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CN-122007359-A - Method for solving slab narrow-face transverse crack defect and application

CN122007359ACN 122007359 ACN122007359 ACN 122007359ACN-122007359-A

Abstract

The invention provides a method for solving the defect of transverse cracks on a narrow surface of a plate blank and application thereof. A method for solving the transverse crack defect of the narrow surface of a slab comprises the following steps of S1, setting the taper coefficient of a crystallizer to be 1.20-1.40% for a normal peritectic steel grade with carbon content of 0.08-0.12%, S2, calculating the heat flow density of the wide surface and the narrow surface based on the flow and water inlet and outlet temperature difference of cooling water of the wide surface and the narrow surface of the crystallizer in the casting process, and controlling the ratio of the heat flow density to be maintained to be 0.8-0.9, S3, and rolling the cast slab meeting the taper and heat flow ratio in a releasing way.

Inventors

  • WANG QINGCHUAN
  • XIE JIANFU
  • DENG BIRONG
  • LIU HONGJUN
  • CHEN SHUGUANG
  • ZHOU JUNJUN
  • WU CHENG

Assignees

  • 湖南华菱涟源钢铁有限公司

Dates

Publication Date
20260512
Application Date
20251217

Claims (10)

  1. 1. A method for solving a slab narrow-face transverse crack defect, comprising the steps of: s1, setting the taper coefficient of a crystallizer to be 1.20-1.40% for normal peritectic steel with carbon content of 0.06% -0.18%, The taper coefficient of the crystallizer is calculated according to the ratio of (upper port width-lower port width)/lower port width, wherein the upper port width is the inner cavity width at the top of the narrow-face copper plate of the crystallizer, and the lower port width is the inner cavity width at the bottom of the narrow-face copper plate of the crystallizer; s2, calculating the heat flux density of the wide surface and the narrow surface based on the flow and water inlet and outlet temperature difference of cooling water of the wide surface and the narrow surface of the crystallizer in the casting process, and controlling the ratio of the heat flux density to the narrow surface to be maintained at 0.8-0.9; s3, rolling the cast slab meeting the taper and heat flow ratio.
  2. 2. The method for solving the transverse crack defect of the narrow surface of the slab according to claim 1, wherein the fluctuation of the cooling water flow rate of the narrow surface of the crystallizer is monitored before casting the normal peritectic steel, and the fluctuation range is ensured not to exceed +/-10 m 3 /h.
  3. 3. The method for solving the transverse crack defect of the narrow surface of the slab according to claim 1, wherein the fluctuation of the cooling water flow rate of the narrow surface of the crystallizer is monitored before casting the normal peritectic steel, and the fluctuation range is ensured not to exceed +/-5 m 3 /h.
  4. 4. The method for solving the slab narrow-face transverse crack defect according to claim 1, wherein in the step S3, the slab which does not meet the requirements of the taper coefficient and the heat flux density ratio of the crystallizer is subjected to narrow-face grinding.
  5. 5. The method of claim 1, wherein the narrow-face heat flux density is not less than 1.8 MW/m 2 .
  6. 6. The method for solving the slab narrow-face transverse crack defect according to claim 1, wherein the composition of the orthoperitectic steel comprises at least one of Nb and V, and the total amount of the composition is 0.02% -0.10%.
  7. 7. The method for solving the transverse crack defect of the narrow surface of the slab according to claim 4, wherein the narrow surface of the slab which does not meet the taper or the heat flux density ratio is polished to a polishing depth of 2-4 mm.
  8. 8. The method for solving the transverse crack defect of the narrow surface of the slab according to claim 1, wherein the taper and heat flux density ratio control is implemented at a pulling speed of 0.6-1.8 m/min.
  9. 9. Use of the method for solving the transverse crack defect of the narrow surface of the slab according to any one of claims 1-8 in the engineering field.
  10. 10. The use of claim 9, wherein the engineering field comprises at least one of construction, bridge and construction machinery.

Description

Method for solving slab narrow-face transverse crack defect and application Technical Field The invention relates to the technical field of continuous casting slabs, in particular to a method for solving the defect of transverse cracks on a narrow surface of a slab and application thereof. Background With the increasing market competition in the steel industry, the requirements of customers on the surface quality of high-end hot rolled coils are becoming severe, the product surface quality is directly related to the service performance of downstream end products, and the brand image and market competitiveness of enterprises are affected deeply. Among the numerous surface defects, slab narrow side transverse cracks are a particularly troublesome quality problem that is manifested as microcracks distributed along the thickness of the slab narrow side and concentrated in the trough of the vibration marks. Because the surface of the slab is covered with thicker iron oxide scales in the online production process, the conventional visual or surface detection means are difficult to effectively identify, and because the positions of the slab on the narrow surface are random and the depth is limited, the slab is difficult to stably detect even by adopting methods such as acid washing and the like. At present, a reliable line monitoring technology for the defect is not available, so that a plate blank with the defect is often misjudged to be a qualified product and flows into a subsequent rolling process, and the defect is expanded into a broken edge defect at the edge part of a steel coil in the hot rolling process. When serious, the whole roll of products cannot be honored with orders and is forced to be judged to be wasted, and when slight, the whole roll of products is needed to be subjected to trimming or manual polishing treatment, so that the yield and the production efficiency are obviously reduced, and the manufacturing cost is increased in an intangible way. The prior literature shows that the research on the mechanism and the control technology of the narrow-face transverse crack formation is relatively lack, and no effective solution of the system is formed. The traditional method mainly relies on slab grinding for remedying, but the method has obvious limitations that the hot slab grinding is easy to cover up and leak detection due to high surface temperature, and the cold slab grinding can induce crack growth and aggravate defect degree. In addition, the metal loss is caused in the grinding process, the molten steel yield is reduced, the retention time of the slab in the previous process is prolonged, the material backlog and turnover efficiency is reduced, and meanwhile, a large amount of heat loss is not beneficial to high-temperature hot feeding (hot charging) in the subsequent process, so that the overall hot charging ratio and the energy utilization efficiency are affected. Disclosure of Invention The invention mainly aims to provide a method for solving the defect of a narrow-face transverse crack of a slab and application thereof, and aims to solve the problems that the slab with defects flows into a rolling process and is developed into a hot rolled coil to be rotten, so that the yield is reduced, the coping cost is increased, the hot charging rate is reduced and the like due to the fact that the defect is high in concealment and difficult to detect in the prior art. In order to achieve the above object, the present invention provides a method for solving the defect of a narrow-face transverse crack of a slab, comprising: s1, setting the taper coefficient of a crystallizer to be 1.20-1.40% for normal peritectic steel with carbon content of 0.06% -0.18%, The taper coefficient of the crystallizer is calculated according to the ratio of (upper port width-lower port width)/lower port width, wherein the upper port width is the inner cavity width at the top of the narrow-face copper plate of the crystallizer, and the lower port width is the inner cavity width at the bottom of the narrow-face copper plate of the crystallizer; s2, calculating the heat flux density of the wide surface and the narrow surface based on the flow and water inlet and outlet temperature difference of cooling water of the wide surface and the narrow surface of the crystallizer in the casting process, and controlling the ratio of the heat flux density to the narrow surface to be maintained at 0.8-0.9; s3, rolling the cast slab meeting the taper and heat flow ratio. Aiming at the defect that the slab narrow-face transverse crack easily occurs in the continuous casting process of the normal peritectic steel with the carbon content within the range of 0.06% -0.18%, the invention provides a process control method based on solidification heat transfer uniformity regulation. The steel is extremely easy to form microcracks distributed along the trough of vibration marks in a crystallizer due to volume mutation and thermal stress concent