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Control method for protective atmosphere of bell-type annealing furnace

A bell-type annealing furnace and protective atmosphere technology, applied in the direction of bell-type annealing furnace, heat treatment process control, furnace, etc., to achieve the effect of eliminating chromatic aberration defects

Inactive Publication Date: 2021-09-24
TANGSHAN IRON & STEEL GROUP +1
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

[0005] The method of the present invention aims at optimizing the atmosphere control for edge color difference defects caused by improper atmosphere control in the production of steel coils under the full hydrogen bell annealing process, so as to achieve the purpose of eliminating such defects. At present, there is no clear solution to the atmosphere control

Method used

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  • Control method for protective atmosphere of bell-type annealing furnace

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Experimental program
Comparison scheme
Effect test

Embodiment 1

[0035] The DC04 product is produced by bell furnace annealing, and the thickness of the product is 1.0mm. Among them, the oxygen content of hydrogen is 5ppm, the dew point is -50°C, and the purity is 99.999%; the oxygen content of nitrogen is 4.5ppm, the dew point is -45°C, and the purity is 99.999%.

[0036] The control method is as follows:

[0037] 1) Inner cover cold seal test inspection: the inner cover pressure is 5KPa, within 15 minutes, the pressure drops to 950Pa, then the cold seal test is qualified;

[0038] 2) Safety purge: Before the annealing heating starts, use the protective gas N 2 To purge the air in the inner cover on the furnace table, the nitrogen flow rate is 120Nm 3 / h, nitrogen purge volume 81m 3 , the purge pressure is 3bar, and the residual oxygen concentration in the furnace atmosphere is 1%;

[0039] 3) After the safety purge is completed, fasten the heating cover, start the annealing program and heat according to the established annealing proce...

Embodiment 2

[0044] The HC340LA product is produced by bell furnace annealing, and the thickness of the product is 1.2mm. Among them, hydrogen has an oxygen content of 4ppm, a dew point of -60°C, and a purity of 99.9997%; nitrogen has an oxygen content of 5ppm, a dew point of -40°C, and a purity of 99.9996%.

[0045] The control method is as follows:

[0046] 1) Inner cover cold seal test inspection: The inner cover pressure is 5KPa, within 15 minutes, the pressure drops to 800Pa, and the cold seal test is qualified;

[0047] 2) Safety purge: Before the annealing heating starts, use the protective gas N 2 To purge the air in the inner cover on the furnace table, the nitrogen flow rate is 120Nm 3 / h, nitrogen purge volume 81m 3 , the purge pressure is 7bar, and the residual oxygen concentration in the furnace atmosphere is 0.5%;

[0048] 3) After the safety purge is completed, fasten the heating cover, start the annealing program and heat according to the established annealing process. ...

Embodiment 3

[0053] The DC01 product is produced by bell furnace annealing, and the thickness of the product is 0.8mm. Among them, hydrogen has an oxygen content of 3ppm, a dew point of -55°C, and a purity of 99.999%; nitrogen has an oxygen content of 4ppm, a dew point of -48°C, and a purity of 99.9992%.

[0054] The control method is as follows:

[0055] 1) Inner cover cold seal test inspection: the inner cover pressure is 5KPa, within 15 minutes, the pressure drops to 400Pa, and the cold seal test is qualified;

[0056] 2) Safety purge: Before the annealing heating starts, use the protective gas N 2 The air in the inner cover on the stove top is purged. Nitrogen flow 120Nm 3 / h, nitrogen purge volume 81m 3 , the purge pressure is 5bar, and the residual oxygen concentration in the furnace atmosphere is 0.3%;

[0057] 3) After the safety purge is completed, fasten the heating cover, start the annealing program and heat according to the established annealing process. During the heating...

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Abstract

The invention relates to a control method for a protective atmosphere of a bell-type annealing furnace, and belongs to the technical field of bell-type annealing processes in the metallurgical industry. According to the technical scheme, the method is operated according to the following steps: (1) inner cover cold sealing is tested; (2) safe purging: purging air in an inner cover by adopting N2 before annealing heating is started; (3) after safe purging is finished, a heating cover is buckled up, heating is carried out according to a set annealing process, in the heating process, purging is carried out with H2, N2 in the furnace is completely removed, and the purpose of all-hydrogen annealing is achieved; (4) before heating is finished, inner cover heat sealing testing is carried out, and it is ensured that an inner cover heat sealing testing test is qualified; and (5) when the temperature of a coil base is cooled to the tapping temperature, purging replacement is conducted on H2 in the furnace through protective gas N2. The method has the beneficial effects that Mn and Si elements in the steel can be inhibited from being enriched on the surface in a weak oxygen atmosphere and forming granular aggregates to cover the surface of the strip steel, so that the aim of eliminating the color difference defect of the edge part of a steel coil is fulfilled.

Description

technical field [0001] The invention relates to a method for controlling the protective atmosphere of a bell annealing furnace, belonging to the technical field of bell annealing technology in the metallurgical industry. Background technique [0002] Bell annealing generally refers to the annealing of cold-rolled strips in a bell furnace in the form of stacks. At present, full-hydrogen bell annealing is mostly used. The cold-rolled steel coil is sent to the bell annealing furnace for annealing treatment without degreasing in the state of a small amount of residual emulsion, and is cooled in a hydrogen atmosphere. The production cycle is long, but Product specifications and output changes are highly flexible. [0003] Due to the long production cycle of bell annealing and the high temperature of the steel coil for a long time, the Mn and Si elements in the steel are easily enriched on the surface in a weak oxygen atmosphere, and form granular aggregates to cover the surface ...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): C21D1/26C21D1/74C21D11/00C21D9/663
CPCC21D1/26C21D1/74C21D11/00C21D9/663
Inventor 齐建群孟凡月王浩宇刘春波张选峰张茜
Owner TANGSHAN IRON & STEEL GROUP
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