CN104357617A - Method for secondarily refining super-clean molten metal in AOD furnace - Google Patents
Method for secondarily refining super-clean molten metal in AOD furnace Download PDFInfo
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- CN104357617A CN104357617A CN201410600635.5A CN201410600635A CN104357617A CN 104357617 A CN104357617 A CN 104357617A CN 201410600635 A CN201410600635 A CN 201410600635A CN 104357617 A CN104357617 A CN 104357617A
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Abstract
The invention discloses a method for secondarily refining super-clean molten metal in an AOD (Argon Oxygen Decarburization) furnace. The method comprises the following steps: primarily refined molten metal is refined after the primarily refining molten metal enters the AOD furnace, and after the first-time refining is completed, a large amount of mixed furnace slag generated after first-time refining is partly removed, then a new slagging material is added, a carburant is renewedly added for carbon addition, and the decarburization refining and reducing are performed again to further decrease impurities, harmful elements, gases and the like in the molten metal. The degree of purity of the molten metal is improved through the two-times refining in the AOD furnace, the gas content in the molten metal is further reduced, and meanwhile, the comprehensive mechanical property of the material is improved, so that the market requirement on high-quality castings is met.
Description
technical field:
The present invention relates to casting field, particularly relate to a kind of method of AOD furnace secondary refining super clean molten metal.
background technology:
Existing AOD furnace (refining unit of argon oxygen decarburizing process) refinery practice completes pouring cast part afterwards by initial refining.Can meet the demands for general foundry goods, but for the foundry goods requiring high cleanliness and ultra low gas content, be mingled with, AOD initial refining does not often reach requirement sometimes, if want to reach requirement, traditional method is that the method taking AOD to add two refinings such as VOD has been come, but too high with this method cost, complicated operation, risk are larger.
Therefore, need to adopt more rational method, such that cost is lower, simple to operate, risk is less, and the quality of molten metal can reach reasonable effect, be only the problem needing solution at present.
summary of the invention:
In order to make up prior art problem, the object of this invention is to provide a kind of method of AOD furnace secondary refining super clean molten metal, cost is lower, simple to operate, risk is less, and the quality of molten metal can reach reasonable effect.
Technical scheme of the present invention is as follows:
The method of AOD furnace secondary refining super clean molten metal, is characterized in that, comprise the steps:
1), carry out load melting at intermediate frequency furnace, in intermediate frequency furnace, adjust the Chemical Composition of furnace charge, temperature and required mixed carbon comtent, as following table:
, after fusing, obtain the molten metal of required refining;
2), then the molten metal of required refining entered in AOD furnace carry out initial refining:
First carry out thermometric, when temperature is less than 1600 DEG C, add required molten metal gross weight be 0.1% ~ 2% aluminium block carry out warming temperature, the first step, gas blows, and uses O
2: Ar is that 5:1 ~ 4:1 blows; When temperature reaches 1690 ~ 1710 DEG C, need O
2: Ar is adjusted to 2:1 ~ 1:1; When temperature reaches 1710 ~ 1720 DEG C, adding required molten metal gross weight is the lime of 0.2% ~ 4%, and O
2: Ar ratio is adjusted to 1:2 ~ 1:3 and blows;
Second step, when after blowing certain hour, according to fire door flame conditions, estimate carbon content, if flame is very low and have a large amount of black smoke, sampling carries out chemical analysis, and analytical results carbon content is less than 0.02%, can enter reduction period;
3rd step, before starting reduction, carry out thermometric, temperature, at 1630 ~ 1650 DEG C, can enter reduction period; Temperature is greater than 1650 DEG C, argon gas stirring need be carried out, the amount of the reductive agent added needed for reduction need calculate according to oxygen consuming amount, mixed carbon comtent and Metal Weight etc., recovery time is no less than 5min, after reduction terminates, carry out sampling analysis, analytical results reaches composition requirement, and temperature is at 1600 ~ 1650 DEG C, and initial refining terminates;
3), except slag operation: after initial refining terminates, that can carry out AOD furnace removes slag operation, directly carries out grate deslagging, when the amount removing 2/5 ~ 3/5 of slag, stops deslagging;
4), add new slag making materials and carry out joining carbon operation: first in stove, add lime, add-on with in step 3 except the quantity of slag is identical, then add carburelant, the carburelant added need be increased to 0.5 ~ 0.6% by carbon content and allocate into;
5), secondary refining process; After lime and carburelant are allocated into, can carry out secondary refining, secondary refining process is identical with initial refining;
6), after secondary refining terminates, when final composition and temperature reach requirement, can tap and carry out cast product.
The method of described AOD furnace secondary refining super clean molten metal, is characterized in that, in initial refining, the first step, also can adopt following steps to carry out gas and blow, use O
2: N
2for 5:1 ~ 4:1 blows; When temperature reaches 1690 ~ 1710 DEG C, need O
2: N
2be adjusted to 2:1 ~ 1:1; When temperature reaches 1710 ~ 1720 DEG C, adding required molten metal gross weight is the lime of 0.2% ~ 4%, and O
2: Ar ratio is adjusted to 1:2 ~ 1:3 and blows.
The method of described AOD furnace secondary refining super clean molten metal, it is characterized in that, the reductive agent in initial refining process selects aluminium block or ferrosilicon, and add required molten metal gross weight is 0.1% ~ 2%.
Advantage of the present invention is:
Present method operates by same AOD furnace, effectively can reduce the calorific loss in molten metal, and present method operating process is simple simultaneously, do not increase new operation difficulties, operating process is easy to control, and cost increases less, improves a lot than the quality of molten metal of traditional AOD furnace initial refining.
Gas content in molten metal experimentally after result secondary refining on average reduces by 30 ~ 50%, mainly the content of nitrogen and hydrogen declines obviously, after carbon steel and low alloy steel foundry goods initial refining, general nitrogen content is 40 ~ 50PPM, can reach 20 ~ 30PPM after secondary refining; General hydrogen richness is 2 ~ 3PPM after initial refining, can reach 1 ~ 2PPM after secondary refining.Decline not obvious, because secondary refining still needs to carry out oxygen blast operation for oxygen level.
Be about 250PPM for nitrogen content after initial refining stainless steel (18 ~ 8 type), after secondary refining, nitrogen content can reach below 130PPM;
Basic identical with carbon steel for hydrogen richness, can 1 ~ 2PPM be reached.
For abros (for Meng Laier alloy), the nitrogen content after initial refining is generally 3 ~ 5PPM, is generally 1 ~ 2PPM after secondary refining; Be generally 2 ~ 3PPM after hydrogen richness initial refining, after secondary refining, can below 1PPM be reached.Inclusion content simultaneously in molten steel also significantly reduces; Mainly nitride, oxide compound and some metal inclusions (mainly the metal inclusion of low melting point) etc., because the dividing potential drop effect of the carbon monoxide bubble that secondary refining produces and argon gas can take away inclusion and the gas of molten steel further, thus can further cleaning molten steel.And comprehensive mechanical property increases, particularly impact value improves obviously, and also decline to some extent than after initial refining for sulphur content, on average can decline about 20PPM.
For carbon steel and low-alloy, after initial refining, low-temperature impact is about 80J, can reach more than 100J, and be generally about 50PPM after sulphur content initial refining, and can reach below 30PPM after secondary refining after secondary refining;
Be generally about 80PPM for the sulphur content after stainless steel initial refining, and can reach below 50PPM after secondary refining, can reach about 130J for after-196 degree low-temperature impact secondary refinings, what have beats even constantly.
Present method improves the inner quality of molten metal, reduces smelting high-purity clean metal liquid cost, reduces operation easier, reduce risks, and the production that can meet for high quality and high request foundry goods, for enterprise has won client, simultaneously also for client reduces cost for the buying of high quality casting.
embodiment:
CF3M material in ASTM A351:
The method of AOD furnace secondary refining super clean molten metal, is characterized in that, comprise the steps:
1), carry out load melting at intermediate frequency furnace, in intermediate frequency furnace, adjust the Chemical Composition of furnace charge, temperature and required mixed carbon comtent, as following table:
, after fusing, obtain the molten metal of required refining;
2), then the molten metal of required refining entered in AOD furnace carry out initial refining:
First carry out thermometric, when temperature is less than 1600 DEG C, add required molten metal gross weight be 0.1% ~ 2% aluminium block carry out warming temperature, the first step, gas blows, and uses O
2: Ar is that 5:1 ~ 4:1 blows; When temperature reaches 1690 ~ 1710 DEG C, need O
2: Ar is adjusted to 2:1 ~ 1:1; When temperature reaches 1710 ~ 1720 DEG C, adding required molten metal gross weight is the lime of 0.2% ~ 4%, and O
2: Ar ratio is adjusted to 1:2 ~ 1:3 and blows;
Second step, when after blowing certain hour, according to fire door flame conditions, estimate carbon content, if flame is very low and have a large amount of black smoke, sampling carries out chemical analysis, and analytical results carbon content is less than 0.02%, can enter reduction period;
3rd step, before starting reduction, carry out thermometric, temperature, at 1630 ~ 1650 DEG C, can enter reduction period; Temperature is greater than 1650 DEG C, argon gas stirring need be carried out, the amount of the reductive agent added needed for reduction need calculate according to oxygen consuming amount, mixed carbon comtent and Metal Weight etc., recovery time is no less than 5min, after reduction terminates, carry out sampling analysis, analytical results reaches composition requirement, and temperature is at 1600 ~ 1650 DEG C, and initial refining terminates;
3), except slag operation: after initial refining terminates, that can carry out AOD furnace removes slag operation, directly carries out grate deslagging, when the amount removing 2/5 ~ 3/5 of slag, stops deslagging;
4), add new slag making materials and carry out joining carbon operation: first in stove, add lime, add-on with in step 3 except the quantity of slag is identical, then add carburelant, the carburelant added need be increased to 0.5 ~ 0.6% by carbon content and allocate into;
5), secondary refining process; After lime and carburelant are allocated into, can carry out secondary refining, secondary refining process is identical with initial refining;
6), after secondary refining terminates, when final composition and temperature reach requirement, can tap and carry out cast product.
The method of described AOD furnace secondary refining super clean molten metal, is characterized in that, in initial refining, the first step, also can adopt following steps to carry out gas and blow, use O
2: N
2for 5:1 ~ 4:1 blows; When temperature reaches 1690 ~ 1710 DEG C, need O
2: N
2be adjusted to 2:1 ~ 1:1; When temperature reaches 1710 ~ 1720 DEG C, adding required molten metal gross weight is the lime of 0.2% ~ 4%, and O
2: Ar ratio is adjusted to 1:2 ~ 1:3 and blows.
Reductive agent in initial refining process selects aluminium block or ferrosilicon, and add required molten metal gross weight is 0.1% ~ 2%.
Claims (3)
1. a method for AOD furnace secondary refining super clean molten metal, is characterized in that, comprise the steps:
1), carry out load melting at intermediate frequency furnace, in intermediate frequency furnace, adjust the Chemical Composition of furnace charge, temperature and required mixed carbon comtent, as following table:
, after fusing, obtain the molten metal of required refining;
2), then the molten metal of required refining entered in AOD furnace carry out initial refining:
First carry out thermometric, when temperature is less than 1600 DEG C, add required molten metal gross weight be 0.1% ~ 2% aluminium block carry out warming temperature, the first step, gas blows, and uses O
2: Ar is that 5:1 ~ 4:1 blows; When temperature reaches 1690 ~ 1710 DEG C, need O
2: Ar is adjusted to 2:1 ~ 1:1; When temperature reaches 1710 ~ 1720 DEG C, adding required molten metal gross weight is the lime of 0.2% ~ 4%, and O
2: Ar ratio is adjusted to 1:2 ~ 1:3 and blows;
Second step, when after blowing certain hour, according to fire door flame conditions, estimate carbon content, if flame is very low and have a large amount of black smoke, sampling carries out chemical analysis, and analytical results carbon content is less than 0.02%, can enter reduction period;
3rd step, before starting reduction, carry out thermometric, temperature, at 1630 ~ 1650 DEG C, can enter reduction period; Temperature is greater than 1650 DEG C, argon gas stirring need be carried out, the amount of the reductive agent added needed for reduction need calculate according to oxygen consuming amount, mixed carbon comtent and Metal Weight etc., recovery time is no less than 5min, after reduction terminates, carry out sampling analysis, analytical results reaches composition requirement, and temperature is at 1600 ~ 1650 DEG C, and initial refining terminates;
3), except slag operation: after initial refining terminates, that can carry out AOD furnace removes slag operation, directly carries out grate deslagging, when the amount removing 2/5 ~ 3/5 of slag, stops deslagging;
4), add new slag making materials and carry out joining carbon operation: first in stove, add lime, add-on with in step 3 except the quantity of slag is identical, then add carburelant, the carburelant added need be increased to 0.5 ~ 0.6% by carbon content and allocate into;
5), secondary refining process; After lime and carburelant are allocated into, can carry out secondary refining, secondary refining process is identical with initial refining;
6), after secondary refining terminates, when final composition and temperature reach requirement, can tap and carry out cast product.
2. the method for AOD furnace secondary refining super clean molten metal according to claim 1, is characterized in that, in initial refining, the first step, also can adopt following steps to carry out gas and blow, use O
2: N
2for 5:1 ~ 4:1 blows; When temperature reaches 1690 ~ 1710 DEG C, need O
2: N
2be adjusted to 2:1 ~ 1:1; When temperature reaches 1710 ~ 1720 DEG C, adding required molten metal gross weight is the lime of 0.2% ~ 4%, and O
2: Ar ratio is adjusted to 1:2 ~ 1:3 and blows.
3. the method for AOD furnace secondary refining super clean molten metal according to claim 1, it is characterized in that, the reductive agent in initial refining process selects aluminium block or ferrosilicon, and add required molten metal gross weight is 0.1% ~ 2%.
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Cited By (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN107043843A (en) * | 2017-05-24 | 2017-08-15 | 孙雪梅 | A kind of intermediate frequency argon oxygen refinery practice |
| CN108193019A (en) * | 2017-12-27 | 2018-06-22 | 安徽应流铸业有限公司 | A kind of hot investment casting smelting and pouring technique |
| CN110016535A (en) * | 2019-03-01 | 2019-07-16 | 鞍钢股份有限公司 | A method of it improves and nitrogen content in stability contorting stainless steel |
| CN114317892A (en) * | 2021-12-24 | 2022-04-12 | 湖州盛特隆金属制品有限公司 | AOD secondary blowing-back decarburization method for ultra-low carbon steel smelting |
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| US20040173055A1 (en) * | 2002-12-24 | 2004-09-09 | Song Hyo Seok | Method for refining stainless steel with high purity |
| CN102560001A (en) * | 2011-12-09 | 2012-07-11 | 浙江中达特钢股份有限公司 | Desulfurization and oxygen process for smelting stainless steel by small-capacity AOD furnace double-slag method |
| CN102943148A (en) * | 2012-11-30 | 2013-02-27 | 张家港浦项不锈钢有限公司 | Method for producing high-purity stainless steel |
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2014
- 2014-10-31 CN CN201410600635.5A patent/CN104357617A/en active Pending
Patent Citations (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US20040173055A1 (en) * | 2002-12-24 | 2004-09-09 | Song Hyo Seok | Method for refining stainless steel with high purity |
| CN102560001A (en) * | 2011-12-09 | 2012-07-11 | 浙江中达特钢股份有限公司 | Desulfurization and oxygen process for smelting stainless steel by small-capacity AOD furnace double-slag method |
| CN102943148A (en) * | 2012-11-30 | 2013-02-27 | 张家港浦项不锈钢有限公司 | Method for producing high-purity stainless steel |
Non-Patent Citations (1)
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| 王新华: "《钢铁冶金-炼钢学》", 30 June 2007, 高等教育出版社 * |
Cited By (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN107043843A (en) * | 2017-05-24 | 2017-08-15 | 孙雪梅 | A kind of intermediate frequency argon oxygen refinery practice |
| CN108193019A (en) * | 2017-12-27 | 2018-06-22 | 安徽应流铸业有限公司 | A kind of hot investment casting smelting and pouring technique |
| CN110016535A (en) * | 2019-03-01 | 2019-07-16 | 鞍钢股份有限公司 | A method of it improves and nitrogen content in stability contorting stainless steel |
| CN114317892A (en) * | 2021-12-24 | 2022-04-12 | 湖州盛特隆金属制品有限公司 | AOD secondary blowing-back decarburization method for ultra-low carbon steel smelting |
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Application publication date: 20150218 |