Anneal technique for producing SPCC steel grade with zincing wire annealing oven

An annealing process, an annealing furnace technology, applied in furnaces, heat treatment furnaces, manufacturing tools, etc., can solve problems such as galvanizing line shutdown or semi-stop production, continuous annealing furnace complex structure, substrate surface oxidation, etc., to reduce depreciation losses, eliminate The effect of increasing the production cycle and elongation rate

Inactive Publication Date: 2008-09-24
HEBEI IRON AND STEEL
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

[0002] The cold-rolled sheet galvanizing line is a special production line for the production of cold-rolled galvanized sheets. The continuous annealing furnace with an open flame heating section used in this production line has a complex structure, high strip speed, and difficult control
At present, many large, medium and small galvanizing lines have been built and put into operation, but due to the influence of equipment level and market factors, except for the galvanizing lines of several large steel mills, almost all other galvanizing lines are in a state of suspension or semi-stop production
In order to improve the utilization rate of equipment and reduce the loss caused by vacant equipment to the enterprise, it is a good choice to transform the galvanized sheet production line into an annealing production line and produce annealed sheet with a large market demand.
However, to transform the galvanizing production line into an annealing production line, in addition to some necessary transformations on the equipment, the annealing process needs to be greatly adjusted. According to the characteristics of the galvanizing line, the heating system, cooling system, and strip temperature should be reasonable. Optimize the control, especially the direct combustion heating method has stricter requirements on the annealing system. If the control is not good, it will easily cause the oxidation of the substrate surface

Method used

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  • Anneal technique for producing SPCC steel grade with zincing wire annealing oven

Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0028] Example 1: Variety SPCC, specification 1.0*1250mm, process: the operating speed of the production line is 53mpmin, after the strip steel is cleaned, the strip steel enters the furnace, and after being preheated to 170°C in the preheating section, the strip steel enters the direct combustion section Heated by an open flame to 624°C, the strip steel is heated to 740°C by the radiant tube heating section, the strip steel in the soaking section of the radiant tube is kept at 720°C by the electric radiant tube, and the strip steel is cooled to 200°C in the spray cooling section, and the furnace temperature is 140°C ℃. Protective gas: Nitrogen flow rate 701m 3 / hr, pressure 4.3bar, oxygen content 6.79ppm; hydrogen flow rate 65.6m 3 / hr, pressure 2.7bar, percentage 7.80%; gas pressure 83.1mdar; dew point of direct combustion section: -39.81°C, dew point of zone 1 of spray cooling section: -60°C.

Embodiment 2

[0029] Example 2: Variety SPCC, specification 1.5*1250mm, process: the operating speed of the production line is 38mpmin, after the strip steel is cleaned, the strip steel enters the furnace, and after being preheated to 140°C in the preheating section, the strip steel enters the direct combustion section The steel strip is heated to 610°C by an open flame, and the strip steel is heated to 764°C by the radiant tube heating section. The strip steel is kept at 690°C in the soaking section of the radiant tube, and is cooled to 230°C in the spray cooling section, and the furnace temperature is 180°C. Protective gas: nitrogen flow 500m 3 / hr, pressure 4.1bar, oxygen content 6.93ppm; hydrogen flow rate 65.5m 3 / hr, pressure 2.4bar, percentage 7.92%; gas pressure 96.5mdar; dew point of direct combustion section: -40°C, dew point of zone 1 of spray cooling section: -67°C.

Embodiment 3

[0030] Example 3: Variety SPCC, specification 0.5*1250mm, technological process: the operating speed of the production line is 76mpmin, after the strip steel is cleaned, the strip steel enters the furnace, and after being preheated to 180°C in the preheating section, the strip steel enters the direct combustion section The steel strip is heated to 630°C by the open flame, and the strip steel is heated to 790°C by the radiant tube heating section. The strip steel is kept at 730°C in the radiant tube soaking section, and the strip steel is cooled to 190°C in the spray cooling section, and the furnace temperature is 160°C. Protective gas: Nitrogen flow rate 701m 3 / hr, pressure 1.3bar, oxygen content 7ppm; hydrogen flow 90m 3 / hr, pressure 2.7bar, percentage 8.03%; gas pressure 83.1mdar; dew point of direct combustion section: -40°C, dew point of zone 1 of spray cooling section: -69°C.

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Abstract

An annealing process of producing SPCC steel in annealing furnace on galvanizing line belongs to the field of the heat treatment technology of metal. Using the process can also meet the strength and plasticity requirement of strip steel on continuous annealing line. The method comprises the following procedures: the steel is heated to 630 minus or plus 20 DEG C by open fire; the steel is heated to 760 minus or plus 20 DEG C by a radiant tube; dew point is controlled below minus 40 DEG C; the steel is maintained at 710 minus or plus 20 DEG C by radiant tube; dew point is controlled below minus 40 DEG C; the strip steel is sprayed to 210 minus or plus 20 DEG C, the dew point of the first area of the spray section is controlled below minus 60 DEG C; and is cooled to 160 minus or plus 20 DEG C. The method can be used on the annealing furnace of the galvanizing line and be suitable for annealing of SPCC steel. The method can eliminate the internal stress of the rolling processing of strip steel, promote the plasticity and the toughness of the strip steel, and meet the strength and the plasticity requirement of the strip steel on the continuous annealing line. The tensile strength of product is approximately at 380Megapascal, the yield strength is below 330Megapascal, and the elongation is more than 36 percent. The grain size of product stabilizes between 11 and 13 Mum, the elongation and the stamping property are all at the higher level. The method can avoid the idle of the production equipment of galvanizing line and reduce the depreciation loss of equipment.

Description

technical field [0001] The invention relates to an annealing process, in particular to an annealing process for producing annealed plates in an annealing furnace of a cold-rolled sheet galvanizing line, and belongs to the technical field of metal heat treatment. Background technique [0002] The cold-rolled sheet galvanizing line is a special production line for the production of cold-rolled galvanized sheets. The continuous annealing furnace with an open flame heating section used in this production line has a complex structure, high strip speed, and difficult control. At present, many large, medium and small galvanizing lines have been built and put into operation, but due to the influence of equipment level and market factors, except for the galvanizing lines of several large steel mills, almost all other galvanizing lines are in a state of suspension or semi-stop production . In order to improve the utilization rate of equipment and reduce the loss caused by vacant equi...

Claims

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Application Information

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IPC IPC(8): C21D9/54C21D1/26
Inventor 李建英齐长发孙长杰杨丽芳姚连胜孙力于世川张静梅淑文杨青
Owner HEBEI IRON AND STEEL
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