CN101633974B - Smelting process of ultra low oxygen steel - Google Patents
Smelting process of ultra low oxygen steel Download PDFInfo
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- CN101633974B CN101633974B CN2009100636406A CN200910063640A CN101633974B CN 101633974 B CN101633974 B CN 101633974B CN 2009100636406 A CN2009100636406 A CN 2009100636406A CN 200910063640 A CN200910063640 A CN 200910063640A CN 101633974 B CN101633974 B CN 101633974B
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Abstract
The invention relates to a smelting method of ultra low oxygen steel, including the following steps: step one, steel-making raw material and carbon granules are put into a crucible, the crucible is placed into a vacuum furnace; the weight of the carbon granules is (0.75-1.0)*w[o]* that of the steel-making raw material, wherein w[o] is weight concentration of oxygen in the steel-making raw material; step two, smelting in the vacuum furnace is carried out; step three, pouring is carried out, inert gas is led in until atmospheric pressure is formed, an ingot mould is taken out, and an ingot is drawn, thus obtaining finished product. The invention utilizes reaction between carbon and oxygen to deoxidize, and the product CO or CO2 is gas and is extremely easy to be volatilized and removed under vacuum, thus speeding up deoxidization reaction. The invention adopts the carbon granules as deoxidizing agent and adopts the vacuum furnace for smelting, the total oxygen content of the prepared steel can be less than 20ppm, and inclusion content is low.
Description
Technical field
The present invention relates to the smelting process of the smelting process of steel, particularly ultra low oxygen steel.
Background technology
Oxygen exists with two kinds of forms in molten steel.A kind of is that dissolved oxygen is also claimed free oxygen, and a kind of is the oxygen that inclusion morphology exists, and is called fixed oxygen.No matter be dissolved oxygen or fixed oxygen, they all are extremely harmful to the performance of steel and alloy.Dissolved oxygen can make the alloying element oxidation of adding, thereby has increased the scaling loss of element, has reduced yield of alloy, and oxidation products increases the The amount of inclusions in steel and the alloy, has reduced the purity of steel and alloy.Dissolved oxygen is separated out owing to solubleness reduces along with temperature reduces in addition, and oxygen of separating out and carbon reaction generate the CO bubble, causes the inner pore that forms of steel ingot or foundry goods with loose, can cause waste product when serious; The oxygen of separating out can also make element oxidations such as aluminium in the molten steel, silicon, manganese; In the process of setting, also possibly form the eutectic of FeO and FeS, and distribute, hot-short when this can cause steel ingot hot-work along crystal boundary.Solidifying back oxygen mainly is present in the steel with the inclusion of oxide compound or oxysulfide.The form of these inclusiones, quantity, size, distribution situation and the characteristic of itself all produce significantly influence to the processing characteristics and the use properties of steel.
Just become the key that improves steel product quality so how to reduce the oxygen level of molten steel.The purpose of deoxidation is exactly the total oxygen that will reduce in the steel, promptly reduces dissolved oxygen and fixed oxygen in the steel.
At present; The steel method of deoxidation adopts elements such as aluminium, calcium, manganese, silicon, barium, rare earth as reductor mostly, and the final product of these reductors is a MOX, can only reduce dissolved oxygen; The total oxygen in the steel can not be reduced, thereby the harm that oxygen causes in the steel can not be fundamentally eliminated.In addition, above-mentioned reductor has increased the content of inclusion when reducing oxygen level, pollute molten steel easily, is unfavorable for smelting ultra-clean steel.
Summary of the invention
Technical problem to be solved by this invention is: a kind of smelting process of ultra low oxygen steel is provided, and the total oxygen of the steel of this method preparation can be below 20ppm.
The present invention solves the problems of the technologies described above the technical scheme that is adopted:
A kind of smelting process of ultra low oxygen steel, it may further comprise the steps:
Step (1), steelmaking feed and carbon granules are put into crucible, crucible is placed vacuum oven; The weight of carbon granules is: (0.75～1.0) * w [o] * steelmaking feed weight, and w [o] is the weight concentration of oxygen in the steelmaking feed;
Step (2), the step of in vacuum oven, smelting;
Step (3), cast charge into rare gas element to normal atmosphere, take out ingot mould, take off the ingot finished product;
Step (2) is specially:
Step (2.1), melt being warming up under the vacuum tightness 1800-2200Pa more than 1650 ℃ to steelmaking feed;
Step (2.2), vacuum degree control is no longer seethed with excitement to molten steel at 3000-5000Pa;
Step (2.3), add alloying element, in vacuum oven, charge into rare gas element, vacuum degree control more than 5000Pa, was kept 10-20 minute to molten steel.
A kind of smelting process of ultra low oxygen steel, it may further comprise the steps:
Step (1), steelmaking feed, alloying element and carbon granules are put into crucible, crucible is placed vacuum oven; The weight of carbon granules is: (0.75～1.0) * w [o] * steelmaking feed weight, and w [o] is the weight concentration of oxygen in the steelmaking feed;
Step (2), the step of in vacuum oven, smelting;
Step (3), cast charge into rare gas element to normal atmosphere, take out ingot mould, take off the ingot finished product;
Step (2) is specially:
Step (2.1), melt being warming up under the vacuum tightness 1800-2200Pa more than 1650 ℃ to steelmaking feed;
Step (2.2), vacuum degree control is no longer seethed with excitement to molten steel at 3000-5000Pa;
Step (2.3), in vacuum oven, charge into rare gas element, vacuum degree control more than 5000Pa, was kept 10-20 minute.
In the such scheme, said carbon granules is the carbon granules through overbaking, and its storing temperature is greater than 600 ℃, and storing time was greater than 2 hours.
In the such scheme, the granularity of said carbon granules is 5-20mm.
In the such scheme, step (1) is specially:
Carbon granules is put into crucible bottom, steelmaking feed is placed on the carbon granules top, crucible is placed vacuum oven.
In the such scheme, the granularity of said carbon granules is 5-10mm.
Compared with prior art, the present invention has the following advantages:
1, reductor is selected: the prior art reductor has elements such as aluminium, calcium, manganese, silicon, barium, rare earth; The final product of these reductors is a MOX; When reducing oxygen level, increased the content of inclusion; Deoxidation products on the one hand polluted molten steel and has been unfavorable for smelting ultra-clean steel, if can not all be removed and can not effectively reduce molten steel total oxygen content on the other hand.
The present invention utilizes carbon oxygen reflection deoxidation, and product is CO or CO
2Be gas, highly volatile is sloughed under vacuum condition, and the reactions formula is constantly advanced, thereby promotes the carrying out of deoxygenation.
[C]+[O]→CO(g)↑
The present invention adopts carbon granules as reductor, adopts vacuum oven to smelt, the total oxygen of the steel of preparation can be below 20ppm and the content of inclusion low.
Add if 2 carbon granules melt the back at steelmaking feed, can make reaction between carbon and oxygen very violent, a large amount of gases overflow rapidly, and boiling is violent, even make the whole tidal bulge of molten steel face overflow crucible, and damage equipment causes the accident.Especially dry when not enough in carbon granules baking, add molten steel suddenly and can cause the diffusion of volatilizing fast of carbon granules contained humidity, cause molten steel acutely to seethe with excitement more, aggravated said process, damage equipment causes the accident.
The present invention adds carbon granules and steelmaking feed simultaneously, has alleviated the molten steel splash, has stopped pernicious industrial accident and equipment breakdowns such as frame material and molten steel overflow greatly.
3, carbon granules is the carbon granules through overbaking.
Carbon granules must be dry, because moist carbon granules contains moisture, under the high-temperature vacuum state, moisture can decompose, and separates out O
2And H
2, increase molten steel oxygen level and hydrogen richness.
2H
2O→2H
2(g)↑+O
2(g)↑
Water (comprising crystal water) in carbon granules volatilization rapidly under the high-temperature vacuum state simultaneously produces water vapor H
2O (1/s) → H
2O (g) ↑, cause molten steel acutely to seethe with excitement, cause crucible Central Plains charge bridge, in case it is invalid to smash material, then smelts and must interrupt.
The ebullient molten steel sticks on the inductor block after spilling crucible most probably in addition, causes the inductor block short circuit, can't send electricity, perhaps damages inductor block.No matter which kind of result is very serious.
Therefore carbon granules used herein is through overbaking, and its storing temperature is greater than 600 ℃, and storing time is greater than 2 hours, thereby guaranteeing that crystal water can toast removes.
4, the granularity of the speed of deoxygenation and degree and carbon relation is very big.
Granularity is more little, and specific surface area is just big more, and the interface of reaction is just big more, but too small granularity is inappropriate, because its proportion of undersized is just very little, as easy as rolling off a log in the floating accumulation of molten steel surface, effective contact area of deoxygenation is diminished; On the other hand, owing to be operation under vacuum state, tiny carbon granules or carbon dust usually by vacuum pump suction loss, had both influenced the effect of deoxygenation and can stop up the vacuum system pipeline, and vacuum-lines is caused damage.
Granularity is excessive, and speed of response is slow, and is consuming time longer, must cause the staple MgO of anti-material under vacuum state, to decompose:
MgO → [Mg]+[O] separates out oxygen, increases the finished product total oxygen content on the contrary.
During the granularity 5-20mm of carbon granules, effect is preferable.
5, at the crucible lowest layer, along with crucible temperature progressively raises, carbon granules is also progressively toasted with the carbon granules cloth in the present invention, and moisture constantly volatilizees; And along with steelmaking feed progressively melts, molten steel after the thawing and carbon granules reaction are progressively slowly carried out, and have further alleviated the molten steel splash, have stopped pernicious industrial accident and equipment breakdowns such as frame material and molten steel overflow greatly.
In the step process of 6, in vacuum oven, smelting, the basic goal of control is to prevent the frame material, reaction is thoroughly carried out smoothly, thereby deoxidation is abundant, smelts direct motion.
According to the reaction between carbon and oxygen equation:
[C]+[O]→CO(g)↑
Its equilibrium constant K=pco/fc [C] fo [O]=pco/m
The carbon oxygen concn amasss m=pco/K
By on can know: molten steel temperature one regularly, equilibrium constant K is a constant, it is high more to smelt environment vacuum tightness so, pco is low more, then the long-pending m of carbon oxygen concn is more little, just oxygen level is low more in the molten steel, m is directly proportional with pco.
So the key of reaction process and extent control is the control of vacuum tightness: vacuum tightness is high more, react thorough more, speed of response is fast more, and the molten steel Shaoxing opera that splashes is strong, and reaction process is difficult to control more, even the frame material steel that overflows, damage equipment.
Reaction process is also closely related with temperature, and this reaction itself is little thermopositive reaction, and temperature is high, and is slow more on the reaction theory; When but temperature was high, molten steel melted fast, and [O] that provides is fast more, thereby speed of response is accelerated, and also caused the molten steel Shaoxing opera that splashes strong easily, and reaction process is difficult to control more.
The present invention begin to melt forward and backward, with vacuum degree control at 1800-2200Pa, treat that molten steel melts fully after; Gas clean-up slowly promotes reaction to advance again, reaches 3000-5000Pa until vacuum tightness; Molten steel no longer seethes, and can increase power, and argon filling makes vacuum chamber pressure reach 5000Pa; Increase power simultaneously to 80kw, the step of beginning alloying.
7, in the actual production, during the granularity 5-10mm of carbon granules, best results.
Description of drawings
Fig. 1 is the vacuum tightness/time chart in the vacuum oven smelting process of the embodiment of the invention
Fig. 2 is the graph of a relation of molten steel oxygen level, reaction time consumption and carbon granules granularity
Embodiment
The smelting process embodiment 1 of ultra low oxygen steel of the present invention, it may further comprise the steps:
Step (1), steelmaking feed 50kg and 15g carbon granules are put into crucible, carbon granules is put into crucible bottom, steelmaking feed is placed on the carbon granules top, crucible is placed the 50kg vacuum induction furnace; The weight of carbon granules is: 0.75*w [o] * steelmaking feed weight, w [o] is the weight concentration 400ppm of oxygen in the steelmaking feed.The granularity of carbon granules is 5-10mm.
Said carbon granules is the carbon granules through overbaking, and its storing temperature is greater than 600 ℃, and storing time was greater than 2 hours.
Step (2), the step of in vacuum oven, smelting; Be specially:
Vacuum tightness/timing relationship in the vacuum oven smelting process is as shown in Figure 1.
Step (2.1), melt being warming up under the vacuum tightness 1800-2200Pa more than 1650 ℃ to steelmaking feed;
Before beginning thawing, the high-power electricity that send of trying one's best shortens smelting cycle; After beginning to melt, carbon oxygen begins reaction, is attended by that sparks fly off molten steel, and vacuum tightness also slightly descends, and should suitably reduce power this moment, controls reaction speed, accidents such as prevention frame material; Along with raw material constantly melts, to a half, can suitably reduce vacuum tightness again, because molten steel is many more, the danger of frame material is big more; Melting the later stage, reduce vacuum tightness, be controlled at 1800-2200Pa, because will prevent the cold steel material at the crucible top material that collapses suddenly, the material that collapses can cause cold burden directly to sink to crucible bottom, bottom steel is waterborne gushes moment and promptly possibly cause serious accidents such as excessive steel.
Step (2.2), vacuum degree control is no longer seethed with excitement to molten steel at 3000-5000Pa;
After treating that molten steel melts fully, gas clean-up slowly promotes reaction to advance again, reaches about 3-5Pa until vacuum tightness, and molten steel no longer seethes, and can increase power, and argon filling makes vacuum chamber pressure reach 3000-5000Pa, increases power simultaneously to 80kw, the beginning alloying.
The step of step (2.3), alloying.Be specially:
Add alloying element to molten steel, Al 15g charges into argon gas in vacuum oven, vacuum degree control more than 5000Pa, is kept 10-20 minute slowly deoxidation.
Step (3), cast, cast finish and cooled off 8-10 minute, charge into argon gas to normal atmosphere, open Vakuumkammer, take out ingot mould, take off the ingot finished product.
The smelting process embodiment 2 of ultra low oxygen steel of the present invention, its step and embodiment 1 are basic identical, and difference is:
Step (1) is specially:
Steelmaking feed 50kg, alloy element copper 10g, Mo15g and 20g carbon granules are put into crucible, crucible is placed vacuum oven; The weight of carbon granules is: 1.0*w [o] * steelmaking feed weight, w [o] is the weight concentration 400ppm of oxygen in the steelmaking feed.
Step (2.3) is specially:
In vacuum oven, charge into rare gas element, vacuum degree control more than 5000Pa, was kept 10-20 minute, slowly deoxidation.
The total oxygen of the steel of the embodiment of the invention 1,2 preparation can be below 20ppm and the content of inclusion low.
Through test of many times, obtain the graph of a relation of molten steel oxygen level shown in Figure 2, reaction time consumption and carbon granules granularity, from figure, can draw: the granularity of said carbon granules is that 5-10mm is best.
Claims (3)
1. the smelting process of a ultra low oxygen steel, it may further comprise the steps:
Step (1), steelmaking feed and carbon granules are put into crucible, carbon granules is put into crucible bottom, steelmaking feed is placed on the carbon granules top, crucible is placed vacuum oven; The weight of carbon granules is: (0.75～1.0) * w [o] * steelmaking feed weight, and w [o] is the weight concentration of oxygen in the steelmaking feed;
Step (2), the step of in vacuum oven, smelting;
Step (3), cast charge into rare gas element to normal atmosphere, take out ingot mould, take off the ingot finished product;
Step (2) is specially:
Step (2.1), melt being warming up under the vacuum tightness 1800-2200Pa more than 1650 ℃ to steelmaking feed;
Step (2.2), vacuum degree control is no longer seethed with excitement to molten steel at 3000-5000Pa;
Step (2.3), add alloying element, in vacuum oven, charge into rare gas element, vacuum degree control more than 5000Pa, was kept 10-20 minute to molten steel;
The granularity of said carbon granules is 5-20mm; Said carbon granules is the carbon granules through overbaking, and its storing temperature is greater than 600 ℃, and storing time was greater than 2 hours.
2. the smelting process of a ultra low oxygen steel, it may further comprise the steps:
Step (1), steelmaking feed, alloying element and carbon granules are put into crucible, carbon granules is put into crucible bottom, steelmaking feed is placed on the carbon granules top, crucible is placed vacuum oven; The weight of carbon granules is: (0.75～1.0) * w [o] * steelmaking feed weight, and w [o] is the weight concentration of oxygen in the steelmaking feed;
Step (2), the step of in vacuum oven, smelting;
Step (3), cast charge into rare gas element to normal atmosphere, take out ingot mould, take off the ingot finished product;
Step (2) is specially:
Step (2.1), melt being warming up under the vacuum tightness 1800-2200Pa more than 1650 ℃ to steelmaking feed;
Step (2.2), vacuum degree control is no longer seethed with excitement to molten steel at 3000-5000Pa;
Step (2.3), in vacuum oven, charge into rare gas element, vacuum degree control more than 5000Pa, was kept 10-20 minute;
The granularity of said carbon granules is 5-20mm; Said carbon granules is the carbon granules through overbaking, and its storing temperature is greater than 600 ℃, and storing time was greater than 2 hours.
3. according to claim 1 or claim 2 smelting process, it is characterized in that: the granularity of said carbon granules is 5-10mm.
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Families Citing this family (5)
| Publication number | Priority date | Publication date | Assignee | Title |
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| CN102181656B (en) * | 2011-04-07 | 2012-07-25 | 武汉钢铁(集团)公司 | Method for smelting high-purity steel through vacuum induction furnace |
| CN102443679B (en) * | 2011-12-07 | 2016-03-30 | 鞍钢股份有限公司 | Production method of steel with ultralow oxide inclusions |
| CN103924030B (en) * | 2014-04-09 | 2015-05-06 | 中国科学院金属研究所 | Smelting method of ultra-low oxygen pure steel |
| CN109628696B (en) * | 2019-01-31 | 2021-04-27 | 武汉钢铁有限公司 | Vacuum melting process of aluminum-free low-oxygen steel |
| CN110079724B (en) * | 2019-06-12 | 2020-06-02 | 中天钢铁集团有限公司 | Smelting method of ultralow-oxygen medium-low carbon steel |
Citations (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN1676621A (en) * | 2004-03-30 | 2005-10-05 | 宝山钢铁股份有限公司 | Suboxide steel production method |
| CN101440436A (en) * | 2007-11-21 | 2009-05-27 | 中国科学院金属研究所 | Purified smelting technique for high-temperature superalloy |
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Patent Citations (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN1676621A (en) * | 2004-03-30 | 2005-10-05 | 宝山钢铁股份有限公司 | Suboxide steel production method |
| CN101440436A (en) * | 2007-11-21 | 2009-05-27 | 中国科学院金属研究所 | Purified smelting technique for high-temperature superalloy |
Non-Patent Citations (2)
| Title |
|---|
| JP昭60-159109A 1985.08.20 |
| 薛正良等.用氧化钙坩锅真空感应熔炼超低氧钢的脱氧动力学.《钢铁研究学报》.2003,第15卷(第5期),5-8，13. * |
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