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CN-122007176-A - Method for improving rolling stability of steel for 700 MPa-level high-strength container

CN122007176ACN 122007176 ACN122007176 ACN 122007176ACN-122007176-A

Abstract

The invention discloses a method for improving rolling stability of steel for a 700 MPa-level high-strength container, and belongs to the technical field of steel rolling processes. The invention greatly improves the stability and the yield of the steel rolling for the 700 MPa-grade high-strength container on the premise of not increasing the equipment cost, solves the head forward folding and the middle rolling scrap steel clamping accidents caused by strip steel deflection in the rolling process, reduces the accident rate and the accident handling time, improves the rolling mill operation rate and the rolling efficiency, realizes high-efficiency, low-cost and mass production and ensures the contract execution rate by a series of effective technical measures such as full-process optimization, process parameter solidification, equipment precision improvement, temperature and intermediate billet thickness linkage control, tension solidification, low-angle threading and the like. The method is proper, the operation flow is complete, the scheme measures are effective, the method is easy to master, and the operation and the implementation are convenient.

Inventors

  • LI JINFENG
  • Liu Wangchen
  • SONG YUNTAO
  • WANG YUSHENG
  • AI CHENGSHEN
  • WANG GANG
  • SONG XIAOMING
  • LI JIANGWEI
  • WANG DAWEI
  • Deng Pengzhao
  • WANG CUN
  • FU QINGCAI

Assignees

  • 鞍钢股份有限公司

Dates

Publication Date
20260512
Application Date
20260310

Claims (10)

  1. 1. The method for improving the rolling stability of the steel for the 700 MPa-level high-strength container is characterized by comprising the following steps of: s1, determining total in-furnace time of a casting blank and time of the casting blank in a soaking section and two heating sections according to the target thickness of a finished product and the charging temperature of the casting blank, wherein the time of the casting blank in the soaking section is controlled to be 45-60 min, the temperature difference between the head and the tail of a heating furnace is less than or equal to 20 ℃, and the heating tapping temperature is 1250-1260 ℃; S2, rough rolling is conducted, a rolling center line is adjusted to ensure centering rolling, tapping rhythm is adjusted to avoid waiting for steel, the temperature of rough rolling RT2 is 1080-1120 ℃, the temperature difference between the head and the tail of a middle blank is less than or equal to 10 ℃, and the temperature is adjusted to keep the side bending of the middle blank of a transition material consistent; S3, selecting an HMD mode by using finish rolling flying shears, wherein the head shearing quantity is more than or equal to 230mm, the tail shearing quantity is more than or equal to 200mm, the looper investment ILQ is functional, the finish rolling temperature is 905-925 ℃, the descaling mode is selected according to the target thickness of a finished product, the convexity of strip steel is 35-50 mu m, the bending force of the front three finishing mills is 80-95 t, the bending force of the rear four finishing mills is 40-75 t, the load of a secondary pre-finishing mill is reduced from front to back, and the load difference of adjacent frames is less than or equal to 500 tons.
  2. 2. The method for improving rolling stability of steel for 700 MPa-level high-strength container according to claim 1, wherein the determining the total in-furnace time of the casting blank and the time of the casting blank in the soaking section and the two heating sections according to the target thickness of the finished product in S1 is specifically as follows: When the target thickness is less than or equal to 2.0mm, the casting blank charging temperature is more than 300 ℃, the time of the soaking section and the two heating sections is 75min-90min, and the total furnace time is 195min-215min; the target thickness is less than or equal to 2.0mm, the casting blank charging temperature is less than or equal to 300 ℃, the time of the soaking section and the two heating sections is 80min-100min, and the total furnace time is 205min-225min; The target thickness is 2.0mm-3.0mm, the casting blank charging temperature is more than 300 ℃, the time of the soaking section and the two heating sections is 70min-90min, and the total furnace time is 190min-210min; The target thickness is 2.0mm-3.0mm, the casting blank charging temperature is less than or equal to 300 ℃, the time of the soaking section and the two heating sections is 75min-100min, and the total furnace time is 200min-220min.
  3. 3. The method for improving rolling stability of the steel for the 700MPa grade high-strength container according to claim 1, wherein the step S2 is characterized in that a rolling center line is adjusted to ensure centering rolling, specifically, before the steel for the 700MPa grade high-strength container is intensively rolled, a transition material is rolled, the width difference between the transition material and the steel for the 700MPa grade high-strength container is controlled to be less than or equal to 40mm, the thickness difference is controlled to be less than or equal to 0.45mm, the rolling center line is adjusted by the transition material, and centering rolling is ensured, wherein the number of the transition materials is more than or equal to 10.
  4. 4. The method for improving rolling stability of steel for 700 MPa-level high-strength container according to claim 1, wherein the step S3 is specifically to select a descaling mode according to a target thickness of a finished product: when the target thickness is less than or equal to 2.0mm, single-row descaling is adopted, cooling water is cooled between frames before entering steel, roll gap water is not fed in by return water. When the target thickness is 2.0mm-3.0mm, double rows of descaling are adopted, cooling water is used between the steel feeding front frames, roll gap water is used, and return water is not input.
  5. 5. The method for improving rolling stability of steel for 700 MPa-grade high-strength container according to claim 4, wherein when the finish rolling temperature is >915 ℃, the next piece of steel is fed into the roll gap cooling water of the first and second finishing mills in order.
  6. 6. The method for improving the rolling stability of steel for 700MPa grade high-strength container according to claim 1, wherein the temperature is controlled by adopting a speed mode after the last rolling mill passes through the strip.
  7. 7. The method for improving rolling stability of steel for 700 MPa-level high-strength container according to claim 1, wherein the first to third finishing mills decrease roll bending force from one stand to another.
  8. 8. The method for improving the rolling stability of steel for 700MPa grade high-strength container according to claim 1, wherein the head of the strip steel is controlled by micro-medium waves.
  9. 9. The method for improving rolling stability of steel for 700 MPa-level high-strength container according to claim 1, wherein the rough rolling RT2 temperature is controlled by controlling the flow of rough rolling descaling cooling water.
  10. 10. The method for improving rolling stability of steel for 700 MPa-level high-strength container according to claim 1, wherein the thickness of the intermediate billet is controlled to be 36-40mm.

Description

Method for improving rolling stability of steel for 700 MPa-level high-strength container Technical Field The invention belongs to the technical field of steel rolling processes, and particularly relates to a method for improving rolling stability of steel for a 700 MPa-level high-strength container. Background The 700Mpa high-strength steel for the container is mainly used for manufacturing high-strength weather-resistant container bodies, lightweight container structural members, truck frames of vehicle structures, trailer stringers and the like, can reduce the weight by more than 30%, improves the load and fuel economy, reduces the self weight of the container bodies and improves the transportation efficiency. When the steel is rolled, due to the characteristics of large fluctuation of the temperature of incoming materials before finish rolling, large lateral bending of rough rolling materials, irregular head and tail shapes of intermediate billets, uneven load distribution of a finishing mill and the like, great difficulty is brought to finish rolling operation adjustment, rolling is unstable during finish rolling, the head is folded forward when strip steel is off tracking, the accident time of tail throwing, steel clamping and the like is increased, the rolling success rate is reduced, the operation rate of the rolling mill is influenced, meanwhile, the appearance size and the plate shape precision are difficult to control, great harm is caused to production and product quality, and smooth production and contract delivery are influenced. Therefore, how to improve the rolling stability of the steel for the 700 MPa-level high-strength container becomes an important subject to be solved at present. Disclosure of Invention In view of the above, the invention aims to provide a method for improving the rolling stability of steel for a 700 MPa-grade high-strength container, which is easy to operate and adjust and ensures smooth production. In order to achieve the above object, the present invention provides the following technical solutions: In a first aspect, the invention provides a method for improving rolling stability of steel for a 700 MPa-level high-strength container, comprising the following steps: s1, determining total in-furnace time of a casting blank and time of the casting blank in a soaking section and two heating sections according to the target thickness of a finished product and the charging temperature of the casting blank, wherein the time of the casting blank in the soaking section is controlled to be 45-60 min, the temperature difference between the head and the tail of a heating furnace is less than or equal to 20 ℃, and the heating tapping temperature is 1250-1260 ℃; S2, rough rolling is conducted, a rolling center line is adjusted to ensure centering rolling, tapping rhythm is adjusted to avoid waiting for steel, the temperature of rough rolling RT2 is 1080-1120 ℃, the temperature difference between the head and the tail of a middle blank is less than or equal to 10 ℃, and the temperature is adjusted to keep the side bending of the middle blank of a transition material consistent; S3, selecting an HMD mode by using finish rolling flying shears, wherein the head shearing quantity is more than or equal to 230mm, the tail shearing quantity is more than or equal to 200mm, the looper investment ILQ is functional, the finish rolling temperature is 905-925 ℃, the descaling mode is selected according to the target thickness of a finished product, the convexity of strip steel is 35-50 mu m, the bending force of the front three finishing mills is 80-95 t, the bending force of the rear four finishing mills is 40-75 t, the load of a secondary pre-finishing mill is reduced from front to back, and the load difference of adjacent frames is less than or equal to 500 tons. Wherein, the steel is not allowed to swing in the process. The loop input ILQ is used for performing closed-loop control on two variables of loop angle and tension. Wherein F1-F5 is put into hot rolling oil of a front 5-frame rolling mill of a finishing mill. Wherein, loop input ILQ functions, the angle of the strip steel head threading loop is controlled at 22 degrees and the tension is set in an incremental way. Based on the above technical scheme, further, in S1, the total furnace time of the casting blank and the time of the casting blank in the soaking section and the two heating sections are determined according to the target thickness of the finished product specifically: When the target thickness is less than or equal to 2.0mm, the casting blank charging temperature is more than 300 ℃, the time of the soaking section and the two heating sections is 75min-90min, and the total furnace time is 195min-215min; the target thickness is less than or equal to 2.0mm, the casting blank charging temperature is less than or equal to 300 ℃, the time of the soaking section and the two heating sections is 80min-100min, and the total furnac