US 12,378,622 B2
High-strength steel bar and production method thereof
Yu Zhang, Suzhou (CN); Han Ma, Suzhou (CN); Yun Zhou, Suzhou (CN); and Huande Chen, Suzhou (CN)
Assigned to INSTITUTE OF RESEARCH OF IRON & STEEL, JIANGSU PROVINCE/SHA-STEEL, CO., LTD., Suzhou (CN); HANGJIAGANG HONGCHANG STEEL PLATE CO., LTD., Suzhou (CN); and JIANGSU SHAGANG GROUP CO., LTD., Suzhou (CN)
Appl. No. 17/613,917
Filed by INSTITUTE OF RESEARCH OF IRON & STEEL, JIANGSU PROVINCE/SHA-STEEL, CO., LTD., Suzhou (CN); ZHANGJIAGANG HONGCHANG STEEL PLATE CO., LTD., Suzhou (CN); and JIANGSU SHAGANG GROUP CO., LTD., Suzhou (CN)
PCT Filed Jul. 22, 2019, PCT No. PCT/CN2019/096977
§ 371(c)(1), (2) Date Nov. 23, 2021,
PCT Pub. No. WO2020/232818, PCT Pub. Date Nov. 26, 2020.
Claims priority of application No. 201910434471.6 (CN), filed on May 23, 2019.
Prior Publication US 2022/0220573 A1, Jul. 14, 2022
Int. Cl. C21D 9/00 (2006.01); B22D 11/115 (2006.01); C21D 6/00 (2006.01); C21D 8/06 (2006.01); C22C 38/02 (2006.01); C22C 38/04 (2006.01); C22C 38/06 (2006.01); C22C 38/44 (2006.01); C22C 38/46 (2006.01); C22C 38/48 (2006.01); C22C 38/50 (2006.01); C22C 38/54 (2006.01)
CPC C21D 9/0075 (2013.01) [B22D 11/115 (2013.01); C21D 6/004 (2013.01); C21D 6/005 (2013.01); C21D 6/008 (2013.01); C21D 8/065 (2013.01); C22C 38/02 (2013.01); C22C 38/04 (2013.01); C22C 38/06 (2013.01); C22C 38/44 (2013.01); C22C 38/46 (2013.01); C22C 38/48 (2013.01); C22C 38/50 (2013.01); C22C 38/54 (2013.01); C21D 2211/002 (2013.01); C21D 2211/005 (2013.01); C21D 2211/009 (2013.01)] 16 Claims
 
1. A high-strength steel bar, comprising, by mass percentage, the following chemical components: C: 0.15-0.32%, Si+Mn: 0.5-1.9%, Mn+Cr+Mo+Ni: 1.1-2.1%, V: 0.02-0.8%, at least one of Nb, Ti and Al: 0.01-0.3%, and a balance of Fe and inevitable impurities; wherein Mn=(2.5-3.5)Si, and a carbon equivalent satisfies Ceq=C+Mn/6+(Cr+Mo+V)/5+(Cu+Ni)/15≤0.56%;
a microstructure of the high-strength steel bar comprises ferrite, pearlite, bainite and a precipitated phase;
the ferrite has a volume percentage of 5-35% and a size of 2-15 μm, the pearlite has a volume percentage of 30-70%, the bainite has a volume percentage of 5-35% and a size of 5-25 μm;
the high-strength steel bar has a yield strength≥600 MPa, a yield ratio≤0.78, an elongation after fracture≥25%, and an uniform elongation≥15%.