CN-122007163-A - Continuous casting and rolling production method of medium plate

CN122007163ACN 122007163 ACN122007163 ACN 122007163ACN-122007163-A

Abstract

The invention discloses a continuous casting and rolling production method of a medium plate, which comprises the key process steps of 1) heating the surface of a casting blank by adopting a roller hearth type tunnel kiln heating furnace or an electric induction surface heating device, wherein the surface heating speed of the casting blank is 20-200 ℃ per minute, the transverse surface temperature of the casting blank after heating is extremely poor at 10-60 ℃, 2) rolling an intermediate blank, namely rolling the casting blank into the intermediate blank by adopting a two-roller or four-roller mill, wherein the rolling reduction ratio of the intermediate blank is 10% -20% for a single pass, 3) descaling, namely removing oxidized iron scales on the surface of the casting blank by adopting a high-pressure water descaling machine or a shot blasting descaling device with high-pressure water and sand, and 4) finishing by adopting flame cleaning equipment or mechanical finishing and finishing equipment, and finishing, and removing the surface defects of the casting blank or the intermediate blank. The defect that the thick plate UT is unqualified due to the loose center and shrinkage cavity of the casting blank in the extra thick plate production can be avoided, the defect detection level of the UT is improved, and the defect that the thickness, width, length and super tolerance of the product are caused by surface defect grinding is prevented from causing poor size or waste.

Inventors

XU RONGJUN
LIU JIWEN
GAO QING
CHI YUNGUANG
JIA JIN
XU LONGYUN

Assignees

湖南华菱湘潭钢铁有限公司

Dates

Publication Date: 20260512
Application Date: 20260328

Claims (3)

1. The continuous casting and rolling production method of the medium plate is characterized by comprising the following steps of slab continuous casting, casting blank flame cutting, casting blank surface heating, descaling, intermediate blank rolling, casting blank or intermediate blank surface inspection, casting blank offline, grinding finishing and subsequent traditional medium plate rolling, wherein the key process steps comprise: 1) Heating the surface of the casting blank by adopting a roller hearth type tunnel kiln heating furnace or an electric induction surface heating device, wherein the heating power of the edge part of the casting blank in the width direction of the casting blank is higher than the middle heating power of the casting blank, the surface heating speed of the casting blank is 20-200 ℃ per minute, and the temperature of the transverse surface of the casting blank after heating is extremely 10-60 ℃; 2) Rolling the intermediate billet, namely rolling a casting blank into the intermediate billet by using a two-roll or four-roll mill, wherein the intermediate billet can be a reversible mill or a non-reversible mill for unidirectional rolling, the rolling reduction rate of the intermediate billet is 10% -20% in a single pass, the rolling mill is a low-speed high-torque mill, the rolling force is 50000-100000 kN, and the rolling speed is 0.5-3 m/s; 3) Descaling, namely removing scale on the surface of a casting blank by using a high-pressure water descaling machine or a shot blasting descaling device with high-pressure water and sand, wherein the pressure of the high-pressure water is 10-30 MPa; 4) And (3) finishing and grinding, namely finishing and grinding by using flame cleaning equipment or mechanical finishing and grinding equipment, and removing surface defects of the casting blank or intermediate blank.
2. The continuous casting and rolling production method of the medium plate according to claim 1, wherein the rolling is carried out in the step 2), namely, a casting blank is rolled into an intermediate blank by using a two-roll rolling mill, the rolling mill is a two-roll irreversible rolling mill, the roll diameter is 1100mm, the roll length is 2500mm, the maximum rolling force is 80000kN, and the single-pass maximum rolling reduction is 15%.
3. The continuous casting and rolling production method of the medium plate according to claim 1, wherein the rolling is carried out in the step 2), namely a casting blank is rolled into an intermediate blank by a four-roll mill, the rolling mill is a four-roll reversible mill, the roll diameter of a working roll is 1000mm, the length of a roll body is 2400mm, and the maximum rolling force is 70000kN and the single pass reduction is 10%.

Description

Continuous casting and rolling production method of medium plate Technical Field The invention belongs to the technical field of steel plate production, and relates to a continuous casting and rolling production method of a medium plate. Background The steel sheet products are classified according to thickness, and steel sheets with thickness greater than 100mm are defined as extra thick plates. The extra-thick plate has extremely high strength and toughness, can bear extreme load and severe environment, and is widely applied to the field of heavy industry, such as ship manufacturing, bridge engineering, pressure vessels, nuclear power equipment, ocean platforms, large-scale mechanical manufacturing and the like. In recent years, with the breakthrough of metallurgical technology, the ultra-thick plate gradually develops towards the directions of light weight, large single weight and super specification, and meanwhile, the welding suitability is improved, the integrated design of a large structure is promoted, and the ultra-thick plate becomes an important support for upgrading the high-end manufacturing industry. Along with the rapid development of economic construction, the demand of super-thick steel plates with single weight larger than 20t and thickness larger than 100mm used in pressure vessels, large-span steel structures, hydropower stations and the like is gradually increased, and the safety and stability of large-scale devices are considered, so that various performance indexes of the steel plates used by the super-thick steel plates are more and more strict. For example, various properties such as higher strength, higher low-temperature toughness, required lamellar tearing resistance, easier welding, required corrosion resistance, fire resistance, weather resistance, and higher internal defect requirements are required. The existing super-thick blank main production technology comprises die casting, welding compounding, super-thick blank continuous casting technology and the like. The method is characterized in that the method comprises the steps of providing an original blank with larger thickness to ensure enough compression ratio, requiring that a large cast ingot or casting blank has extremely high cleanliness, enhancing segregation and loosening control in the solidification process, selecting a better raw material solidification mode for providing a raw material with better quality for the extra thick plate, optimizing and improving, reducing the influence of segregation and loosening on lamellar tearing resistance of the extra thick plate, rolling the extra thick plate with stronger equipment capability, eliminating defects of loosening of the raw material and the like by utilizing the penetration effect of large rolling force, fully crushing the large rolling force in the rolling process to refine grains to obtain a relatively uniform and fine structure, and utilizing a 'differential temperature rolling' method to ensure that the surface temperature of the blank is low and the deformation resistance is large in the rolling process to enable the rolling force to permeate the core. In order to improve the loosening and segregation in the solidification process of a thick plate casting blank, JP 2018114514A discloses a continuous casting method of steel, proposes PCCS (Porosity Control of Casting Slab) technology, and adopts a pair of rollers with super-large roller diameters to implement large reduction on the casting blank at the solidification end point of the casting blank, so that the density of the casting blank is remarkably improved. CN201410695742.0 discloses a heavy pressing fan-shaped section for improving slab loosening shrinkage defect and its using method, which uses single roller heavy pressing technology, single roller heavy pressing with liquid core is carried out at solid phase fraction fs=0.95, a heavy pressing fan-shaped section is added at the end of continuous casting machine, which is a common fan-shaped section with 6 pairs of phi 300mm rollers, two pairs of phi 230mm rollers are removed, and a pair of phi 500mm pressing rollers are changed. The single-roller heavy pressing device has the advantages that the efficiency of improving the center porosity of a thick plate casting blank is high, and the center porosity is effectively improved. The method has the problems that firstly, the position of a solidification tail end is influenced by the fact that the position under heavy pressure is fixed, the steel grade, the casting temperature, the cooling and the pulling speed are high in adjustment difficulty, secondly, when the solid phase fraction fs is close to 1, the steel has zero strength and zero plasticity, the large deformation amount at the moment is easy to generate central cracks, thirdly, the reduction of a sensor is larger than the actual deformation amount due to the fact that the frame of a sector section is not high enough in rigidity and elastic deformation,