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A Method of Improving the Quality of the Center of Extra-thick Plates and the Qualification Rate of Flaw Detection

A technology of extra-thick plate and pass rate, applied in the direction of profile control, etc., can solve the problems of uneven deformation of the extra-thick core, long transportation distance, complicated process, etc. Efficiency, the effect of improving the rolling rhythm

Active Publication Date: 2019-11-08
NORTHEASTERN UNIV LIAONING
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

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Problems solved by technology

[0004] Chinese Patent CN101773931A "A Method for Vacuum Composite Rolling of Extra-Heavy Plates", Chinese Patent CN102009332A "A Method for Producing Extra-Heavy Plates by Lamination Rolling and Welding Process", and Chinese Patent CN101439348A "A Process for Producing Extra-Heavy Plates" A number of patents have proposed the method of multiple continuous casting slabs being welded and combined rolling to produce extra-heavy plates. The above method can effectively solve the problem of large compression ratios required for the production of extra-thick plates. As the original blank, the process is relatively complicated, and there is still uneven deformation of the extra-thick core
[0005] Chinese patent CN 103111464A "A Method for Manufacturing Extra-Heavy Plates" introduces a method of rolling extra-thick plates by means of surface forced cooling, and this method uses the transportation of the steel plate to the cooling zone after rolling instead of using a rolling mill The nearby online instant cooling device, due to the long transportation distance, it is difficult to accurately control the temperature of the steel plate, and it does not involve the process control of the online instant cooling system
This patent mainly focuses on the introduction of the mechanical design, device structure and production layout of the instant cooling system, and proposes a production example of using 190mm continuous casting slabs to produce thick plates, but for the production of extra thick slabs using continuous casting slabs with a thickness of 200mm or more The specific process is not mentioned, and the control method for key cooling process parameters is missing

Method used

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  • A Method of Improving the Quality of the Center of Extra-thick Plates and the Qualification Rate of Flaw Detection
  • A Method of Improving the Quality of the Center of Extra-thick Plates and the Qualification Rate of Flaw Detection
  • A Method of Improving the Quality of the Center of Extra-thick Plates and the Qualification Rate of Flaw Detection

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Effect test

Embodiment 1

[0026] The 400mm thick continuous casting slab is used to produce Q235 steel, the thickness of the finished product is 120mm, and the chemical composition is shown in Table 1. After the continuous casting slab leaves the heating furnace, it is descaled by high-pressure water, and enters the longitudinal rolling stage after two passes of widening and cross-rolling, and then uses the instant cooling equipment near the frame for forced cooling. The process schematic diagram is as follows figure 1 shown. When cooling, the initial temperature of the surface of the continuous casting slab is 980°C, and it enters the cooling zone at a speed of 3m / s. 3 / h, a total of 6 sets of headers were opened, and the return temperature was controlled at 870°C for rolling after cooling, and the reduction rate after cooling was 18%. After 820°C, it is rolled normally, and the final rolling temperature is 780°C. During the rolling process, the shape of the plate is good, and then it enters the post...

Embodiment 2

[0029] 45# steel is produced by rolling a 400mm thick continuous casting slab, and the thickness of the finished product is 200mm. The chemical composition is shown in Table 1. After the continuous casting slab leaves the heating furnace, it is descaled by high-pressure water, and the non-steel directly enters the longitudinal rolling stage, followed by forced cooling in the third pass. When cooling, the initial temperature of the surface of the continuous casting slab is 960℃, and it enters the cooling zone at a speed of 2m / s. 3 / h, a total of 6 sets of headers were opened, and water was repeatedly penetrated twice in the cooling zone. After cooling, the return temperature was controlled at 850°C for rolling. After cooling, the reduction rate was 13%, followed by conventional rolling, and the final rolling temperature Controlled at 800°C. Compared with the conventional rolling process, the core flaw detection level of the 45# extra-thick steel plate obtained by the above met...

Embodiment 3

[0035] The Q460 steel is produced by rolling a 400mm thick continuous casting slab, and the thickness of the finished product is 80mm. The chemical composition is shown in Table 1. After the continuous casting slab leaves the heating furnace, it is descaled by high-pressure water, and enters two-stage rolling, and cooling between passes is carried out in the process of rough rolling and finishing rolling. When cooling, the speed of the roller table enters the cooling zone at a speed of 1.5m / s, the roller speed in the cooling zone is 1m / s, the ratio of upper and lower water is 1:4, and the total flow rate of a single set of headers is 350m 3 / h, a total of 6 sets of headers were opened, the reduction ratio was greater than 12% after cooling, the initial temperature of rough rolling was 1050°C, and the finish rolling temperature was controlled at about 800°C, and there was no warping during rolling. The Q460 slab prepared by the above method has uniform structure and stable perf...

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Abstract

The invention provides a method for improving the core quality and flaw detection pass rate of extra-thick plates, and belongs to the technical field of iron and steel metallurgy. This method is based on the online instant refrigeration system between passes to improve the core quality and flaw detection qualification rate of extra thick plates (≥80mm). The specific process steps are as follows: the continuous casting billet (≥200mm) does not transfer to steel or the steel transfer ends and enters the longitudinal rolling stage. During the rolling gap, the instant cooling system near the rolling mill is used for one or more passes of online cooling. The initial surface temperature is 850~1000℃, and it enters the cooling zone at a speed of 2~6m / s. The roll speed in the cooling zone is 1~ 3m / s, the upper and lower water ratio is 1:2~1:6, the total flow rate of a single set of headers is 200~400m 3 / h, the return temperature after cooling is controlled at 750~900℃ for rolling, and the reduction rate after cooling is higher than 12%. This method increases the deformation of the core of the thick plate through temperature difference rolling, significantly improves the core quality and flaw detection pass rate, and increases the yield rate.

Description

technical field [0001] The invention belongs to the technical field of iron and steel rolling in the metallurgical industry, and relates to a method for improving the quality of the core part of an extra-thick plate and the qualified rate of flaw detection based on an on-line instant cooling system between passes. Background technique [0002] In recent years, with the technological progress and rapid development of my country's transportation, petrochemical, heavy machinery, marine engineering, nuclear power and military industries, higher technical requirements have been put forward for the quality, performance, specifications and dimensions of steel products. However, the current domestic production of extra-thick plates still faces production technical problems such as low production efficiency, poor performance stability, and poor quality uniformity. [0003] The traditional rolling process of extra-heavy plates improves the core quality by increasing the pass reduction...

Claims

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Application Information

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Patent Type & Authority Patents(China)
IPC IPC(8): B21B37/44
CPCB21B37/44
Inventor 王斌王丙兴田勇张田韩毅付天亮李勇王昭东王国栋
Owner NORTHEASTERN UNIV LIAONING
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