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    • 专利摘要:
    The present invention relates to a process for preparing an RAFM steel reinforced by nano-precipitated phase and belongs to the technical field of steel for nuclear energy. The process involves first preparing an intermediate FeTaC alloy and then preparing the steel in that order through a smelting process, a forging process, a rolling process and a heat treatment process. The process according to the present invention uses the intermediate FeTaC alloy to replace the pure metal Ta and avoids the loss on ignition of the steel due to the strong oxidizing activity of the metal Ta in the smelting process. Combined with high temperature carbon deoxidation technology to suppress the loss on ignition of the Ta element, the efficiency of Ta can reach over 90%. By optimizing the rolling process so as to promote the precipitation by uniform dispersion of high density of TaC in nano-precipitated phase, so as to produce the grain strengthening and refining effects, an ultra-fine martensite steel is obtained with a excellent high temperature creep property and neutron radiation resistance property. The creep-rupture strength of RAFM steel exceeds 5000 hours in a loaded condition at 550 ° C and 195 MPa. Figure for the abstract: Fig.
    公开号:FR3091297A1
    申请号:FR1915638
    申请日:2019-12-26
    公开日:2020-07-03
    发明作者:Yanyun Zhao；Qunying Huang；Shaojun Liu；Xiaodong Mao；Bo Huang；Yican Wu
    申请人:Hefei Institutes of Physical Science of CAS；
    IPC主号:
    专利说明:

    Description
    Title of the invention: Method for manufacturing a ferritic / martensitic steel with reduced activation reinforced by a nanoprecipitate phase.
    Reference to related requests
    The present invention claims the benefit of priority over the Chinese document ri CN 201811636716.5 filed on December 29, 2018 with the Chinese office CNIPA. Technical area
    The present invention relates to the technical field of steel intended for nuclear energy and relates particularly to a method for manufacturing a ferritic / martensitic steel with reduced activation (RAEM, Reduced Activation Eemtic / Martensitic in English) reinforced by nano-precipitated phase.
    Background
    Nuclear power is an important part of the electrical industry. Improving the safety and profitability of nuclear power remains a major problem in the development of nuclear power. The Eorum International Generation IV (GIE) has estimated that lead-based fast neutron reactors are the first fourth generation reactors for which industrial demonstration and commercial applications should be obtained while fusion reactors are energy systems which will eventually provide a solution to the energy crisis of humanity. Structural materials are a critical factor in the design of lead-based fast neutron reactors and fusion reactors. However, the operating environment of fast double neutron reactors and fusion reactors is complex and demanding, which has implications for the very high performance requirements of structural materials. First, it is necessary that the material has good resistance to high temperatures, anti-irradiation performance and a high thermal load capacity in intense neutron irradiation situations. Second, the material must have low activation characteristics; in other words, the material must be difficult to activate after neutron irradiation and have a low residual radioactivity, it must be able to be eliminated and recycled, so as to meet the requirement of a nuclear energy "clean" at l 'to come up. It is generally recognized internationally that the structural materials of innovative nuclear energy systems will need to have excellent performance such as resistance to radiation, resistance to high temperatures and low activation.
    [0005] Femtic / Martensitic Reduced Activation Steel (RAEM) is a new type of low-activation anti-irradiation steel based on a mature industrial base. RAFM steel mainly replaces Mo, Nb, Cu and Ni in common steel with W, Ta, V and Mn used to obtain a low activation property and at the same time a good swelling characteristic under anti-neutron radiation. RAFM steel is therefore generally considered to be a good candidate as a structural material used in lead-based fast neutron reactors and fusion reactors. Ta is the most easily oxidized element in the main elements of the RAFM alloy. Ta is also a microalloy element present in low content. It is difficult to precisely control the Ta content when melting RAFM steel. At present, vacuum melting and deoxidation of Al or Ce are generally used to control loss on ignition during the oxidation of the Ta element in the melting of RAFM steel. However, Al and Ce are easily activated elements and will remain so in molten steel, which easily increases the activated impurities in RAFM steel. This reduces the low activation properties of the material. This is why it is necessary to find another deoxidation process.
    Summary
    In the industrial-scale melting process, the Ta element contained in RAFM steel makes it possible to easily obtain a loss on ignition but is difficult to control precisely. The present description relates to a process for preparing a RAFM steel reinforced by nano-precipitated phase. The process uses an intermediate FeTaC alloy to replace the pure Ta metal and opts for high temperature carbon deoxidation technology to suppress the loss on ignition of the Ta element in RAFM steel during the melting process, so as to precisely control the Ta element. In parallel, combined with a reasonable rolling process, the TaC nanophase is uniformly precipitated with high density and can produce reinforcing and anchoring effects, allowing RAFM steel to achieve excellent finishing properties at high temperature.
    In order to achieve the above objective, this description opts for the following technical solutions:
    A method for preparing a RAFM steel reinforced by nano-precipitated phase in which the steel is composed of Fe, Cr, W, Ta, V, Mn and C and in which the percentage by mass of each component is a choice traditional in the field.
    (1) Manufacture of the FeTaC intermediate alloy:
    Add Fe to the melting furnace, evacuate to 0.01-0.1 Pa and then load with a high purity argon gas (purity greater than 99.999%) at 0.05-0.08 MPa; heat to 1550-1600 ° C to melt the pure Fe then add C for carbon deoxidation under vacuum; when the content of O in the water of molten Fe is less than 5 ppm, add Ta and keep hot for 1-2 hours, so as to completely deoxidize the carbon, eliminate the loss on ignition during the oxidation of l element Ta and obtain the intermediate alloy FeTaC; the composition and the percentage by mass of the intermediate alloy FeTaC are: 1-21.7% of Ta, 0.5-2% of C, the remainder consisting of Fe; C in excess in the FeTaC intermediate alloy can be used as a deoxidizer in step (2).
    Preferably, after adding Ta in step (1), an electromagnetic stirring is carried out for 10-20 minutes.
    (2) Merger process:
    Add Fe to the vacuum induction furnace, evacuate to 0.1-1 Pa and then load with high purity argon gas (purity greater than 99.999%) at 0.005-0.01 MPa; heat to 1550-1600 ° C to melt the Fe and add C to reduce O to 5-50 ppm; then add in this order Cr, W, V and the intermediate alloy FeTaC prepared in step (1) according to the indicated proportions; once the fusion is obtained, bring to a vacuum lower than IPa and maintain it for 3-10 minutes; charge with high purity argon at 0.05-0.08 MPa then add Mn, carry out electromagnetic stirring for 40-60 minutes, so as to guarantee the uniform distribution of the elements of the alloy and use C in the FeTaC intermediate alloy prepared in step (1) for deoxidation to obtain molten steel; monitor the components in the molten steel and add the metallic element, the intermediate alloying element FeTaC and C according to the test results. Once the O content in the molten steel is less than 5 ppm and each component meets the requirements, the steel is pitted at 1550-1610 ° C and poured under vacuum to obtain an ingot. The ingot is then refined under vacuum and remelted to obtain a remelted ingot which is then annealed to obtain a low-activation anti-irradiation steel ingot meeting the requirements of composition and internal structure. The temperature of the whole melting process is greater than or equal to 1550 ° C, to ensure that C has a lower Gibbs free energy for oxidation and to prevent the bonding of O and Ta through C.
    (3) Forging process:
    The steel ingot obtained in step (2) is maintained at 1100-1200 ° C for 5-8 hours then forged at 850-1050 ° C and the forging ratio is> 4: 1 to obtain a slab ; the forged slab is loaded into the annealing furnace for cooling, then the cooled slab is annealed and cooled to room temperature to obtain the annealed slab with a stable structure.
    Preferably, in step (2) and in step (3), the annealing temperature is 750-790 ° C and the holding time is 8-10 hours.
    (4) Laminating process:
    The annealed slab obtained in step (3) is heated to 1200-1250 C and maintained at this temperature for 1-3 hours to guarantee the evolution of most of the elements Ta towards a solid solution; 5-10 rough rolling mills follow at 1000-1100 ° C and the slab is rolled to a thickness of 30-80 mm to reduce the amount of precipitation of large TaC in the rolling process; the slab is then subjected to 4-6 continuous rolling passes, with an initial rolling temperature of 950-1000 C and a final rolling temperature of 750-850 ° C; air cooling is performed after rolling and the total deformation is 60% or more, and rolling at medium temperature can transform the mass precipitation of TaC with a diameter less than 20 nm to obtain a RAFM steel containing a large amount of TaC in the nano-precipitated phase.
    Preferably, the deformation of each raw rolling pass in step (4) is less than or equal to 30%.
    Preferably, the deformation of each hot continuous rolling pass in step (4) is less than or equal to 50%.
    (5) Heat treatment process: the steel containing the nano-precipitated phase obtained in step (4) is quenched and returned then cooled to room temperature to obtain a RAFM steel reinforced by nano-precipitated phase.
    Preferably, the quenching treatment of step (5) consists in: maintaining the RAFM steel containing the nano-precipitated phase obtained in step (4) at 1000 + 10 ° C for 20-40 minutes then to cool it to room temperature by spraying water;
    the steel is maintained at 1000 + 10 ° C and the TaC in the nano-precipitated phase is not fully dissolved in the solid state in austenite; the undissolved TAC phase in the solid state can effectively prevent the magnification of the austenite grains in the heat preservation stage, so as to produce a uniform fine grain structure and effectively improve the strength and hardness materials.
    Preferably, the tempering treatment in step (5) consists in: keeping the steel hot for 90-120 minutes at 740 + 10 ° C and then cooling it in air to room temperature. During the tempering process, the precipitated phase of Cr-rich M23C6 is precipitated at the limits, for example at the grain limit and the batten limit, which makes it possible to prevent the dislocation race during the high-end finishing process. temperature, thereby improving the creep resistance of the material.
    Beneficial effect
    The method according to the present invention uses T intermediate alloy EeTaC to replace the pure metal Ta and opts for the carbon deoxidation technology under vacuum at high temperature to eliminate the loss on ignition of the structural steel resulting from the significant oxidation activity of the metal Ta during the melting process. Ta efficiency can exceed 90%, achieving precise control of the Ta element in the fusion process. Combined with a reasonable rolling process, uniform high density precipitation of the very small dispersive phase is obtained such that
    Nano-sized TaC. During a reasonable heat treatment process, the nano-precipitated phase pins the newly nucleated austenite grains during the re-austenization process, thereby preventing their growth. This technology makes it possible to obtain primary austenite grains of 5-15 μιη and to improve the impact resistance of the material. At the same time, uniform high-density precipitation of TaC can effectively improve the slip resistance of dislocations during the high-temperature finishing process and increase the material's breaking-breaking strength by more than 4 times at 550 ° C. TaC can effectively prevent the growth of primary austenite grains during the heat treatment process, thereby improving the structural stability of materials in high temperature maintenance which is more suitable for the needs of future fourth generation reactors and fusion in terms of resistance to high temperatures and radiation of the material.
    The tensile strength of RAFM steel prepared according to this description is greater than 400 MPa at 600 ° C and the resistance to finage-breaking exceeds 5000 h in stress conditions of 550 ° C and 195 MPa.
    Brief description of the drawings
    [Fig.l] is a breaking curve in the finishing of the steel prepared at 550 ° C and 195 MPa according to embodiment 1 of the present invention.
    The present invention is described in detail below with reference to specific embodiments. However, the following embodiments limit the interpretation of the invention and the scope of protection of the invention includes the entire content of the claims without being limited to the present embodiment.
    The purity of the high purity argon gas of the following embodiments is greater than 99.999%.
    Embodiment 1: manufacture of 50 kilograms of RAFM steel reinforced by nano-precipitated phase
    The composition and the percentage by mass of the steel are: 9.0% by weight of Cr, 1.5% by weight of W, 0.55% by weight of Mn, 0.15% by weight of Ta, 0.2% by weight of V, 0.10% by weight of C, the remainder consisting of Fe.
    (1) Manufacture of the intermediate FeTaC alloy: add 9.85 kg of Fe blocks with a purity greater than 99.9% to the vacuum induction furnace 1, evacuate to 0.01 Pa and then load with high purity argon gas to reach 0.05 MPa; heat to 1550 ° C to melt the pure Fe and add 0.5% by weight of carbon powder for deoxidation of carbon in vacuo. When the content of O in pure molten Fe is 3 ppm, add 0.1 kg of Ta, keep warm for 1 hour before pouring. The intermediate alloy EeTaC with a Ta content of 1% by weight is prepared; the content of other unavoidable impurities is less than 5 ppm. (During the preparation of the intermediate alloy EeTaC, the compositions are added according to 98.5% of Fe, 1% of Ta, and 0.5% of C. However, during the preparation process, the actual content of C is reduced due to the deoxidation obtained using C. In the following steps, the content of the element in the alloy is adjusted according to the actual content of the molten steel.)
    (2) Fusion process: once the vacuum induction furnace 2 has been evacuated to 0.1 Pa, the high purity argon is charged at 0.005 MPa, 37 kg of Fe blocks with a purity greater than 99 , 9% are added and the temperature is raised to 1550 ° C; once the Fe has melted, carbon powder is added for deoxidation of the carbon under vacuum. When the O content in pure molten iron is 5 ppm, 4.5 kg of pure metal blocks of Cr and 0.75 kg of blocks of W are added. Once the fusion is complete, 0.1 kg of pure metal blocks of V and 7.5 kg of FeTaC intermediate alloy prepared in step (1) are added in this order. Once the fusion is obtained, bring to a vacuum lower than IPa and maintain it for 3 minutes. Charge with high purity argon at 0.05 MPa then add 0.28 kg of metal Mn, carry out electromagnetic stirring for 40 minutes, so as to guarantee the uniform distribution of the elements of the alloy and use C in the FeTaC intermediate alloy prepared in step (1) for deoxidation, to obtain molten steel. Monitor the components in the molten steel and add the metallic element, the FeTaC intermediate alloying element and the carbon powder according to the test results. Once the O content in the molten steel is less than 5 ppm and each component meets the requirements, the steel is pitted at 1550 ° C and poured under vacuum to obtain an ingot. The temperature of the whole melting process is greater than or equal to 1550 ° C, to ensure that C has a lower Gibbs free energy for oxidation and to prevent the bonding of O and Ta through C.
    (3) Refine the ingot obtained in step (2) and then remelt it under vacuum with a degree of consumable vacuum of 0.1 Pa, a voltage of 23 V and a current of 10,000 A, so as to obtain a redesigned consumable ingot. The melted consumable ingot obtained is then annealed at an annealing temperature of 750 ° C. for a holding time of 10 hours, so as to obtain a RAFM steel ingot having the required composition and internal structure.
    (4) Forging of the steel ingot obtained in step (3): the steel ingot is heated to
    1100 ° C for 8 hours then is forged and roughed at the forging temperature of 1050 ° C and the forging ratio is 5: 1. After forging, the slab is loaded into the annealing furnace so as to cool slowly. The cooled slab is then annealed at a temperature of 750 ° C for an annealing time of 10 hours and then it is air-cooled to room temperature to obtain a slab with a stable structure.
    (5) Lamination of the forged slab: heat the ingot to 1200 ° C for a holding time of 3 hours then perform 5 passes of raw rolling at 1000 ° C, the deformation of each raw rolling is 20% and the slab is laminated to a thickness of 80 mm; the slab is then rolled by 4 continuous rolling passes at 950 ° C with a final rolling temperature of 750 ° C; the deformation of each continuous rolling pass is 11% and air cooling is carried out after rolling; a RAFM steel is obtained containing a large amount of TaC in the nanoprecipitate phase. The steel is 50 mm thick.
    (6) After rolling, the RAFM steel containing a large amount of TaC in the nano-precipitated phase is thermized. Specifically, the heat treatment process includes quenching and tempering. The steel is kept at 1000 ° C for 40 minutes in a heat treatment furnace and then cooled to room temperature by spraying water after casting. The hardened steel retains heat for 120 minutes at 740 ° C in the heat treatment furnace and is then cooled in air to reach room temperature after casting. Finally, we obtain a steel reinforced by nano-precipitated phase with a martensite structure.
    The Ta content in the final material is calculated by means of a composition test and according to the quantity of Ta added during the preparation process, the calculated yield of Ta is greater than 90%.
    The structure of the steel plate obtained is observed using a transmission electron microscope. The average size of TaC is calculated by calculating the size of 200 TaC in the nano-precipitated phase. Microscopic statistical analysis shows that the average size of TaC in the nano-precipitated phase is 12 nm.
    The tensile properties of the plate obtained are tested according to ISO 6892. The results show that at room temperature, the elastic limit is 602 MPa, the tensile strength is 778 MPa and the extensibility is 21%; at 600 ° C, the yield strength is 453 MPa and the tensile strength is 578 MPa.
    The finishing properties of the steel plate obtained are tested according to ISO 204; the results indicate that the resistance to finishing-breaking is 7325 h in stress conditions of 550 ° C and 195 MPa.
    Embodiment 2: manufacture of 50 kilograms of RAFM steel reinforced by nano-precipitated phase
    The composition and the percentage by mass of the steel are: 9.0% by weight of Cr, 1.5% by weight of W, 0.55% by weight of Mn, 0.15% by weight of Ta, 0.2% by weight of V, 0.10% by weight of C, the remainder consisting of Fe.
    (1) Manufacture of the intermediate FeTaC alloy: add 1.9 kg of Fe blocks with a purity greater than 99.9% to the vacuum induction furnace 1, evacuate to 0.1 Pa and then load with high purity argon gas to reach 0.08 MPa; heat up to 1600 ° C to melt the pure Fe and add 0.04 kg of carbon powder in the molten pure Fe for vacuum carbon deoxidation. When the O content in pure molten Fe is 3 ppm, add 0.1 kg of Ta, keep warm for 2 hours before pouring; the FeTaC intermediate alloy with a Ta content of 5% by weight is prepared, the content of other impurities is less than 5 ppm.
    (2) Fusion process: once the vacuum induction furnace 2 has been evacuated to 1 Pa, the high purity argon is charged to reach 0.01 MPa, 43 kg of Fe blocks with a purity greater than 99.9% are added, the temperature is raised to 1650 ° C to melt the Fe and the carbon powder is added for the deoxidation of the carbon under vacuum. When the content of O in the pure molten iron is 50 ppm, 4.5 kg of blocks of pure metal Cr and 0.75 kg of blocks of W are added. Once the fusion is complete, 0.1 kg of blocks of pure metal V and 1.5 kg of intermediate alloy FeTaC prepared in step (1) are added in this order; once the fusion is obtained, bring to a vacuum lower than IPa and maintain it for 10 minutes. Charge with argon at 0.08 MPa then add 0.28 kg of metal Mn, carry out electromagnetic stirring for 60 minutes, so as to guarantee the uniform distribution of the elements of the alloy and use C in the intermediate alloy FeTaC prepared in step (1) for deoxidation. Monitor the components in the molten steel, add the metallic element, the FeTaC intermediate alloying element and the carbon powder according to the test results. Once the O content in the molten steel is less than 5 ppm and each component meets the requirements, the steel is pitted at 1610 ° C and poured under vacuum to obtain an ingot. The temperature of the whole melting process is greater than or equal to 1550 ° C, to ensure that C has a lower Gibbs free energy for oxidation and to prevent the bonding of O and Ta through C.
    (3) Refine the ingot obtained in step (2) and then remelt it under vacuum using a vacuum arc furnace at a vacuum degree of 0.1 Pa, a voltage of 24 V and a current of 10500 A, so as to obtain a melted consumable ingot. The melted consumable ingot obtained is then annealed at an annealing temperature of 790 ° C. for a holding time of 8 hours, so as to obtain a RAFM steel ingot having the required internal structure and composition.
    (4) Forging the ingot obtained in step (3): the steel ingot is heated at 1200 ° C for 5 hours then it is forged at the forging temperature of 1050 ° C and the forging ratio is of 5: 1. Once forged, the slab is loaded into the annealing furnace so as to cool slowly. The cooled slab is then annealed at a temperature of 790 ° C and the annealing time is 8 hours, then it is air-cooled to room temperature to obtain a slab with a stable structure.
    (5) Lamination of the forged slab: heat the ingot to 1250 ° C for a holding time of 1 hour then perform 10 passes of raw rolling at 1000 ° C, so that the slab is rolled to a thickness of 30 mm; the steel plate is then heated to 950 ° C and then rolled with 6 continuous rolling passes at the final rolling temperature of 750 ° C; the deformation of each continuous rolling is 9% and the air cooling is carried out after rolling; a RAFM steel is obtained containing a large amount of TaC in the nano-precipitated phase. The steel is 18 mm thick.
    (6) After rolling, the RAFM steel containing a large amount of TaC in the nano-precipitated phase is thermized. Specifically, the heat treatment process includes quenching and tempering. The steel is kept at 1000 ° C for 20 minutes in a heat treatment furnace and then cooled to room temperature by spraying water after casting. The hardened steel retains heat for 90 minutes at 740 ° C in the heat treatment furnace and is then air-cooled to room temperature after casting. Finally, we obtain a RAFM steel reinforced by nano-precipitated phase with a martensite structure.
    The Ta content in the final material is calculated by means of a composition test and as a function of the amount of Ta added during the preparation process, the Ta yield calculated is greater than 90%.
    The structure of the steel plate obtained is observed using a transmission electron microscope. The average size of TaC is calculated by calculating the size of 200 TaC in the nano-precipitated phase. Microscopic statistical analysis shows that the average size of TaC in the nano-precipitated phase is 14nm.
    The tensile properties of the steel plate obtained are tested according to ISO 6892. The results show that at ambient temperature, the elastic limit is 623 MPa, the tensile strength is 781 Pa and l elongation is 21%; at 600 ° C, the yield strength is 433 MPa and the tensile strength is 564 MPa.
    The finishing properties of the steel plate obtained are tested according to ISO 204: as shown in FIG. 1, the results indicate that the resistance to finishing-breaking in stress conditions is 7638 h at 550 ° C. and 195 MPa.
    Embodiment 3: manufacture of 50 kilograms of low-activation anti-irradiation steel reinforced by nano-precipitated phase
    The composition and the percentage by mass of the steel are: 9.0% by weight of Cr, 1.5% by weight of W, 0.55% by weight of Mn, 0.15% by weight of Ta, 0.2% by weight of V, 0.10% by weight of C, the remainder consisting of Fe.
    (1) Manufacture of the intermediate FeTaC alloy: add 3.9 kg of Fe blocks with a purity greater than 99.9% to the vacuum induction furnace 1, evacuate to 0.05 Pa and then load with high purity argon gas to reach 0.06 MPa; heat to 1580 ° C to melt the pure Fe and add 0.04 kg of carbon powder in the molten pure Fe for vacuum carbon deoxidation. When the O content in the
    Pure molten Fe is 3 ppm, add 0.1 kg of Ta, maintain at this temperature for
    1.5 hours before pouring; 4 kg of FeTaC intermediate alloy with a Ta content of
    2.5% by weight is prepared, the content of other impurities is less than 5 ppm.
    Fusion process: once the vacuum induction furnace has been evacuated to 0.5 Pa, the high purity argon is charged to reach 0.008 MPa, 41 kg of Fe blocks with a purity greater than 99.9% are added, the temperature is raised to 1580 ° C to melt the Fe and the carbon powder is added for the deoxidation of the carbon under vacuum. When the content of O in pure molten iron is 25 ppm, 4.5 kg of blocks of pure metal Cr and 0.75 kg of blocks of W are added. Once the fusion is complete, 0.1 kg of blocks of pure metal V and 3.75 kg of intermediate alloy FeTaC prepared in step (1) are added in this order; once the fusion is obtained, bring to a vacuum lower than IPa and maintain it for 8 minutes. Charge with argon at 0.07 MPa then add 0.28 kg of metal Mn, carry out electromagnetic stirring for 50 minutes, so as to guarantee the uniform distribution of the elements of the alloy and use C in the intermediate alloy FeTaC prepared in step (1) for deoxidation.
    (3) Refine the ingot obtained in step (2) and then melt it using a vacuum arc furnace to a degree of consumable vacuum of 0.1 Pa, a voltage of 24 V and a current of 10500 A, so as to obtain a melted consumable ingot. The ingot obtained is then annealed at an annealing temperature of 790 ° C. for a holding time of 8 hours, so as to obtain a RAFM steel ingot which has the required composition and internal structure.
    (4) Forging of the ingot obtained in step (3): the ingot is heated at 1150 ° C for 6 hours then it is forged at the forging temperature of 1000 ° C and the forging ratio is 5 : 1. After forging, the slab is loaded into the annealing furnace so as to cool slowly. The cooled slab is then annealed at a temperature of 770 ° C and the annealing time is 9 hours, then it is air-cooled to room temperature to obtain a slab with a stable structure.
    (5) Lamination of the forged slab: heat the ingot to 1220 ° C with a holding time of 2 hours then perform 8 passes of raw rolling at 1050 ° C, so that the slab is rolled to a thickness of 50 mm; the slab is then heated to 1000 ° C to perform 5 continuous rolling passes at the final rolling temperature of 800 ° C; the deformation of each continuous rolling is 10% and air cooling is carried out after rolling; a RAFM steel is obtained containing a large amount of TaC in the nano-precipitated phase. The steel is 30 mm thick.
    (6) After rolling, the RAFM steel containing a large amount of TaC in the nano-precipitated phase is thermized. Specifically, the heat treatment process includes quenching and tempering. The steel is kept at 1000 ° C for 30 minutes in a heat treatment furnace and then cooled to room temperature by spraying water after casting. The hardened steel then retains heat for 100 minutes at 740 ° C in the heat treatment furnace and is then air-cooled to room temperature after casting. Finally, we obtain a RALM steel reinforced by nano-precipitated phase with martensite structure.
    The Ta content in the final material is calculated by means of a composition test and as a function of the amount of Ta added during the preparation process, the calculated yield of Ta is greater than 90%.
    The structure of the steel plate obtained is observed by means of a transmission electron microscope. The average size of TaC is calculated by calculating the size of 200 TaC in the nano-precipitated phase. Microscopic statistical analysis shows that the average size of TaC in the nano-precipitated phase is 12 nm.
    The tensile properties of the steel plate obtained are tested according to ISO 6892. The results show that at ambient temperature, the elastic limit is 617 MPa, the tensile strength is 774 Pa and l elongation is 20%; at 600 ° C, the yield strength is 419 MPa and the tensile strength is 571 MPa.
    The creep properties of the steel plate obtained are tested according to ISO 204: the results show that the creep-rupture strength is 8124 h in stress conditions of 550 ° C and 195 MPa.
    The foregoing is only a few specific embodiments of the present invention, but the scope of protection of the present invention is not limited to it. Any variation or replacement readily apparent to those skilled in the art, within the technical scope of the invention, is covered by the present invention.
    权利要求:
    Claims (4)
    [1" id="c-fr-0001]
    [Claim 1]
    Claims
    Process for manufacturing a nanoprecipitated phase reinforced RAFM steel, in which the steel consists of Fe, Cr, W, Ta, V, Mn and C, the process comprising:
    (1) the manufacture of an intermediate FeTaC alloy: add Fe to the vacuum induction furnace, evacuate at 0.01-0, IPa then charge with an argon gas at 0.05-0.08 MPa; heat to 1550-1600 ° C to melt the Fe then add C for carbon deoxidation under vacuum; when the O content is less than 5 ppm, add Ta and keep hot for 1-2 hours, so as to obtain an intermediate alloy FeTaC; the composition and the percentage by mass of the intermediate alloy FeTaC are: 1-21.7% of Ta, 0.5-2% of C, the remainder consisting of Fe;
    [2" id="c-fr-0002]
    (2) melting process: add Fe to a vacuum induction furnace, evacuate to 0.1-1 Pa then charge with an argon gas at 0.005-0.01 MPa; heat to 1550-1650 ° C to melt the Fe and add C for carbon deoxidation in vacuo until the O content is 5-50 ppm; then add in this order Cr, W, V and Γ FeTaC intermediate alloy prepared in step (1); once the fusion has been achieved, bring to a vacuum lower than IPa and maintain in this state for 3-10 minutes; charge with argon at 0.05-0.08 MPa then add Mn, carry out electromagnetic stirring for 40-60 minutes to obtain a molten steel; add the metallic element, the intermediate alloy element FeTaC and C by monitoring the components in the molten steel; once the O content in the molten steel is less than 5 ppm and each component meets the requirements, the steel is pitted at 1550-1610 ° C and poured under vacuum to obtain an ingot; the ingot is refined, remelted under vacuum and then annealed to obtain a steel ingot;
    [3" id="c-fr-0003]
    (3) forging process: the steel ingot obtained in step (2) is maintained at 1100-1200 ° C for 5-8 hours then forged at a temperature of 850-1050 ° C and with a higher forging ratio at 4: 1, loaded into the annealing furnace for cooling, then once cooled, the steel ingot is annealed and air cooled to room temperature to obtain a slab;
    [4" id="c-fr-0004]
    (4) rolling process: the slab obtained in step (3) is heated to 1200-1250 ° C and maintained for 1-3 hours, subjected to 5-10 passes of raw rolling at 1000-1100 ° C to obtain a slab of a
    thickness of 30-80 mm then subjected to 4-6 continuous rolling passes, the initial rolling temperature is 950-1000 ° C and the final rolling temperature is 750-850 ° C; air cooling is carried out after rolling, the total deformation is 60% or more and a RAFM steel is obtained containing a TaC in the nano-precipitated phase;(5) heat treatment process: the RAFM steel containing the nano-precipitated phase obtained in step (4) is quenched and annealed then cooled to room temperature to obtain a RAFM steel reinforced by nano-precipitated phase. [Claim 2] A method of manufacturing a nanoprecipitated phase-reinforced RAFM steel according to claim 1, wherein, after adding Ta in step (1), electromagnetic stirring is carried out for 10-20 minutes. [Claim 3] A method of manufacturing a nanoprecipitated phase-reinforced RAFM steel according to claim 1, wherein during the annealing treatment of step (2) and step (3), the annealing temperature is 750-790 ° C and the holding time is 8-10 hours. [Claim 4] A method of manufacturing a nanoprecipitated phase-reinforced RAFM steel according to claim 1, wherein the deformation of each raw rolling in step (4) is less than or equal to 30%. [Claim 5] The method of manufacturing a nanoprecipitated phase-reinforced RAFM steel according to claim 1, wherein the deformation of each continuous hot rolling in step (4) is less than or equal to 50%. [Claim 6] Method for manufacturing a nanoprecipitated phase reinforced RAFM steel according to claim 1, in which the quenching treatment in step (5) consists in: maintaining the RAFM steel containing the nanoprecipitated phase obtained in step (4) at 1000 + 10 ° C for 20-40 minutes and then cool it to room temperature with water. [Claim 7] A method of manufacturing a nanoprecipitated phase-reinforced RAFM steel according to claim 1, wherein the tempering treatment in step (5) consists in: keeping the hardened RAFM steel hot for 90-120 minutes at 740 + 10 ° C then cool it in air to room temperature.
    1/1
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    同族专利:
    公开号 | 公开日
    CN109594009A|2019-04-09|
    CN109594009B|2021-02-26|
    引用文献:
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    CN111519108B|2020-06-09|2021-03-12|西安建筑科技大学|Zirconium-reinforced low-activation martensitic steel and preparation method thereof|
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    法律状态:
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    2021-11-19| PLSC| Publication of the preliminary search report|Effective date: 20211119 |
    2021-12-27| PLFP| Fee payment|Year of fee payment: 3 |
    优先权:
    申请号 | 申请日 | 专利标题
    CN2018116367165|2018-12-29|
    CN201811636716.5A|CN109594009B|2018-12-29|2018-12-29|Preparation method of nano precipitated phase reinforced anti-irradiation low-activation steel|
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