Ultrahigh-strength hot-rolled steel sheet and steel strip having good fatigue and reaming properties and manufacturing method therefor

US11578380B2 · kind B2 · utility

Assignee

• BAOSHAN IRON & STEEL CO., LTD. · CN

Inventors

• Hanlong ZHANG · Shanghai, CN
• Yulong Zhang · Qingdao, CN
• Li WANG · Shanghai, CN

Key dates

• Filing date: Jun 25, 2019
• Grant date: Feb 14, 2023
• Expiry date: Aug 15, 2039

Classification

• Technology area (CPC C): Chemistry; Metallurgy
• CPC primary: C21D2211/004
• WIPO field: Materials, metallurgy
• WIPO sector: Chemistry

Abstract

An ultra-high-strength hot-rolled steel plate and steel strip having good fatigue and reaming properties and a manufacturing method therefor. The weight percentages of the components of the steel plate and the steel strip are: C: 0.07-0.14%, Si: 0.1-0.4%, Mn: 1.55-2.00%, P≤0.015%, S≤0.004%, Al: 0.01-0.05%, N≤0.005%, Cr: 0.15-0.50%, V: 0.1-0.35%, Nb: 0.01%-0.06%, Mo: 0.15-0.50%, Ti≤0.02%, and the balance of Fe and unavoidable impurities. Such components need to meet: 1.0≤[(Cr/52)/(C/4)+(Nb/93+Ti/48+V/51+Mo/96)/(C/12)]≤1.6. The tensile strength of the ultrahigh-strength hot-rolled steel plate and steel strip is ≥780 MPa, the yield strength thereof is ≥660 MPa, the tensile fatigue limit (10 million cycles) FL thereof is ≥570 MPa, or the fatigue limit to tensile strength FL/Rm thereof is ≥0.72. The reaming rate meets: if an original hole is a punched hole, the reaming rate thereof is >85%; and if the original hole is a reamed hole, the reaming rate thereof is >120%.