Method for increasing scale removal effect of medium and heavy plate

A high-pressure water descaling and thick steel plate technology, which is applied in the field of metallurgy, can solve the problems that cannot meet the high standard of steel plate surface quality level, so as to improve the descaling effect and eliminate the effect of "pitting"

Inactive Publication Date: 2010-05-05
TIANJIN IRON & STEEL GRP
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

This conventional descaling process cannot meet the requirements of high-level steel plate surface quality standards for wind tower steel, high-rise building steel and other high-grade varieties.

Method used

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  • Method for increasing scale removal effect of medium and heavy plate
  • Method for increasing scale removal effect of medium and heavy plate
  • Method for increasing scale removal effect of medium and heavy plate

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Experimental program
Comparison scheme
Effect test

specific Embodiment approach

[0014] Specific embodiments of the present invention include:

[0015] 1. Chemical composition design.

[0016] The chemical composition of low-alloy high-strength medium-thick plates follows GB / T1591-2008, which requires the element Si≤0.50%. Fayalite (FeO-Fe) formed according to Si element 2 SiO 4 ), the principle of enhancing the adhesion of oxide scale and making it difficult to remove, through the comparison of industrial experiments with different Si contents, the optimum Si content design range of 0.15-0.35% is determined.

[0017] 2. Heating furnace temperature control

[0018] In the heating section of the heating furnace, a high-temperature rapid heating method is adopted, and the furnace temperature is controlled at 1200-1280 °C to reduce the thickness of the billet generated by primary oxidation in the furnace and reduce the thickness ratio of FeO in the iron sheet structure.

[0019] 3. Billet tapping temperature

[0020] The production of low-alloy high-stre...

Embodiment 1

[0023] (1), chemical composition

[0024]

[0025] (2), slab size, steel plate specification

[0026] Slab size: 250*1600*3350mm (cold), steel plate size: 22*2480*8000mm

[0027] (3), rolling process parameters

[0028] Furnace temperature control in the heating section: 1200-1250°C. The billet tapping temperature is 1120°C, the second-stage finishing rolling temperature: 930°C, and the thickness of the intermediate billet to be heated: 60mm

[0029] (4) Slab primary oxidation, secondary oxidation descaling rate and surface condition of steel plate

[0030] After the inspection of 10 slabs and steel plates in one furnace, the descaling rate of the slab’s primary oxide scale after the descaling box reaches 100%, and the average descaling rate of the secondary oxide scale of the finish rolling reaches 95%. The finished steel plate is inspected after shot blasting , there is no "pitting" defect visible to the naked eye on the surface.

Embodiment 2

[0032] (1), chemical composition

[0033]

[0034] (2), slab size, steel plate specification

[0035] Slab size: 250*1600*3350mm (cold), steel plate size: 50*2480*8000mm

[0036] (3), rolling process parameters

[0037] Furnace temperature control in the heating section: 1200-1270°C. The billet tapping temperature is 1140°C, the second-stage finish rolling start-rolling temperature is 910°C, and the thickness of the intermediate billet to be warmed is 110mm.

[0038] (4) Slab primary oxidation, secondary oxidation descaling rate and surface condition of steel plate

[0039] After testing 9 pieces of slabs and steel plates in one furnace, the descaling rate of the slab’s primary oxide scale after the descaling box reaches 100%, and the average descaling rate of the secondary oxide scale of the finish rolling reaches 97%. The finished steel plate is inspected after shot blasting , there is no "pitting" defect visible to the naked eye on the surface.

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Abstract

The invention belongs to the technical field of metallurgical technology, in particular to the technology for improving the scale removal effect of a medium and heavy plate. Pocking marks on the surface of the medium and heavy plate are the main defect which affects the surface quality thereof and one of projects to be constantly studied and improved. The invention provides a method for improving the scale removal effect of the medium and heavy plate in order to meet the requirements of high-grade varieties on the surface quality of a steel plate. The method comprises the following steps of: in working procedures of a converter and an LF furnace, the range of Si in molten steel elements is controlled to be 0.15%-035%; in the working procedures of a rolled steel, the furnace temperature in a heating section of the heating furnace is controlled to be 1200-1280 DEG C; and the tapping temperature of a billet steel is 1120-1140 DEG C; wherein the standard thickness of the heavy plate is 10-60mm. The method increases the scale removal effect on iron scale of the billet steel; wherein the scale removal rate of primary iron scale of the billet steel reaches 100%; the scale removal rate of finish rolling secondary iron scale of the billet steel reaches or surpasses 95%, thus putting an end to the generation of the pocking marks of the steel plate and meeting the requirements of the high-grade varieties.

Description

technical field [0001] The invention belongs to the technical field of metallurgy, and in particular provides a method for improving the descaling effect of medium-thick steel plates. technical background [0002] The problem of "pitting" on the surface of medium and heavy plates, especially low alloy high strength medium and heavy plates, has always been the main defect affecting the surface quality level of low alloy high strength medium and heavy plates. The main reason for its formation is primary or secondary oxide scale. It is not removed before and during rolling, and the residual iron oxide scale is pressed into the steel plate matrix during rolling. During the use of the steel plate by the user, after cold deformation or shot blasting, the iron scale originally embedded on the surface of the steel plate matrix Falling off, pits appear on the surface of the steel plate. That is the so-called "pitting". Optimizing the scale structure and heating furnace process, imp...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): B21B45/06
Inventor 吴德桂贺建哲巩文旭卢建军谭海鹏
Owner TIANJIN IRON & STEEL GRP
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