CA2014265A1 - Process to produce alloy steel grades - Google Patents
Process to produce alloy steel gradesInfo
- Publication number
- CA2014265A1 CA2014265A1 CA002014265A CA2014265A CA2014265A1 CA 2014265 A1 CA2014265 A1 CA 2014265A1 CA 002014265 A CA002014265 A CA 002014265A CA 2014265 A CA2014265 A CA 2014265A CA 2014265 A1 CA2014265 A1 CA 2014265A1
- Authority
- CA
- Canada
- Prior art keywords
- melt
- process according
- gas
- carburization
- steel
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Abandoned
Links
Classifications
-
- C—CHEMISTRY; METALLURGY
- C21—METALLURGY OF IRON
- C21C—PROCESSING OF PIG-IRON, e.g. REFINING, MANUFACTURE OF WROUGHT-IRON OR STEEL; TREATMENT IN MOLTEN STATE OF FERROUS ALLOYS
- C21C5/00—Manufacture of carbon-steel, e.g. plain mild steel, medium carbon steel or cast steel or stainless steel
- C21C5/28—Manufacture of steel in the converter
- C21C5/30—Regulating or controlling the blowing
- C21C5/35—Blowing from above and through the bath
-
- C—CHEMISTRY; METALLURGY
- C21—METALLURGY OF IRON
- C21C—PROCESSING OF PIG-IRON, e.g. REFINING, MANUFACTURE OF WROUGHT-IRON OR STEEL; TREATMENT IN MOLTEN STATE OF FERROUS ALLOYS
- C21C7/00—Treating molten ferrous alloys, e.g. steel, not covered by groups C21C1/00 - C21C5/00
- C21C7/04—Removing impurities by adding a treating agent
- C21C7/068—Decarburising
- C21C7/0685—Decarburising of stainless steel
-
- C—CHEMISTRY; METALLURGY
- C21—METALLURGY OF IRON
- C21C—PROCESSING OF PIG-IRON, e.g. REFINING, MANUFACTURE OF WROUGHT-IRON OR STEEL; TREATMENT IN MOLTEN STATE OF FERROUS ALLOYS
- C21C7/00—Treating molten ferrous alloys, e.g. steel, not covered by groups C21C1/00 - C21C5/00
- C21C7/04—Removing impurities by adding a treating agent
- C21C7/072—Treatment with gases
Landscapes
- Chemical & Material Sciences (AREA)
- Engineering & Computer Science (AREA)
- Materials Engineering (AREA)
- Metallurgy (AREA)
- Organic Chemistry (AREA)
- Manufacturing & Machinery (AREA)
- Carbon Steel Or Casting Steel Manufacturing (AREA)
- Treatment Of Steel In Its Molten State (AREA)
Abstract
PROCESS FOR THE PRODUCTION OF ALLOY STEEL GRADES
Abstract of Disclosure In secondary steel refining, in addition to the process gas oxygen, the gases nitrogen and argon are employed as treatment gases in the bottom blowing converter. Oxygen and argon can be partially replaced by inexpensive CO2. The invention provides a process which makes it possible to completely replace nitrogen and argon by CO2.
Abstract of Disclosure In secondary steel refining, in addition to the process gas oxygen, the gases nitrogen and argon are employed as treatment gases in the bottom blowing converter. Oxygen and argon can be partially replaced by inexpensive CO2. The invention provides a process which makes it possible to completely replace nitrogen and argon by CO2.
Description
2~r~2t~
Bac~ground of Invention The aftertreatment of alloy steel grades in bottomblowing converters is carried out with oxygen as the process gas, and with nitrogen and argon as the treatment gas~ Such secondary steel-refining processes are known by the abbreviations MRP (Metal Refining Process), AOD (Argon-Oxygen Decarburization), UBD (Under Bottom Blowing Decarburization) and ASM (Argon Secondary Metallurgy). They serve to refine low-alloy up to high-alloy steel grades in converter ~ypes of the same name having bottom-bath nozzles, whereby the steel grades are smelted in an arc furnace.
Non-alloy types of steel are not usually produced in such convert-ers. However, in order to achieve high quality, there are manu-facturers who, despite higher costs, refine non-alloy steel types in such converters even though refining in an arc furnace would be less expensive.
In this context, it is known from West German patent no. DE-PS 2,430,975 to partially replace the nitrogen and the argon by mixing them with CO2, West German patent no. DE-PS
934,772 shows a process for the production of non-alloy steel in a Bessemer-Thomas converter, which is low in toxic gases. In this process, CO2 is admitted into the bath either as a gas or by adding limestone alone or else mixed with oxygen.
Summary of the Invention It is common practice in secondary steel refining to first smelt the steel melt in a smelting furnace and then to transfer it to a fresh tank, in other words, a converter. The melt is treated in this converter in that the process and treatment gases are blown into the melt through the bottom of the converter.
For this purpose, metallic jacket gas nozzles are usually employed, with which the process gas is admitted through the middle nozzle, s and the treatment gases are admitted through the ring nozzle.
The treatment gases admitted through the ring nozzle are inert gases and they serve primarily to cool the metallic nozzles during the blowing process and to blend the melt. In this case, the inert gases are Ar and N2. By partially replacing these inert gases with C02, it is possible to reduce the specific gas costs.
Treatment of the melt in the converter is carried out in three process phases, namely, decarburizing, heating and mixing.
Desulfurizing and alloying are done concurrently with the heating step. These three phases are followed by sampling, temperature measurement and the addition of metallic and non-metallic solids, and they are carried out at different times.
The Drawin~s Figures 1-2 schematically show the process se~uence for treatment with N2 and Ar for the alloy grade and steel grade 42 CrMo 4, respectively, in accordance with this invention.
Detailed Description Figure 1 schematically shows a process sequence for treatment with the inert gases N2 and Ar for the alloy steel grade 42 CrMo 4. This sequence encompasses the decarburization by means of area A, heating by means of area B and mixing by means of area C. The measured points x for the temperature measurements and y for the sampling are given below the line which depicts the time course in minutes. Beneath that, the concentration curves of nitrogen and sulfur as well as carbon (N, S, C), and the temperature curve T are given. The use of the process gas oxygen and of the inert and treatment gases argon and nitrogen with respect to time and amounts are presented in the lower section of Figure 1.
2~ SS
The invention is based on the task of further reducing the gas-related costs within the scope of the secondary steel refining of alloy steel grades.
The process according to the invention stems from the surprising observation that the inert gases N2 and Ar can be replaced by C02 not only partially but completely, as a result of which the gas-related costs in secondary refining of steel can be drastically reduced. The volume of C02 admitted to the melt per time unit has to ~e such that sufficient mixing energy is applied to the melt. Then it is possible for all of the reac-tions to take place under conditions of equilibrium. In the process according to the invention, N2 and Ar can be completely replaced by C02 in all three process phases of the steel treatment, that is, during decarburization, heating and mixing.
The schematic sequence of the process according to the invention is shown in Figure 2, likewise for steel grade 42 CrMo 4 as in Figure 1. This clearly shows that essentially the same treatment result is obtained.
The C02 has differing effects in the individual process phases. This is described below.
When the converter is moved from the lying or horizontal position to the upright, blowing position at the beginning of the treatment process, the nozzles must receive inert gas in order to prevent the melt from penetrating them. For the sake of safety, it is only possible to admit C02 when the blowing position has been reached. Corresponding measures must be taken when the converter is tipped back to its lying position. The volumes of gas admitted to the nozzles during such changes of the position of the converter are called safety volumes.
2~3 4~,5 During decarbur~zation of the melt with oxygen, the C2 makes up the safety gas volume when the converter is placed in the blowing position. Subsequently, oxygen is blown in through the middle nozzle, and the ring nozzle is continuously cooled by means of C02. By admitting oxygen and C02 together, the partial pressure of the N2 and H2 is reduced during the decarburization phase. This leads to degasing of the melt. At the same time, a charging of the melt with the gases N2 and H2 is prevented, so that, for the most part, steel types low in N2 and ~2 are obtained.
With the reaction of C02 + C = 2 CO, C02 is additionally employed to decarburize the melt, that is to say, C02 is an addi-tional oxygen carrier in the decarburization phase.
During the subsequent heating phase, the use of C02 for desulfurization and alloying has a different effect. In this context, the melt is heated up to the desired temperature by means of the exothermic reaction of oxygen with the aluminum, silicon or aluminum-silicon mixture added. Up until now, in the treatment phase, only argon has been used as the treatment gas since nitrogen would dissolve in the melt, thus giving rise to an undesired charging of the melt with nitrogen.
When replacing argon with C02, the following reactions must be taken into consideration:
Bac~ground of Invention The aftertreatment of alloy steel grades in bottomblowing converters is carried out with oxygen as the process gas, and with nitrogen and argon as the treatment gas~ Such secondary steel-refining processes are known by the abbreviations MRP (Metal Refining Process), AOD (Argon-Oxygen Decarburization), UBD (Under Bottom Blowing Decarburization) and ASM (Argon Secondary Metallurgy). They serve to refine low-alloy up to high-alloy steel grades in converter ~ypes of the same name having bottom-bath nozzles, whereby the steel grades are smelted in an arc furnace.
Non-alloy types of steel are not usually produced in such convert-ers. However, in order to achieve high quality, there are manu-facturers who, despite higher costs, refine non-alloy steel types in such converters even though refining in an arc furnace would be less expensive.
In this context, it is known from West German patent no. DE-PS 2,430,975 to partially replace the nitrogen and the argon by mixing them with CO2, West German patent no. DE-PS
934,772 shows a process for the production of non-alloy steel in a Bessemer-Thomas converter, which is low in toxic gases. In this process, CO2 is admitted into the bath either as a gas or by adding limestone alone or else mixed with oxygen.
Summary of the Invention It is common practice in secondary steel refining to first smelt the steel melt in a smelting furnace and then to transfer it to a fresh tank, in other words, a converter. The melt is treated in this converter in that the process and treatment gases are blown into the melt through the bottom of the converter.
For this purpose, metallic jacket gas nozzles are usually employed, with which the process gas is admitted through the middle nozzle, s and the treatment gases are admitted through the ring nozzle.
The treatment gases admitted through the ring nozzle are inert gases and they serve primarily to cool the metallic nozzles during the blowing process and to blend the melt. In this case, the inert gases are Ar and N2. By partially replacing these inert gases with C02, it is possible to reduce the specific gas costs.
Treatment of the melt in the converter is carried out in three process phases, namely, decarburizing, heating and mixing.
Desulfurizing and alloying are done concurrently with the heating step. These three phases are followed by sampling, temperature measurement and the addition of metallic and non-metallic solids, and they are carried out at different times.
The Drawin~s Figures 1-2 schematically show the process se~uence for treatment with N2 and Ar for the alloy grade and steel grade 42 CrMo 4, respectively, in accordance with this invention.
Detailed Description Figure 1 schematically shows a process sequence for treatment with the inert gases N2 and Ar for the alloy steel grade 42 CrMo 4. This sequence encompasses the decarburization by means of area A, heating by means of area B and mixing by means of area C. The measured points x for the temperature measurements and y for the sampling are given below the line which depicts the time course in minutes. Beneath that, the concentration curves of nitrogen and sulfur as well as carbon (N, S, C), and the temperature curve T are given. The use of the process gas oxygen and of the inert and treatment gases argon and nitrogen with respect to time and amounts are presented in the lower section of Figure 1.
2~ SS
The invention is based on the task of further reducing the gas-related costs within the scope of the secondary steel refining of alloy steel grades.
The process according to the invention stems from the surprising observation that the inert gases N2 and Ar can be replaced by C02 not only partially but completely, as a result of which the gas-related costs in secondary refining of steel can be drastically reduced. The volume of C02 admitted to the melt per time unit has to ~e such that sufficient mixing energy is applied to the melt. Then it is possible for all of the reac-tions to take place under conditions of equilibrium. In the process according to the invention, N2 and Ar can be completely replaced by C02 in all three process phases of the steel treatment, that is, during decarburization, heating and mixing.
The schematic sequence of the process according to the invention is shown in Figure 2, likewise for steel grade 42 CrMo 4 as in Figure 1. This clearly shows that essentially the same treatment result is obtained.
The C02 has differing effects in the individual process phases. This is described below.
When the converter is moved from the lying or horizontal position to the upright, blowing position at the beginning of the treatment process, the nozzles must receive inert gas in order to prevent the melt from penetrating them. For the sake of safety, it is only possible to admit C02 when the blowing position has been reached. Corresponding measures must be taken when the converter is tipped back to its lying position. The volumes of gas admitted to the nozzles during such changes of the position of the converter are called safety volumes.
2~3 4~,5 During decarbur~zation of the melt with oxygen, the C2 makes up the safety gas volume when the converter is placed in the blowing position. Subsequently, oxygen is blown in through the middle nozzle, and the ring nozzle is continuously cooled by means of C02. By admitting oxygen and C02 together, the partial pressure of the N2 and H2 is reduced during the decarburization phase. This leads to degasing of the melt. At the same time, a charging of the melt with the gases N2 and H2 is prevented, so that, for the most part, steel types low in N2 and ~2 are obtained.
With the reaction of C02 + C = 2 CO, C02 is additionally employed to decarburize the melt, that is to say, C02 is an addi-tional oxygen carrier in the decarburization phase.
During the subsequent heating phase, the use of C02 for desulfurization and alloying has a different effect. In this context, the melt is heated up to the desired temperature by means of the exothermic reaction of oxygen with the aluminum, silicon or aluminum-silicon mixture added. Up until now, in the treatment phase, only argon has been used as the treatment gas since nitrogen would dissolve in the melt, thus giving rise to an undesired charging of the melt with nitrogen.
When replacing argon with C02, the following reactions must be taken into consideration:
3 C2 + 4 Al = 2 A1203 + 3 C (I) 3C02 + 2 Al = A1203 + 3CO (2) or C02~Si=SiO2+C (3) C2 ~ Si = SiO + CO (4) Both reactions take place during the heating phase, as a function of the concentration of aluminum in the melt.
2~t~, ~
Analogous to equation (1) or (3), the melt is carburized during the heating phase, the C02 is completely reduced by the aluminum and a carbon atom is released. At the same time, reaction ~2) or (4), that is to say, the partial reduction of C02 takes place, and these reactions do not result in the carburization of the melt. For each melt, it is possible to calculate the carburization of the melt in advance during the heating phase and then to take this into consideration by means of more thorough decarburization during the decarburization step.
As can be seen in Figures 1 and 2, a carburization of the melt takes place during the heating phase. This carburiza-tion can be calculated on the basis of the following calculation:
536x Qx Cf dC =
dC - carburization rate in ppm C/min Q - flow volume of C02-inert gas m3/min Cf - carburization factor 0.3 to 0.5 G - melt weight in tons In a 10-ton converter with the carburization factor Cf ~ 0.5, at an inert gas volume of 2 m3, the carburization rate is dC = 536 x 2 x 0.5/10 = 53.6 ppm C/min.
2~3 ~
Tables 1 and 2 below present the effect of the use of C2 according to the invention in the decarburization and heating phase for several steel grades. Table 1, which shows the degasing of the melt measured according to the content of nitrogen, also shows the operational results of the commonly used process with nitrogen and argon, as well as the results of the process according to the invention.
Table 1: Degasing of the melt, measured aocording to the nitrogen content gas oonsumpdon gas content melt 2 N2 Ar C02 nitroge~
steelgrade m3/t m31tm31t m31t start end 20 Mn 5 12.9 3.4 5.9 - 99 43 17 CrMo 55 12,1 3.7 6.0 - 122 75 42 CrMo 4 11.0 3.5 2.4 - 125 107 17 CrMoV S. l l 16.6 2.4 8.0 - 105 77 10 MnMo 74 16.1 - - 9.8 96 69 17 CrMo 5.11 17.1 - - 10.9 110 76 42 CrMo 4 12.6 - - 7.9 104 62 34 NiCrMo 14 18.6 - - 11.7 106 73 Table 2: Decarburization of the melt during the heating step Steel grade carbon content gas consumption heating start end 2 C2 with Al % % m3/min m3/t m3/mlnm3/n kg/t 10 MnMo 74 0.04 0.08 9.0 6.0 2.4 3.0 10 17 CrMoV S.ll 0.12 0.16 3.0 9.0 2.3 3.0 10 42 CrMo 4 0.27 0.30 9.0 5.6 2.4 2.7 9 35 CrNiMo 14 0.27 0.32 9.0 6.6 2.4 3.5 11 A crucial factor for the effectiveness of the process according to the invention, particularly during the heating phase, is the purity of the C02. After all, the reduction of the melt by means of aluminum brings about a higher degree of solubility 2~4~
of nitrogen in the steel. For this reason, the nitrogen and hydrogen impurities in the C02 are absorbed by the melt and can no longer be removed. In order to prevent this" for the metallurgi-cal treatment of steel according to the invention, technically pure C02 with a maximum of 500 vpm of N2 and 50 vpm of H20 must be used. This degree of purity is preferably obtained by evaporat-ing the C02 from the liquid phase.
In the mixed phase, according to the invention, C02 also completely replaced the argon. According to the state of the art, shortly before tapping, the melt is mixed with argon for 1 to 2 minutes so that temperature equilibrium can be achieved.
When argon is replaced by C02, an oxidation of the melt takes places directly before tapping after the reactions mentioned during the description of the heating phase. By means of the stoichiometric addition of approximately 1.0 kg of Al/M3 of C02, this change of the analysis is compensated for. The simultaneous carburization can be ignored, since it only amounts to 50 ppm and thus falls within the analysis tolerance limits.
2~t~, ~
Analogous to equation (1) or (3), the melt is carburized during the heating phase, the C02 is completely reduced by the aluminum and a carbon atom is released. At the same time, reaction ~2) or (4), that is to say, the partial reduction of C02 takes place, and these reactions do not result in the carburization of the melt. For each melt, it is possible to calculate the carburization of the melt in advance during the heating phase and then to take this into consideration by means of more thorough decarburization during the decarburization step.
As can be seen in Figures 1 and 2, a carburization of the melt takes place during the heating phase. This carburiza-tion can be calculated on the basis of the following calculation:
536x Qx Cf dC =
dC - carburization rate in ppm C/min Q - flow volume of C02-inert gas m3/min Cf - carburization factor 0.3 to 0.5 G - melt weight in tons In a 10-ton converter with the carburization factor Cf ~ 0.5, at an inert gas volume of 2 m3, the carburization rate is dC = 536 x 2 x 0.5/10 = 53.6 ppm C/min.
2~3 ~
Tables 1 and 2 below present the effect of the use of C2 according to the invention in the decarburization and heating phase for several steel grades. Table 1, which shows the degasing of the melt measured according to the content of nitrogen, also shows the operational results of the commonly used process with nitrogen and argon, as well as the results of the process according to the invention.
Table 1: Degasing of the melt, measured aocording to the nitrogen content gas oonsumpdon gas content melt 2 N2 Ar C02 nitroge~
steelgrade m3/t m31tm31t m31t start end 20 Mn 5 12.9 3.4 5.9 - 99 43 17 CrMo 55 12,1 3.7 6.0 - 122 75 42 CrMo 4 11.0 3.5 2.4 - 125 107 17 CrMoV S. l l 16.6 2.4 8.0 - 105 77 10 MnMo 74 16.1 - - 9.8 96 69 17 CrMo 5.11 17.1 - - 10.9 110 76 42 CrMo 4 12.6 - - 7.9 104 62 34 NiCrMo 14 18.6 - - 11.7 106 73 Table 2: Decarburization of the melt during the heating step Steel grade carbon content gas consumption heating start end 2 C2 with Al % % m3/min m3/t m3/mlnm3/n kg/t 10 MnMo 74 0.04 0.08 9.0 6.0 2.4 3.0 10 17 CrMoV S.ll 0.12 0.16 3.0 9.0 2.3 3.0 10 42 CrMo 4 0.27 0.30 9.0 5.6 2.4 2.7 9 35 CrNiMo 14 0.27 0.32 9.0 6.6 2.4 3.5 11 A crucial factor for the effectiveness of the process according to the invention, particularly during the heating phase, is the purity of the C02. After all, the reduction of the melt by means of aluminum brings about a higher degree of solubility 2~4~
of nitrogen in the steel. For this reason, the nitrogen and hydrogen impurities in the C02 are absorbed by the melt and can no longer be removed. In order to prevent this" for the metallurgi-cal treatment of steel according to the invention, technically pure C02 with a maximum of 500 vpm of N2 and 50 vpm of H20 must be used. This degree of purity is preferably obtained by evaporat-ing the C02 from the liquid phase.
In the mixed phase, according to the invention, C02 also completely replaced the argon. According to the state of the art, shortly before tapping, the melt is mixed with argon for 1 to 2 minutes so that temperature equilibrium can be achieved.
When argon is replaced by C02, an oxidation of the melt takes places directly before tapping after the reactions mentioned during the description of the heating phase. By means of the stoichiometric addition of approximately 1.0 kg of Al/M3 of C02, this change of the analysis is compensated for. The simultaneous carburization can be ignored, since it only amounts to 50 ppm and thus falls within the analysis tolerance limits.
Claims (8)
1. In a process for the production of non-alloy and alloy steel grades with up to 10% of alloy elements in a secondary steel-refining converter, in which, during the process sequence consisting of the decarburization, heating and mixing phases, oxygen as the process gas and/or a treatment gas is intermittently blown in by means of nozzles located on the bottom of the converter, the improvement being in that the treatment gas is gaseous CO2.
2. Process according to Claim 1, in which the oxygen and the treatment gas are blown in through metallic jacket gas nozzles, characterized in that, in the intervals with only CO2 feed, the CO2 is admitted through the ring nozzle as well as through the middle nozzle.
3. Process according to Claim 1 or 2, characterized in that the CO2 contains at the maximum 500 vpm of N2 and at the maximum 50 vpm of H2O.
4. Process according to one of Claims 1 through 3, characterized in that the gaseous CO2 is obtained by means of evaporation of the liquid phase.
5. Process according to one of the Claims l through 4, characterized in that 0.2 to 1.0 m3/min of CO2 are blown in per ton of steel.
6. Process according to one of Claims l through 5, characterized in that a carburization of the melt is brought about during the heating phase by the necessary addition of Al or Si.
7. Process according to Claim 6, characterized in that the carburization rate dC is determined according to the formula wherein dC is the carburization rate in ppm C/min Q is the flow volume of CO2-inert gas m3/min of is the carburization factor 0.3 to 0.5, and G is the weight of the melt in tons.
8. Process according to one of the Claims 1 through 7, characterized in that a change of the analysis as a result of the reoxidation of the melt during the mixed phase with pure CO2 is prevented by the stoichiometric addition of 1.0 kg of aluminum/m3 of CO2.
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| DE3912061A DE3912061A1 (en) | 1989-04-13 | 1989-04-13 | METHOD FOR PRODUCING ALLOY STEEL BRANDS |
| DEP3912061.9 | 1989-04-13 |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA2014265A1 true CA2014265A1 (en) | 1990-10-13 |
Family
ID=6378545
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA002014265A Abandoned CA2014265A1 (en) | 1989-04-13 | 1990-04-10 | Process to produce alloy steel grades |
Country Status (5)
| Country | Link |
|---|---|
| EP (1) | EP0392239A1 (en) |
| JP (1) | JPH02294421A (en) |
| CA (1) | CA2014265A1 (en) |
| DE (1) | DE3912061A1 (en) |
| ZA (1) | ZA902827B (en) |
Families Citing this family (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| DE19608530C2 (en) * | 1996-02-09 | 1999-01-14 | Eisenbau Essen Gmbh | Use of pure CO¶2¶ gas or a gas essentially containing CO¶2¶ as a carrier gas in the treatment of steel in an electric arc furnace |
| US9045805B2 (en) | 2013-03-12 | 2015-06-02 | Ati Properties, Inc. | Alloy refining methods |
| DE102014011231A1 (en) * | 2014-07-23 | 2016-01-28 | Sms Group Gmbh | Process for Nickel Pig Iron (NPI) decarburization in the AOD converter |
Family Cites Families (6)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| GB809407A (en) * | 1956-10-09 | 1959-02-25 | Union Carbide Corp | Process for alloying steel |
| US3861888A (en) * | 1973-06-28 | 1975-01-21 | Union Carbide Corp | Use of CO{HD 2 {B in argon-oxygen refining of molten metal |
| FR2394610A1 (en) * | 1977-06-13 | 1979-01-12 | Siderurgie Fse Inst Rech | Cooling converter tuyeres or lances - using liq. carbon di:oxide fed from reservoir by volumetric pump |
| DE2820555A1 (en) * | 1978-05-11 | 1979-11-15 | Basf Ag | PROCESSES FOR THE TREATMENT OF PIG IRON AND STEEL MELT RESPECTIVELY. ALLOYS |
| ATE17874T1 (en) * | 1979-06-29 | 1986-02-15 | William H Moore | METHOD OF RETURNING SCRAP STEEL. |
| HU196632B (en) * | 1984-08-01 | 1988-12-28 | Vasipari Kutato Fejleszto | Process for producing high-purity steels |
-
1989
- 1989-04-13 DE DE3912061A patent/DE3912061A1/en not_active Withdrawn
-
1990
- 1990-03-24 EP EP90105648A patent/EP0392239A1/en not_active Withdrawn
- 1990-04-10 CA CA002014265A patent/CA2014265A1/en not_active Abandoned
- 1990-04-12 ZA ZA902827A patent/ZA902827B/en unknown
- 1990-04-13 JP JP2096632A patent/JPH02294421A/en active Pending
Also Published As
| Publication number | Publication date |
|---|---|
| DE3912061A1 (en) | 1990-10-18 |
| EP0392239A1 (en) | 1990-10-17 |
| JPH02294421A (en) | 1990-12-05 |
| ZA902827B (en) | 1991-01-30 |
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