CN110527925B - Cast steel added with rare earth elements - Google Patents

Cast steel added with rare earth elements Download PDF

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Publication number
CN110527925B
CN110527925B CN201910880787.8A CN201910880787A CN110527925B CN 110527925 B CN110527925 B CN 110527925B CN 201910880787 A CN201910880787 A CN 201910880787A CN 110527925 B CN110527925 B CN 110527925B
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cast steel
parts
rare earth
earth element
steel
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CN110527925A (en
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高文通
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Ningbo Yinzhou Fuchun Precision Casting Co ltd
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Ningbo Yinzhou Fuchun Precision Casting Co ltd
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    • 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
    • C21C5/52—Manufacture of steel in electric furnaces
    • 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
    • C21C7/06—Deoxidising, e.g. killing
    • 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
    • C—CHEMISTRY; METALLURGY
    • C21—METALLURGY OF IRON
    • C21D—MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUS METALS OR ALLOYS; MAKING METAL MALLEABLE, e.g. BY DECARBURISATION OR TEMPERING
    • C21D1/00—General methods or devices for heat treatment, e.g. annealing, hardening, quenching or tempering
    • C21D1/18—Hardening; Quenching with or without subsequent tempering
    • C—CHEMISTRY; METALLURGY
    • C21—METALLURGY OF IRON
    • C21D—MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUS METALS OR ALLOYS; MAKING METAL MALLEABLE, e.g. BY DECARBURISATION OR TEMPERING
    • C21D1/00—General methods or devices for heat treatment, e.g. annealing, hardening, quenching or tempering
    • C21D1/56—General methods or devices for heat treatment, e.g. annealing, hardening, quenching or tempering characterised by the quenching agents
    • C21D1/60—Aqueous agents
    • C—CHEMISTRY; METALLURGY
    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22C—ALLOYS
    • C22C33/00—Making ferrous alloys
    • C22C33/04—Making ferrous alloys by melting
    • C22C33/06—Making ferrous alloys by melting using master alloys
    • C—CHEMISTRY; METALLURGY
    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22C—ALLOYS
    • C22C38/00—Ferrous alloys, e.g. steel alloys
    • C22C38/002—Ferrous alloys, e.g. steel alloys containing In, Mg, or other elements not provided for in one single group C22C38/001 - C22C38/60
    • C—CHEMISTRY; METALLURGY
    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22C—ALLOYS
    • C22C38/00—Ferrous alloys, e.g. steel alloys
    • C22C38/005—Ferrous alloys, e.g. steel alloys containing rare earths, i.e. Sc, Y, Lanthanides
    • C—CHEMISTRY; METALLURGY
    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22C—ALLOYS
    • C22C38/00—Ferrous alloys, e.g. steel alloys
    • C22C38/02—Ferrous alloys, e.g. steel alloys containing silicon
    • C—CHEMISTRY; METALLURGY
    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22C—ALLOYS
    • C22C38/00—Ferrous alloys, e.g. steel alloys
    • C22C38/04—Ferrous alloys, e.g. steel alloys containing manganese
    • C—CHEMISTRY; METALLURGY
    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22C—ALLOYS
    • C22C38/00—Ferrous alloys, e.g. steel alloys
    • C22C38/06—Ferrous alloys, e.g. steel alloys containing aluminium
    • C—CHEMISTRY; METALLURGY
    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22C—ALLOYS
    • C22C38/00—Ferrous alloys, e.g. steel alloys
    • C22C38/18—Ferrous alloys, e.g. steel alloys containing chromium
    • C22C38/22—Ferrous alloys, e.g. steel alloys containing chromium with molybdenum or tungsten
    • C—CHEMISTRY; METALLURGY
    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22C—ALLOYS
    • C22C38/00—Ferrous alloys, e.g. steel alloys
    • C22C38/18—Ferrous alloys, e.g. steel alloys containing chromium
    • C22C38/24—Ferrous alloys, e.g. steel alloys containing chromium with vanadium
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02P—CLIMATE CHANGE MITIGATION TECHNOLOGIES IN THE PRODUCTION OR PROCESSING OF GOODS
    • Y02P10/00—Technologies related to metal processing
    • Y02P10/20—Recycling

Abstract

The invention relates to the field of cast steel, in particular to cast steel added with rare earth elements. The invention discloses a cast steel added with rare earth elements, which is characterized by comprising the following components in percentage by mass: c: 0.12% -0.28%, Si: 0.7% -1.3%, Mn: 0.3% -0.9%, Cr: 3% -9%, Mo: 0.01% -0.5%, V: 0.05% -1%, Al: 0.01-0.05%, rare earth element RE: 0.2 to 0.6 percent of the total weight of the alloy, less than or equal to 0.03 percent of S, less than or equal to 0.03 percent of P and the balance of Fe. The invention solves the problem that the existing cast steel added with rare earth elements has poor toughness although the hardness is very high.

Description

Cast steel added with rare earth elements
Technical Field
The invention relates to the field of cast steel, in particular to cast steel added with rare earth elements.
Background
Economic losses of materials such as steel due to atmospheric corrosion account for a large proportion of material failures. However, as a steel material used in a large amount in an atmospheric environment, studies on the corrosiveness of cast steel have been long paid attention to. On the surface of a great deal of research, the rare earth elements can not only improve the corrosion resistance of steel by refining grains and the like, but also produce other special effects, for example, the high-temperature oxidation resistance of stainless steel can be improved by adding rare earth yttrium.
China is a major rare earth country with the most abundant rare earth resources and the most abundant output in the world and is also a major steel country with the first steel yield, and if the beneficial effects of rare earth on carbon steel can be effectively utilized, trace rare earth is added into low-carbon steel and alloy steel, so that the quality of the steel is improved, and the international competitiveness of the steel in China is enhanced. However, conventional cast steels containing rare earth elements have high hardness but often have insufficient toughness.
Disclosure of Invention
Aiming at the problems, the invention provides a cast steel added with rare earth elements, which comprises the following components in percentage by mass:
c: 0.12% -0.28%, Si: 0.7% -1.3%, Mn: 0.3% -0.9%, Cr: 3% -9%, Mo: 0.01% -0.5%, V: 0.05% -1%, Al: 0.01-0.05%, rare earth element RE: 0.2 to 0.6 percent of S, less than or equal to 0.03 percent of P, and the balance of Fe;
the rare earth element RE is prepared from the following components in percentage by mass La: ce: y is a mixture of 1-4: 6: 2;
the cast steel comprises the following raw materials in parts by weight:
40-50 parts of pig iron, 15-25 parts of scrap steel, 2.5-4.5 parts of ferrosilicon, 1.2-2.4 parts of ferromanganese, 7-15 parts of ferrochromium, 0.2-2 parts of ferromolybdenum, 1.1-2.1 parts of ferrovanadium, 0.01-0.05 part of aluminum particles and 0.3-0.8 part of rare earth element RE.
Preferably, the cast steel consists of the following components in percentage by mass:
c: 0.18% -0.22%, Si: 1.0% -1.2%, Mn: 0.7-0.9%, Cr: 5% -7%, Mo: 0.05% -0.1%, V: 0.05% -1%, Al: 0.03% -0.04%, rare earth element RE: 0.3 to 0.5 percent of the total weight of the alloy, less than or equal to 0.03 percent of S, less than or equal to 0.03 percent of P and the balance of Fe;
the rare earth element RE is prepared from the following components in percentage by mass La: ce: y is a mixture of 3:6: 2;
the cast steel comprises the following raw materials in parts by weight:
44-48 parts of pig iron, 28-22 parts of scrap steel, 3.8-4.3 parts of ferrosilicon, 2.0-2.4 parts of ferromanganese, 9-12 parts of ferrochromium, 0.8-1.2 parts of ferromolybdenum, 1.1-2.1 parts of ferrovanadium, 0.03-0.05 part of aluminum particles and 0.5-0.7 part of rare earth element RE.
The invention also aims to provide a preparation method of the cast steel added with the rare earth element, which comprises the following steps:
step 1, weighing La, Ce and Y according to the amount, placing the La, Ce and Y in a ball mill under the protection of argon for mechanical ball milling to obtain a nano rare earth element RE;
step 2, weighing pig iron and scrap steel according to the amount, putting the pig iron and the scrap steel into an electric furnace for melting, adding the ferrosilicon, ferromanganese, ferrochrome, ferromolybdenum and ferrovanadium which are weighed according to the amount, and desulfurizing after melting to ensure that S is less than or equal to 0.005%; dephosphorizing to ensure that P is less than or equal to 0.005 percent; removing slag to obtain mixed molten steel;
step 3, injecting the mixed molten steel into the AOD furnace through a steel ladle, and blowing oxygen for decarburization to enable the carbon content to meet the process requirement;
step 4, transferring the molten steel decarbonized in the step 3 into a refining furnace, detecting the content of each element, adding one or more of ferrosilicon, ferromanganese, ferrochromium, ferromolybdenum and ferrovanadium according to the detection result, and adjusting the content of each element until the technological requirement is met to obtain refined molten steel;
step 5, detecting the oxygen content of the refined molten steel, adding aluminum particles for deoxidation until the oxygen content of the refined molten steel is reduced to 200ppm, and removing slag; vacuumizing the refining furnace, introducing argon, keeping the pressure at 15-20 Pa, adding the nano rare earth element RE prepared in the step 1, heating to 1590-1610 ℃, and stirring for 20-30 min;
and 6, casting and forming to obtain a cast steel material, and performing heat treatment to obtain the cast steel added with the rare earth element.
Preferably, the step of heat-treating in step 6 is:
1) heating the cast steel material to 1060-1080 ℃, preserving heat for 2-4 hours, and cooling to room temperature along with the furnace;
2) removing an oxide layer on the surface of the cast steel material by using a grinding machine;
3) heating the polished cast steel material to 880-920 ℃, preserving heat for 1-3 h, and cooling;
4) tempering the cast steel material cooled in the step 3) at the temperature of 250-260 ℃, preserving heat for 1-3 hours, and cooling in air to room temperature.
More preferably, in the step 1), the cast steel material is heated to 1070 ℃ and is kept warm for 3 hours.
More preferably, in the step 3), the polished cast steel material is heated to 900 ℃ and kept warm for 2 hours.
More preferably, in the step 3), cooling is performed by using a cooling medium, and the cooling medium is saturated CaCl2And (3) solution.
More preferably, in the step 4), the cast steel material cooled in the step 3) is tempered at 480 ℃, kept warm for 2 hours, and cooled to room temperature in air.
The invention has the beneficial effects that:
1. in the prior art, most of cast steel deoxidation uses aluminum particles, and the aluminum particles are required to be added in a large amount under the condition of low oxygen content, and the effect is very slight. Firstly, the melting point of the added rare earth element RE is lower than the temperature of molten steel, so that the RE can be quickly dissolved and melted in the molten steel; secondly, the rare earth element RE has strong binding energy with oxygen, and can react with oxygen in situ to generate rare earth oxide under the condition of low oxygen content. Therefore, the invention not only solves the problems of prolonging the steelmaking time and post-treating slag particles by using a large amount of aluminum particles through controlling oxygen and adding quantitative rare earth element RE; the rare earth oxide generated by the reaction can also obviously improve the endurance strength of the cast steel, reduce the creep rate of the cast steel and improve the high-temperature mechanical property of the cast steel; in addition, the rare earth metal RE can also react with Al2O3The impurities are modified to generate REAlO3And the fatigue life of the cast steel can be greatly prolonged by waiting for the rare earth inclusions.
2. The rare earth elements RE used in the invention comprise La, Ce and Y, the combination of oxides of La and Ce can improve the corrosion resistance and oxidation resistance of the cast steel, the combination of oxides of Ce and Y can improve the dispersion hardening and high temperature resistance mechanical properties of the cast steel, and after the three rare earth elements are mixed according to a reasonable proportion, the crystal grains of the cast steel can be refined, and the yield strength, plasticity and toughness of the cast steel can be improved; slowing down the austenite-bainite transformation during the smelting of cast steel and being beneficial to improving the hardenability of the steel. In addition, the wear resistance, high temperature resistance, corrosion resistance and other performances are improved.
3. The heat treatment process adopts the steps of annealing, grinding, quenching and tempering, so that the prepared cast iron has higher hardness and tensile strength. In the step 1) of the heat treatment process, the hardness of the cast steel is increased along with the increase of the annealing temperature, and when the temperature reaches 1060-1080 ℃, the hardness is the maximum; in the heat treatment step 2), an oxide layer generated by burning on the surface of the cast steel is removed by adopting a polishing mode, so that the effects of subsequent quenching and tempering are facilitatedFruit; in the heat treatment step 3), the invention uses CaCl saturated with a low-cost cooling medium2The solution is quenched and then cooled, the medium has the characteristic of high-temperature quick cooling and medium-temperature slow cooling, namely when a sample is cooled, water contained in the cooling medium can quickly cool steel, pro-eutectoid ferrite and pearlite are prevented from appearing in the steel, and after the water is completely vaporized, the cooling medium can be sintered on the surface of a workpiece to play a role in heat preservation and prolong the medium-temperature region transformation time, so that the low-temperature impact toughness of the cast steel obtained in the mode can be greatly improved; in the heat treatment step 4), along with the increase of the tempering temperature, the toughness of the cast steel is increased firstly and then reduced, and the tensile strength is gradually increased.
4. The cast steel prepared by the invention not only has higher yield strength, but also has higher toughness, and the preparation method is simple and easy to control, and is suitable for application in industrial production.
Detailed Description
For the sake of understanding, the present invention will be described in detail below with reference to specific examples. It is specifically intended that the present embodiments be considered as illustrative only, and that various modifications and changes in light thereof will be suggested to persons skilled in the art and are to be included within the scope of the present invention.
Example 1
A preparation method of cast steel added with rare earth elements comprises the following steps:
step 1, weighing 0.12 part of La, 0.36 part of Ce and 0.12 part of Y, and placing the materials in a ball mill under the protection of argon for mechanical ball milling to obtain a nano rare earth element RE;
step 2, weighing 45 parts of pig iron and 20 parts of scrap steel, putting into an electric furnace for melting, adding 3 parts of ferrosilicon, 1.8 parts of ferromanganese, 12 parts of ferrochromium, 1.2 parts of ferromolybdenum and 1.6 parts of ferrovanadium, and desulfurizing after melting to ensure that S is less than or equal to 0.005%; dephosphorizing to ensure that P is less than or equal to 0.005 percent; removing slag to obtain mixed molten steel;
step 3, injecting the mixed molten steel into the AOD furnace through a steel ladle, and blowing oxygen for decarburization to enable the carbon content to meet the process requirement;
step 4, transferring the molten steel decarbonized in the step 3 into a refining furnace, detecting the content of each element, adding one or more of ferrosilicon, ferromanganese, ferrochromium, ferromolybdenum and ferrovanadium according to the detection result, and adjusting the content of each element until the technological requirement is met to obtain refined molten steel;
step 5, detecting the oxygen content of the refined molten steel, adding 0.03 part of aluminum particles for deoxidation until the oxygen content of the refined molten steel is reduced to 200ppm, and removing slag; vacuumizing the refining furnace, introducing argon, keeping the pressure at 18Pa, adding the nano rare earth element RE prepared in the step 1, heating to 1600 ℃, and stirring for 25 min;
step 6, casting and forming to obtain a cast steel material;
step 7, heat treatment:
1) heating the cast steel material to 1070 ℃, preserving heat for 3 hours, and cooling to room temperature along with the furnace;
2) removing an oxide layer on the surface of the cast steel material by using a grinding machine;
3) heating the polished cast steel material to 900 ℃, preserving heat for 2h, and using saturated CaCl2Cooling the solution as a cooling medium;
4) tempering the cast steel material cooled in the step 3) at the temperature of 255 ℃, preserving heat for 2 hours, and cooling in air to room temperature;
and obtaining the cast steel with the product added with the rare earth element.
Through detection, the content of each element of the product cast steel prepared by the preparation method is as follows:
c: 0.2%, Si: 1.2%, Mn: 0.8%, Cr: 6%, Mo: 0.36%, V: 0.71%, Al: 0.03%, La: 0.08%, Ce: 0.24%, Y: 0.08%, S: 0.012%, P: 0.008% and the balance of Fe and inevitable impurities.
Example 2
A preparation method of cast steel added with rare earth elements comprises the following steps:
step 1, weighing 0.04 parts of La, 0.12 parts of Ce and 0.04 parts of Y, and placing the materials in a ball mill under the protection of argon for mechanical ball milling to obtain a nano rare earth element RE;
step 2, weighing 40 parts of pig iron and 15 parts of scrap steel, putting into an electric furnace for melting, adding 2.5 parts of ferrosilicon, 1.2 parts of ferromanganese, 7 parts of ferrochromium, 0.2 part of ferromolybdenum and 1.1 part of ferrovanadium, and desulfurizing after melting to ensure that S is less than or equal to 0.005%; dephosphorizing to ensure that P is less than or equal to 0.005 percent; removing slag to obtain mixed molten steel;
step 3, injecting the mixed molten steel into the AOD furnace through a steel ladle, and blowing oxygen for decarburization to enable the carbon content to meet the process requirement;
step 4, transferring the molten steel decarbonized in the step 3 into a refining furnace, detecting the content of each element, adding one or more of ferrosilicon, ferromanganese, ferrochromium, ferromolybdenum and ferrovanadium according to the detection result, and adjusting the content of each element until the technological requirement is met to obtain refined molten steel;
step 5, detecting the oxygen content of the refined molten steel, adding 0.01 part of aluminum particles for deoxidation until the oxygen content of the refined molten steel is reduced to 200ppm, and removing slag; vacuumizing the refining furnace, introducing argon, keeping the pressure at 15Pa, adding the nano rare earth element RE prepared in the step 1, heating to 1590 ℃, and stirring for 20 min;
step 6, casting and forming to obtain a cast steel material;
step 7, heat treatment:
1) heating the cast steel material to 1060 ℃, preserving heat for 2 hours, and cooling to room temperature along with the furnace;
2) removing an oxide layer on the surface of the cast steel material by using a grinding machine;
3) heating the polished cast steel material to 880 ℃, preserving heat for 1h, and using saturated CaCl2Cooling the solution as a cooling medium;
4) tempering the cast steel material cooled in the step 3) at the temperature of 250 ℃, preserving heat for 1h, and cooling in air to room temperature;
and obtaining the cast steel with the product added with the rare earth element.
Through detection, the content of each element of the product cast steel prepared by the preparation method is as follows:
c: 0.13%, Si: 0.8%, Mn: 0.3%, Cr: 3.7%, Mo: 0.07%, V: 0.12%, Al: 0.01%, La: 0.04%, Ce: 0.12%, Y: 0.04%, S: 0.025%, P: 0.018%, and the balance of Fe and inevitable impurities.
Example 3
A raw material of cast steel added with rare earth elements comprises the following components in parts by weight:
50 parts of pig iron, 25 parts of scrap steel, 4.5 parts of ferrosilicon, 2.4 parts of ferromanganese, 15 parts of ferrochrome, 2 parts of ferromolybdenum, 2.1 parts of ferrovanadium, 0.05 part of aluminum particles, 0.16 part of rare earth element La, 0.48 part of rare earth element Ce and 0.16 part of rare earth element Y;
the preparation method of the cast steel added with the rare earth elements comprises the following steps:
step 1, weighing 0.16 part of La, 0.48 part of Ce and 0.16 part of Y, and placing the materials in a ball mill under the protection of argon for mechanical ball milling to obtain a nano rare earth element RE;
step 2, weighing 50 parts of pig iron and 25 parts of scrap steel, putting into an electric furnace for melting, adding 4.5 parts of ferrosilicon, 2.4 parts of ferromanganese, 15 parts of ferrochromium, 2 parts of ferromolybdenum and 2.1 parts of ferrovanadium, and desulfurizing after melting to ensure that S is less than or equal to 0.005%; dephosphorizing to ensure that P is less than or equal to 0.005 percent; removing slag to obtain mixed molten steel;
step 3, injecting the mixed molten steel into the AOD furnace through a steel ladle, and blowing oxygen for decarburization to enable the carbon content to meet the process requirement;
step 4, transferring the molten steel decarbonized in the step 3 into a refining furnace, detecting the content of each element, adding one or more of ferrosilicon, ferromanganese, ferrochromium, ferromolybdenum and ferrovanadium according to the detection result, and adjusting the content of each element until the technological requirement is met to obtain refined molten steel;
step 5, detecting the oxygen content of the refined molten steel, adding 0.05 part of aluminum particles for deoxidation until the oxygen content of the refined molten steel is reduced to 200ppm, and removing slag; vacuumizing the refining furnace, introducing argon, keeping the pressure at 20Pa, adding the nano rare earth element RE prepared in the step 1, heating to 1610 ℃, and stirring for 30 min;
step 6, casting and forming to obtain a cast steel material;
step 7, heat treatment:
1) heating the cast steel material to 1080 ℃, preserving heat for 4 hours, and cooling to room temperature along with the furnace;
2) removing an oxide layer on the surface of the cast steel material by using a grinding machine;
3) heating the polished cast steel material to 880 ℃, preserving heat for 3 hours, and using saturated CaCl2Cooling the solution as a cooling medium;
4) tempering the cast steel material cooled in the step 3) at the temperature of 260 ℃, preserving heat for 3 hours, and cooling in air to room temperature;
finally obtaining the cast steel with the product added with the rare earth element.
Through detection, the content of each element of the product cast steel prepared by the preparation method is as follows:
c: 0.22%, Si: 1.2%, Mn: 0.9%, Cr: 7%, Mo: 0.1%, V: 0.98%, Al: 0.04%, La: 0.16%, Ce: 0.48%, Y: 0.16%, S: 0.025%, P: 0.018%, and the balance of Fe and inevitable impurities.
Comparative example 1
The commercially available cast steel added with the rare earth element comprises the following chemical components in percentage by mass: c: 0.11 to 0.14; si: 0.20 to 0.30; mn: 0.80 to 1.0; cr: 9.00 to 9.60; mo: 1.40-1.60; ni: 0.10 to 0.20; co: 0.90 to 1.10; v: 0.18 to 0.22; n: 0.015 to 0.030; nb: 0.05 to 0.07; b: 0.008 to 0.013; rare earth: 0.01 to 0.05; p is less than or equal to 0.015; s is less than or equal to 0.010; cu is less than or equal to 0.10; as is less than or equal to 0.025; sb is less than or equal to 0.001; sn is less than or equal to 0.015; a1 is less than or equal to 0.010; h is less than or equal to 7 ppm; o is less than or equal to 90ppm, and the balance of Fe and inevitable impurities; wherein the rare earth is a mixed rare earth composed of two or more of Ce, La, Y, Pr and Nd.
In order to more clearly illustrate the content of the present invention, the present invention performs performance tests on example 1, example 2, example 3 and comparative example 1, and the results are shown in table 1:
TABLE 1 Performance test results
Figure BDA0002205827490000071
As can be seen from the above table, although the cast steels prepared in examples 1, 2, 3 of the present invention were slightly lower than comparative example 1 in terms of hardness; however, in 3 examples of the present invention, the tensile strength was about 1000MPa, the impact toughness (-40 ℃ C.) was about 50J, the yield strength was > 800MPa, the elongation was > 20%, and the reduction of area was > 35%, which are higher than those of comparative example 1.
Finally, it should be noted that the above embodiments are only used for illustrating the technical solutions of the present invention, and not for limiting the protection scope of the present invention, although the present invention is described in detail with reference to the preferred embodiments, it should be understood by those skilled in the art that modifications or equivalent substitutions can be made on the technical solutions of the present invention without departing from the spirit and scope of the technical solutions of the present invention.

Claims (6)

1. The cast steel added with the rare earth elements is characterized by comprising the following components in percentage by mass:
c: 0.12% -0.28%, Si: 0.7% -1.3%, Mn: 0.3% -0.9%, Cr: 3% -9%, Mo: 0.01% -0.5%, V: 0.05% -1%, Al: 0.01-0.05%, rare earth element RE: 0.2 to 0.6 percent of S, less than or equal to 0.03 percent of P, and the balance of Fe;
the rare earth element RE is prepared from the following components in percentage by mass La: ce: y is a mixture of 1-4: 6: 2;
the cast steel comprises the following raw materials in parts by weight:
40-50 parts of pig iron, 15-25 parts of scrap steel, 2.5-4.5 parts of ferrosilicon, 1.2-2.4 parts of ferromanganese, 7-15 parts of ferrochromium, 0.2-2 parts of ferromolybdenum, 1.1-2.1 parts of ferrovanadium, 0.01-0.05 part of aluminum particles and 0.3-0.8 part of rare earth element RE;
the preparation method of the cast steel comprises the following steps:
step 1, weighing La, Ce and Y according to the amount, placing the La, Ce and Y in a ball mill under the protection of argon for mechanical ball milling to obtain a nano rare earth element RE;
step 2, weighing pig iron and scrap steel according to the amount, putting the pig iron and the scrap steel into an electric furnace for melting, adding the ferrosilicon, ferromanganese, ferrochrome, ferromolybdenum and ferrovanadium which are weighed according to the amount, and desulfurizing after melting to ensure that S is less than or equal to 0.005%; dephosphorizing to ensure that P is less than or equal to 0.005 percent; removing slag to obtain mixed molten steel;
step 3, injecting the mixed molten steel into the AOD furnace through a steel ladle, and blowing oxygen for decarburization to enable the carbon content to meet the process requirement;
step 4, transferring the molten steel decarbonized in the step 3 into a refining furnace, detecting the content of each element, adding one or more of ferrosilicon, ferromanganese, ferrochromium, ferromolybdenum and ferrovanadium according to the detection result, and adjusting the content of each element until the technological requirement is met to obtain refined molten steel;
step 5, detecting the oxygen content of the refined molten steel, adding aluminum particles for deoxidation until the oxygen content of the refined molten steel is reduced to 200ppm, and removing slag; vacuumizing the refining furnace, introducing argon, keeping the pressure at 15-20 Pa, adding the nano rare earth element RE prepared in the step 1, heating to 1590-1610 ℃, and stirring for 20-30 min;
and 6, casting and forming to obtain a cast steel material, and performing heat treatment to obtain the cast steel added with the rare earth element.
2. The cast steel added with rare earth elements as claimed in claim 1, characterized in that it consists of, in mass%:
c: 0.18% -0.22%, Si: 1.0% -1.2%, Mn: 0.7-0.9%, Cr: 5% -7%, Mo: 0.05% -0.1%, V: 0.05% -1%, Al: 0.03% -0.04%, rare earth element RE: 0.3 to 0.5 percent of the total weight of the alloy, less than or equal to 0.03 percent of S, less than or equal to 0.03 percent of P and the balance of Fe;
the rare earth element RE is prepared from the following components in percentage by mass La: ce: y is a mixture of 3:6: 2;
the cast steel comprises the following raw materials in parts by weight:
44-48 parts of pig iron, 28-22 parts of scrap steel, 3.8-4.3 parts of ferrosilicon, 2.0-2.4 parts of ferromanganese, 9-12 parts of ferrochromium, 0.8-1.2 parts of ferromolybdenum, 1.1-2.1 parts of ferrovanadium, 0.03-0.05 part of aluminum particles and 0.5-0.7 part of rare earth element RE.
3. The method for producing cast steel according to claim 1, characterized in that the step of heat treatment in step 6 is specifically as follows:
1) heating the cast steel material to 1060-1080 ℃, preserving heat for 2-4 hours, and cooling to room temperature along with the furnace;
2) removing an oxide layer on the surface of the cast steel material by using a grinding machine;
3) heating the polished cast steel material to 880-920 ℃, preserving heat for 1-3 h, and cooling;
4) tempering the cast steel material cooled in the step 3) at the temperature of 250-260 ℃, preserving heat for 1-3 hours, and cooling in air to room temperature.
4. The method for producing a cast steel according to claim 3, wherein in step 1), the cast steel material is heated to 1070 ℃ and kept warm for 3 hours.
5. The method for manufacturing cast steel according to claim 3, wherein in step 3), the ground cast steel material is heated to 900 ℃ and kept warm for 2 hours.
6. Method for producing cast steel according to claim 3, characterized in that in step 3) cooling is performed with a cooling medium, which is saturated CaCl2And (3) solution.
CN201910880787.8A 2019-09-18 2019-09-18 Cast steel added with rare earth elements Expired - Fee Related CN110527925B (en)

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