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Method for reducing thickness of oxide scale on surface of hot-rolled steel sheet

A technology for surface oxidation and hot-rolling of steel sheets, applied in metal rolling, temperature control, metal rolling, etc., can solve the problem of reducing the heating temperature or holding time of the slab, affecting the uniformity of the structure in the cooling process, and unfavorable alloying elements uniformity, etc. To solve the problem, to achieve the effect of reducing the amount of acid used for pickling, reducing the time of pickling, and convenient operation

Inactive Publication Date: 2013-10-09
武汉钢铁有限公司
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  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

[0007] However, the above method has the following problems: 1) reducing the slab heating temperature or holding time is not conducive to the homogenization of alloy elements in the steel, and is likely to cause defects such as dendrite segregation and banded structure; 2) reducing the rough rolling and finishing rolling temperatures It will affect the subsequent cooling process and microstructure uniformity, and the finishing temperature is too low, which is easy to cause mixed crystals; 3) The control of silicon content increases the difficulty of smelting and will affect the final mechanical properties of the steel; 4) Control the front section Rapid cooling puts forward higher requirements for existing cooling equipment; 5) Adding iron oxide scale removal device increases facilities and investment

Method used

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  • Method for reducing thickness of oxide scale on surface of hot-rolled steel sheet
  • Method for reducing thickness of oxide scale on surface of hot-rolled steel sheet
  • Method for reducing thickness of oxide scale on surface of hot-rolled steel sheet

Examples

Experimental program
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Effect test

Embodiment 1

[0045] The roughing mill is a four-roller reversible roughing unit with vertical rollers. Its maximum rolling pressure is 5000t, and the capacity of the main drive motor is 2×7500kW. Width 1562mm.

[0046] First, the continuous casting slab is dephosphorized with vertical rolls; then rough rolling is carried out, the rough rolling pass is set to 8 passes, the reduction of each pass is controlled to be 25.11mm, and the rough rolling total deformation is 84.6%. Embodiment Table 1 shows the rolling data of the continuous casting slab of 1 in each pass.

[0047] Another example of rolling with the conventional rough rolling method is set as the comparative example 1 of embodiment 1, at first the continuous casting slab is dephosphorized with vertical rolls; Considering the biting ability and thickness fluctuation in the first and second passes, the reduction amount is slightly smaller, and the reduction amount in the third pass is the largest, and then the reduction amount of eac...

Embodiment 2

[0054] The rough rolling mill is a four-high reversing mill with a maximum rolling pressure of 58854kN, a maximum rolling torque of 5493kJ, and a main drive motor with a capacity of 2×4600kW; 2600mm.

[0055] First, the continuous casting slab is subjected to conventional dephosphorization; then rough rolling is carried out, and the rough rolling pass is set to 7 passes. The reductions are all 20.00mm, and the total rough rolling deformation is 70%.

[0056] In addition, an example of rolling with conventional rough rolling method is set as the comparative example 2 of embodiment 2. At first, the conventional dephosphorization of the continuous casting slab is carried out; Biting ability and thickness fluctuate, the amount of reduction is slightly smaller, and the amount of reduction in the second pass is the largest, and then the reduction amount of each pass is controlled to decrease from pass to pass, and the total deformation of rough rolling is guaranteed to be 70%. The...

Embodiment 3

[0063] The roughing mill is a semi-continuous roughing mill consisting of a two-high irreversible rolling mill and a four-high reversing rolling mill. The diameter of the working rolls of the two-high mill is 1200-1350mm, the maximum rolling pressure is 3000t, the capacity of the main drive motor is 2×5000kW; the diameter of the working rolls of the four-roll mill is 1100-1200mm, the maximum rolling pressure is 4500t, the main drive motor The capacity is 2×7500kW; the thickness of the continuous casting billet is 240mm, the width is 1400mm, the length is 11900mm, the thickness of the intermediate billet is 38mm, and the width is 1289mm. The total rough rolling deformation is 84.3%.

[0064] First, the continuous casting slab is subjected to conventional dephosphorization; then rough rolling is carried out, and the rough rolling pass is set to 6 passes, of which, the two-roll rolling mill is rolled for one pass, and the four-roll mill is rolled for five passes. The reduction i...

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Abstract

The invention discloses a method for reducing the thickness of oxide scale on the surface of a hot-rolled steel sheet. The method for reducing the thickness of the oxide scale on the surface of the hot-rolled steel sheet comprises the steps of dephosphorization before rough rolling of a continuous casting billet, and control over rough rolling, wherein the total deformation of the rough rolling is 70%-85%, and the rolling reduction of passes of the rough rolling is controlled to be equal. The process of rough rolling is controlled, the pass load is distributed again, the rolling reduction of the passes can be equal, and the body surface of a slab is gradually increased along with reduction of the temperature. The body surface ratio of the slab in each pass is smaller than that of a slab in a corresponding pass in a rolling method that the rolling reduction decreases pass by pass under the premise that the total deformation of the rough rolling is the same, thus, the purpose of reducing the thickness of the oxide scale and the purpose of pressing the oxide scale are achieved, the surface quality of the hot-rolled steel sheet is improved, the acid amount and the time for acid pickling in the follow-up working procedure are reduced, and production efficiency and metal yield are improved. When the method for reducing the thickness of the oxide scale on the surface of the hot-rolled steel sheet is adopted, the size of a recrystallized austenite grain can be reduced, and the method for reducing the thickness of the oxide scale on the surface of the hot-rolled steel sheet is beneficial to obtaining even microstructures, and improves strength, ductility and toughness of the hot-rolled steel sheet.

Description

technical field [0001] The invention relates to a steel rolling process control technology, in particular to a method for reducing the thickness of oxide scale on the surface of a hot-rolled steel plate. Background technique [0002] At present, the development of hot rolling technology mainly focuses on the precise control of plate shape, thickness accuracy, temperature and performance. With the rapid development of the automobile and home appliance industries, downstream users have increasingly stringent requirements for steel surface quality. Quality objections or even product returns are often caused by improper control of surface oxide scale, which seriously hinders the improvement of product grades. In the past, pickling, cold rolling, hot-dip galvanizing or coating have been used for surface treatment. In recent years, the introduction of energy-saving and emission-reduction guidelines has prompted downstream industries to meet increasingly stringent environmental pro...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): B21B37/00B21B37/74B21B37/16
Inventor 韩斌蔡珍李国彬黄全伟谭文杨奕刘洋
Owner 武汉钢铁有限公司
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