Cold-rolled high-strength steel plate having excellent phosphating performance and formability and manufacturing method therefor

US11505844B2 · kind B2 · utility

Assignee

• BAOSHAN IRON & STEEL CO., LTD. · CN

Inventors

• SHU-XIANG ZHOU · Nanhu, CN
• Yong Zhong · Lo Wu, CN
• Xinyan JIN · Shanghai, CN
• Li WANG · Shanghai, CN

Key dates

• Filing date: Aug 29, 2017
• Grant date: Nov 22, 2022
• Expiry date: Sep 18, 2038

Classification

• Technology area (CPC C): Chemistry; Metallurgy
• CPC primary: C21D2211/008
• WIPO field: Materials, metallurgy
• WIPO sector: Chemistry

Abstract

A cold-rolled steel plate (1) and a manufacturing method therefor. The chemical composition of the steel plate (1) in percentage by weight is: C 0.15-0.25%, Si 1.50-2.50%, Mn 2.00-3.00%, P≤0.02%, S≤0.01%, Al 0.03-0.06%, N≤0.01%, with the balance being Fe and impurities. The surface layer has an inner oxide layer (2) with a thickness of 1-5 μm, and there is no enrichment of Si or Mn on the surface. The steel plate (1) has good phosphating performance and formability, with a tensile strength of ≥1180 MPa and an elongation of ≥14%, and has a complex-phase structure of ferrite, martensite, and retained austenite, the content of the retained austenite being not lower than 5%. A dew point is at −25° C. to 10° C. in continuous annealing, such that external oxidation transitions to internal oxidation.