CN110016624B - Lanthanum modified high-hardness alloy and casting method thereof - Google Patents

Lanthanum modified high-hardness alloy and casting method thereof Download PDF

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CN110016624B
CN110016624B CN201910407613.XA CN201910407613A CN110016624B CN 110016624 B CN110016624 B CN 110016624B CN 201910407613 A CN201910407613 A CN 201910407613A CN 110016624 B CN110016624 B CN 110016624B
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CN110016624A (en
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罗丰华
卢静
王冠
刘浪飞
吴卫文
王哲
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Central South University
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    • C—CHEMISTRY; METALLURGY
    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22C—ALLOYS
    • C22C33/00—Making ferrous alloys
    • C22C33/006—Making ferrous alloys compositions used for making ferrous alloys
    • 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
    • C22C38/005—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
    • C22C38/04—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
    • C22C38/18—Ferrous alloys, e.g. steel alloys containing chromium
    • C22C38/24—Ferrous alloys, e.g. steel alloys containing chromium with vanadium
    • 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
    • C22C38/26—Ferrous alloys, e.g. steel alloys containing chromium with niobium or tantalum
    • 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
    • C22C38/32—Ferrous alloys, e.g. steel alloys containing chromium with boron

Abstract

A lanthanum modified high-hardness alloy and a casting method thereof, wherein the contents of all elements of the alloy are Cr: 9.0-13.0, B: 2.6-2.9, C:0.7 to 0.9, Nb: 0.4-0.8, V: 0.4-0.8, Mn content less than 0.3, La: 0.03-0.7 wt% of Fe, and the balance being Fe, wherein the total amount of C, B is 3.3-3.6 wt%; C/Cr content ratio: 0.06 to 0.08; the total amount of Nb and V is 0.5-1.0, and Fe-La is prepared first2O3And pressing Fe-lanthanum carbonate or Fe-lanthanum nitrate powder into a compact, and casting the alloy after batching, smelting and modifying the alloy, wherein the casting temperature range is 1250-1320 ℃. The alloy HRC 66.2-71.0 of the invention has impact toughness of 8.6-14.6J/cm2The bending strength reaches 800-1345 MPa.

Description

Lanthanum modified high-hardness alloy and casting method thereof
Technical Field
The invention belongs to the field of high-hardness wear-resistant cast iron, and relates to a preparation method of wear-resistant corrosion-resistant cast iron consisting of rare earth lanthanum modified fine hard phase, supersaturated solid solution and martensite matrix phase, which can be widely used for manufacturing mechanical wear-resistant parts in the industries of machinery, chemical engineering, electric power, metallurgy and the like.
Technical Field
Fe-Cr-B-C wear-resistant casting alloy mainly containing Fe2B or M2B is a hard phase, has good toughness, high hardness, high corrosion resistance, good smelting-casting manufacturability and very wide application prospect.
Modification treatment is one of effective methods for improving the texture and mechanical properties of Fe-Cr-B-C alloy. The modificator can be classified into strong carbon, nitrogen, sulfide-forming elements such as Ti, V, etc., and strong undercooling elements such as surface active elements Rare Earth (RE), Mg, etc., according to their effects.
The rare earth elements are gathered on a liquid-solid growth interface to limit the growth of crystal grains so as to improve the hardness, strength and wear resistance of the alloy; and the structure is refined, so that the boride is in broken net shape and granular distribution, and the impact toughness is improved. The research shows that: the addition of 0.6% cerium (Ce) to the Fe-Cr-B-C alloy improves the impact toughness by 86.4%. Adding 1.0% (Ce + La) of mixed alterant into Fe-Cr-B alloy, the hardness of the alloy is increased from 52HRC to 70.2HRC, and the impact toughness is increased from 3.36J/cm2Increased to 6.38J/cm2。
The rare earth modification can be a single modification method of rare earth alloy or rare earth wire, or composite modification treatment can be adopted, namely a mixture of elements such as N, Ti, V, Mg, Si and the like and rare earth is used as a modifier. The silicon-magnesium mixed rare earth alterant is most commonly a composite modification method, and researches show that: after the Fe-Cr-B-C alloy is modified by RE-Si-Mg, the impact toughness is improved by 72.2 percent compared with that before modification; after RE-Ti modification and heat treatment, the impact toughness is improved by 1.8 times; the RE-Mg modified impact toughness is improved by 34.6 percent; after the RE-Ti-N is modified, the net structure is completely disappeared, and the toughness is improved by 133.3%; after RE-Mg-V-Ti modification treatment, the impact toughness reaches 15.6J/cm2(ii) a After RE-Ti-Si-V modification treatment, the impact toughness reaches 12J/cm2The above.
These methods using rare earth modification all have a common difficulty, namely high activity pure rare earth, rare earth alloy or composite rare earth materials. Due to the high activity of the rare earth, the structure and the performance of the alterant or the alloy after the alteration treatment are difficult to control, and the alteration effect is difficult to ensure.
Document 1: LM cathode study-emission principle and present study [ D ]]Beijing university of industry, 2001: pp 44-50. Document 1 analyzes carbonized La2O3Chemical equilibrium of Mo alloy:
3Mo2C(s)+La2O3(s)＝2La(s,l)+3CO(g)+6Mo
due to Mo2C has much smaller change of free enthalpy of reduction reaction for generating the simple substance La, so that the equilibrium partial pressure of La and CO of reaction products is also 10 orders of magnitude higher. When the temperature is higher than 1673K, namely 1400 ℃, and the CO partial pressure is lower than E-9atm, the reaction formula automatically proceeds to the right, namely, the simple substance La is generated by reduction.
Patent document 2: the prepared wear-resistant alloy has the authorized bulletin number CN 105695884B, the hardness of HRC 66-70 and the impact toughness of 4-9J/cm2. The alloy has high hardness, but insufficient impact toughness, low strength index and low bending strength within the range of 346-477 MPa, and limits the application of the alloy to occasions with large external load and impact resistance.
Disclosure of Invention
The invention aims to provide a lanthanum modified high-hardness alloy and a casting method thereof. The method adopts lanthanum oxide (La)2O3) Lanthanum nitrate or lanthanum carbonate is used as a modifier, and carbides and borides in the Fe-Cr-B-C alloy in a high-temperature melting state have thermodynamic conditions for promoting the formation of high-activity La elements and form La-containing compounds with C, B, so that the structure of the cast alloy is refined, and the borides are in a net-breaking shape and are in granular distribution, thereby improving the impact toughness.
Due to La2O3The lanthanum nitrate and lanthanum carbonate powder have low density, and the La element loss caused by the upward floating of the slag when the lanthanum nitrate and lanthanum carbonate powder are directly added into the melt, thereby losing the modification effect, therefore, the La is adopted by the invention2O3Lanthanum nitrate or lanthanum carbonate powder and iron powder are evenly mixed, pressed into powder pressing blocks and then melted with Fe-Cr-B-C casting alloy. Wherein: (1) la2O3The mass ratio of the powder to the iron powder is approximately 1: 4-20, and a mixed compact of Fe-4.06-17.05 wt.% La is formed. (2) The mass ratio of the lanthanum nitrate powder to the iron powder is 1: 3-9, and a mixed briquetting containing 3.21-8.02% of Fe and La is formed. (3) The mass ratio of the lanthanum carbonate powder to the iron powder is 1: 4-19, and a mixed briquette of Fe-12.16-3.04 wt.% La is formed.
Wherein (1) La2O3The powder is white amorphous powder of La2O3The content is more than 99.0 percent; (2) the lanthanum nitrate is white amorphous powder, and the lanthanum nitrate content of the lanthanum nitrate exceeds 99.0 percent; (3) lanthanum carbonate is a white amorphous powder with a lanthanum carbonate content of over 99.0%. Because lanthanum nitrate and lanthanum carbonate are hydrated compounds, drying and dehydration treatment are carried out before batching.
The Fe powder is reduced Fe powder or water atomized Fe powder, and the Fe powder can contain alloy elements in the modified cast iron or elements in the impurity range, such as Ni, V, Cr and the like, so as to be subject to the conditions of not influencing briquetting and influencing the batching calculation.
If the La content is too low, the Fe content is too high, which affects the ingredient calculation; when the La content is too high, green compact formation is difficult. Due to La2O3Or lanthanum nitrate or lanthanum carbonate and iron powder mixture, and the La content of the mixture, thereby forming Fe-La mixed briquettes with different content ranges.
The high-wear-resistance and high-corrosion-resistance Fe-Cr-B-C alloy disclosed by patent document 2 is selected as a base alloy, and 0.03-0.7 wt.% of La element is added for modification. Forming a multi-element eutectic alloy containing Fe, Cr, B, C, Nb, V, La and other elements, wherein the mass percentage of each element is Cr: 9.0-13.0, B: 2.6-2.9, C:0.7 to 0.9, Nb: 0.4-0.8, V: 0.4-0.8, Mn content less than 0.3, La:0.03 to 0.7, S, P: less than or equal to 0.01, and the balance being Fe. Where C, B sums: 3.3 to 3.6; C/Cr content ratio: 0.06 to 0.08; the sum of Nb and V is 0.5 to 1.0. With La2O3Preparing materials in a form, wherein the content of La is controlled to be 0.05-0.5 wt.%; or proportioning in the form of lanthanum nitrate, wherein the content of La is controlled to be 0.04-0.6 wt.%; or the lanthanum carbonate is used for preparing the material, and the content of the La is controlled to be 0.03-0.7 wt.%.
In patent document 2, for the specific preparation of an alloy, ferrochrome (high carbon, medium carbon, and micro carbon), ferroboron, ferroniobium, ferrovanadium, pure iron, and the like can be used in accordance with the component requirements. The raw materials and their components are listed in table 1.
TABLE 1 raw materials and compositions applicable to the preparation of the alloys of the invention
Figure BDA0002061749710000031
The raw material components of table 1 are not exclusive, and the specific components are determined by the raw materials that are actually available. Where ferrochrome, metallic chromium, ferroboron, ferroniobium and ferrovanadium provide the Cr, B, Nb and V content of the inventive alloy, high carbon ferrochrome is used to balance the C content. The pure iron can be electrician pure iron, electromagnetic pure iron or industrial pure iron.
The method specifically comprises the following steps:
(1) preparation of La-containing iron powder compact serving as rare earth La modified carrier
Fe-La2O3Powder briquetting: adopting iron powder and La2O3After the powders are mixed evenly, the mixture is pressed into powder briquettes. La2O3The mass ratio of the powder to the iron powder is approximately 1: 4-20, namely Fe-La with the La content of 4.06-17.05% of Fe2O3And (4) mixing and briquetting.
Or a Fe-lanthanum nitrate powder compact: iron powder and lanthanum nitrate powder are uniformly mixed and molded into powder briquettes. The mass ratio of the lanthanum nitrate powder to the iron powder is approximately 1: 3-9, and the Fe-lanthanum nitrate mixed briquette with Fe-3.21-8.02% of La is formed.
Or Fe-lanthanum carbonate powder compacts: iron powder and lanthanum carbonate powder are uniformly mixed and molded into powder compacts. The mass ratio of the lanthanum carbonate powder to the iron powder is approximately 1: 4-19, and the Fe-lanthanum carbonate mixed briquette containing Fe-12.16-3.04 wt.% La is formed.
(2) Alloy proportioning, smelting and modification treatment
Weighing corresponding raw materials according to the component requirement proportion of the Fe-Cr-B-C alloy, and firstly, mixing Fe-La2O3The powder compact, the Fe-lanthanum nitrate powder compact or the Fe-lanthanum carbonate powder compact is placed inThe furnace bottom forms the La element modification in the set component range. Then ferrochrome, chromium metal, ferroboron, ferroniobium, ferrovanadium and pure iron are put in. The alloy can be prepared by smelting in an induction furnace, a vacuum induction furnace and the like.
For Fe-La2O3Powder briquetting, wherein the melting temperature is 1500-1600 ℃, the power of an electric furnace is reduced after complete melting, the temperature of a melt is reduced to 1300-1350 ℃, or for Fe-lanthanum nitrate powder briquetting, the melting temperature is 1520-1620 ℃, the power of the electric furnace is reduced after complete melting, the temperature of the melt is reduced to 1320-1370 ℃, or for Fe-lanthanum carbonate powder briquetting, the temperature is 1550-1650 ℃, the power of the electric furnace is reduced after complete melting, and the temperature of the melt is reduced to 1300-1360 ℃; then, deoxidizing by using pure aluminum accounting for 0.1-0.15% of the total amount of the ingredients; and (5) keeping the temperature and standing for about 5-10 minutes after deoxidation.
(3) Casting of
The casting temperature range is 1250-1320 ℃.
The alloy of the invention is a deep eutectic composition, and can form a non-equilibrium matrix structure, such as an amorphous structure, a nanocrystalline structure or a martensite structure, under the condition of common sand mold casting. The alloy melt of the invention has good fluidity and can be cast and formed by various methods, such as sand mold casting or investment casting, lost foam casting, metal mold casting, ceramic mold casting, die casting, centrifugal casting and other special casting methods. The cooling speed from the solidification temperature to 600 ℃ should not be lower than 60 ℃/min, but volume change can be caused due to nonequilibrium transformation, and stress cracking phenomenon can be caused due to inconsistent temperature when large castings are prepared, so that the castings should be free from the constraint of the mold at the temperature of 600-800 ℃. The ingot can be subjected to a stress relief annealing process at a temperature of less than 600 ℃ and necessary machining procedures.
The iron powder in the step (1) is reduced iron powder with the purity of more than or equal to 98.5 percent and the granularity of 100 meshes or water atomized iron powder with the purity of more than or equal to 99.0 percent and the granularity of 100 meshes or alloy iron powder with equivalent granularity and a small amount of alloy ingredients which do not influence casting. It is also possible to select a powder of smaller particle size, so as to be able to be pressed with green strength that does not affect the preparation of the subsequent charge and burden.
And (2) uniformly mixing the materials in the step (1) into a mixing barrel type mixing material, a V-shaped mixing material or a stirring mixing material to realize substantial uniformity.
The pressed blank in the step (1) is formed by die pressing, the pressing pressure is 100-600 MPa, and the size of the pressed blank is not limited. Cold isostatic pressing methods may also be employed.
Step (2) adding Fe-La2O3The powder compact is placed at the bottom of the furnace, and aims to: ferrochromium, ferroboron and the like have lower melting temperature than pure iron, and therefore, the ferrochromium, ferroboron and the like are preferentially melted to infiltrate into Fe-La at the bottom2O3Compacting the powder to gradually melt the pure iron powder and release La2O3Powder particles.
The purpose of putting the Fe-lanthanum nitrate or Fe-lanthanum carbonate powder pressing block at the bottom of the furnace is as follows: substances such as ferrochromium, ferroboron and the like have lower melting temperature than pure iron, so that the substances can be preferentially melted to infiltrate the Fe-lanthanum nitrate or Fe-lanthanum carbonate powder compact at the bottom, and the pure iron powder is gradually melted; meanwhile, lanthanum nitrate or lanthanum carbonate is decomposed into fine La under the action of heat2O3And oxynitride, or CO2. Wherein the nitrogen oxide gas molecules, or CO2The floating process of the floating device is beneficial to removing slag from the solution; while the released fine particles La2O3The density of (2) is lower.
Due to La2O3Has a low density of about 6.51g/cm3The melt will gradually float up. In La2O3Process of powder floating up by Fe3C、Cr3C2The isocarbides are reduced to form active La elements and react with C, B to form La (B, C)6The compound of (1). Through the modification of La, the reticular structure and the acicular boride distributed along the crystal disappear, the alloy consists of a primary crystal matrix phase and a eutectic structure, and the eutectic structure is formed by interpenetration of a fine matrix phase and a hard phase, so that the strength and the impact toughness of the alloy are improved.
La2O3The CO gas formed in the powder floating and reaction processes also has the functions of degassing and deslagging, thereby further purifying the melt.
If La is present2O3Powder, lanthanum nitrate powder and lanthanum carbonateThe powder is not prepared into briquettes in advance and is placed at the bottom of the furnace, so the powder can easily and quickly float to the surface of the melt, the oxygen content on the surface of the melt is high, and La is contained2O3Is not easy to be reduced to form active La, and loses the metamorphic effect.
Said Fe3C、Cr3C2The carbide is formed by the reaction of high carbon ferrochrome and C and Fe element during melting, because of Fe3C、Cr3C2Isocarbides have lower stability at high temperature than Mo2C and the melting temperature exceeds the 1400℃ reaction temperature described in document 1, the partial pressure of CO gas in the melt is also extremely low, and therefore the reduction reaction to form active La can proceed. EDS spectroscopy also indicates that the casting alloy phase contains La element.
And (3) casting, namely casting by means of water cooling, iron mold, cold iron placed in a mold and the like, so as to further promote the unbalanced transformation of the matrix and form high-hardness martensite.
The La modification method of the present invention is not limited to Fe-Cr-B-C alloys, but can also be applied to other cast iron and steel smelting modification and refining treatment with high C content. Due to La2O3Lanthanum nitrate or lanthanum carbonate has slightly different La content and activity, which causes slightly different process and modification effect.
The main characteristic of the invention is that La is directly used2O3The powder, lanthanum nitrate and lanthanum carbonate powder are mixed with iron powder to form a powder compact which is used as a La element modification carrier. Utilizing Fe in Fe-Cr-B-C alloy high-temperature melt3C、Cr3C2The reduction of the isocarbides forms active La elements and reacts with C, B to form La (B, C)6The compound of (2) avoids the appearance of boride net-shaped and needle-shaped structures, promotes the formation of fine eutectic structures, and plays a role in modifying and toughening refined structures. The matrix phase of the ingot casting structure is a non-equilibrium structure strengthened by Cr, B and C with high hardness; the hard phase is a high-hardness boron and carbon compound and forms a fine eutectic structure with the matrix phase. Using Fe-La2O3The hardness of the cast ingot prepared by the powder briquetting reaches HRC 68.2-71.0, and the impact toughness reaches 8.6-11.2J/cm2Bending strength ofThe hardness of the cast ingot reaches HRC 67.5-69.0 and the impact toughness reaches 8.9-12.2J/cm under 800-920 MPa or the cast ingot prepared by using the Fe-lanthanum nitrate powder pressing block2The bending strength reaches 900-1120 MPa, or the hardness of the cast ingot prepared by using the Fe-lanthanum carbonate powder pressing block reaches HRC 66.2-70.0, and the impact toughness reaches 10.7-14.6J/cm2The bending strength reaches 1000-1345 MPa.
Drawings
FIG. 1 cast structure of example 1 of the invention;
FIG. 2 cast alloy X-ray diffraction pattern of inventive example 1;
FIG. 3 EDS spectra and composition of matrix phase of casting of example 1 of the invention;
FIG. 4 cast structure of example 10 of the present invention;
FIG. 5 EDS spectra and composition of matrix phase of casting of example 10 of the invention.
FIG. 6 cast structure of example 17 of the present invention;
Detailed Description
The various melting and casting methods of the present invention are not limited by the following examples, and any modifications and variations within the scope of the claims of the present invention are within the scope of the present invention.
Selecting high-carbon ferrochrome, micro-carbon ferrochrome, metal chromium, ferroboron, ferroniobium, ferrovanadium, industrial pure iron, pure iron powder and La2O3The alloy is prepared from raw materials of powder, lanthanum nitrate powder, lanthanum carbonate powder, pure aluminum and the like within the component range required by the invention.
Example 1 iron powder with La2O3After the powders are mixed evenly, the mixture is pressed into powder briquettes. La2O3The mass ratio of powder to iron powder is approximately 1:4, i.e., Fe-La forming Fe-17.05 wt.% La2O3And (4) mixing and briquetting. Used as a carrier for rare earth La modification.
Selecting high-carbon ferrochrome, micro-carbon ferrochrome, ferroboron, ferroniobium, ferrovanadium, industrial pure iron and the Fe-La2O3The mixed briquettes are taken as raw materials and have the following component ranges: 10.0 wt.% Cr; 2.9 wt.%; 0.7 wt.% C; 0.4 wt.% Nb; 0.2 wt.% V; 0.5 wt.% La; control of impurity elementsSee table 2. Small amounts of Al, Mn, N, etc. impurities do not cause radical changes in the properties of the alloy and are therefore not listed in Table 2. After weighing the corresponding raw materials according to the required mixture ratio of the components, adopting induction melting and sand mould casting. The method comprises the following specific steps:
mixing Fe-La2O3The powder pressing block is placed at the bottom of the furnace, and then ferrochrome, metal chromium, ferroboron, ferroniobium, ferrovanadium and pure iron are placed in the furnace. The melting temperature is 1600 ℃; after the materials are completely melted, reducing the power of the electric furnace, reducing the temperature of the melt to 1350 ℃, and deoxidizing by using pure aluminum accounting for 0.15 percent of the total amount of the ingredients; the incubation was continued for about 10 minutes. The casting temperature range was 1300 ℃. About 6 minutes after casting, the sand mold was opened, at which point the ingot temperature was below 800 ℃ and the cooling rate from the solidification temperature to 800 ℃ was about 70 ℃/min. And air-cooling to room temperature. The integral hardness of the obtained cast ingot reaches HRC69.3, and the impact toughness reaches 11.2J/cm2The bending strength reaches 918 MPa.
FIG. 1 is a cast alloy structure, mainly including an Fe primary crystal phase and a eutectic phase, wherein the eutectic phase is a eutectic structure of an Fe phase and boron and carbon compounds; FIG. 2 is an X-ray diffraction pattern of a cast alloy showing that the alloy matrix is an alpha-Fe phase, the diffraction peak is broad and is broad around 65 degrees, and therefore, the matrix is a martensite phase with a large amount of Cr dissolved in solid, and the carbon and boron compounds are Fe2B、Fe3C and Cr23C6A complex compound based thereon and exhibiting La (B, C)6The presence of a compound; FIG. 3 is EDS spectrum and analysis result of casting alloy matrix phase, EDS can only qualitatively analyze components, and the result shows that La element exists in alloy, which illustrates that La element2O3The La element is alloyed with the melt to play a role in modifying the melt.
Example 2 iron powder with La2O3After the powders are mixed evenly, the mixture is pressed into powder briquettes. La2O3The mass ratio of powder to iron powder is approximately 1:20, i.e., Fe-La forming Fe-4.06 wt.% La2O3And (4) mixing and briquetting. Used as a carrier for rare earth La modification.
Selecting high-carbon ferrochrome, metallic chromium, ferroboron, ferroniobium, industrial pure iron and the Fe-La2O3MixingThe briquette is used as a raw material and comprises the following components: 10.0 wt.% Cr; 2.7 wt.%; 0.7 wt.% C; 0.5 wt.% Nb; 0.05 wt.% La; the impurity elements are controlled as shown in Table 2. Small amounts of Al, Mn, N, etc. impurities do not cause radical changes in the properties of the alloy and are therefore not listed in Table 2. After the corresponding raw materials are weighed according to the component requirement, a vacuum induction furnace can be adopted for smelting and water-cooling iron mold casting. The method comprises the following specific steps:
mixing Fe-La2O3The powder pressed block is placed at the bottom of the furnace, and then ferrochrome, metal chromium, ferroboron, ferroniobium and pure iron are placed in the furnace. The melting temperature is 1500 ℃; after the materials are completely melted, reducing the power of the electric furnace, reducing the temperature of the melt to 1300 ℃, and deoxidizing by using pure aluminum accounting for 0.1 percent of the total amount of the ingredients; the incubation was continued for about 5 minutes. The casting temperature range was 1250 ℃. About 10 minutes after casting, the water-cooled iron mold was opened, at which point the ingot temperature was below 600 ℃ and the cooling rate from the solidification temperature to 600 ℃ was about 70 ℃/min. And air-cooling to room temperature. The integral hardness of the obtained cast ingot reaches HRC70.0, and the impact toughness reaches 8.6J/cm2The bending strength reaches 800 MPa.
Example 3 use of iron powder with La2O3After the powders are mixed evenly, the mixture is pressed into powder briquettes. La2O3The mass ratio of powder to iron powder is approximately 1:10, i.e., Fe-La forming Fe-7.75 wt.% La2O3And (4) mixing and briquetting. Used as a carrier for rare earth La modification.
Selecting high-carbon ferrochrome, micro-carbon ferrochrome, ferroboron, ferroniobium, industrial pure iron and the Fe-La2O3The mixed briquettes are taken as raw materials and have the following component ranges: cr:10.0 wt.%; b:2.7 wt.%; 0.8 wt.% C; 0.6 wt.% Nb; 0.3 wt.% La; the impurity elements are controlled as shown in Table 2. Small amounts of Al, Mn, N, etc. impurities do not cause radical changes in the properties of the alloy and are therefore not listed in Table 2. After weighing corresponding raw materials according to the component requirement, adopting induction melting and investment casting, and specifically comprising the following steps:
mixing Fe-La2O3The powder pressing block is placed at the bottom of the furnace, and then ferrochrome, metal chromium, ferroboron, ferroniobium, ferrovanadium and pure iron are placed in the furnace. The melting temperature is 1580 ℃; after the melt is completely melted, the power of the electric furnace is reduced, and the temperature of the melt is reducedAfter the temperature is lowered to 1320 ℃, pure aluminum accounting for 0.12 percent of the total amount of the ingredients is used for deoxidation; the incubation was continued for about 8 minutes. The casting temperature range was 1280 ℃. And opening the sand mold investment mold about 10 minutes after the casting is finished, wherein the ingot casting temperature is lower than 700 ℃, and the cooling rate from the solidification temperature to 700 ℃ is about 60 ℃/min. And air-cooling to room temperature. The integral hardness of the obtained cast ingot reaches HRC69.8, and the impact toughness reaches 9.6J/cm2The bending strength reaches 824 MPa.
Example 4 use of iron powder with La2O3After the powders are mixed evenly, the mixture is pressed into powder briquettes. La2O3The mass ratio of powder to iron powder is approximately 1:15, i.e., Fe-La forming Fe-5.33 wt.% La2O3And (4) mixing and briquetting. Used as a carrier for rare earth La modification.
Selecting high-carbon ferrochrome, metal chromium, ferroboron, ferroniobium, ferrovanadium, industrial pure iron and the Fe-La2O3The mixed briquettes are taken as raw materials and have the following component ranges: cr: 11.0 wt.%; b:2.7 wt.%; 0.7 wt.% C; 0.2 wt.% Nb; 0.4 wt.% V; 0.1 wt.% La; the impurity elements are controlled as shown in Table 2. Small amounts of Al, Mn, N, etc. impurities do not cause radical changes in the properties of the alloy and are therefore not listed in Table 2. After weighing corresponding raw materials according to the component requirement, adopting induction melting and sand mold casting, and specifically comprising the following steps:
mixing Fe-La2O3The powder pressing block is placed at the bottom of the furnace, and then ferrochrome, metal chromium, ferroboron, ferroniobium, ferrovanadium and pure iron are placed in the furnace. The melting temperature is 1560 ℃; after the materials are completely melted, reducing the power of the electric furnace, reducing the temperature of the melt to 1330 ℃, and deoxidizing by using pure aluminum accounting for 0.13 percent of the total amount of the ingredients; the incubation was continued for about 9 minutes. The casting temperature range was 1280 ℃. About 7 minutes after casting, the sand mold was opened, at which point the ingot temperature was below 800 ℃ and the cooling rate from the solidification temperature to 800 ℃ was about 60 ℃/min. And air-cooling to room temperature. The integral hardness of the obtained cast ingot reaches HRC68.2, and the impact toughness reaches 10.6J/cm2The bending strength reaches 896 MPa.
Example 5 iron powder with La2O3After the powders are mixed evenly, the mixture is pressed into powder briquettes. La2O3The mass ratio of the powder to the iron powder is approximately 1:12,i.e., Fe-La forming Fe-6.56 wt.% La2O3And (4) mixing and briquetting. Used as a carrier for rare earth La modification.
Selecting high-carbon ferrochrome, micro-carbon ferrochrome, ferroboron, ferroniobium, ferrovanadium, industrial pure iron and the Fe-La2O3The mixed briquettes are taken as raw materials and have the following component ranges: cr:10.0 wt.%; b: 2.6 wt.%; c: 0.6 wt.%; nb: 0.3 wt.%; v: 0.1 wt.%; 0.2 wt.% La; the impurity elements are controlled as shown in Table 2. Small amounts of Al, Mn, N, etc. impurities do not cause radical changes in the properties of the alloy and are therefore not listed in Table 2. After weighing corresponding raw materials according to the component requirement, adopting induction melting and lost foam casting, and specifically comprising the following steps:
mixing Fe-La2O3The powder pressing block is placed at the bottom of the furnace, and then ferrochrome, metal chromium, ferroboron, ferroniobium, ferrovanadium and pure iron are placed in the furnace. The melting temperature is 1550 ℃; after the materials are completely melted, reducing the power of the electric furnace, reducing the temperature of the melt to 1325 ℃, and deoxidizing by using pure aluminum accounting for 0.12 percent of the total amount of the ingredients; the incubation was continued for about 6 minutes. The casting temperature range was 1285 ℃. And opening the lost foam sand mold about 8 minutes after the casting is finished, wherein the ingot casting temperature is lower than 700 ℃, and the cooling rate from the solidification temperature to 700 ℃ is about 70 ℃/min. And air-cooling to room temperature. The integral hardness of the obtained cast ingot reaches HRC70, and the impact toughness reaches 9.5J/cm2The bending strength reaches 912 MPa.
Example 6 use of iron powder with La2O3After the powders are mixed evenly, the mixture is pressed into powder briquettes. La2O3The mass ratio of powder to iron powder is approximately 1:8, i.e., Fe-La forming Fe-9.47 wt.% La2O3And (4) mixing and briquetting. Used as a carrier for rare earth La modification.
Selecting high-carbon ferrochrome, micro-carbon ferrochrome, ferroboron, ferroniobium, industrial pure iron and the Fe-La2O3The mixed briquettes are taken as raw materials and have the following component ranges: cr:10.0 wt.%; b: 2.6 wt.%; c:0.8 wt.%; nb: 0.8 wt.%; 0.08 wt.% La; the impurity elements are controlled as shown in Table 2. Small amounts of Al, Mn, N, etc. impurities do not cause radical changes in the properties of the alloy and are therefore not listed in Table 2. Weighing corresponding raw materials according to the required proportion of components, and then adopting vacuum induction meltingSmelting and iron mold casting, which comprises the following steps:
mixing Fe-La2O3The powder pressing block is placed at the bottom of the furnace, and then ferrochrome, metal chromium, ferroboron, ferroniobium, ferrovanadium and pure iron are placed in the furnace. The melting temperature is 1590 ℃; after the materials are completely melted, reducing the power of the electric furnace, reducing the temperature of the melt to 1315 ℃, and deoxidizing by using pure aluminum accounting for 0.14% of the total amount of the ingredients; the incubation was continued for about 7 minutes. The casting temperature range was 1290 ℃. About 10 minutes after casting, the iron mold was opened, at which point the ingot temperature was below 600 ℃ and the cooling rate from the solidification temperature to 600 ℃ was about 70 ℃/min. And air-cooling to room temperature. The integral hardness of the obtained cast ingot reaches HRC69.5, and the impact toughness reaches 10.6J/cm2The bending strength reaches 912 MPa.
Example 7 iron powder with La2O3After the powders are mixed evenly, the mixture is pressed into powder briquettes. La2O3The mass ratio of powder to iron powder is approximately 1:9, i.e., Fe-La forming Fe-8.53 wt.% La2O3And (4) mixing and briquetting. Used as a carrier for rare earth La modification.
Selecting high-carbon ferrochrome, micro-carbon ferrochrome, ferroboron, ferroniobium, ferrovanadium, industrial pure iron and the Fe-La2O3The mixed briquettes are taken as raw materials and have the following component ranges: cr: 11.0 wt.%; b: 2.6 wt.%; c: 0.9 wt.%; nb:0.2 wt.%; v:0.2 wt.%; 0.18 wt.% La; the impurity elements are controlled as shown in Table 2. Small amounts of Al, Mn, N, etc. impurities do not cause radical changes in the properties of the alloy and are therefore not listed in Table 2. After the corresponding raw materials are weighed according to the component requirement, induction melting and lost foam casting can be adopted. The method comprises the following specific steps:
mixing Fe-La2O3The powder pressing block is placed at the bottom of the furnace, and then ferrochrome, metal chromium, ferroboron, ferroniobium, ferrovanadium and pure iron are placed in the furnace. The melting temperature is 1560 ℃; after the materials are completely melted, reducing the power of the electric furnace, reducing the temperature of the melt to 1340 ℃, and deoxidizing by using pure aluminum accounting for 0.13 percent of the total amount of the ingredients; the incubation was continued for about 8 minutes. The casting temperature range was 1270 ℃. About 9 minutes after casting, the lost foam mold was opened, at which point the ingot temperature was below 600 ℃ and the cooling rate from the solidification temperature to 600 ℃ was about 70 ℃/min. Air-cooled to roomAnd (4) warming. The integral hardness of the obtained cast ingot reaches HRC69.9, and the impact toughness reaches 9.9J/cm2The bending strength reaches 920 MPa.
Example 8 use of iron powder with La2O3After the powders are mixed evenly, the mixture is pressed into powder briquettes. La2O3The mass ratio of powder to iron powder is approximately 1:6, i.e., Fe-La forming Fe-12.18 wt.% La2O3And (4) mixing and briquetting. Used as a carrier for rare earth La modification.
Selecting high-carbon ferrochrome, micro-carbon ferrochrome, ferroboron, ferroniobium, ferrovanadium, industrial pure iron and the Fe-La2O3The mixed briquettes are taken as raw materials and have the following component ranges: cr: 13.0 wt.%; b: 2.6 wt.%; c:0.8 wt.%; nb:0.6 wt.%; v:0.4 wt.%; 0.42 wt.% La; the impurity elements are controlled as shown in Table 2. Small amounts of Al, Mn, N, etc. impurities do not cause radical changes in the properties of the alloy and are therefore not listed in Table 2. After weighing corresponding raw materials according to the component requirement, adopting induction melting and lost foam casting, and specifically comprising the following steps:
mixing Fe-La2O3The powder pressing block is placed at the bottom of the furnace, and then ferrochrome, metal chromium, ferroboron, ferroniobium, ferrovanadium and pure iron are placed in the furnace. The melting temperature is 1550 ℃; after the materials are completely melted, reducing the power of the electric furnace, reducing the temperature of the melt to 1330 ℃, and deoxidizing by using pure aluminum accounting for 0.12 percent of the total amount of the ingredients; the incubation was continued for about 6 minutes.
The casting temperature range was 1270 ℃. About 9 minutes after casting, the lost foam mold was opened, at which point the ingot temperature was below 700 ℃ and the cooling rate from the solidification temperature to 700 ℃ was about 60 ℃/min. And air-cooling to room temperature. The integral hardness of the obtained cast ingot reaches HRC71, and the impact toughness reaches 10.2J/cm2The bending strength reaches 896 MPa.
Example 9 iron powder and lanthanum nitrate powder were mixed uniformly and pressed into a powder compact. The mass ratio of lanthanum nitrate powder to iron powder was approximately 1:3, i.e., an Fe-lanthanum nitrate mixed compact of Fe-8.02 wt.% La was formed. Used as a carrier for rare earth La modification.
High-carbon ferrochrome, micro-carbon ferrochrome, ferroboron, ferroniobium, ferrovanadium, industrial pure iron and the Fe-lanthanum nitrate mixed briquetting are selected as raw materials, and the component ranges are as follows: 10.0 wt.% Cr; 2.9 wt.%; 0.7 wt.% C; 0.4 wt.% Nb; 0.2 wt.% V; 0.6 wt.% La; the impurity elements are controlled as shown in Table 2. Small amounts of Al, Mn, N, etc. impurities do not cause radical changes in the properties of the alloy and are therefore not listed in Table 2. After weighing the corresponding raw materials according to the required mixture ratio of the components, adopting induction melting and sand mould casting. The method comprises the following specific steps:
putting the Fe-lanthanum nitrate powder pressing block at the bottom of the furnace, and then putting ferrochrome, metal chromium, ferroboron, ferroniobium, ferrovanadium and pure iron. The melting temperature is 1620 ℃; after the materials are completely melted, reducing the power of the electric furnace, reducing the temperature of the melt to 1370 ℃, and deoxidizing by using pure aluminum accounting for 0.15 percent of the total amount of the ingredients; the incubation was continued for about 10 minutes. The casting temperature range was 1320 ℃. About 6 minutes after casting, the sand mold was opened, at which point the ingot temperature was below 800 ℃ and the cooling rate from the solidification temperature to 800 ℃ was about 70 ℃/min. And air-cooling to room temperature. The integral hardness of the obtained cast ingot reaches HRC68.3, and the impact toughness reaches 12.2J/cm2The bending strength reaches 1002 MPa.
Example 10 iron powder and lanthanum nitrate powder were mixed uniformly and pressed into a powder compact. The mass ratio of lanthanum nitrate powder to iron powder was approximately 1:9, i.e., an Fe-lanthanum nitrate mixed compact of Fe-3.21 wt.% La was formed. Used as a carrier for rare earth La modification.
Selecting high-carbon ferrochrome, metallic chromium, ferroboron, ferroniobium, industrial pure iron and the Fe-La2O3The mixed briquettes are taken as raw materials and have the following component ranges: 10.0 wt.% Cr; 2.7 wt.%; 0.7 wt.% C; 0.5 wt.% Nb; 0.04 wt.% La; the impurity elements are controlled as shown in Table 2. Small amounts of Al, Mn, N, etc. impurities do not cause radical changes in the properties of the alloy and are therefore not listed in Table 2. After the corresponding raw materials are weighed according to the component requirement, a vacuum induction furnace can be adopted for smelting and water-cooling iron mold casting. The method comprises the following specific steps:
putting the Fe-lanthanum nitrate powder pressing block at the bottom of the furnace, and then putting ferrochrome, metal chromium, ferroboron, ferroniobium and pure iron. The melting temperature is 1520 ℃; after the materials are completely melted, reducing the power of the electric furnace, reducing the temperature of the melt to 1320 ℃, and deoxidizing by using pure aluminum accounting for 0.1 percent of the total amount of the ingredients; the incubation was continued for about 5 minutes. The casting temperature is within 1260DEG C. After about 10 minutes of casting, the water-cooled iron mold was opened, at which point the ingot temperature was below 600 ℃ and the cooling rate from the solidification temperature to 600 ℃ was about 70 ℃/min. And air-cooling to room temperature. The integral hardness of the obtained cast ingot reaches HRC69.0, and the impact toughness reaches 9.6J/cm2Bending strength of 900MPa
FIG. 4 is a cast alloy structure, mainly including a primary Fe phase and a eutectic phase, wherein the eutectic phase is a eutectic structure of an Fe phase and boron and carbon compounds; FIG. 5 is EDS spectrum of matrix phase of cast alloy and analysis result, EDS can only qualitatively analyze components, and result shows that La element exists in alloy, which illustrates La element2O3The La element is alloyed with the melt to play a role in modifying the melt. .
Example 11. iron powder and lanthanum nitrate powder were mixed uniformly and then molded into a powder compact. The mass ratio of lanthanum nitrate powder to iron powder was approximately 1:5, i.e., an Fe-lanthanum nitrate mixed compact of Fe-5.35 wt.% La was formed. Used as a carrier for rare earth La modification.
Selecting high-carbon ferrochrome, micro-carbon ferrochrome, ferroboron, ferroniobium, industrial pure iron and the Fe-La2O3The mixed briquettes are taken as raw materials and have the following component ranges: cr:10.0 wt.%; b:2.7 wt.%; 0.8 wt.% C; 0.6 wt.% Nb; 0.4 wt.% La; the impurity elements are controlled as shown in Table 2. Small amounts of Al, Mn, N, etc. impurities do not cause radical changes in the properties of the alloy and are therefore not listed in Table 2. After weighing corresponding raw materials according to the component requirement, adopting induction melting and investment casting, and specifically comprising the following steps:
putting the Fe-lanthanum nitrate powder pressing block at the bottom of the furnace, and then putting ferrochrome, metal chromium, ferroboron, ferroniobium, ferrovanadium and pure iron. The melting temperature is 1580 ℃; after the materials are completely melted, reducing the power of the electric furnace, reducing the temperature of the melt to 1325 ℃, and deoxidizing by using pure aluminum accounting for 0.12 percent of the total amount of the ingredients; the incubation was continued for about 8 minutes. The casting temperature range was 1280 ℃. After about 10 minutes of casting, the sand pattern investment is opened, at which point the ingot temperature is below 700 ℃ and the cooling rate from the solidification temperature to 700 ℃ is about 60 ℃/minute. And air-cooling to room temperature. The integral hardness of the obtained cast ingot reaches HRC68.8, and the impact toughness reaches 10.2J/cm2Bending strength of 925MPa。
Example 12 iron powder and lanthanum nitrate powder were mixed uniformly and pressed into a powder compact. The mass ratio of lanthanum nitrate powder to iron powder was approximately 1:5, i.e., an Fe-lanthanum nitrate mixed compact of Fe-5.35 wt.% La was formed. Used as a carrier for rare earth La modification.
Selecting high-carbon ferrochrome, metal chromium, ferroboron, ferroniobium, ferrovanadium, industrial pure iron and the Fe-La2O3The mixed briquettes are taken as raw materials and have the following component ranges: cr: 11.0 wt.%; b:2.7 wt.%; 0.7 wt.% C; 0.2 wt.% Nb; 0.4 wt.% V; 0.2 wt.% La; the impurity elements are controlled as shown in Table 2. Small amounts of Al, Mn, N, etc. impurities do not cause radical changes in the properties of the alloy and are therefore not listed in Table 2. After weighing corresponding raw materials according to the component requirement, adopting induction melting and sand mold casting, and specifically comprising the following steps:
putting the Fe-lanthanum nitrate powder pressing block at the bottom of the furnace, and then putting ferrochrome, metal chromium, ferroboron, ferroniobium, ferrovanadium and pure iron. The melting temperature is 1600 ℃; after the materials are completely melted, reducing the power of the electric furnace, reducing the temperature of the melt to 1340 ℃, and deoxidizing by using pure aluminum accounting for 0.13 percent of the total amount of the ingredients; the incubation was continued for about 9 minutes. The casting temperature range was 1280 ℃. About 7 minutes after casting, the sand mold was opened, at which point the ingot temperature was below 800 ℃ and the cooling rate from the solidification temperature to 800 ℃ was about 60 ℃/min. And air-cooling to room temperature. The integral hardness of the obtained cast ingot reaches HRC67.5, and the impact toughness reaches 11.2J/cm2The bending strength reaches 1096 MPa.
Example 13 iron powder and lanthanum nitrate powder were mixed uniformly and pressed into a powder compact. The mass ratio of lanthanum nitrate powder to iron powder was approximately 1:6, i.e., an Fe-lanthanum nitrate mixed compact of Fe-4.58 wt.% La was formed. Used as a carrier for rare earth La modification.
High-carbon ferrochrome, micro-carbon ferrochrome, ferroboron, ferroniobium, ferrovanadium, industrial pure iron and the Fe-lanthanum nitrate mixed briquetting are selected as raw materials, and the component ranges are as follows: cr:10.0 wt.%; b: 2.6 wt.%; c: 0.6 wt.%; nb: 0.3 wt.%; v: 0.1 wt.%; 0.05 wt.% La; the impurity elements are controlled as shown in Table 2. Small amounts of Al, Mn, N, etc. impurities do not cause radical changes in the properties of the alloy and are therefore not listed in Table 2. After weighing corresponding raw materials according to the component requirement, adopting induction melting and lost foam casting, and specifically comprising the following steps:
putting the Fe-lanthanum nitrate powder pressing block at the bottom of the furnace, and then putting ferrochrome, metal chromium, ferroboron, ferroniobium, ferrovanadium and pure iron. The melting temperature is 1620 ℃; after the materials are completely melted, reducing the power of the electric furnace, reducing the temperature of the melt to 1325 ℃, and deoxidizing by using pure aluminum accounting for 0.12 percent of the total amount of the ingredients; the incubation was continued for about 6 minutes. The casting temperature range was 1285 ℃. And opening the lost foam sand mold about 8 minutes after the casting is finished, wherein the ingot casting temperature is lower than 700 ℃, and the cooling rate from the solidification temperature to 700 ℃ is about 70 ℃/min. And air-cooling to room temperature. The integral hardness of the obtained cast ingot reaches HRC68.5, and the impact toughness reaches 10.5J/cm2The bending strength reaches 1012 MPa.
Example 14. iron powder and lanthanum nitrate powder were mixed uniformly and then molded into a powder compact. The mass ratio of lanthanum nitrate powder to iron powder was approximately 1:8, i.e., an Fe-lanthanum nitrate mixed compact of Fe-3.56 wt.% La was formed. Used as a carrier for rare earth La modification.
Selecting high-carbon ferrochrome, micro-carbon ferrochrome, ferroboron, ferroniobium, industrial pure iron and the Fe-La2O3The mixed briquettes are taken as raw materials and have the following component ranges: cr:10.0 wt.%; b: 2.6 wt.%; c:0.8 wt.%; nb: 0.8 wt.%; 0.08 wt.% La; the impurity elements are controlled as shown in Table 2. Small amounts of Al, Mn, N, etc. impurities do not cause radical changes in the properties of the alloy and are therefore not listed in Table 2. After weighing corresponding raw materials according to the component requirement, adopting vacuum induction melting and iron mold casting, and specifically comprising the following steps:
putting the Fe-lanthanum nitrate powder pressing block at the bottom of the furnace, and then putting ferrochrome, metal chromium, ferroboron, ferroniobium, ferrovanadium and pure iron. The melting temperature is 1590 ℃; after the materials are completely melted, reducing the power of the electric furnace, reducing the temperature of the melt to 1335 ℃, and deoxidizing by using pure aluminum accounting for 0.14 percent of the total amount of the ingredients; the incubation was continued for about 7 minutes. The casting temperature range was 1290 ℃. After about 10 minutes of casting, the iron mold was opened, at which point the ingot temperature was below 600 ℃ and the cooling rate from the solidification temperature to 600 ℃ was about 70 ℃/min. And air-cooling to room temperature. The integral hardness of the obtained cast ingot reaches HRC68.2The impact toughness reaches 10.2J/cm2The bending strength reaches 980 MPa.
Example 15 iron powder and lanthanum nitrate powder were mixed uniformly and pressed into a powder compact. The mass ratio of lanthanum nitrate powder to iron powder was approximately 1:4, i.e., an Fe-lanthanum nitrate mixed compact of Fe-6.42 wt.% La was formed. Used as a carrier for rare earth La modification.
High-carbon ferrochrome, micro-carbon ferrochrome, ferroboron, ferroniobium, ferrovanadium, industrial pure iron and the Fe-lanthanum nitrate mixed briquetting are selected as raw materials, and the component ranges are as follows: cr: 11.0 wt.%; b: 2.6 wt.%; c: 0.9 wt.%; nb:0.2 wt.%; v:0.2 wt.%; 0.18 wt.% La; the impurity elements are controlled as shown in Table 2. Small amounts of Al, Mn, N, etc. impurities do not cause radical changes in the properties of the alloy and are therefore not listed in Table 2. After the corresponding raw materials are weighed according to the component requirement, induction melting and lost foam casting can be adopted. The method comprises the following specific steps:
putting the Fe-lanthanum nitrate powder pressing block at the bottom of the furnace, and then putting ferrochrome, metal chromium, ferroboron, ferroniobium, ferrovanadium and pure iron. The melting temperature is 1610 ℃; after the materials are completely melted, reducing the power of the electric furnace, reducing the temperature of the melt to 1340 ℃, and deoxidizing by using pure aluminum accounting for 0.13 percent of the total amount of the ingredients; the incubation was continued for about 8 minutes. The casting temperature range was 1270 ℃. About 9 minutes after casting, the lost foam mold was opened, at which point the ingot temperature was below 600 ℃ and the cooling rate from the solidification temperature to 600 ℃ was about 70 ℃/min. And air-cooling to room temperature. The integral hardness of the obtained cast ingot reaches HRC68.6, and the impact toughness reaches 8.9J/cm2The bending strength reaches 1120 MPa.
Example 16. iron powder and lanthanum nitrate powder were mixed uniformly and pressed into a powder compact. The mass ratio of lanthanum nitrate powder to iron powder was approximately 1:7, i.e., an Fe-lanthanum nitrate mixed compact of Fe-4.01 wt.% La was formed. Used as a carrier for rare earth La modification.
High-carbon ferrochrome, micro-carbon ferrochrome, ferroboron, ferroniobium, ferrovanadium, industrial pure iron and the Fe-lanthanum nitrate mixed briquetting are selected as raw materials, and the component ranges are as follows: cr: 13.0 wt.%; b: 2.6 wt.%; c:0.8 wt.%; nb:0.6 wt.%; v:0.4 wt.%; 0.32 wt.% La; the impurity elements are controlled as shown in Table 2. Small amounts of Al, Mn, N, etc. impurities do not cause radical changes in the properties of the alloy and are therefore not listed in Table 2. After weighing corresponding raw materials according to the component requirement, adopting induction melting and lost foam casting, and specifically comprising the following steps:
putting the Fe-lanthanum nitrate powder pressing block at the bottom of the furnace, and then putting ferrochrome, metal chromium, ferroboron, ferroniobium, ferrovanadium and pure iron. The melting temperature is 1600 ℃; after the materials are completely melted, reducing the power of the electric furnace, reducing the temperature of the melt to 1350 ℃, and deoxidizing by using pure aluminum accounting for 0.12 percent of the total amount of the ingredients; the incubation was continued for about 6 minutes. The casting temperature range was 1280 ℃. About 9 minutes after casting, the lost foam mold was opened, at which point the ingot temperature was below 700 ℃ and the cooling rate from the solidification temperature to 700 ℃ was about 60 ℃/min. And air-cooling to room temperature. The integral hardness of the obtained cast ingot reaches HRC69.0, and the impact toughness reaches 9.2J/cm2The bending strength reaches 1092 MPa.
Example 17 iron powder and lanthanum carbonate powder were mixed uniformly and pressed into a powder compact. The mass ratio of lanthanum carbonate powder to iron powder was approximately 1:4, i.e., an Fe-lanthanum carbonate mixed compact of Fe-12.16 wt.% La was formed. Used as a carrier for rare earth La modification.
High-carbon ferrochrome, micro-carbon ferrochrome, ferroboron, ferroniobium, ferrovanadium, industrial pure iron and the Fe-lanthanum carbonate mixed pressed block are selected as raw materials, and the component ranges are as follows: 10.0 wt.% Cr; 2.9 wt.%; 0.7 wt.% C; 0.4 wt.% Nb; 0.2 wt.% V; 0.7 wt.% La; the impurity elements are controlled as shown in Table 2. Small amounts of Al, Mn, N, etc. impurities do not cause radical changes in the properties of the alloy and are therefore not listed in Table 2. After weighing the corresponding raw materials according to the required mixture ratio of the components, adopting induction melting and sand mould casting. The method comprises the following specific steps:
putting the Fe-lanthanum carbonate powder pressed block at the bottom of the furnace, and then putting ferrochrome, metal chromium, ferroboron, ferroniobium, ferrovanadium and pure iron. The melting temperature was 1650 ℃; after the materials are completely melted, reducing the power of the electric furnace, reducing the temperature of the melt to 1360 ℃, and deoxidizing by using pure aluminum accounting for 0.15 percent of the total amount of the ingredients; the incubation was continued for about 10 minutes. The casting temperature range was 1320 ℃. About 6 minutes after casting, the sand mold was opened, at which point the ingot temperature was below 800 ℃ and the cooling rate from the solidification temperature to 800 ℃ was about 70 ℃/min. And air-cooling to room temperature. The integral hardness of the obtained cast ingot reaches HRC67.3, the impact toughness reaches 13.6J/cm2, and the bending strength reaches 1218 MPa.
FIG. 6 shows a cast alloy structure mainly including an Fe primary crystal phase and a eutectic phase, wherein the eutectic phase is a eutectic structure of an Fe phase and boron and carbon compounds.
EXAMPLE 18 iron powder and lanthanum carbonate powder were mixed uniformly and then molded into a powder compact. The mass ratio of lanthanum carbonate powder to iron powder was approximately 1:19, i.e., an Fe-lanthanum carbonate mixed compact of Fe-3.04 wt.% La was formed. Used as a carrier for rare earth La modification.
Selecting high-carbon ferrochrome, metallic chromium, ferroboron, ferroniobium, industrial pure iron and the Fe-La2O3The mixed briquettes are taken as raw materials and have the following component ranges: 10.0 wt.% Cr; 2.7 wt.%; 0.7 wt.% C; 0.5 wt.% Nb; 0.03 wt.% La; the impurity elements are controlled as shown in Table 2. Small amounts of Al, Mn, N, etc. impurities do not cause radical changes in the properties of the alloy and are therefore not listed in Table 2. After the corresponding raw materials are weighed according to the component requirement, a vacuum induction furnace can be adopted for smelting and water-cooling iron mold casting. The method comprises the following specific steps:
putting the Fe-lanthanum carbonate powder pressed block at the bottom of the furnace, and then putting ferrochrome, metal chromium, ferroboron, ferroniobium and pure iron. The melting temperature is 1550 ℃; after the materials are completely melted, reducing the power of the electric furnace, reducing the temperature of the melt to 1300 ℃, and deoxidizing by using pure aluminum accounting for 0.1 percent of the total amount of the ingredients; the incubation was continued for about 5 minutes. The casting temperature range was 1260 ℃. About 10 minutes after casting, the water-cooled iron mold was opened, at which point the ingot temperature was below 600 ℃ and the cooling rate from the solidification temperature to 600 ℃ was about 70 ℃/min. And air-cooling to room temperature. The integral hardness of the obtained cast ingot reaches HRC68.0, and the impact toughness reaches 10.7J/cm2The bending strength reaches 1000 MPa.
Example 19 iron powder and lanthanum carbonate powder were mixed uniformly and pressed into a powder compact. The mass ratio of lanthanum carbonate powder to iron powder was approximately 1:9, i.e., an Fe-lanthanum carbonate mixed compact of Fe-6.08 wt.% La was formed. Used as a carrier for rare earth La modification.
Selecting high-carbon ferrochrome, micro-carbon ferrochrome, ferroboron, ferroniobium, industrial pure iron and the Fe-La2O3The mixed briquettes are taken as raw materials and have the following component ranges: cr:10.0 wt.%; b:2.7 wt.%; 0.8 wt.% C; 0.6 wt.% Nb; 0.5 wt.% La; the impurity elements are controlled as shown in Table 2. Small amounts of Al, Mn, N, etc. impurities do not cause radical changes in the properties of the alloy and are therefore not listed in Table 2. After weighing corresponding raw materials according to the component requirement, adopting induction melting and investment casting, and specifically comprising the following steps:
putting the Fe-lanthanum carbonate powder pressed block at the bottom of the furnace, and then putting ferrochrome, metal chromium, ferroboron, ferroniobium, ferrovanadium and pure iron. The melting temperature is 1600 ℃; after the materials are completely melted, reducing the power of the electric furnace, reducing the temperature of the melt to 1320 ℃, and deoxidizing by using pure aluminum accounting for 0.12 percent of the total amount of the ingredients; the incubation was continued for about 8 minutes. The casting temperature range was 1280 ℃. And opening the sand mold investment mold about 10 minutes after the casting is finished, wherein the ingot casting temperature is lower than 700 ℃, and the cooling rate from the solidification temperature to 700 ℃ is about 60 ℃/min. And air-cooling to room temperature. The integral hardness of the obtained cast ingot reaches HRC68.8, and the impact toughness reaches 11.6J/cm2The bending strength reaches 1214 MPa.
Example 20 iron powder and lanthanum carbonate powder were mixed uniformly and pressed into a powder compact. The mass ratio of lanthanum carbonate powder to iron powder was approximately 1:14, i.e., an Fe-lanthanum carbonate mixed compact of Fe-4.05 wt.% La was formed. Used as a carrier for rare earth La modification.
Selecting high-carbon ferrochrome, metal chromium, ferroboron, ferroniobium, ferrovanadium, industrial pure iron and the Fe-La2O3The mixed briquettes are taken as raw materials and have the following component ranges: cr: 11.0 wt.%; b:2.7 wt.%; 0.7 wt.% C; 0.2 wt.% Nb; 0.4 wt.% V; 0.2 wt.% La; the impurity elements are controlled as shown in Table 2. Small amounts of Al, Mn, N, etc. impurities do not cause radical changes in the properties of the alloy and are therefore not listed in Table 2. After weighing corresponding raw materials according to the component requirement, adopting induction melting and sand mold casting, and specifically comprising the following steps:
putting the Fe-lanthanum carbonate powder pressed block at the bottom of the furnace, and then putting ferrochrome, metal chromium, ferroboron, ferroniobium, ferrovanadium and pure iron. The melting temperature is 1620 ℃; after the materials are completely melted, reducing the power of the electric furnace, reducing the temperature of the melt to 1340 ℃, and deoxidizing by using pure aluminum accounting for 0.13 percent of the total amount of the ingredients; continue to useAnd standing for about 9 minutes at the constant temperature. The casting temperature range was 1280 ℃. About 7 minutes after casting, the sand mold was opened, at which point the ingot temperature was below 800 ℃ and the cooling rate from the solidification temperature to 800 ℃ was about 60 ℃/min. And air-cooling to room temperature. The integral hardness of the obtained cast ingot reaches HRC66.2, and the impact toughness reaches 14.6J/cm2The bending strength reaches 1325 MPa.
Example 21 iron powder and lanthanum carbonate powder were mixed uniformly and pressed into a powder compact. The mass ratio of lanthanum carbonate powder to iron powder was approximately 1:12, i.e., an Fe-lanthanum carbonate mixed compact of Fe-4.68 wt.% La was formed. Used as a carrier for rare earth La modification.
High-carbon ferrochrome, micro-carbon ferrochrome, ferroboron, ferroniobium, ferrovanadium, industrial pure iron and the Fe-lanthanum carbonate mixed pressed block are selected as raw materials, and the component ranges are as follows: cr:10.0 wt.%; b: 2.6 wt.%; c: 0.6 wt.%; nb: 0.3 wt.%; v: 0.1 wt.%; 0.18 wt.% La; the impurity elements are controlled as shown in Table 2. Small amounts of Al, Mn, N, etc. impurities do not cause radical changes in the properties of the alloy and are therefore not listed in Table 2. After weighing corresponding raw materials according to the component requirement, adopting induction melting and lost foam casting, and specifically comprising the following steps:
putting the Fe-lanthanum carbonate powder pressed block at the bottom of the furnace, and then putting ferrochrome, metal chromium, ferroboron, ferroniobium, ferrovanadium and pure iron. The melting temperature is 1620 ℃; after the materials are completely melted, reducing the power of the electric furnace, reducing the temperature of the melt to 1325 ℃, and deoxidizing by using pure aluminum accounting for 0.12 percent of the total amount of the ingredients; the incubation was continued for about 6 minutes. The casting temperature range was 1285 ℃. And opening the lost foam sand mold about 8 minutes after the casting is finished, wherein the ingot casting temperature is lower than 700 ℃, and the cooling rate from the solidification temperature to 700 ℃ is about 70 ℃/min. And air-cooling to room temperature. The integral hardness of the obtained cast ingot reaches HRC69, and the impact toughness reaches 12.5J/cm2The bending strength reaches 1212 MPa.
EXAMPLE 22 iron powder and lanthanum carbonate powder were mixed uniformly and then molded into a powder compact. The mass ratio of lanthanum carbonate powder to iron powder was approximately 1:8, i.e., an Fe-lanthanum carbonate mixed compact of Fe-6.75 wt.% La was formed. Used as a carrier for rare earth La modification.
Selecting high-carbon ferrochrome, micro-carbon ferrochrome, ferroboron,Ferrocolumbium, industrially pure iron and the above Fe-La2O3The mixed briquettes are taken as raw materials and have the following component ranges: cr:10.0 wt.%; b: 2.6 wt.%; c:0.8 wt.%; nb: 0.8 wt.%; 0.38 wt.% La; the impurity elements are controlled as shown in Table 2. Small amounts of Al, Mn, N, etc. impurities do not cause radical changes in the properties of the alloy and are therefore not listed in Table 2. After weighing corresponding raw materials according to the component requirement, adopting vacuum induction melting and iron mold casting, and specifically comprising the following steps:
putting the Fe-lanthanum carbonate powder pressed block at the bottom of the furnace, and then putting ferrochrome, metal chromium, ferroboron, ferroniobium, ferrovanadium and pure iron. The melting temperature is 1590 ℃; after the materials are completely melted, reducing the power of the electric furnace, reducing the temperature of the melt to 1315 ℃, and deoxidizing by using pure aluminum accounting for 0.14% of the total amount of the ingredients; the incubation was continued for about 7 minutes. The casting temperature range was 1290 ℃. About 10 minutes after casting, the iron mold was opened, at which point the ingot temperature was below 600 ℃ and the cooling rate from the solidification temperature to 600 ℃ was about 70 ℃/min. And air-cooling to room temperature. The integral hardness of the obtained cast ingot reaches HRC68.5, and the impact toughness reaches 12.6J/cm2The bending strength reaches 1345 MPa.
Example 23 iron powder and lanthanum carbonate powder were mixed uniformly and pressed into a powder compact. The mass ratio of lanthanum carbonate powder to iron powder was approximately 1:10, i.e., an Fe-lanthanum carbonate mixed compact of Fe-5.53 wt.% La was formed. Used as a carrier for rare earth La modification.
High-carbon ferrochrome, micro-carbon ferrochrome, ferroboron, ferroniobium, ferrovanadium, industrial pure iron and the Fe-lanthanum carbonate mixed pressed block are selected as raw materials, and the component ranges are as follows: cr: 11.0 wt.%; b: 2.6 wt.%; c: 0.9 wt.%; nb:0.2 wt.%; v:0.2 wt.%; 0.56 wt.% La; the impurity elements are controlled as shown in Table 2. Small amounts of Al, Mn, N, etc. impurities do not cause radical changes in the properties of the alloy and are therefore not listed in Table 2. After the corresponding raw materials are weighed according to the component requirement, induction melting and lost foam casting can be adopted. The method comprises the following specific steps:
putting the Fe-lanthanum carbonate powder pressed block at the bottom of the furnace, and then putting ferrochrome, metal chromium, ferroboron, ferroniobium, ferrovanadium and pure iron. The melting temperature is 1610 ℃; after the melt is completely melted, the power of the electric furnace is reduced, and the melt is heatedReducing the temperature to 1340 ℃, and then deoxidizing by using pure aluminum accounting for 0.13 percent of the total amount of the ingredients; the incubation was continued for about 8 minutes. The casting temperature range was 1270 ℃. About 9 minutes after casting, the lost foam mold was opened, at which point the ingot temperature was below 600 ℃ and the cooling rate from the solidification temperature to 600 ℃ was about 70 ℃/min. And air-cooling to room temperature. The integral hardness of the obtained cast ingot reaches HRC67.9, and the impact toughness reaches 12.9J/cm2The bending strength reaches 1320 MPa.
EXAMPLE 24 iron powder and lanthanum carbonate powder were mixed uniformly and then molded into a powder compact. The mass ratio of lanthanum carbonate powder to iron powder was approximately 1:16, i.e., an Fe-lanthanum carbonate mixed compact of Fe-3.58 wt.% La was formed. Used as a carrier for rare earth La modification.
High-carbon ferrochrome, micro-carbon ferrochrome, ferroboron, ferroniobium, ferrovanadium, industrial pure iron and the Fe-lanthanum carbonate mixed pressed block are selected as raw materials, and the component ranges are as follows: cr: 13.0 wt.%; b: 2.6 wt.%; c:0.8 wt.%; nb:0.6 wt.%; v:0.4 wt.%; 0.42 wt.% La; the impurity elements are controlled as shown in Table 2. Small amounts of Al, Mn, N, etc. impurities do not cause radical changes in the properties of the alloy and are therefore not listed in Table 2. After weighing corresponding raw materials according to the component requirement, adopting induction melting and lost foam casting, and specifically comprising the following steps:
putting the Fe-lanthanum carbonate powder pressed block at the bottom of the furnace, and then putting ferrochrome, metal chromium, ferroboron, ferroniobium, ferrovanadium and pure iron. The melting temperature is 1620 ℃; after the materials are completely melted, reducing the power of the electric furnace, reducing the temperature of the melt to 1350 ℃, and deoxidizing by using pure aluminum accounting for 0.12 percent of the total amount of the ingredients; the incubation was continued for about 6 minutes. The casting temperature range was 1300 ℃. About 9 minutes after casting, the lost foam mold was opened, at which point the ingot temperature was below 700 ℃ and the cooling rate from the solidification temperature to 700 ℃ was about 60 ℃/min. And air-cooling to room temperature. The integral hardness of the obtained cast ingot reaches HRC70, and the impact toughness reaches 12.2J/cm2The bending strength reaches 1296 MPa.
The properties of the cast alloys prepared in the examples were measured as follows:
1. hardness tests were conducted on the cast metals of the examples using an HR-150A Rockwell hardness machine with a load of 150Kg, and an average value was taken after five points were hit and is shown in Table 2.
2. The impact toughness of the cast metals of the examples was tested using a JBS-300B impact tester at a range of 150J, and the average value of five samples was taken and is shown in Table 2.
3. Three-point bending tests were conducted on an electronic universal testing machine for example cast metal materials, with sample dimensions of 2X 5X 50mm rectangular test specimens with a span of 30mm, and the average bending strengths of three identically treated samples are listed in Table 2.
TABLE 2 compositions and hardness, impact toughness and flexural strength of the examples
Figure BDA0002061749710000181
Figure BDA0002061749710000191

Claims (5)

1. A lanthanum modified high-hardness alloy is characterized in that: the alloy comprises the following elements in percentage by mass: 9.0-13.0, B: 2.6-2.9, C:0.7 to 0.9, Nb: 0.4-0.8, V: 0.4-0.8, Mn content less than 0.3, La:0.03 to 0.7, S, P: not more than 0.01, and the balance of Fe, wherein C, B comprises the following components in percentage by mass: 3.3 to 3.6; C/Cr mass ratio: 0.06 to 0.08; the total mass percentage of Nb and V is as follows: 0.5 to 1.0; the casting method of the lanthanum modified high-hardness alloy comprises the following steps of:
(1) preparation of La-containing iron powder compact
Adopting iron powder and La2O3Mixing the powders, molding into powder compact, La2O3The mass ratio of the powder to the iron powder is 1: 4-20, and Fe-La with the Fe content of 4.06-17.05% La is formed2O3Mixing and briquetting; or uniformly mixing iron powder and lanthanum nitrate powder, and then molding into powder briquettes, wherein the mass ratio of the lanthanum nitrate powder to the iron powder is 1: 3-9, so as to form Fe-lanthanum nitrate mixed briquettes with Fe-3.21-8.02% of La; or uniformly mixing iron powder and lanthanum carbonate powder, and molding into powder briquettes, wherein the mass ratio of the lanthanum carbonate powder to the iron powder is 1: 4-19, and Fe-12.16-3.04 wt% is formedLa% Fe-lanthanum carbonate mixed briquetting serving as a carrier for rare earth La modification;
(2) alloy proportioning, smelting and modification treatment
Weighing corresponding raw materials according to the component requirement proportion of the Fe-Cr-B-C alloy, and then adding 0.03-0.7% of La element for modification: firstly, Fe-La is added2O3Placing a powder pressing block, a Fe-lanthanum carbonate powder pressing block or a Fe-lanthanum nitrate powder pressing block at the bottom of a furnace, then placing ferrochrome, metal chromium, ferroboron, ferroniobium, ferrovanadium and pure iron, and smelting by adopting an induction furnace to prepare alloy, wherein the melting temperature is 1500-1650 ℃; after the melt is completely melted, reducing the power of the electric furnace, and reducing the temperature of the melt to 1300-1370 ℃; deoxidizing by using pure aluminum accounting for 0.1-0.15% of the total amount of the ingredients; keeping the temperature and standing for 5-10 minutes;
(3) casting of
The casting temperature range is 1250-1320 ℃, the alloy is a deep eutectic composition, a non-equilibrium matrix structure can be formed under the common sand mold casting condition, the alloy can be cast and formed by various methods, and the cooling speed from the solidification temperature to 600 ℃ is not lower than 60 ℃/min;
la directly used for lanthanum modified high-hardness alloy2O3Mixing the powder, lanthanum nitrate and lanthanum carbonate powder with iron powder to form a powder compact serving as a La element modification carrier; utilizing Fe in Fe-Cr-B-C alloy high-temperature melt3C、Cr3C2The reduction of the isocarbides forms active La elements and reacts with C, B to form La (B, C)6The compound of (2) avoids the appearance of boride net-shaped and needle-shaped structures, promotes the formation of fine eutectic structures, and plays a role in modifying and toughening refined structures; the matrix phase of the ingot casting structure is a non-equilibrium structure strengthened by Cr, B and C with high hardness; the hard phase is a high-hardness boron and carbon compound and forms a fine eutectic structure with the matrix phase; using Fe-La2O3The hardness of the cast ingot prepared by the powder briquetting reaches HRC 68.2-71.0, and the impact toughness reaches 8.6-11.2J/cm2The bending strength reaches 800-920 MPa; the hardness of the cast ingot prepared by using the Fe-lanthanum nitrate powder pressing block reaches HRC 67.5-69.0, and the impact toughness reaches 8.9-12.2J/cm2The bending strength reaches 900-1120 MPa; using Fe-lanthanum carbonate powderThe hardness of the ingot prepared by the briquetting reaches HRC 66.2-70.0, and the impact toughness reaches 10.7-14.6J/cm2The bending strength reaches 1000-1345 MPa.
2. The method of casting a lanthanum deteriorated high hardness alloy as set forth in claim 1, characterized by comprising the steps of:
(1) preparation of La-containing iron powder compact
Adopting iron powder and La2O3Mixing the powders, molding into powder compact, La2O3The mass ratio of the powder to the iron powder is 1: 4-20, and Fe-La with the Fe content of 4.06-17.05% La is formed2O3Mixing and briquetting; or uniformly mixing iron powder and lanthanum nitrate powder, and then molding into powder briquettes, wherein the mass ratio of the lanthanum nitrate powder to the iron powder is 1: 3-9, so as to form Fe-lanthanum nitrate mixed briquettes with Fe-3.21-8.02% of La; or uniformly mixing iron powder and lanthanum carbonate powder, and then molding into a powder compact, wherein the mass ratio of the lanthanum carbonate powder to the iron powder is 1: 4-19, so as to form a Fe-lanthanum carbonate mixed compact of Fe-12.16-3.04 wt.% La, which is used as a carrier for rare earth La modification;
(2) alloy proportioning, smelting and modification treatment
Weighing corresponding raw materials according to the component requirement proportion of the Fe-Cr-B-C alloy, and then adding 0.03-0.7% of La element for modification: firstly, Fe-La is added2O3Placing a powder pressing block, a Fe-lanthanum carbonate powder pressing block or a Fe-lanthanum nitrate powder pressing block at the bottom of a furnace, then placing ferrochrome, metal chromium, ferroboron, ferroniobium, ferrovanadium and pure iron, and smelting by adopting an induction furnace to prepare alloy, wherein the melting temperature is 1500-1650 ℃; after the melt is completely melted, reducing the power of the electric furnace, and reducing the temperature of the melt to 1300-1370 ℃; deoxidizing by using pure aluminum accounting for 0.1-0.15% of the total amount of the ingredients; keeping the temperature and standing for 5-10 minutes;
(3) casting of
The casting temperature range is 1250-1320 ℃, the alloy is a deep eutectic composition, a non-equilibrium matrix structure can be formed under the common sand mold casting condition, the casting forming can be realized by various methods, and the cooling speed from the solidification temperature to 600 ℃ is not lower than 60 ℃/min.
3. The method of casting a lanthanum modified high hardness alloy as claimed in claim 2, wherein: when a large casting is prepared, the constraint of the mold is removed from the casting at the temperature of 600-800 ℃.
4. The method of casting a lanthanum modified high hardness alloy as claimed in claim 2, wherein: the iron powder in the step (1) is reduced iron powder with the purity of more than or equal to 98.5 percent and the granularity of 100 meshes, or water atomized iron powder with the purity of more than or equal to 99.0 percent and the granularity of 100 meshes, or alloy iron powder with the purity of more than or equal to 99.0 percent and the granularity of 100 meshes.
5. The method of casting a lanthanum modified high hardness alloy as claimed in claim 2, wherein: the pressing pressure of the step (1) of die forming is 100-600 MPa.
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