Ingot slow cool annealing process for low-carbon steel

A low-carbon alloy steel and annealing process technology, applied in the field of iron and steel metallurgy, can solve problems such as poor plasticity, reduce thermal stress and tissue stress, and avoid cracks.

Inactive Publication Date: 2007-03-14
INNER MONGOLIA NORTH HEAVY INDS GROUP
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Problems solved by technology

Any measures to prevent cracks it adopts are considered from reducing the cooling rate of the steel ingot after demoulding. Since the formation temperature of ferrite is much higher than that of medium carbon steel for low-carbon alloy steel, the steel ingot has not been demolded. Ferrite wi

Method used

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  • Ingot slow cool annealing process for low-carbon steel
  • Ingot slow cool annealing process for low-carbon steel

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Embodiment Construction

[0009] After the steel ingot of the present invention is removed from the mold, put it into the furnace as soon as possible and heat it up as soon as possible. When the temperature rises to 850±15°C, keep it warm for 30min / 100mm. 100mm, the temperature drop in the furnace is ≤20°C / h, when the temperature drops to 650±15°C, the average holding time: ≥1h / 100mm, the temperature drop in the furnace is ≤20°C / h, out of the furnace, and the temperature out of the furnace is ≤200°C.

[0010] The hundreds of steel ingots annealed by Inner Mongolia North Heavy Industry Group Co., Ltd. using the above-mentioned process have never cracked again. The steel grades involved are: 21CrMo10, 12Cr2MoG, 12Cr1MoVG, 17CrNiMo6, 20CrMnMo, 20CrNiMo, etc.

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Abstract

The present invention is low carbon steel ingot slowly cooling annealing process and belongs to the field of ferrous metallurgy technology. The low carbon steel ingot slowly cooling annealing process includes heating demolded steel ingot in a furnace to 800-900 deg.c, maintaining for some time, cooling in the furnace to 760+/-15 deg.c, maintaining for some time, cooling in the furnace to 650+/-15 deg.c, and discharging at the temperature not higher than 200 deg.c. The present invention has raised steel ingot demolding temperature, heating and temperature maintaining after demolding to eliminate stress caused by inside and outside temperature difference and stepped maintaining and cooling, and can reduce stress during steel ingot cooling and avoid cracking.

Description

1. Technical field [0001] The invention relates to a slow cooling and annealing process for a low-carbon alloy steel ingot, belonging to the field of iron and steel metallurgy. 2. Background technology [0002] At present, in the metallurgical industry, steel ingots are annealed by furnace cooling, pit cooling, or heat preservation at around 650°C for a certain period of time before furnace cooling and pit cooling. After cold or annealing, cracks appear in a large number of steel ingots. If the cracks are mild, the cracks need to be cut and used. If the cracks are serious, the steel ingots will be scrapped directly, seriously affecting the quality and yield of the steel ingots. [0003] The disadvantages of the original process are: after the steel ingot is demoulded, after waiting for a period of time, when the temperature is 650±10°C, it is kept warm, cooled in the furnace, and then released from the furnace. Any measures to prevent cracks it adopts are considered from re...

Claims

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Application Information

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IPC IPC(8): C21D1/26C21D11/00
Inventor 李连贵胡永平石宝凤李登仁王亚明
Owner INNER MONGOLIA NORTH HEAVY INDS GROUP
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