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A Method for Eliminating Transverse Cracks at the Corner of Slab under High Scrap Steel Ratio Production Mode

A technology of production mode and scrap steel ratio, which is applied in the field of iron and steel smelting, can solve problems affecting steel quality, etc., and achieve the effects of ensuring smooth production, reducing additives, and reducing heat loss

Active Publication Date: 2020-01-07
天铁热轧板有限公司
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

In addition, when the ratio of high scrap to steel is mixed with cold and hot steel materials, it is necessary to use heat-carrying materials to compensate for the heat loss caused by the high ratio of scrap to steel. Usually, the heat-carrying materials used in steel mills are C-containing materials, and the C-containing materials mainly include: Coke, coal powder, etc., such heat-carrying materials have a high N content, and the N brought into the steel during use affects the quality of the steel

Method used

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Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0052] Example 1: The steel type is SPHC, the chemical composition is C: 0.04%, Mn: 0.205%, Si: 0.01%, P: 0.017%, S: 0.015%, Als: 0.030%, and the furnace charge is 100% by weight. tons, including 18.2 tons of steel scrap. Described steel scrap is heavy steel scrap, detects trace element content in scrap steel as follows: Cu% is 0.198, As% is 0.083, Sn% is 0.054, Ni% is 0.207, calculates Cueq according to formula as follows:

[0053] Cueq=0.198%×0.2+3×0.083%×0.2+8×0.054%×0.2-0.207%×0.2=0.134%. The slagging material is made of high-quality lime, no heat-carrying material is added, the N content in the steel is 0.0019%, the ferro-titanium is added according to Ti / N≥3.0 during the smelting process, the ferro-titanium addition is 0.21kg / t, and the Ti content in the steel is 0.0060% , Ti / N=0.006 / 0.0019=3.16

[0054] The physical performance test of the slab: the yield strength is 268MPa, the tensile strength is 350MPa, and the elongation is 46.5%.

[0055] The corners of the slab...

Embodiment 2

[0056] Example 2: The steel type is SPHC, the chemical composition is C: 0.04%, Mn: 0.205%, Si: 0.01%, P: 0.017%, S: 0.015%, Als: 0.030%, and the furnace charge is 100% by weight. tons, including 23 tons of steel scrap. Described steel scrap is light material steel scrap, detects trace element content in the scrap steel as follows: Cu% is 0.082, As% is 0.046, Sn% is 0.021, Ni% is 0.228, calculates Cueq according to formula as follows:

[0057] Cueq=0.082%×0.25+3×0.046%×0.25+8×0.021%×0.25-0.228%×0.25=0.040%.

[0058] The slagging material is made of high-quality lime, the consumption of steel material is 1100kg / t, the amount of molten iron added is 77t / furnace, the amount of scrap steel added is 23t / furnace, the heat of molten iron is 2041.63MJ / t, and the ratio of scrap iron and steel to iron in scrap is 7: 3. The heat of scrap iron and steel is 147.77MJ / t, the heat of iron block is 808.95MJ / t, and the heat of coke is 13056.2MJ / t, which is brought into the calculation formula ...

Embodiment 3

[0065] Example 3: The steel type is SPHC, the chemical composition is C: 0.04%, Mn: 0.205%, Si: 0.01%, P: 0.017%, S: 0.015%, Als: 0.030%, and the furnace charge is 100% by weight. tons, including 27 tons of steel scrap. Described steel scrap is light material steel scrap, detects trace element content in scrap steel as follows: Cu% is 0.148, As% is 0.103, Sn% is 0.024, Ni% is 0.267, calculates Cueq according to formula as follows:

[0066] Cueq=0.148%×0.30+3×0.103%×0.30+8×0.024%×0.30-0.267%×0.30=0.115%.

[0067] The slagging material is made of high-quality lime, the consumption of steel material is 1100kg / t, the amount of molten iron added is 73t / furnace, the amount of scrap steel added is 27t / furnace, the heat of molten iron is 2041.63MJ / t, and the ratio of scrap iron and steel to iron in scrap is 7: 3. The heat of scrap iron and steel is 147.77MJ / t, the heat of iron block is 808.95MJ / t, and the heat of coke is 13056.2MJ / t, which is brought into the calculation formula as f...

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Abstract

A method for eliminating casting blank corner transverse cracks under a high-scrap-ratio production mode comprises the following steps that a, scrap steel classified preparation is conducted; b, control over scrap steel adding in the converter smelting process is conducted, specifically, the relation of Cueq<=0.15% serves as a scrap steel adding principle; c, heat-carrying materials are added in the converter smelting process, specifically, according to the temperature and component of molten iron and the adding quantity of scrap steel, the adding quantity of the heat-carrying materials is determined; and d, control of the N content in the converter smelting process is conduced, specifically, good-quality white ash is adopted for slagging materials, and the content of N in the steel is conducted to be smaller than or equal to 50 ppm. According to the method for eliminating the casting blank corner transverse cracks under the high-scrap-ratio production mode, quantum chemistry calculation of the influence of the content of elements such as Cu, Ni, As and N in the scrap steel on the casting blank corner quality is obtained according to long-term exploration and repeated tests, the adding quantity and types of the scrap steel are controlled in a refined mode, and the adverse factor of the high microelement content on the casting blank quality is eliminated; through titanium nitrogen fixation, steel hardening caused by the high N content is prevented; and the casting blank corner cracks can be effectively controlled under the condition of the converter large-scrap-ratio production mode.

Description

technical field [0001] The invention relates to a method for iron and steel smelting, in particular to a method for eliminating transverse cracks at corners of billets in a production mode with a high ratio of scrap to steel, and belongs to the technical field of iron and steel smelting. Background technique [0002] As an infinitely recyclable resource, scrap steel has high economic, environmental and social benefits. It not only saves energy and reduces emissions, but also improves the utilization rate of scrap steel, which can effectively solve the problem of excess scrap steel resources. Observing from the current situation, the steel scrap industry has a huge room for development, and its development trend is also very impressive. In response to the relevant national environmental protection policies, major iron and steel enterprises chose to operate less blast furnaces and more converters, which led to a large increase in the proportion of scrap steel entering the furn...

Claims

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Application Information

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Patent Type & Authority Patents(China)
IPC IPC(8): C22C33/06C21C5/36C22C38/02C22C38/04C22C38/06C22C38/08C22C38/14C22C38/16
CPCC21C5/36C22C33/06C22C38/001C22C38/008C22C38/02C22C38/04C22C38/06C22C38/08C22C38/14C22C38/16Y02P10/20
Inventor 黄伟丽杨志刚谷珊珊陈四平朱红芳韩伟旗
Owner 天铁热轧板有限公司
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