A method for smelting low-density steel containing rare earth Fe-Mn-Al-C system

Abstract

The invention relates to the field of low-density steel production, and discloses a smelting method for Fe-Mn-Al-C-based low-density steel containing rare earths. The method comprises the following steps: firstly, batching according to the composition of the Fe-Mn-Al-C-based low-density steel, firstly adding Fe into a medium-frequency furnace for heating; when the temperature of the molten steel is 1450-1500°C, adding a slag-forming agent, and the slag-forming agent is melted and covers the molten steel; when the molten steel is melted, C, Mn and Al are added; the molten steel is heated to 1600-1620°C, kept warm for 0.5 hours, and cooled to 50°C above the liquidus line of the low-density molten steel; and finally heating the molten steel to 1600-1620°C. When the temperature is between ℃ and 100℃, after measuring the temperature and composition, the steel is taken out of the furnace and poured into an ingot mold; the Fe‑Mn‑Al‑C series low-density steel is smelted; the present application adopts a CaO‑Al2O3‑SiO2‑RE2O3 slag-forming agent to smelt the Fe‑Mn‑Al‑C series low-density steel in an electric furnace. The CaO‑Al2O3‑SiO2‑RE2O3 slag-forming agent can reduce the content of oxygen and sulfur in the molten steel, reduce the influence of alumina inclusions in the steel on the performance of the low-density steel, and reduce the influence of MnS inclusions in the molten steel, and has the characteristics of low cost and simple operation.

Description

Technical Field

[0001] The invention relates to the field of low-density steel production, and in particular to a smelting method for rare earth Fe-Mn-Al-C series low-density steel. Background Art

[0002] The yield strength of Fe-Mn-Al-C low-density steel is generally 0.4~1.0GPa, the tensile strength is 0.6~2.0GPa, the elongation after fracture is 30~100%, and it has excellent mechanical properties. It has good wear resistance, corrosion resistance, oxidation resistance, impact resistance and aging hardening. It is an ideal material for the new generation of advanced high-strength steel for automobiles. It can achieve vehicle lightweighting and meet the technical requirements of vehicle energy conservation and emission reduction, economy and environmental protection, and improving fuel efficiency. It has great application prospects in vehicle structure weight reduction and complex working conditions.

[0003] However, Fe-Mn-Al-C low-density steel contains more Al elements, and it is easy to form Al2O3, AlN, MnS, -Al2O3 and composite inclusions composed of them during the smelting process, such as: MnO-Al2O3-AlN, MnO-Al2O3-MnS, MnO-Al2O3-AlN-MnS composite inclusions, which reduce the performance of Fe-Mn-Al-C low-density steel. In particular, AlN and MnS inclusions are the main reasons for the deterioration of plasticity of low-density steel. How to reduce the influence of AlN and MnS inclusions on the performance of low-density steel needs to be solved urgently. Therefore, in the existing Fe-Mn-Al-C low-density steel smelting process, a trace amount of Ti is added to generate TiN to reduce the influence of AlN on the steel performance; a vacuum degassing method is also used in the smelting process of Fe-Mn-Al-C low-density steel to reduce the O and N content in the steel, reduce the generation of Al2O3 and AlN inclusions, and prevent the performance of the steel from decreasing; and smelting is also carried out in a vacuum furnace to prevent air from contacting the molten steel, causing the Al in the steel to generate Al2O3 or AlN to pollute the molten steel. Summary of the invention

[0004] The object of the present invention is to provide a smelting method of rare earth Fe-Mn-Al-C series low-density steel to solve the problem of how to reduce the influence of AlN and MnS inclusions on the performance of low-density steel proposed in the above background technology.

[0005] The technical solution adopted by the present invention is as follows: A smelting method of a rare earth Fe-Mn-Al-C series low-density steel comprises the following steps:

[0006] Step 1: First, prepare the materials according to the composition of Fe-Mn-Al-C low-density steel, and add Fe into the medium frequency furnace for heating;

[0007] Step 2: When the temperature of the molten steel is 1450℃~1500℃, add slag-forming agent, the slag-forming agent is CaO-Al2O3-SiO2-RE2O3;

[0008] Step 3: When the molten steel is clear, add C, Mn and Al;

[0009] Step 4: The molten steel is heated to 1600°C~1620°C, kept warm for 0.5 hours, cooled to the liquidus of the low-density molten steel at 50°C~100°C, and after measuring the temperature and composition, it is taken out of the furnace and poured into an ingot mold; Fe-Mn-Al-C low-density steel is obtained by smelting.

[0010] Furthermore, Fe-Mn-Al-C (Al=1%~12%, Mn<2.0%, C=0.1%-2.5%, balance Fe) is smelted to obtain low-manganese Fe-Mn-Al-C series low-density steel.

[0011] Furthermore, Fe-Mn-Al-C (Al=1%~12%, Mn=2.0%~10%, C=0.1%-2.5%, and the balance is Fe) is smelted to obtain medium manganese Fe-Mn-Al-C series low-density steel.

[0012] Furthermore, Fe-Mn-Al-C (Al=1%~12%, Mn>10.0%, C=0.1%-2.5%, balance Fe) is smelted to obtain high manganese Fe-Mn-Al-C low-density steel.

[0013] Furthermore, the composition range of the slag-forming agent is CaO (20%~60%)-Al2O3 (20%~40%)-SiO2 (5%~30%)-RE2O3 (5%~30%).

[0014] The invention has the beneficial effects that: during the smelting process of Fe-Mn-Al-C series low-density steel, a CaO-Al2O3-SiO2-RE2O3 slag-forming agent is added, the slag-forming agent is melted into a liquid state at a high temperature of the molten steel, and the surface of the molten steel is covered, so that the slag layer isolates air and the molten steel, reduces the content of oxygen and sulfur in the molten steel, avoids oxidation or nitridation of aluminum in the molten steel to generate Al2O3 or AlN inclusions, makes MgO from the furnace lining in the molten steel react with Al2O3 to generate MgO·Al2O3, purifies the molten steel, and a trace amount of rare earth oxide enters the steel to modify the distribution and morphology of MnS inclusions in the steel, reduces the influence of MnS on the steel performance, and has the characteristics of low cost and simple operation. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] Figure 1 It is a schematic diagram of the flow chart structure of the present invention.

[0016] Figure 2 Schematic diagram of the structure after the slag-forming agent is melted.

[0017] Figure 3 This is an electron microscope image of low-manganese Fe-Mn-Al-C low-density steel.

[0018] Figure 4 This is an electron microscope image of medium manganese Fe-Mn-Al-C low-density steel.

[0019] Figure 5 This is an electron microscope image of high manganese Fe-Mn-Al-C low-density steel.

[0020] In the figure: 1. Molten steel; 2. Slag-forming agent layer. Implementation

[0021] Embodiments of the present invention are described in detail below. The embodiments described below with reference to the accompanying drawings are exemplary and are only used to explain the present invention, and should not be construed as limiting the present invention. Example

[0022] A method for smelting rare earth Fe-Mn-Al-C low-density steel comprises the following steps:

[0023] Step 1: First, prepare the material according to the composition of low-manganese Fe-Mn-Al-C low-density steel, where Al=1%, Mn=0.1%, C=0.1%, and the balance is Fe. First, add Fe into the medium frequency furnace for heating;

[0024] Step 2: When the temperature of the molten steel is 1450℃~1500℃, add slag-forming agent, the slag-forming agent melts and covers the molten steel, and the composition of the slag-forming agent is: CaO50%-Al2O330%-SiO25%-RE2O35%;

[0025] Step 3: When the molten steel is clear, add C, Mn and Al, where Al=1%, Mn=0.1% and C=0.1%;

[0026] Step 4: The molten steel is heated to 1600°C~1620°C, kept warm for 0.5 hours, cooled to the liquidus line of low-density molten steel at 50°C~100°C, and after measuring the temperature and composition, it is taken out of the furnace and poured into an ingot mold; low-manganese Fe-Mn-Al-C low-density steel is obtained by smelting. Figure 3 Shown is an electron microscope image obtained using nitric acid + picric acid + alcohol as etching agents. Example

[0027] A method for smelting rare earth Fe-Mn-Al-C low-density steel comprises the following steps:

[0028] Step 1: First, prepare the material according to the composition of low-manganese Fe-Mn-Al-C low-density steel, in which Al=6.5%, Mn=1.0%, C=1.3%, and the balance is Fe, and first add Fe into the medium frequency furnace for heating;

[0029] Step 2: When the temperature of the molten steel is 1450℃~1500℃, add slag-forming agent, the slag-forming agent melts and covers the molten steel, and the composition of the slag-forming agent is: CaO55%-Al2O335%-SiO27.5%-RE2O37.5%;

[0030] Step 3: When the molten steel is clear, add C, Mn and Al, where Al=6%, Mn=1.0% and C=1.3%;

[0031] Step 4: The molten steel is heated to 1600°C~1620°C, kept warm for 0.5 hours, cooled to the liquidus of the low-density molten steel at 50°C~100°C, and after measuring the temperature and composition, it is taken out of the furnace and poured into an ingot mold; low-manganese Fe-Mn-Al-C low-density steel is obtained by smelting. Example

[0032] A method for smelting rare earth Fe-Mn-Al-C low-density steel comprises the following steps:

[0033] Step 1: First, prepare the material according to the composition of low-manganese Fe-Mn-Al-C low-density steel, in which Al=12%, Mn=2.0%, C=1.3%, and the balance is Fe, and first add Fe into the medium frequency furnace for heating;

[0034] Step 2: When the temperature of the molten steel is 1450℃~1500℃, add slag-forming agent, the slag-forming agent melts and covers the molten steel, and the composition of the slag-forming agent is: CaO60%-Al2O340%-SiO210%-RE2O310%;

[0035] Step 3: When the molten steel is clear, add C, Mn and Al, where Al=12%, Mn=2.0%, C=2.5%;

[0036] Step 4: The molten steel is heated to 1600°C~1620°C, kept warm for 0.5 hours, cooled to the liquidus of the low-density molten steel at 50°C~100°C, and after measuring the temperature and composition, it is taken out of the furnace and poured into an ingot mold; low-manganese Fe-Mn-Al-C low-density steel is obtained by smelting. Example

[0037] A method for smelting rare earth Fe-Mn-Al-C low-density steel comprises the following steps:

[0038] Step 1: First, prepare the material according to the composition of medium manganese Fe-Mn-Al-C low-density steel, in which Al=1%, Mn=2.0%, C=0.1%, and the balance is Fe, and first add Fe into the medium frequency furnace for heating;

[0039] Step 2: When the temperature of the molten steel is 1500℃~1550℃, add slag-forming agent, the slag-forming agent melts and covers the molten steel, and the composition of the slag-forming agent is: CaO20%-Al2O320%-SiO210%-RE2O320%;

[0040] Step 3: When the molten steel is clear, add C, Mn and Al, where Al = 1%, Mn = 2.0%, and C = 0.1%;

[0041] Step 4: The molten steel is heated to 1600°C~1620°C, kept warm for 0.5 hours, cooled to the liquidus line of low-density molten steel at 50°C~100°C, and after measuring the temperature and composition, it is taken out of the furnace and poured into an ingot mold; medium manganese Fe-Mn-Al-C low-density steel is obtained by smelting. Figure 4 Shown is an electron microscope image obtained using nitric acid + picric acid + alcohol as etching agents. Example

[0042] A method for smelting rare earth Fe-Mn-Al-C low-density steel comprises the following steps:

[0043] Step 1: First, prepare the material according to the composition of medium manganese Fe-Mn-Al-C low-density steel, in which Al=6.5%, Mn=6%, C=1.3%, and the balance is Fe. First, add Fe into the medium frequency furnace for heating;

[0044] Step 2: When the temperature of the molten steel is 1500℃~1550℃, add slag-forming agent, the slag-forming agent melts and covers the molten steel, and the composition of the slag-forming agent is: CaO25%-Al2O325%-SiO215%-RE2O325%;

[0045] Step 3: When the molten steel is clear, add C, Mn and Al, where Al=6.5%, Mn=6% and C=1.3%;

[0046] Step 4: The molten steel is heated to 1600°C~1620°C, kept warm for 0.5 hours, cooled to the liquidus of the low-density molten steel at 50°C~100°C, and after measuring the temperature and composition, it is taken out of the furnace and poured into an ingot mold; medium manganese Fe-Mn-Al-C low-density steel is obtained by smelting. Example

[0047] A method for smelting rare earth Fe-Mn-Al-C low-density steel comprises the following steps:

[0048] Step 1: First, prepare the material according to the composition of medium manganese Fe-Mn-Al-C low-density steel, in which Al=12%, Mn=10%, C=2.5%, and the balance is Fe. First, add Fe into the medium frequency furnace for heating;

[0049] Step 2: When the temperature of the molten steel is 1500℃~1550℃, add slag-forming agent, the slag-forming agent melts and covers the molten steel, and the composition of the slag-forming agent is: CaO30%-Al2O330%-SiO220%-RE2O330%;

[0050] Step 3: When the molten steel is clear, add C, Mn and Al, where Al=12%, Mn=10% and C=2.5%;

[0051] Step 4: The molten steel is heated to 1600°C~1620°C, kept warm for 0.5 hours, cooled to the liquidus of the low-density molten steel at 50°C~100°C, and after measuring the temperature and composition, it is taken out of the furnace and poured into an ingot mold; medium manganese Fe-Mn-Al-C low-density steel is obtained by smelting. Example

[0052] A method for smelting rare earth Fe-Mn-Al-C low-density steel comprises the following steps:

[0053] Step 1: First, prepare the material according to the composition of high manganese Fe-Mn-Al-C low-density steel, where Al=1%, Mn=10%, C=0.1%, and the balance is Fe. First, add Fe into the medium frequency furnace for heating;

[0054] Step 2: When the temperature of the molten steel is 1500℃~1550℃, add slag-forming agent, the slag-forming agent melts and covers the molten steel, and the composition of the slag-forming agent is: CaO40%-Al2O330%-SiO220%-RE2O310%;

[0055] Step 3: When the molten steel is clear, add C, Mn and Al, where Al = 1%, Mn = 10%, and C = 0.1%;

[0056] Step 4: The molten steel is heated to 1600℃~1620℃, kept warm for 0.5 hours, cooled to the liquidus line of low-density molten steel at 50℃~100℃, and after measuring the temperature and composition, it is poured into an ingot mold; smelting to obtain high-manganese Fe-Mn-Al-C low-density steel, such as Figure 5 Shown is an electron microscope image obtained using nitric acid + picric acid + alcohol as etching agents. Example

[0057] A method for smelting rare earth Fe-Mn-Al-C low-density steel comprises the following steps:

[0058] Step 1: First, prepare the material according to the composition of high manganese Fe-Mn-Al-C low-density steel, where Al=6.5%, Mn=15%, C=1.3%, and the balance is Fe. First, add Fe into the medium frequency furnace for heating;

[0059] Step 2: When the temperature of the molten steel is 1500℃~1550℃, add slag-forming agent, the slag-forming agent melts and covers the molten steel, and the composition of the slag-forming agent is: CaO50%-Al2O335%-SiO225%-RE2O315%;

[0060] Step 3: When the molten steel is clear, add C, Mn and Al, where Al=6.5%, Mn=15% and C=1.3%;

[0061] Step 4: The molten steel is heated to 1600°C~1620°C, kept warm for 0.5 hours, cooled to the liquidus of the low-density molten steel at 50°C~100°C, and after measuring the temperature and composition, it is taken out of the furnace and poured into an ingot mold; high manganese Fe-Mn-Al-C low-density steel is obtained by smelting. Example

[0062] A method for smelting rare earth Fe-Mn-Al-C low-density steel comprises the following steps:

[0063] Step 1: First, prepare the material according to the composition of high manganese Fe-Mn-Al-C low-density steel, in which Al=12%, Mn=20%, C=2.5%, and the balance is Fe. First, add Fe into the medium frequency furnace for heating;

[0064] Step 2: When the temperature of the molten steel is 1500℃~1550℃, add slag-forming agent, the slag-forming agent melts and covers the molten steel, and the composition of the slag-forming agent is: CaO60%-Al2O340%-SiO230%-RE2O320%;

[0065] Step 3: When the molten steel is clear, add C, Mn and Al, where Al=12%, Mn=20%, C=2.5%;

[0066] Step 4: The molten steel is heated to 1600°C~1620°C, kept warm for 0.5 hours, cooled to the liquidus of the low-density molten steel at 50°C~100°C, and after measuring the temperature and composition, it is taken out of the furnace and poured into an ingot mold; high manganese Fe-Mn-Al-C low-density steel is obtained by smelting.

[0067] The low manganese, medium manganese and high manganese Fe-Mn-Al-C low-density steels smelted in the above 9 embodiments have a measured composition standard deviation within ±0.1% (wt.%) of the required composition for smelting Fe-Mn-Al-C low-density steel.

[0068] As an optimization of the above embodiment, the Fe is industrial pure iron, C is electrode graphite carbon, Al is industrial pure aluminum ingot, and Mn is ferromanganese.

[0069] As an optimization of the above embodiment, in step 3, after the slag-forming agent covers the molten steel, Al and C are added, the molten steel is melted, and then Mn is added.

[0070] As an optimization of the above embodiment, the slag-forming agent used for smelting low-density steel can be pre-melted slag, or a mechanical mixture of oxides of different components of slag prepared according to the slag-forming agent composition, and the particle size of the oxides is 1~5mm, so that the oxides can be easily melted into liquid at high temperature of molten steel.

[0071] As an optimization of the above embodiment, RE2O3 in the slag-forming agent used for smelting low-density steel is mainly lanthanum-cerium rare earth oxide, which can be rare earth lanthanum oxide or rare earth cerium oxide; the mass percentage content of other oxides in the slag is 98% CaO, Al2O3 or SiO2.

[0072] As an optimization of the above embodiment, the medium frequency furnace used for smelting low-density steel is a non-vacuum induction furnace or a vacuum induction furnace.

[0073] As an optimization of the above embodiment, the pouring temperature of the molten steel is 1500~1580℃.

[0074] Although the present invention has been described in detail with reference to the aforementioned examples, it is still possible for those skilled in the art to make and modify the technical solutions described in the aforementioned embodiments, or to make equivalent substitutions for some of the technical features therein. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included in the protection scope of the present invention.

Claims

1. A method for smelting a rare earth Fe-Mn-Al-C low-density steel, characterized in that The steps include: Step 1: First, prepare the material according to the composition of Fe-Mn-Al-C low-density steel, Al 1%-12%, Mn <2.0%, C0.1%-2.5%, and the balance is Fe; first add Fe into the medium frequency furnace for heating; Step 2: When the temperature of the molten steel is 1450℃~1500℃, add slag-forming agent, the components of the slag-forming agent are: 50% ~ 60% CaO, 30% ~ 40% Al2O3, 5% ~ 10% SiO2, 5% ~ 10% RE2O3; The slag-forming agent melts and covers the molten steel; Step 3: When the molten steel is clear, add C, Mn and Al, wherein Al is 1% to 12%, Mn is less than 2.0%, and C is 0.1% to 2.5%; Step 4: The molten steel is heated to 1600°C-1620°C, kept warm for 0.5 hours, cooled to the liquidus of the low-density molten steel at 50°C-100°C, and after measuring the temperature and composition, it is taken out of the furnace and poured into an ingot mold; low-manganese Fe-Mn-Al-C low-density steel is obtained by smelting.

2. A method for smelting rare earth Fe-Mn-Al-C low-density steel, characterized in that The steps include: Step 1: First, prepare the materials according to the composition of Fe-Mn-Al-C low-density steel, Al 1%-12%, Mn 2.0%-10%, C 0.1%-2.5%, and the balance is Fe; first add Fe into the medium frequency furnace for heating; Step 2: When the temperature of the molten steel is 1450℃~1500℃, add slag-forming agent, the components of the slag-forming agent are: 20% ~ 30% CaO, 20% ~ 30% Al2O3, 10% ~ 20% SiO2, 20% ~ 30% RE2O3; The slag-forming agent melts and covers the molten steel; Step 3: When the molten steel is clear, add C, Mn and Al, wherein Al is 1% to 12%, Mn is 2.0% to 10%, and C is 0.1% to 2.5%; Step 4: The molten steel is heated to 1600°C-1620°C, kept warm for 0.5 hours, cooled to the liquidus of the low-density molten steel at 50°C-100°C, and after measuring the temperature and composition, it is taken out of the furnace and poured into an ingot mold; medium manganese Fe-Mn-Al-C low-density steel is obtained by smelting.

3. A method for smelting rare earth Fe-Mn-Al-C low-density steel, characterized in that The steps include: Step 1: First, prepare the material according to the composition of Fe-Mn-Al-C low-density steel, Al 1%-12%, Mn>10.0%, C0.1%-2.5%, and the balance is Fe; first add Fe into the medium frequency furnace for heating; Step 2: When the temperature of the molten steel is 1450℃~1500℃, add slag-forming agent, the components of the slag-forming agent are: 40% ~ 60% CaO, 30% ~ 40% Al2O3, 20% ~ 30% SiO2, 10% ~ 20% RE2O3; The slag-forming agent melts and covers the molten steel; Step 3: When the molten steel is clear, add C, Mn and Al, wherein Al is 1% to 12%, Mn>10.0%, and C is 0.1% to 2.5%; Step 4: The molten steel is heated to 1600°C-1620°C, kept warm for 0.5 hours, cooled to the liquidus of the low-density molten steel at 50°C-100°C, and after measuring the temperature and composition, it is taken out of the furnace and poured into an ingot mold; high manganese Fe-Mn-Al-C low-density steel is obtained by smelting.

4. A method for smelting a rare earth-containing Fe-Mn-Al-C low-density steel according to any one of claims 1 to 3, characterized in that In step 3, after the slag-forming agent covers the molten steel, Al and C are added, the molten steel is melted, and then Mn is added.

5. A method for smelting a rare earth-containing Fe-Mn-Al-C low-density steel according to any one of claims 1 to 3, characterized in that The slag-making agent used for smelting low-density steel is pre-melted slag or a mechanical mixture of oxides of different components of slag prepared according to the composition of the slag-making agent, and the particle size of the oxides is 1 to 5 mm.

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