CN103045968A

CN103045968A - Hot rolled steel sheet

Info

Publication number: CN103045968A
Application number: CN2012105431029A
Authority: CN
Inventors: 朱新勇
Original assignee: QINGDAO SHENGHAN CHROMATOGRAPHY TECHNOLOGY Co Ltd
Current assignee: QINGDAO SHENGHAN CHROMATOGRAPHY TECHNOLOGY Co Ltd
Priority date: 2012-12-16
Filing date: 2012-12-16
Publication date: 2013-04-17

Abstract

The present invention provides a hot rolled steel sheet, comprising by weight: 0.002-0.004% of C, 0.015-0.03% of N, 0.09-0.1% of Cu, 0.15-0.2%of Cr, 0.10-1.80% of Mn, 0.11-0.14% of Ti, 0.16-0.18% of Zr, P <= 0.1%, Si <= 1.0%, S <= 0.1%, Al <= 0.1%, and the balance being Fe and unavoidable impurities. The surface oxide layer of the steel sheet has an average thickness of less than 10 [mu]m, the content of Fe3O4 in the oxide layer is greater than 90%, grain size is of 5.5-6.5 grade, the grain size is 15-25 [mu]m, the volume fraction of ferrite is greater than 90%, the yield strength is less than 210 MPa, the tensile strength is less than 300 MPa, and the elongation is higher than 40%. The present invention can reduce the phase transformation point Ar3 from austenite to ferrite, reduce the coiling temperature, and improve the surface and edge quality of a continuous casting slab, and has the advantages of simple preparation method, low production cost, stable product quality and good stamping property.

Description

A kind of hot-rolled steel sheet

Technical field

The present invention relates to a kind of hot-rolled steel sheet.

Background technology

Along with developing rapidly of China's metallurgical industry, hot-rolled sheet, band have been widely used in the every profession and trade, and the output of hot-rolled sheet, band is also improving constantly.In succession introduction and the operation of conventional hot rolling line (CSP) and many CSPs (TSCR) production line having promoted plate, band than when increasing, have also driven increasing substantially of cold-reduced sheet output.Therefore numerous enterprises has been integrated into a complete industrial production flow process with hot continuous rolling production line (CSP) or TSCR production line and rolling mill production line.But TSCR or CSP production line are because the process characteristic of self makes the yield strength of hot-rolled sheet coil apparently higher than the yield strength of the hot rolled strip of traditional process, therefore can not satisfy the requirement of cold rolling materials.Along with the fast development of the industries such as China's automobile, electrical equipment, building, for the processing enterprise of many production stamping parts, when consideration reduces production costs, wish that employing has the good hot-rolled sheet of processing characteristics and replaces cold-reduced sheet.Chinese invention patent application (application number: 200610124131.6, the applying date: 2006.12.8) disclose " a kind of method of producing hot rolled steel plate for cold formation ", the method adopts Electric furnace steel making+continuous casting and rolling technique of sheet bar, B/N (mol ratio) in the control steel is 0.3～0.8, because B/N (mol ratio) is controlled at 0.8 when following, the rate of recovery of B is very low, and the yield strength of hot-rolled steel sheet is reduced to below the 270MPa.It is 950～1100 ℃ that the charging temperature of strand requires, and guarantees relatively difficulty of this temperature during production.

When adopting the CSP production technique to produce thin size hot-rolled coiled sheet, because the cooling rate of thin plate is very large, so mostly be rolling section of γ+α two-phase region at last frame place, form easily the ferrite mixed grain structure, therefore getable steel plate be organized as the hot rolling texture of poor processability.In order effectively to reduce the yield strength of steel plate, the general performance that adopts measures such as improving strand heating, finish to gauge and coiling temperature to improve product.Above-mentioned Technology has to the negative impact that preparation brings of hot-rolled sheet coil: 1) form easily thicker iron scale in the high temperature coiling surface of hot-rolled sheet, therefore cause the surface quality of sheet material obviously to descend.2) because the strip coiling temperature is high, cause reduce the work-ing life of reeling machine.3) owing to the impact of high temperature coiling, coiled sheet has the possibility of the volume that collapses often, is prone to the defective of surperficial cross break seal during uncoiling.

In present rolling method, not yet find effectively to overcome the solution of defects.

Summary of the invention

The present invention proposes a kind of hot rolled steel plate for punch process.

Technical scheme of the present invention is: a kind of hot-rolled steel sheet, it is characterized in that the composition of described steel plate contains C:0.002-0.004%, N:0.015-0.03% in % by weight, Cu:0.09-0.1%, Cr:0.15-0.2%, Mn:0.10～1.80%, Ti:0.11-0.14%, Zr:0.16-0.18%, P≤0.1%, Si≤1.0%, S≤0.1%, Al≤0.1%, remainder is Fe and inevitable impurity, the mean thickness of surface of steel plate zone of oxidation＜10 μ m, Fe in the zone of oxidation ₃O ₄Content＞90%, grain fineness number is 5.5～6.5 grades, grain-size is 15-25 μ m, ferritic volume fraction is greater than 90%, yield strength is lower than 210MPa, tensile strength is lower than 300MPa, unit elongation is higher than 40%.

The present invention can reduce austenite to ferritic transformation temperature A _R3, reduce coiling temperature, improve continuously cast bloom surface and quality of edges, have that the preparation method is simple, production cost is low, constant product quality and have the advantage such as good stamping performance can satisfy customer requirements fully.Can also change in addition the interior tissue of processed steel, reduce the A of this steel grade _R3Transformation temperature and expansion austenite temperature province mutually, and effectively reduce the ferrite nucleation rate.

Embodiment

The preparation method of hot-rolled steel sheet may further comprise the steps:

1) mol ratio of boron and nitrogen is 0.81～1.10 in the refining process molten steel;

2) nitrogen content in the casting process, tundish in the molten steel is not higher than 60ppm;

Temperature was 900～949 ℃ when 3) strand entered soaking pit, and tapping temperature is 1050～1099 ℃;

When 4) finishing finish rolling and finish to gauge, board temperature is controlled at the Ar that the traditional technology condition does not add boron soft steel ₃40～60 ℃ scope under the transformation temperature;

5) strip is cooled to 540～650 ℃ with the speed of cooling of 5～20 ℃/s after the finish to gauge;

6) coiling temperature of strip is controlled between 540～630 ℃.

Embodiment:

Produce a kind of hot-rolled steel sheet, it is characterized in that the composition of described steel plate contains C:0.002-0.004%, N:0.015-0.03% in % by weight, Cu:0.09-0.1%, Cr:0.15-0.2%, Mn:0.10～1.80%, Ti:0.11-0.14%, Zr:0.16-0.18%, P≤0.1%, Si≤1.0%, S≤0.1%, Al≤0.1%, remainder is Fe and inevitable impurity, the mean thickness of surface of steel plate zone of oxidation＜10 μ m, Fe in the zone of oxidation ₃O ₄Content＞90%, grain fineness number is 5.5～6.5 grades, grain-size is 15-25 μ m, ferritic volume fraction is greater than 90%, yield strength is lower than 210MPa, tensile strength is lower than 300MPa, unit elongation is higher than 40%.

Claims

1. hot-rolled steel sheet, it is characterized in that the composition of described steel plate contains C:0.002-0.004%, N:0.015-0.03% in % by weight, Cu:0.09-0.1%, Cr:0.15-0.2%, Mn:0.10～1.80%, Ti:0.11-0.14%, Zr:0.16-0.18%, P≤0.1%, Si≤1.0%, S≤0.1%, Al≤0.1%, remainder is Fe and inevitable impurity, the mean thickness of surface of steel plate zone of oxidation＜10 μ m, Fe in the zone of oxidation ₃O ₄Content＞90%, grain fineness number is 5.5～6.5 grades, grain-size is 15-25 μ m, ferritic volume fraction is greater than 90%, yield strength is lower than 210MPa, tensile strength is lower than 300MPa, unit elongation is higher than 40%.