements and impurities, wherein the above alloy elements make Eq(Mn) according to the following formula (1) no less than 1.82,
Eq(Mn)=Mn+0.26 Si+3.50P+1.30 Cr+2.67 Mo  (1)
which method comprises the steps of:
1) Austenitizing: heating the high-strength steel to Ac3+20° C. to 950° C. for a time of 1-300 min;
2) Carbide precipitation: cooling the high-strength steel after the step of austenitizing to Ar3-10° C. to 870° C. for a time of 5-300 min, then further cooling to 100° C. or less, wherein the average cooling rate of the further cooling is not less than 1° CS; and
3) Tempering: heating the high-strength steel after the step of carbide precipitation to 120-280° C. for a time of 5-360 min.