Effective control method for pitted surface of plain carbon steel/Nb-containing steel plate of 20-30 mm thickness

A control method and technology of ordinary carbon steel, applied in the direction of temperature control, rolling mill control device, metal rolling, etc., can solve the problems of no rolling process definition, difficult to remove iron oxide scale, serious oxidation burning loss, etc., to improve product profit , Reduce the probability of pockmarked surface and improve the effect of yield

Active Publication Date: 2015-04-22
TIANJIN IRON & STEEL GRP
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

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Problems solved by technology

[0004] But, the problem that said method exists is: CN103831303A and CN101704026A all adopt high-temperature heating, and tapping temperature is controlled between 1140-1245 ℃, and oxidation burning loss is more serious, and the iron oxide scale that produces is difficult to remove
CN103831303A defines the tapping temperature, descaling pressure, rol

Method used

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Examples

Experimental program
Comparison scheme
Effect test

Example Embodiment

[0023] Example 1

[0024] Q235B plain carbon steel billet is heated → high pressure water descaling → rough rolling → finishing rolling → ACC laminar cooling → straightening → cooling → finishing → storage process, rolling into a 20mm medium and thick plate finished product, the implementation plan is:

[0025] (1) Blank specifications: 250mm×1600mm×2750mm

[0026] The mass percentage of chemical composition: C: 0.17%, Si: 0.27%, Mn: 0.52%, P: 0.026%, S: 0.018%, the rest is Fe;

[0027] (2) Adopting a step-by-step double regenerative heating furnace with three stages of heating: preheating, heating and soaking. In order to prevent the coarse austenite grains of ordinary carbon steel, a low-temperature rapid heating method is adopted. The preheating section: 784 ℃; heating section: 1120℃, soaking section: 1190℃, the total heating time is controlled at 224min; the tapping temperature is controlled at 1110℃, the high-pressure water descaling pressure is 22Mpa, to ensure that the oxide sc...

Example Embodiment

[0030] Example 2

[0031] Q345B billet is heated→high pressure water descaling→rough rolling→finishing rolling→ACC laminar cooling→straightening→cooling→finishing→stocking process, rolled into a 25m thick plate finished product, the implementation plan is:

[0032] (1) Blank specifications: 250mm×2100mm×2780mm

[0033] The mass percentage of chemical composition: C: 0.16%, Si: 0.37%, Mn: 1.48%, P: 0.019%, S: 0.012%, Alt: 0.024%, the rest is Fe;

[0034] (2) Adopting a step-by-step double regenerative heating furnace with three heating stages including preheating, heating and soaking. It adopts low-temperature rapid heating method, preheating section: 854℃; heating section: 1150℃, soaking section: 1210 ℃, the total heating time is controlled at 245min; the tapping temperature is controlled at 1120℃, and the high-pressure water descaling pressure is 21Mpa;

[0035] (3) Two-stage rolling is adopted, the rough rolling opening temperature is 1090℃, 7 passes are rolled in total, and there ar...

Example Embodiment

[0037] Example 3

[0038] A572Gr50 Nb-containing steel billet is heated → high pressure water descaling → rough rolling → finishing rolling → ACC laminar cooling → straightening → cooling → finishing → storage process, rolling into a 30mm medium and thick plate finished product, the implementation plan is:

[0039] (1) Blank specifications: 250mm×1800mm×3260mm

[0040] Chemical composition mass percentage: C: 0.15%, Si: 0.41%, Mn: 1.51%, P: 0.017%, S: 0.011%, Alt: 0.03%, Nb: 0.015%, the rest is Fe;

[0041] (2) Adopting a step-by-step double regenerative heating furnace with three heating stages including preheating, heating and soaking. It adopts low-temperature rapid heating method, preheating section: 870℃; heating section: 1110℃, soaking section: 1220 ℃, the total heating time is controlled at 261min; the tapping temperature is controlled at 1145℃, and the high-pressure water descaling pressure is 22Mpa;

[0042] (3) Two-stage rolling is adopted, the rough rolling opening temperatu...

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Abstract

The invention discloses an effective control method for the pitted surface of a plain carbon steel/Nb-containing steel plate of 20-30 mm thickness. A steel plate billet is rolled into a finished plate of 20-30 mm thickness through the processes of heating, high-pressure water descaling, rough rolling, finish rolling, ACC laminar flow cooling, straightening, cooling, finishing and storage. The control method includes the steps that a three-stage heating mode of preheating, heating and uniform heating is adopted for the steel plate billet, the tapping temperature ranges from 1050 DEG C to 1135 DEG C as required, and high-pressure water descaling pressure ranges from 20 MPa to 23 MPa; two-stage controlled-rolling is adopted, rough rolling is conducted three to five times for descaling, finish rolling is conducted two to four times for descaling, and the finishing rolling temperature is controlled between 820 DEG C and 880 DEG C; an ACC laminar flow mode is adopted, and the finishing cooling temperature is controlled between 680 DEG C and 800 DEG C. A 250 mm*(1600 mm, 1800 mm and 2100 mm)*(2300-3300) mm blank is adopted for the steel plate billet. According to the control method, low-temperature heating and cooling after rolling are adopted; by means of process optimization, the occurrence probability of the pitted surface is lowered, the yield of plates of middle thicknesses is increased, production cost is reduced, and product profits are increased.

Description

technical field [0001] The invention relates to an effective control method for pitting of medium and thick plates, in particular to an effective control method for pitting of 20-30mm medium and thick plates of ordinary carbon steel / Nb-containing steel. Background technique [0002] The pitted surface of medium and heavy plates is one of the difficult surface quality problems faced by all iron and steel enterprises, and it is an important factor affecting the yield of medium and heavy plates. [0003] CN103831303A proposes a method for reducing pits on the surface of wide and thick plates, and solves the problem of pits on the surface of wide and thick plates from two aspects of heating and rolling processes. Similarly, CN101704026A also introduces a method for controlling pitting on the surface of a medium-thick steel plate, which optimizes all technological processes from the blank composition, heating and rolling processes. [0004] However, the problems in the above met...

Claims

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Application Information

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IPC IPC(8): B21B1/24B21B37/00B21B37/74B21B45/08C22C38/04C22C38/12
CPCB21B37/00B21B37/74B21B45/004B21B45/08C22C38/04C22C38/12
Inventor 孙伟佟程志王佩鑫李仕力任茂勇
Owner TIANJIN IRON & STEEL GRP
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