CN103540712B - Nitrogen increasing method of low-carbon high-nitrogen stainless steel ladle - Google Patents
Nitrogen increasing method of low-carbon high-nitrogen stainless steel ladle Download PDFInfo
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- CN103540712B CN103540712B CN201310547297.9A CN201310547297A CN103540712B CN 103540712 B CN103540712 B CN 103540712B CN 201310547297 A CN201310547297 A CN 201310547297A CN 103540712 B CN103540712 B CN 103540712B
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Abstract
The invention relates to a nitrogen increasing method of a low-carbon high-nitrogen stainless steel ladle. The method comprises the following steps of: 1, smelting in an AOD (Argon Oxygen Decarburization) furnace, tapping and drossing, feeding into a VOD (Vacuum Oxygen Decarburization) finery, decarburizing the steel ladle in the VOD finery till the carbon content in the steel is below 0.02%, reducing, covering the steel ladle, under the air pressure of (0.8-1.3)*10<5>Pa, blowing nitrogen into liquid steel through a top lance to carry out nitrogen alloying, increasing the nitrogen till the temperature of the liquid steel is not lower than the liquidus temperature 20 DEG C above zero; and 2, lifting the steel ladle into an LF (Ladle Furnace), heating, covering the steel ladle, under the air pressure of (0.8-1.3)*10<5>Pa, blowing the nitrogen into the liquid steel through the top lance to carry out nitrogen alloying, enabling the temperature of the liquid steel to be not lower than the liquidus temperature 20 DEG C above zero while increasing the nitrogen, blowing and stirring for 1-5 minutes at the speed of blowing 7-15L of argon into per ton of liquid steel per minute through a steel ladle bottom blowing device and uniformly mixing the liquid steel. The nitrogen increasing method disclosed by the invention has the advantages that the carbon content in the steel is controlled below 0.02% and the nitrogen content is up to 0.60-0.80%.
Description
Technical field
The present invention relates to the method for a kind of low-carbon high-nitrogen stainless steel ladle nitrogen pick-up, be specifically that in finished product, carbon content is not more than 0.03 percent, nitrogen content is not less than the method for the nitrogen pick-up of 0.60 percent.
Background technology
Nitrogen adds in steel as alloy element and plays stable austenite, improves the effect such as steel mechanical property and solidity to corrosion.For this reason, nitrogen in steel content, for meeting performance requriements, controls more than 0.60% by part stainless steel.
Carry out nitrogen alloying with nitro-alloys such as the alternative nitrogenized manganese of the nitrogen of cheapness or chromium nitrides, improve purity of steel, reduce production cost, reduce the pollution adding nitro-alloy and bring to steel and environment.
The method of existing nitrogen pick-up, produce high nitrogen stainless steel, different refining furnace has its features:
The first, when AOD furnace produces high nitrogen stainless steel, take off to less than 0.02% by carbon content in steel, particularly the Fe content steel grade that is greater than 10%, not only smelting cycle is long affects production capacity, but also affects lining life.
AOD furnace has certain advantage to control nitrogen in steel content, by the control of nitrogen in steel content at 0.40-0.60%, but by more difficult more than 0.60% for the control of nitrogen in steel content, can be only had and use nitro-alloy nitrogen pick-up by stove bottom-blowing device.
The second, carbon content in steel can be taken off to less than 0.02% with VOD refining furnace, but nitrogen in steel content is taken off to less than 0.08% while decarburization, for high nitrogen stainless steel, also needs nitrogen pick-up.If by ladle bottom blowing nitrogen pick-up, after the reduction of VOD refining furnace, increase to more than 0.40% by nitrogen in steel content, molten steel temperature is limited, and molten steel temperature, lower than its liquidus temperature, can cause solidification of molten steel, cannot continue to produce.
Summary of the invention
For overcoming the deficiency of existing low-carbon high-nitrogen stainless steel in the method for nitrogen pick-up, the invention provides the method for a kind of low-carbon high-nitrogen stainless steel ladle nitrogen pick-up, it can take into account the control of carbon and nitrogen content in steel, and by carbon content control in steel below 0.02%, nitrogen content reaches 0.60-0.80%.
Technical scheme of the present invention is:
For high nitrogen stainless steel, smelt in AOD furnace, carbon content in steel takes off to less than 0.02% at VOD refining furnace, after reduction, in 0.8-1.3 × 10 after skimming by tapping
5under Pa, ladle buckle closure, to be blown in molten steel by nitrogen by top rifle and to carry out nitrogen alloying, nitrogen pick-up to molten steel temperature is not less than steel grade liquidus temperature+20 DEG C, afterwards nitrogen pick-up after LF stove is by molten steel heating, until nitrogen in steel content reaches requirement.
A method for low-carbon high-nitrogen stainless steel ladle nitrogen pick-up, it comprises following step successively:
ismelt in AOD furnace, tapping enters VOD refining furnace after skimming, and band slag thickness 0-60mm in ladle, in ladle, spatial altitude is greater than 1000mm.At VOD refining furnace, carbon content in steel is taken off to less than 0.02%, reduction.
Ladle buckle closure, in 0.8-1.3 × 10
5under Pa air pressure, by pressure 0.8 ~ 1.5MPa nitrogen, be blown in molten steel by top rifle and carry out nitrogen alloying, top lance spray nozzle inserts degree of depth 800-1300mm in molten steel, and nitrogen pick-up can not lower than its liquidus temperature+20 DEG C to molten steel temperature; Assay nitrogen in steel content
.
iIto fill the ladle handling of molten steel to LF stove, after intensification, ladle buckle closure, in 0.8-1.3 × 10
5under Pa air pressure, by pressure 0.8 ~ 1.5MPa nitrogen, be blown in molten steel carried out nitrogen alloying by top rifle, top lance spray nozzle inserts degree of depth 800-1300mm in molten steel, and during nitrogen pick-up, molten steel temperature can not lower than its liquidus temperature+20 DEG C, until nitrogen pick-up reaches steel grade requirement.Mention top rifle and be warming up to pouring temperature again, be blown into argon gas 7-15L by ladle bottom blowing air feeder by molten steel per minute per ton, blow and stir 1-5min mixing molten steel, cast afterwards.
The present invention can take into account the control of carbon and nitrogen content in steel, can by carbon content control in steel below 0.02%, and nitrogen content reaches 0.60-0.80%; Substitute nitro-alloy with the nitrogen of cheapness, carry out nitrogen alloying, not only can improve purity of steel, reduce production cost, shorten AOD furnace tap to tap time, improve production capacity, and thoroughly eliminate the pollution that when adding nitro-alloy nitrogen pick-up, huge flue dust brings to environment.
Embodiment
Describe the embodiment of the method for a kind of low-carbon high-nitrogen stainless steel ladle nitrogen pick-up in detail below in conjunction with embodiment, but the specific embodiment of the present invention is not limited to following embodiment.
Embodiment
The present embodiment carries out on 180t AOD, 180t VOD and 180t LF stove, top rifle peak flow
8000l/min, steel grade TSMF166, liquidus temperature 1412 DEG C, chemical composition percent mass proportioning:
C≤0.03；Si≤1.00；Mn 15.00-19.00；P≤0.030；S≤0.010；
Cr 17.00-19.00；Ni≤0.80；Mo 0.40-0.80；N≥0.40；
All the other are Fe and inevitable impurity.
The present embodiment comprises following step successively:
iafter AOD tapping is skimmed, molten steel amount 145t, ladle band slag thickness 40mm, steel package space 2200mm, molten steel chemical composition percent mass proportioning:
C 0.32; Si 0.07; Mn 1.95; P 0.012; S 0.010; Cr 21.60; Ni 0.55; Mo 0.70; N 0.479; All the other are Fe and inevitable impurity.
Reduce after a VOD decarburization
Enter VOD Liquid Steel in Refining Furnace temperature 1610 DEG C, at VOD refining furnace oxygen blast 916m
3after decarburization, add lime 4.5t, fluorite 1.2t, ferrosilicon 1.72t (Si content 75%), electrolytic manganese 10t (Mn content 99%), in vacuum tightness 1.3 × 10
2under Pa, reduction 13min, vacuum-treat terminates, molten steel temperature 1506 DEG C, molten steel chemical composition percent mass proportioning:
C 0.012; Si 0.50; Mn 7.98; P 0.012; S 0.003; Cr 20.15; Ni 0.51; Mo 0.66; N 0.072; All the other are Fe and inevitable impurity.
The nitrogen pick-up of b VOD refining furnace
Ladle buckle closure, 0.99 × 10
5under Pa air pressure, be blown in molten steel by top rifle by pressure 1.2MPa nitrogen and carry out nitrogen alloying, top lance spray nozzle inserts 1200mm in molten steel, top rifle nitrogen flow 7200L/min, nitrogen pick-up 40min, molten steel temperature 1440 DEG C, molten steel chemical composition percent mass proportioning:
C 0.015; Si 0.51; Mn 7.99; P 0.012; S 0.002; Cr 20.16; Ni 0.51; Mo 0.66; N 0.282; All the other are Fe and inevitable impurity.
Through chemical analysis, N 0.282%, nitrogen in steel content does not reach the requirement of steel grade.
iIto fill the ladle handling of molten steel to LF stove, intensification power transmission 120min, adds electrolytic manganese 21.8t, molten steel temperature 1520 DEG C after alloying, and power transmission 62min heats up again, 0.99 × 10
5under Pa air pressure, be blown in molten steel with pressure 1.1MPa nitrogen carried out nitrogen alloying by top rifle, top lance spray nozzle inserts 1200mm in molten steel, top rifle nitrogen flow 7200L/min, nitrogen pick-up 86min, top rifle proposes molten steel, be warming up to 1510 DEG C, molten steel amount 177.5t, molten steel chemical composition percent mass proportioning:
C 0.018; Si 0.42; Mn 18.65; P 0.012; S 0.002; Cr 17.50; Ni 0.44; Mo 0.57; N 0.663; All the other are Fe and inevitable impurity.
Be blown into argon gas 13L by ladle bottom blowing air feeder by molten steel per minute per ton, blow and stir 3min mixing molten steel, temperature 1495 DEG C, die casting.
Claims (1)
1. a method for low-carbon high-nitrogen stainless steel ladle nitrogen pick-up, it comprises following step successively:
ismelt in AOD furnace, tapping enters VOD refining furnace after skimming, band slag thickness 0-60mm in ladle, and in ladle, spatial altitude is greater than 1000mm; At VOD refining furnace, carbon content in steel is taken off to less than 0.02%, reduction;
Ladle buckle closure, 0.8 × 10
5~ 1.3 × 10
5under Pa air pressure, by pressure 0.8 ~ 1.5MPa nitrogen, be blown in molten steel by top rifle and carry out nitrogen alloying, top lance spray nozzle inserts degree of depth 800-1300mm in molten steel, and nitrogen pick-up to molten steel temperature is not less than its liquidus temperature+20 DEG C; Assay nitrogen in steel content;
iIto fill the ladle handling of molten steel to LF stove, after intensification, ladle buckle closure, 0.8 × 10
5~ 1.3 × 10
5under Pa air pressure, by pressure 0.8 ~ 1.5MPa nitrogen, be blown in molten steel by top rifle and carry out nitrogen alloying, top lance spray nozzle inserts degree of depth 800-1300mm in molten steel, and during nitrogen pick-up, molten steel temperature is not less than its liquidus temperature+20 DEG C, until nitrogen pick-up reaches steel grade requirement; Mention top rifle and be warming up to pouring temperature again, be blown into argon gas 7-15L by ladle bottom blowing air feeder by molten steel per minute per ton, blow and stir 1-5min mixing molten steel.
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| CN106319159A (en) * | 2016-11-10 | 2017-01-11 | 山西太钢不锈钢股份有限公司 | Low-carbon low-silicon austenitic stainless steel refining method |
| WO2018107314A1 (en) * | 2016-12-12 | 2018-06-21 | 机械科学研究总院青岛分院有限公司 | Process for centrifugally casting high-nitrogen austenitic stainless steel pipe at normal pressure |
| CN110016535B (en) * | 2019-03-01 | 2021-02-23 | 鞍钢股份有限公司 | Method for improving and stably controlling nitrogen content in stainless steel |
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| CN102719611A (en) * | 2012-06-27 | 2012-10-10 | 山西太钢不锈钢股份有限公司 | Nitrogen increasing method for stainless steel |
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