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Large steel ingot annealing method

A steel ingot and annealing technology, applied in the field of iron and steel metallurgy, can solve the problem of high production cost, achieve the effects of good heat preservation effect, good annealing effect and elimination of tissue stress

Inactive Publication Date: 2018-01-19
WUYANG IRON & STEEL
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

The above annealing method requires the use of a large annealing furnace to meet the annealing requirements, resulting in higher production costs in some steel mills

Method used

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Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0014] Embodiment 1: The annealing method of this large steel ingot adopts the following specific processes.

[0015] When the 75t steel ingot is annealed, it is annealed with a steel ladle that has been poured for 5 hours and the temperature on the inner wall is 920°C; when the surface of the steel ingot is cooled to 300°C in the ladle, bricks are added between the ladle and the ground to form a gap to speed up the annealing process. Cooling rate: In the 200th hour after being covered, the surface temperature of the steel ingot drops to 94°C, and the ladle is removed for air cooling. After the above-mentioned annealing treatment, the surface of the steel ingot is intact without cracks, and the internal stress is effectively eliminated.

Embodiment 2

[0016] Embodiment 2: The annealing method of this large steel ingot adopts the following specific processes.

[0017] When the 75t steel ingot is annealed, it is annealed with a steel ladle that has been poured for 6 hours and the temperature on the inner wall is 800°C; when the surface of the steel ingot is cooled to 250°C in the ladle, bricks are added between the ladle and the ground to form a gap to speed up the annealing process. Cooling rate: In the 192nd hour after being covered, the surface temperature of the steel ingot dropped to 98°C, and the ladle was removed for air cooling. After the above-mentioned annealing treatment, the surface of the steel ingot is intact without cracks, and the internal stress is effectively eliminated.

Embodiment 3

[0018] Embodiment 3: The annealing method of this large steel ingot adopts the following specific processes.

[0019] When the 75t steel ingot is annealed, it is annealed with a steel ladle that has been poured for 4.5 hours and the temperature on the inner wall is 880°C; when the surface of the steel ingot is cooled to 300°C in the ladle, bricks are added between the ladle and the ground to form a gap to speed up the annealing process. Cooling rate: In the 197th hour after being covered, the surface temperature of the steel ingot dropped to 100°C, and the ladle was removed for air cooling. After the above-mentioned annealing treatment, the surface of the steel ingot is intact without cracks, and the internal stress is effectively eliminated.

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PUM

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Abstract

The invention discloses a large steel ingot annealing method. After being demoulded, a steel ingot is covered with a high-temperature steel ladle poured by molten steel and annealed through waste heatof the high-temperature steel ladle. The high-temperature waste heat of the steel ladle is used for annealing the large steel ingot, extra energy sources are hardly consumed, the annealing effect isgood, and good economic and social benefits are achieved. The high temperature of 800 DEG C or above of the steel ladle and the characteristic of the good heat preservation effect of a fire-resistantheat preservation material of the steel ladle are utilized, and meanwhile the high temperature of the steel ingot in demoulding is utilized; after the steel ladle covers the steel ingot, the temperature of the surface of the steel ingot is increased and can reach 900 DEG C or above; after the temperature reaches the highest point, the temperature of the steel ingot is kept almost unchanged for multiple hours because the heat dissipation time of the steel ingot is approximate to the heat dissipation time of the steel ladle; and then, the steel ingot starts to be cooled slowly, and the temperature difference of the surface and the interior of the steel ingot is quite small so that structural stress can be effectively eliminated, and accordingly the annealing effect basically identical to thecomplete annealing effect is achieved.

Description

technical field [0001] The invention belongs to the field of iron and steel metallurgy, in particular to an annealing method for large steel ingots. Background technique [0002] The solidification time of large steel ingots is long and the structural stress is large, so it is easy to crack or even break during cooling to room temperature or during storage or during heating, rolling, and forging. Usually it needs to be annealed in time, and the stress can be eliminated before reprocessing. The larger the steel ingot and the higher the alloy content, the greater the chance of cracks or even breakage of the steel ingot. The usual practice is to relieve stress annealing of steel ingots: demould steel ingots after cooling, put steel ingots into an annealing furnace, heat to a temperature above Ac1 or above Ac3 for a certain period of time, and then slowly cool down to below 100°C to eliminate stress; then Rolling, forging processing. According to the size of the steel ingot, ...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): C21D1/30C21D6/00C21D9/00
Inventor 王全胜兰瑞金何德志王学智
Owner WUYANG IRON & STEEL