WO2019062741A1 - 一种超超临界火电机组用钢及其制备方法 - Google Patents

一种超超临界火电机组用钢及其制备方法 Download PDF

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WO2019062741A1
WO2019062741A1 PCT/CN2018/107521 CN2018107521W WO2019062741A1 WO 2019062741 A1 WO2019062741 A1 WO 2019062741A1 CN 2018107521 W CN2018107521 W CN 2018107521W WO 2019062741 A1 WO2019062741 A1 WO 2019062741A1
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steel
ultra
thermal power
power unit
supercritical thermal
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French (fr)
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骆素珍
张忠铧
罗明
翟国丽
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宝山钢铁股份有限公司
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Priority to DE112018005465.9T priority patent/DE112018005465T5/de
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    • 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
    • C—CHEMISTRY; METALLURGY
    • C21—METALLURGY OF IRON
    • C21D—MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUS METALS OR ALLOYS; MAKING METAL MALLEABLE, e.g. BY DECARBURISATION OR TEMPERING
    • C21D6/00—Heat treatment of ferrous alloys
    • C21D6/002—Heat treatment of ferrous alloys containing Cr
    • C—CHEMISTRY; METALLURGY
    • C21—METALLURGY OF IRON
    • C21D—MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUS METALS OR ALLOYS; MAKING METAL MALLEABLE, e.g. BY DECARBURISATION OR TEMPERING
    • C21D1/00—General methods or devices for heat treatment, e.g. annealing, hardening, quenching or tempering
    • C21D1/18—Hardening; Quenching with or without subsequent tempering
    • C—CHEMISTRY; METALLURGY
    • C21—METALLURGY OF IRON
    • C21D—MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUS METALS OR ALLOYS; MAKING METAL MALLEABLE, e.g. BY DECARBURISATION OR TEMPERING
    • C21D1/00—General methods or devices for heat treatment, e.g. annealing, hardening, quenching or tempering
    • C21D1/26—Methods of annealing
    • C21D1/28—Normalising
    • 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
    • C22C38/001—Ferrous alloys, e.g. steel alloys containing N
    • C—CHEMISTRY; METALLURGY
    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22C—ALLOYS
    • C22C38/00—Ferrous alloys, e.g. steel alloys
    • C22C38/02—Ferrous alloys, e.g. steel alloys containing silicon
    • C—CHEMISTRY; METALLURGY
    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22C—ALLOYS
    • C22C38/00—Ferrous alloys, e.g. steel alloys
    • C22C38/04—Ferrous alloys, e.g. steel alloys containing manganese
    • C—CHEMISTRY; METALLURGY
    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22C—ALLOYS
    • C22C38/00—Ferrous alloys, e.g. steel alloys
    • C22C38/06—Ferrous alloys, e.g. steel alloys containing aluminium
    • C—CHEMISTRY; METALLURGY
    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22C—ALLOYS
    • C22C38/00—Ferrous alloys, e.g. steel alloys
    • C22C38/18—Ferrous alloys, e.g. steel alloys containing chromium
    • C22C38/20—Ferrous alloys, e.g. steel alloys containing chromium with copper
    • C—CHEMISTRY; METALLURGY
    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22C—ALLOYS
    • C22C38/00—Ferrous alloys, e.g. steel alloys
    • C22C38/18—Ferrous alloys, e.g. steel alloys containing chromium
    • C22C38/22—Ferrous alloys, e.g. steel alloys containing chromium with molybdenum or tungsten
    • C—CHEMISTRY; METALLURGY
    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22C—ALLOYS
    • C22C38/00—Ferrous alloys, e.g. steel alloys
    • C22C38/18—Ferrous alloys, e.g. steel alloys containing chromium
    • C22C38/24—Ferrous alloys, e.g. steel alloys containing chromium with vanadium
    • 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
    • C22C38/30—Ferrous alloys, e.g. steel alloys containing chromium with cobalt

Definitions

  • the invention belongs to the technical field of heat-resistant steel, and particularly relates to a steel for ultra-supercritical thermal power unit and a preparation method thereof, and more particularly to an ultra-supercritical thermal power unit steel with high steam corrosion resistance and high temperature creep performance and Preparation.
  • Nickel-based superalloys have excellent high temperature strength and resistance to steam corrosion. They have been successfully used in high temperature fields such as aircraft engines and steam turbine blades. They can be used for high temperature components of higher efficiency generator sets above 650 °C, but the design of the unit. There is a gradual development process. In the temperature range of 600-650 °C, the use of nickel-based alloys is too expensive, and the price factor restricts the application of nickel-based alloys. Austenitic heat-resistant steels also have high high-temperature strength between 620 and 650 °C, but their thermal expansion coefficient and thermal conductivity are not high, and they have been popularized and applied in thermal power units.
  • the commercially available martensitic heat-resistant steel T/P92 can be used up to 620 ° C, but there is still no mature economical martensitic heat-resistant steel in the world that can reach an upper limit of 650 ° C. This temperature almost reaches the extreme temperature of martensitic/ferritic heat-resistant steel, and the research on strengthening mechanism and the difficulty in research and development of steel grades have unprecedented challenges.
  • U.S. Patent No. 5,591,391 A discloses the ability to produce materials for use in the field of thermal power generation with improved high temperature creep properties and good weldability and resistance to vapor oxidative corrosion. From the perspective of the disclosed composition, it utilizes high Cr, W and Co fortification. The principle also adds rare elements such as Rd and Ta, which contain N in the range of 0.02 to 0.12%. For ferritic heat resistant steel, this is a very high N content, which will bring production and processing. Extremely difficult, and N in addition to V and Nb reaction to form a nitride, the remaining N will also consume a large amount of Cr, W, weakening its solid solution strengthening effect.
  • the object of the present invention is to provide a steel for an ultra-supercritical thermal power unit and a preparation method thereof, which has good resistance to steam corrosion oxidation and high temperature and long-lasting creep performance, and the specific performance is extrapolated at 620-650 ° C for 100,000 hours.
  • the invention is based on the composite synergistic strengthening theory of solid solution strengthening, precipitate strengthening, dislocation strengthening and substructure strengthening of heat resistant steel, fully utilizing solid solution strengthening of Cr, W and Co, stacking fault strengthening of Co and Cu, Cr, V, The dispersion strengthening effect of fine precipitates of Nb, C, N, and the pinning strengthening effect of B at the grain boundary and the boundary between the carbide and the matrix.
  • the specific technical solutions are as follows:
  • the steel for ultra-supercritical thermal power unit has a chemical composition mass percentage of: 8.0 to 10.0%, W: 2.0 to 3.2%, Co: 2.0 to 4.0%, V: 0.1 to 0.3%, and Nb: 0.01 to 0.1. %, B: 0.006 to 0.018%, Cu: 0.2 to 1.0%, Mn: 0.2 to 1.0%, Al: 0.005 to 0.08%, Si: 0.1 to 0.8%, C: 0.06 to 0.12%, and N: 0.003 to 0.010% , P ⁇ 0.02%, S ⁇ 0.01%, Ni ⁇ 0.01%, Re ⁇ 0.01%, Ti ⁇ 0.01%, the balance is Fe and unavoidable impurities, the total amount of unavoidable impurities ⁇ 0.015%, and the above elements are required At the same time, the following relationship is satisfied: 1.6 ⁇ (Cr + 1.4 W + 1.5 Si + 2 Nb + 2 V) / (Co + Cu + 0.3 Mn + 30 C + 20 N) ⁇ 3.2, 0.6
  • V 0.15 to 0.25%.
  • Nb 0.05-0.09%.
  • the chemical composition of the steel for the ultra-supercritical thermal power unit Cu: 0.2 to 0.5%.
  • Mn 0.3 to 0.8%.
  • Si 0.2 to 0.6%.
  • N 0.005 to 0.008%.
  • the steel for the ultra-supercritical thermal power unit is extrapolated at 620-650 ° C for 100,000 hours of permanent strength ⁇ 100 MPa, and the weight gain of steam oxidation corrosion at 650 ° C for 1000 hours is ⁇ 18 mg / cm 2 .
  • the ultra-supercritical thermal power unit steel further has one or more of the following properties: strength Rp 0.2 ⁇ 600 MPa, tensile strength Rm ⁇ 800 MPa, elongation A 50 ⁇ 15%; Impact energy ⁇ 25J at 25°C, impact energy ⁇ 15J at -20°C; yield strength Rp0.2 ⁇ 250MPa at high temperature 600 ⁇ 675°C, tensile strength Rm ⁇ 290MPa, elongation A 50 ⁇ 20%;650°C,120MPa
  • the permanent rupture time is ⁇ 15600h; and the coefficient of thermal expansion is 10-15 ⁇ 10 -6 K.
  • the ultra-supercritical thermal power unit steels described herein have all of the above properties.
  • Cr:Cr element improves the hardenability of steel; it has the effect of solid solution strengthening, and the carbide precipitation and precipitation strengthening formed by Cr and C is the main strengthening phase in steel, which is beneficial to the high temperature and long-term creep property of steel;
  • the Cr element can form a continuous Cr 2 O 3 or (CrFe) 3 O 4 oxide film on the surface of the heat resistant steel, which can impart good resistance to high temperature steam oxidation corrosion of the heat resistant steel.
  • the Cr content is too low, it will not have the solid solution strengthening and precipitation strengthening effect, and the surface of the material is not enough to form a continuous Cr 2 O 3 or (CrFe) 3 O 4 film, which is not conducive to the high temperature steam resistance of the material. Corrosion performance.
  • the present invention controls the Cr content to be 8.0 to 10%, preferably 8.5 to 9.5%.
  • the W:W element has a large atomic radius, it causes a large lattice distortion in the matrix, which plays a significant solid solution strengthening effect than Mo. At the same time, W can also form a precipitate of carbonitride precipitates and diffuse. The role of precipitation strengthening. This is very advantageous for the creep properties and long-term strength of heat-resistant steels above 620 °C. If the W content is too low, a sufficient amount of strengthening phase cannot be formed. However, if the W content is too high, W promotes the generation of a high-temperature ⁇ ferrite phase, and produces a brittle phase such as ⁇ of W, resulting in deterioration of long-term high-temperature properties of the material. Therefore, the present invention should control the W content to be 2.0 to 3.2%, preferably 2.5 to 3.0%.
  • Co element can play a role of solid solution strengthening in steel.
  • Co can reduce the solubility of Ti and Al in steel matrix, change the solubility of Cr and C in steel, and enhance the solid solution strengthening effect of Cr in steel.
  • Co reduces the stacking fault energy of the metal matrix and acts as a stacking fault strengthening, and Co can suppress the generation of the high temperature ⁇ ferrite phase. Therefore, the addition of Co can significantly improve the creep resistance of the alloy and improve the steel. Hot workability and resistance to high temperature corrosion. If Co is added too little, it will not achieve the desired effect, but Co is a rare precious metal. If it is added too much, the steel will lose its competitive advantage. Therefore, the present invention controls the Co content to be 2.0 to 4.0%, preferably 2.5 to 3.5%.
  • V:V improves the high temperature creep rupture strength of the material.
  • V can form fine nitrides and/or carbonitrides in the steel. If the V content is too low, the desired effect is not obtained, and excessive addition of V may cause coarse carbonitrides and coarse grain crystals of the surface oxide to lower the resistance to steam corrosion. Therefore, the present invention controls the V content to be 0.1 to 0.3%, preferably 0.15 to 0.25%.
  • Nb is a stabilizing element of C and N, and can form a carbonitride of Nb, which has an effect of precipitation strengthening, and has a similar effect to V.
  • the present invention controls the Nb content to be 0.01 to 0.1%, preferably 0.05 to 0.08%.
  • B The addition of B element can strengthen the grain boundary, and can occupy the vacancies near the carbide, inhibit its growth, and stabilize the structure. If the B content is too low, the required strengthening effect will not be obtained, but if the B content is too high, the hot workability and weldability of the material will be seriously deteriorated. Therefore, the present invention controls the B content to be between 0.006 and 0.018%, preferably between 0.008 and 0.013%.
  • the N:N element is an austenite forming element.
  • a certain amount of N can inhibit the formation of high-temperature ⁇ ferrite in steel in combination with other austenite forming elements, and can form a fine dispersive distribution with other elements such as Nb and V.
  • Nitrides the stability of these nitrides is much higher than the carbide or carbonitride of the corresponding alloy.
  • the present invention controls the N content to be between 0.003 and 0.01%, preferably between 0.005 and 0.008%.
  • the C:C element can form carbides with elements such as Cr, V, Nb, and W, and enhances the heat strength of the material by means of dispersion strengthening.
  • elements such as Cr, V, Nb, and W
  • the C:C element can form carbides with elements such as Cr, V, Nb, and W, and enhances the heat strength of the material by means of dispersion strengthening.
  • the carbide is too low, the amount of precipitated carbide is small, the desired strengthening effect is not achieved, and the second brittle temperature interval of the steel can be moved to the high temperature range, which is disadvantageous for hot working.
  • High C content is beneficial to suppress the formation of high temperature ⁇ ferrite and improve the thermoplasticity of the second brittle temperature zone of the material; however, excessive C content may lead to excessive precipitation of carbides and excessive solid solution strengthening elements. As a result, the overall long-lasting creep performance is degraded, and in addition, too high a C content is detrimental to the welding performance. Therefore, the present invention controls C to 0.06 to
  • Si:Si can improve the resistance of the material to high temperature steam oxidation corrosion, but the Si is too high, which is unfavorable to the impact toughness of the material.
  • Si will promote the precipitation of the brittle phase, which is not conducive to the long-term creep performance.
  • Excessive Si can deteriorate the thermoplasticity of the first high temperature brittle temperature zone of the material, which is detrimental to the thermal processing of the material. Therefore, the present invention controls the Si content to be 0.1 to 0.8%, preferably 0.2 to 0.6%.
  • Cu is an austenite forming element, which can prevent the production of ⁇ ferrite in steel.
  • the addition of Cu can improve the resistance of steel to high temperature steam oxidation corrosion.
  • the present invention controls the Cu content to be 0.2 to 1.0%, preferably 0.2 to 0.5%.
  • Mn is an austenite forming element, which suppresses the formation of high-temperature ⁇ ferrite. At the same time, Mn stabilizes P and S elements, avoids the formation of low-melting sulfides, and improves the hot workability of materials. However, the Mn content is too low, and P and S cannot be stabilized well, and the desired effect is not obtained. The Mn content is too high, which is not conducive to the impact toughness of the material and reduces the high temperature creep rupture strength of the steel. Therefore, the present invention controls the Mn content to be 0.2 to 1.0%, preferably 0.3 to 0.8%.
  • Al has a significant effect on improving the high temperature steam oxidation corrosion resistance of steel, but Al easily combines with N in steel to form AlN, which is disadvantageous to the high temperature creep property of the material. Therefore, in the present invention, Al is not added as an alloying element. However, in general, smelting adopts Al deoxidation or Al, Si composite deoxidation, and Al as a residual element. Therefore, it is necessary to strictly control the content of Al in the production process, and the content thereof is preferably controlled to be 0.005 to 0.08%, preferably 0.01 to 0.05%.
  • P, S is the raw material of steel or the impurity element introduced in the production process.
  • P can embrittle the grain boundary and deteriorate the toughness and processing property of the material.
  • the S element forms a low melting point sulfide, which degrades the material processing properties as well as its own mechanical properties.
  • the P and S elements can promote high temperature steam oxidation corrosion, and the heat resistant steel has a reduced ability to resist steam corrosion. Therefore, P and S should be controlled at P ⁇ 0.02%, S ⁇ 0.01%, preferably controlled at P ⁇ 0.01%, and S ⁇ 0.005%.
  • Re, Ti, Ni and other elements are not added as alloying elements.
  • Re element can improve the steam corrosion resistance of the material and improve the thermoplasticity, etc., but in the actual smelting production process, the rare earth is easy to form rare earth oxide inclusions, resulting in high temperature creep. The crack nucleates here, which in turn reduces the creep rupture strength of the steel.
  • Ti easily forms a TiN with Ti, and TiN needs to be dissolved at an extremely high temperature. Once formed, it is not easily controlled by heat treatment. Studies have shown that Ni has an adverse effect on the long-term strength of ferritic heat-resistant steel. Therefore, in the case of large-scale production, the production of concentrates cannot be strictly controlled, such as Ni, Ti and Re in the raw materials. The content of Ti, Re and Re should be controlled below 0.01%.
  • the steel of the present invention may also contain other unavoidable impurity elements, such as residues derived from raw materials and slag, refractory materials, etc. during the manufacturing process, such as harmful elements such as Sn, Pb, As, Sb and Zn. It must also be strictly controlled, and the total amount cannot exceed 0.015%.
  • unavoidable impurity elements such as residues derived from raw materials and slag, refractory materials, etc. during the manufacturing process, such as harmful elements such as Sn, Pb, As, Sb and Zn. It must also be strictly controlled, and the total amount cannot exceed 0.015%.
  • the invention In order to control the adverse effects of high-temperature ⁇ ferrite on the manufacturing performance and the high-temperature creep rupture strength, the invention also fully considers the control of the ferrite equivalent and the austenite equivalent ratio in the composition design, and avoids or reduces the source from the source.
  • the high temperature delta ferrite has a quality risk such as cracking during the manufacturing process, and ensures that the steel of the present invention obtains a single tempered martensite structure under the following manufacturing method. Therefore, the alloy composition of the steel of the present invention should also satisfy the following relationship:
  • the invention utilizes the grain boundary strengthening of B and the effect of inhibiting the growth of carbides, thereby improving the high temperature performance of the material.
  • N is added in excess, it will combine with B to form BN, which consumes the B element and does not function as it should. Therefore, in the design of the composition of the present invention, the unified control of B/N is fully considered, and the chemical composition thereof should also satisfy the following relationship: 0.6 ⁇ B / N ⁇ 6, preferably 1 ⁇ B / N ⁇ 3.
  • the chemical composition of the ultra-supercritical thermal power unit described herein meets one or more of the following characteristics: Cr: 8.5 to 9.5%; W: 2.5 to 3.0%; Co: 2.5 ⁇ 3.5%; V: 0.15 to 0.25%; Nb: 0.05 to 0.09%; B: 0.008 to 0.013%; Cu: 0.2 to 0.5%; Mn: 0.3 to 0.8%; Al: 0.01 to 0.05%; Si: 0.2 to 0.6%; C: 0.08 to 0.10%; N: 0.005 to 0.008%; and 1 ⁇ B/N ⁇ 3.
  • Cr 8.5 to 9.5%
  • W 2.5 to 3.0%
  • Co 2.5 to 3.5%
  • V 0.15 to 0.25. %
  • Nb 0.05 to 0.09%
  • B 0.008 to 0.013%
  • Cu 0.2 to 0.5%
  • Mn 0.3 to 0.8%
  • Al 0.01 to 0.05%
  • Si 0.2 to 0.6%
  • C 0.08 to 0.10%
  • N 0.005 to 0.008%
  • the method for preparing steel for ultra-supercritical thermal power unit of the present invention comprises the following steps:
  • the ingot is smelted by vacuum induction furnace, and then the ingot is heated and heated at 1000-1180 ° C for 1 to 6 hours, and then deformed at a high temperature between 920 and 1150 ° C to be processed into a desired size;
  • Normalizing treatment Normalizing temperature 1000 ⁇ 1140 °C, heat preservation for 0.5 to 4 hours, air cooling to room temperature.
  • Tempering treatment tempering temperature 700 ⁇ 820 ° C, heat preservation for 1 to 5 hours, air cooling to room temperature.
  • the above component system designed by the invention has the steel ingot in the first brittle temperature region when the heating temperature is >1200 ° C, and the steel ingot is in the second brittle temperature region when the heating temperature is ⁇ 900 ° C.
  • the heating temperature of the ingot is selected in the invention is 1000 to 1180 ° C, to avoid The problem that the first brittle temperature zone and the second brittle temperature zone of steel in the hot working are too low in thermoplasticity.
  • the present invention performs normalizing treatment in a temperature range of 1000 to 1140 ° C and tempering in a temperature range of 700 to 820 ° C to obtain an optimum effect of precipitation strengthening, dislocation, and slab substructure strengthening of the steel of the present invention. Therefore, in order to ensure sufficient high temperature endurance, the present invention performs the above final heat treatment.
  • the steel produced by the invention has good room temperature mechanical properties, high temperature mechanical properties, and excellent high temperature long-lasting creep strength and high temperature steam corrosion resistance.
  • the specific performance indexes are as follows: room temperature mechanical properties are yield strength Rp0.2 ⁇ 600MPa , tensile strength Rm ⁇ 800MPa, elongation A 50 ⁇ 15%; impact energy ⁇ 25J at 20-25°C, impact energy ⁇ 15J at -20°C; mechanical properties at high temperature 600 ⁇ 675°C: yield strength Rp0.2 ⁇ 250MPa, tensile strength Rm ⁇ 290MPa, elongation A 50 ⁇ 20%; 650°C, 120MPa permanent fracture time ⁇ 15600h; 650°C steam oxidation corrosion 1000hour weight gain is not higher than 18mg/cm 2 , at 620 ⁇ 650 °C extrapolated 100,000 hours long-lasting strength of 100MPa or more, thermal expansion coefficient of 10 ⁇ 15 ⁇ 10 -6 K; at the same time has good manufacturability, especially suitable for the
  • the chemical composition of the steel of the invention optimizes the content of Cu element, does not add rare earth elements, reduces the difficulty of controlling non-metallic inclusions in the smelting process, and reduces the N content, thereby ensuring the impact toughness and welding of the steel. performance.
  • the chemical composition also needs to satisfy: 1.6 ⁇ (Cr + 1.4W + 1.5Si + 2Nb + 2V) / (Co + Cu + 0.3Mn + 30C + 20N) ⁇ 3.2, and 0.6 ⁇ B / N ⁇ 6.
  • the chemical composition system combined with the heating process provided by the invention can well control the formation of high temperature delta ferrite in steel, improve the thermoplasticity of steel, reduce heat The risk of processing defects is formed while ensuring the high temperature and long-term creep properties of the steel.
  • Figure 1 is a schematic view showing the high temperature thermoplasticity of steels of Example 3 and Example 10 at different temperatures.
  • Table 1 shows the compositions of the steels and comparative steels of the examples of the present invention
  • Table 2 shows the key preparation process parameters of the steels of the examples of the present invention and the comparative steels
  • Table 3 shows the overall performance of the steels of the examples of the present invention and the comparative steels.
  • the room temperature mechanical properties of the steel for ultra-supercritical thermal power unit obtained by the present invention are: yield strength Rp0.2 ⁇ 600MPa, tensile strength Rm ⁇ 800MPa, elongation A 50 ⁇ 15%; impact at 20 ⁇ 25°C Work ⁇ 25J, impact energy ⁇ 15J at -20°C; mechanical properties at high temperature 600 ⁇ 675°C: yield strength Rp0.2 ⁇ 250MPa, tensile strength Rm ⁇ 290MPa, elongation A 50 ⁇ 20%;650°C,120MPa
  • the long-term rupture time is ⁇ 15600h; the weight gain of steam oxidation corrosion at 650°C for 1000 hours is not higher than 18mg/cm 2 .
  • the steel plate has excellent high-temperature long-term creep strength and high-temperature steam corrosion resistance, and has good manufacturability, and is particularly suitable for manufacturing boiler tubes or other heat-resistant equipment of ultra-supercritical thermal power units.
  • the above-mentioned component system of the present invention is in the first brittle temperature zone when the heating temperature is >1250 ° C, and the steel ingot is in the second brittle temperature zone when the heating temperature is ⁇ 900 ° C, and the ingot heating temperature is set to 1000 to 1180 ° C when the heating temperature is ⁇ 900 ° C.
  • the problem that the first brittle temperature zone and the second brittle temperature zone of the steel are too low in thermoplasticity is avoided.
  • Example 3 0.080 0.45 0.32 0.013 0.0040 9.25 2.55 3.85 0.214 0.070 0.0088 0.965 0.0040 0.060
  • Example 4 0.099 0.58 0.43 0.018 0.0043 8.28 2.94 3.24 0.153 0.079 0.0099 0.325 0.0034 0.025
  • Example 5 0.074 0.53 0.64 0.013 0.0074 8.94 2.86 2.18 0.133 0.027 0.0086 0.518 0.0042 0.052
  • Example 6 0.076 0.77 0.31 0.005 0.0062 8.74 2.58 3.13 0.210 0.078 0.0109 0.479 0.0077 0.016
  • Example 7 0.117 0.64 0.74 0.003 0.0039 8.65 2.37 2.67 0.172 0.016 0.0172 0.871 0.0060 0.020
  • Example 8 0.095 0.36 0.84 0.004 0.0032 8.56 2.48 2.38 0.284 0.089 0.0100 0.768 0.0040 0.006
  • Example 9 0.075 0.50 0.37 0.008 0.00

Abstract

一种超超临界火电机组用钢及其制备方法，该钢化学成分质量百分比为：Cr：8.0～10.0％，W：2.0～3.2％，Co：2.0～4.0％，V：0.1～0.3％，Nb：0.01～0.1％，B：0.006～0.018％，Cu：0.2～1.0％，Mn：0.2～1.0％，Al：0.005～0.08％，Si：0.1～0.8％，C：0.06～0.12％，N：0.003～0.010％，P≤0.02％，S≤0.01％，Ni≤0.01％，Re≤0.01％，Ti≤0.01％，余量是Fe以及不可避免的杂质，不可避免的杂质总量≤0.015％，且需同时满足：1.6≤(Cr+1.4W+1.5Si+2Nb+2V)/(Co+Cu+0.3Mn+30C+20N)≤3.2，0.6≤B/N≤6。该钢具有良好的抗蒸汽腐蚀氧化和高温持久蠕变性能，具体性能是在620～650℃外推10万小时持久强度≥100MPa；650℃蒸汽氧化腐蚀1000小时的增重≤18mg/cm2，特别适用于超超临界火电机组的锅炉管或其它耐热装备。

Description

一种超超临界火电机组用钢及其制备方法 技术领域
本发明属于耐热钢技术领域，具体涉及一种超超临界火电机组用钢及其制备方法，更具体涉及一种抗蒸汽腐蚀氧化和高温蠕变性能良好的超超临界火电机组用钢及其制备方法。
背景技术
随着我国经济的高速发展，资源和能源需求增速也随之增大，虽然太阳能、风能等新型能源的发展达到甚至超出电力发展规划的预期，但这些新能源的绝对量仍然较低。未来很长一段时期，火力发电仍然是中国电力结构中的主力，占比仍达到70％，这是由我国的国情和自然资源所决定的。但燃煤发电过程产生大量的粉尘、二氧化碳、二氧化硫、氮氧化物等污染物，并且煤炭资源的储量有限，不可再生。因此，为了保护环境、节约资源，需要发展高效经济的高参数、大容量火电机组。
技术人员已经认识到，提高蒸汽参数(压力和温度)是提高发电机组效率的重要和有效的途径。美、德、法、日等国家着手研发超超临界机组(U-USC)，其主蒸汽温度达到650℃，压力34.5MPa以上，高蒸汽参数将带来高的发电效率和较少的环境污染，但蒸汽参数的提高在一定程度上受到单位造价等方面的制约，但最大的瓶颈是受到高强耐热钢发展滞后的制约。随着参数的提高，高温承压部件(如蒸汽管道、阀门、锅炉和汽轮机等)的材料性能也必须相应的提高，它们是否安全工作，对整个机组的安全运行有着十分重要的意义。这就要求高温承压材料具有：1)良好的高温持久和蠕变强度，2)优异的高温组织稳定性，3)良好的抗高温蒸汽氧化腐蚀的性能，4)较小的热膨胀系数，5)良好的冷热加工性能，6)良好的焊接性能。
镍基高温合金具有优异的高温强度和抗蒸汽腐蚀的性能，在飞机发动机、汽轮机叶片等高温领域已经有成功的应用，可用于650℃以上更高效率的发电机组的高温部件，但机组的设计有一个逐步发展的过程，在600～650℃温度区间，使用镍基合金存在造价过高的问题，价格因素制约了镍基合金的应用。奥氏耐热钢等在620～650℃之间也有较高的高温强度，但其热膨胀系数大和热导率不高的问题，制 约了其在火电机组上的推广应用。已经商业化的马氏体耐热钢T/P92的最高使用温度可达620℃，但目前世界上仍没有一种成熟的经济性马氏体耐热钢可以将上限使用温度达到650℃。这一温度几乎达到了马氏体/铁素体型耐热钢的极限温度，强化机制的研究和钢种研发的难度都存在前所未有的挑战。
为此，技术人员开展了相关的研究和开发。美国专利US5591391A公开了能制造用于火力发电领域，具有改善的高温蠕变性能和良好焊接性能和抗蒸汽氧化腐蚀的性能材料，从公开的成分来看，其运用了高Cr、W和Co强化的原理，还加入了Rd和Ta等稀有元素，其含N量在0.02～0.12％之间，对于铁素体耐热钢来说，这是非常高的N含量，这将给生产加工带来极大的难度，并且N除与V和Nb反应形成氮化物外，余下的N还会消耗大量的Cr、W，弱化其固溶强化的效果。
发明内容
本发明的目的在于提供一种超超临界火电机组用钢及其制备方法，该钢具有良好的抗蒸汽腐蚀氧化和高温持久蠕变性能，具体性能是在620～650℃外推10万小时持久强度≥100MPa；650℃蒸汽氧化腐蚀1000小时的增重≤18mg/cm 2，特别适用于超超临界火电机组的锅炉管或其它耐热装备。
为达到上述目的，本发明的技术方案是：
本发明依据耐热钢固溶强化、析出物强化、位错强化和亚结构强化的复合协同强化理论，充分利用Cr、W、Co的固溶强化，Co和Cu层错强化，Cr、V、Nb、C、N的细小析出物的弥散强化作用，以及B在晶界以及碳化物与基体相界处的钉扎强化作用。在各合金元素的匹配设计上，综合考虑材料的可制造性和高温持久蠕变性能。具体技术方案如下：
一种超超临界火电机组用钢，其化学成分质量百分比为：Cr：8.0～10.0％，W：2.0～3.2％，Co：2.0～4.0％，V：0.1～0.3％，Nb：0.01～0.1％，B：0.006～0.018％，Cu：0.2～1.0％，Mn：0.2～1.0％，Al：0.005～0.08％，Si：0.1～0.8％，C：0.06～0.12％，N：0.003～0.010％，P≤0.02％，S≤0.01％，Ni≤0.01％，Re≤0.01％，Ti≤0.01％，余量是Fe以及不可避免的杂质，不可避免的杂质总量≤0.015％，且上述元素需同时满足如下关系：1.6≤(Cr+1.4W+1.5Si+2Nb+2V)/(Co+Cu+0.3Mn+30C+20N)≤3.2，0.6≤B/N≤6。
优选的，所述超超临界火电机组用钢化学成分中：Cr：8.5～9.5％。
优选的，所述超超临界火电机组用钢化学成分中：W：2.5～3.0％。
优选的，所述超超临界火电机组用钢化学成分中：Co：2.5～3.5％。
优选的，所述超超临界火电机组用钢化学成分中：V：0.15～0.25％。
优选的，所述超超临界火电机组用钢化学成分中：Nb：0.05～0.09％。
优选的，所述超超临界火电机组用钢化学成分中：B：0.008～0.013％。
优选的，所述超超临界火电机组用钢化学成分中：Cu：0.2～0.5％。
优选的，所述超超临界火电机组用钢化学成分中：Mn：0.3～0.8％。
优选的，所述超超临界火电机组用钢化学成分中：Al：0.01～0.05％。
优选的，所述超超临界火电机组用钢化学成分中：Si：0.2～0.6％。
优选的，所述超超临界火电机组用钢化学成分中：C：0.08～0.10％。
优选的，所述超超临界火电机组用钢化学成分中：N：0.005～0.008％。
优选的，所述超超临界火电机组用钢的化学成分中：1≤B/N≤3。
进一步，所述超超临界火电机组用钢在620～650℃外推10万小时持久强度≥100MPa，650℃蒸汽氧化腐蚀1000小时的增重≤18mg/cm 2。在某些实施方案中，所述超超临界火电机组用钢还具有以下一项或多项性能：强度Rp0.2≥600MPa，抗拉强度Rm≥800MPa，延伸率A 50≥15％；20-25℃下冲击功≥25J，-20℃下冲击功≥15J；高温600～675℃下屈服强度Rp0.2≥250MPa，抗拉强度Rm≥290MPa，延伸率A 50≥20％；650℃，120MPa的持久断裂时间≥15600h；以及热膨胀系数为10～15×10 -6K。优选地，本文所述的超超临界火电机组用钢具有上述所有性能。
在本发明钢板的成分设计中：
Cr：Cr元素改善钢的淬透性；有固溶强化的效果，Cr与C形成的碳化物弥散析出强化是钢中主要的强化相，有利于钢的高温持久蠕变性能；并且一定量的Cr元素可使耐热钢表面形成连续的Cr 2O 3或(CrFe) 3O 4氧化膜，该氧化膜可以赋予耐热钢良好的抗高温蒸汽氧化腐蚀的能力。但如果Cr含量太低，起不到应有的固溶强化和析出强化效果，且材料表面也不足以形成连续的Cr 2O 3或(CrFe) 3O 4膜，不利于材料的抗高温蒸汽腐蚀的性能。而Cr含量太高，耐热钢的生产加工难度大，容易产生高温δ铁素体，对耐热钢的高温蠕变性能和持久强度不利。因此，本发明将Cr含量控制在8.0～10％，优选在8.5～9.5％。
W：W元素因为原子半径较大，在基体中导致很大的晶格畸变，起到比Mo显著的固溶强化效果，同时，W也能形成碳氮化物的析出相沉淀析出，起到弥散析出强化的作用。这对620℃以上的耐热钢的蠕变性能和持久强度非常有利。若W 含量太低，不能形成足量的强化相，但若W含量过高，W会促进高温δ铁素体相的产生，产生W的σ等脆性相，导致材料长期高温性能恶化。因此，本发明将W含量应控制在2.0～3.2％，优选在2.5～3.0％。
Co：Co元素在钢中能起到固溶强化的作用，Co可降低Ti、Al在钢基体中的溶解度，改变Cr和C在钢中的溶解度，增强Cr在钢中的固溶强化效果，Co降低金属基体的堆垛层错能，起到层错强化的作用，并且Co可抑制高温δ铁素体相的产生，因此，Co的加入能显著提高合金的蠕变抗力，且改善钢的热加工性能和抗高温腐蚀的性能。若Co加入太少，起不到所需要的效果，但Co是稀有贵金属，若加入过多，该钢就失去了应有的成本竞争优势。因此，本发明将Co含量控制在2.0～4.0％，优选在2.5～3.5％。
V：V的加入可以改善材料的高温蠕变断裂强度。V在钢中可形成细小的氮化物和/或碳氮化物。V含量过低起不到所需的效果，V加入过量，可能导致碳氮化物粗大以及表面氧化物的晶粒粗大，降低抗蒸汽腐蚀的性能。因此，本发明将V含量控制在0.1～0.3％，优选在0.15～0.25％。
Nb：Nb是C、N的稳定化元素，可形成Nb的碳氮化物，起到析出强化的效果，作用与V相似。但如果Nb加入量不足，起不到应有的效果。若Nb加入过高，材料的加工性会降低，可能导致其碳氮化物的粗大，热强性反而下降。因此，本发明将Nb含量控制在0.01～0.1％，优选在0.05～0.08％。
B：B元素的加入，可在晶界起到强化作用，并可以占据碳化物附近空位，抑制其长大，起到稳定组织的作用。如果B含量过低，起不到所需要的强化效果，但如果B含量过高，将会严重恶化材料的热加工性能和焊接性能。因此，本发明将B含量控制在0.006～0.018％之间，优选在0.008～0.013％。
N：N元素是奥氏体形成元素，一定量的N可以协同其它奥氏体形成元素抑制钢中高温δ铁素体的形成，并可与其它元素如Nb、V等形成细小的能弥散分布的氮化物，这些氮化物的稳定性大大高于相应合金的碳化物或碳氮化物。但N含量过高，可能导致加工性能和焊接性能等的恶化。因此，本发明将N含量控制在0.003～0.01％之间，优选在0.005～0.008％。
C：C元素可以与Cr、V、Nb和W等元素形成碳化物，通过弥散强化的方式，提高材料的热强性。但碳化物过低，析出的碳化物量少，达不到所需的强化效果，并且可使钢的第二脆性温度区间往高温区间移动，不利于热加工。C含量高，有利 于抑制高温δ铁素体的形成，并改善材料的第二脆性温区的热塑性；但过高的C含量，会导致碳化物析出过量，消耗过多的固溶强化元素，从而使综合的持久蠕变性能下降，另外，C含量过高对焊接性能也不利。因此，本发明将C控制在0.06～0.12％，优选0.08～0.10％。
Si：Si的加入能改善材料的抗高温蒸汽氧化腐蚀的性能，但Si过高，对材料的冲击韧性不利，在高温长期服役时，Si会促进脆性相的沉淀析出，不利于持久蠕变性能的稳定，另外，长时氧化腐蚀产生的SiO 2一旦形成连续内氧化物，可能影响热加换效率等。Si过高会恶化材料的第一高温脆性温度区的热塑性，不利于材料的热加工。因此，本发明将Si含量控制在0.1～0.8％，优选0.2～0.6％。
Cu：Cu是奥氏体形成元素，可阻止钢中产生δ铁素体，Cu的加入可提高钢的抗高温蒸汽氧化腐蚀的性能。但Cu元素含量过高，材料的热加工性能恶化。因此，本发明将Cu含量控制在0.2～1.0％，优选0.2～0.5％。
Mn：Mn是奥氏体形成元素，可抑制高温δ铁素体的形成，同时，Mn稳定P、S元素，避免低熔点硫化物的形成，提高材料的热加工性能。但Mn含量过低，不能很好的稳定P、S，达不到所需的效果，Mn含量过高，不利于材料的冲击韧性，并降低钢的高温蠕变断裂强度。因此，本发明将Mn含量控制在0.2～1.0％，优选0.3～0.8％。
Al：Al对于提高钢的抗高温蒸汽氧化腐蚀有明显的作用，但Al与钢中的N容易结合形成AlN，对材料的高温蠕变性能不利，因此，本发明中，Al不作为合金元素加入，但通常冶炼会采用Al脱氧或Al、Si复合脱氧，Al作为残留元素，因此，在生产过程中需要严格控制Al的含量，其含量宜控制在0.005～0.08％，优选0.01～0.05％。
P、S：P、S是钢铁原辅料或生产过程中引入的杂质元素，P可使晶界脆化，使材料的韧性和加工性能劣化。S元素形成低熔点的硫化物，使材料加工性能以及本身的力学性能下降。另外，P、S元素可促进高温蒸汽氧化腐蚀，使耐热钢的抗蒸汽腐蚀的能力下降。因此，P、S宜控制在P≤0.02％，S≤0.01％，优选控制在P≤0.01％，S≤0.005％。
Re、Ti、Ni等元素不作为合金元素加入，Re元素可以改善材料的抗蒸汽腐蚀的性能和改善热塑性等，但由于在实际冶炼生产过程中，稀土容易形成稀土氧化物夹杂，导致高温蠕变裂纹在此形核，反而降低钢的蠕变断裂强度。Ti容易与N形 成TiN、TiN需要在极高的温度下才能固溶，一旦形成，不容易通过热处理调控。有研究表明，Ni对铁素体耐热钢的持久强度有不利影响，因此，在规模化生产，不能用精料生产的情况下，原辅料中的Ni、Ti和Re等要严格管制，Ni、Ti和Re元素的含量均要控制在0.01％以下。
另外，本发明钢还可能含有其它不可避免的杂质元素，如来自原辅料以及炉渣、耐火材料等在制造过程中产生的残留物，例如Sn、Pb、As、Sb和Zn等有害元素，这些元素也必须严格控制，总量不能超过0.015％。
本发明为了控制高温δ铁素体对制造性能和高温蠕变断裂强度的不利影响，在成分设计时还充分考虑了铁素体当量和奥氏体当量比值的控制，从源头上避免或减少了高温δ铁素体在生产制造过程中产生的开裂等质量风险，并确保本发明钢在下述制造方法下获得单一回火马氏体组织。因此，本发明钢的合金成分还应满足以下关系：
1.6≤(Cr+1.4W+1.5Si+2Nb+2V)/(Co+Cu+0.3Mn+30C+20N)≤3.2。
本发明利用B的晶界强化以及抑制碳化物长大的作用，提高材料的高温性能。但若N加入过量，会与B结合形成BN，消耗掉B元素，起不到应有的作用。因此，本发明在成分设计时，充分考虑B/N的统一控制，其化学成分还应满足以下关系：0.6≤B/N≤6，优选1≤B/N≤3。
应理解，本文所述各元素的含量范围可任意组合。例如，在某些实施方案中，本文所述的所述超超临界火电机组用钢化学成分满足以下一项或多项特征：Cr：8.5～9.5％；W：2.5～3.0％；Co：2.5～3.5％；V：0.15～0.25％；Nb：0.05～0.09％；B：0.008～0.013％；Cu：0.2～0.5％；Mn：0.3～0.8％；Al：0.01～0.05％；Si：0.2～0.6％；C：0.08～0.10％；N：0.005～0.008％；和1≤B/N≤3。在某些实施方案中，本文所述的所述超超临界火电机组用钢化学成分中，Cr：8.5～9.5％；W：2.5～3.0％；Co：2.5～3.5％；V：0.15～0.25％；Nb：0.05～0.09％；B：0.008～0.013％；Cu：0.2～0.5％；Mn：0.3～0.8％；Al：0.01～0.05％；Si：0.2～0.6％；C：0.08～0.10％；N：0.005～0.008％；和1≤B/N≤3。
本发明所述超超临界火电机组用钢的制备方法，其包括如下步骤：
1)按照上述化学成分利用真空感应炉冶炼浇铸成铸锭，然后将铸锭在1000～1180℃加热保温1～6小时，再在920～1150℃之间进行高温变形，加工成所需尺寸；
2)热处理
正火处理：正火温度1000～1140℃，保温0.5～4小时，空冷至室温。
回火处理：回火温度700～820℃，保温1～5小时，空冷至室温。
本发明设计的上述成分体系当加热温度＞1200℃时钢锭处于第一脆性温度区，当加热温度＜900℃时钢锭处于第二脆性温度区，本发明选择钢锭加热温度为1000～1180℃，避免了钢在热加工中的第一脆性温度区和第二脆性温度区热塑性过低的难题。
本发明在1000～1140℃温度区间进行正火处理、在700～820℃温度区间进行回火处理，可以使本发明钢的析出强化、位错和板条亚结构强化达到最佳效果。因此，为了保证足够的高温持久强度，本发明进行上述最终的热处理。
本发明制造的钢具有较好的室温力学性能、高温力学性能，还具有优异的高温持久蠕变强度和抗高温蒸汽腐蚀的性能，具体性能指标如下：室温力学性能为屈服强度Rp0.2≥600MPa，抗拉强度Rm≥800MPa，延伸率A 50≥15％；20-25℃下冲击功≥25J，-20℃下冲击功≥15J；高温600～675℃下力学性能为：屈服强度Rp0.2≥250MPa，抗拉强度Rm≥290MPa，延伸率A 50≥20％；650℃，120MPa的持久断裂时间≥15600h；650℃蒸汽氧化腐蚀1000小时的增重不高于18mg/cm 2，在620～650℃外推10万小时持久强度100MPa以上，热膨胀系数为10～15×10 -6K；同时具有较好的可制造性能，特别适用于制造620～650℃超超临界火电机组锅炉管等耐热部件，但也不限制该钢种在超超临界火电机组以外的其它有耐热需求的环境中应用。本发明成分设计和制造工艺设计均兼顾了利用现有工业管生产装备能力实现产业化的可行性。
本发明的有益效果：
与现有技术比，本发明钢的化学成分中优化了Cu元素含量，不添加稀土元素，降低了冶炼过程中控制非金属夹杂物的难度，并降低N含量，保证了钢的冲击韧性和焊接性能。同时各化学成分还需满足：1.6≤(Cr+1.4W+1.5Si+2Nb+2V)/(Co+Cu+0.3Mn+30C+20N)≤3.2，及0.6≤B/N≤6。该化学成分体系结合本发明提供的加热工艺(加热温度为1000～1180℃，变形温度920～1150℃)，可以很好地控制钢中高温δ铁素体的形成，改善钢的热塑性，降低热加工缺陷形成的风险，同时了保证钢的高温持久蠕变性能。
附图说明
图1为本发明实施例3和实施例10钢在不同温度下的高温热塑性示意图。
具体实施方式
下面结合实施例和附图对本发明做进一步说明。
表1为本发明实施例钢和对比例钢的成分，表2为本发明实施例钢和对比例钢的关键制备工艺参数，表3为本发明实施例钢和对比例钢的综合性能。
实施例1
利用真空感应炉，冶炼达到表1所示化学组成的钢锭50～100Kg，将这些钢锭开坯后，再加热至1180℃，热轧制成16mm厚的热轧板。接着将热轧板在1020℃正火保温1.5小时，空冷至室温，然后在760℃保温2小时，空冷至室温。从上述热处理钢板上截取常温力学、长时失效以及高温蠕变和持久性能评价试样，测得的各种性能如表3所示。
其他实施例的制造和评价过程与实施例1类似，具体制备参数参见表2，性能参见表3。
由表3可知，本发明制备所得超超临界火电机组用钢室温力学性能为：屈服强度Rp0.2≥600MPa，抗拉强度Rm≥800MPa，延伸率A 50≥15％；20～25℃下冲击功≥25J，-20℃下冲击功≥15J；高温600～675℃下力学性能为：屈服强度Rp0.2≥250MPa，抗拉强度Rm≥290MPa，延伸率A 50≥20％；650℃，120MPa的持久断裂时间≥15600h；650℃蒸汽氧化腐蚀1000小时的增重不高于18mg/cm 2。由表3的数据计算可知，在620～650℃外推10万小时持久强度100MPa以上。该钢板具有优异的高温持久蠕变强度和抗高温蒸汽腐蚀的性能，同时具有较好的可制造性能，特别适用于制造超超临界火电机组的锅炉管或其它耐热装备。
由图1可知，本发明上述成分体系在加热温度＞1250℃时钢锭处于第一脆性温度区，当加热温度＜900℃时钢锭处于第二脆性温度区，当钢锭加热温度设置为1000～1180℃，避免了钢在热加工中的第一脆性温度区和第二脆性温度区热塑性过低的难题。
表1(单位：wt％)
序号 C Si Mn P S Cr W Co V Nb B Cu N Al
实施例1 0.085 0.13 0.74 0.008 0.0044 9.47 2.08 3.27 0.130 0.020 0.0122 0.627 0.0070 0.046
实施例2 0.078 0.21 0.24 0.005 0.0090 9.44 2.49 2.28 0.173 0.056 0.0064 0.256 0.0048 0.060
实施例3 0.080 0.45 0.32 0.013 0.0040 9.25 2.55 3.85 0.214 0.070 0.0088 0.965 0.0040 0.060
实施例4 0.099 0.58 0.43 0.018 0.0043 8.28 2.94 3.24 0.153 0.079 0.0099 0.325 0.0034 0.025
实施例5 0.074 0.53 0.64 0.013 0.0074 8.94 2.86 2.18 0.133 0.027 0.0086 0.518 0.0042 0.052
实施例6 0.076 0.77 0.31 0.005 0.0062 8.74 2.58 3.13 0.210 0.078 0.0109 0.479 0.0077 0.016
实施例7 0.117 0.64 0.74 0.003 0.0039 8.65 2.37 2.67 0.172 0.016 0.0172 0.871 0.0060 0.020
实施例8 0.095 0.36 0.84 0.004 0.0032 8.56 2.48 2.38 0.284 0.089 0.0100 0.768 0.0040 0.006
实施例9 0.075 0.50 0.37 0.008 0.0041 9.09 2.54 2.18 0.192 0.094 0.0167 0.571 0.0050 0.043
实施例10 0.110 0.36 0.83 0.000 0.0095 8.92 2.28 2.46 0.252 0.057 0.0147 0.886 0.0072 0.009
实施例11 0.116 0.28 0.59 0.014 0.0046 8.90 2.66 3.33 0.216 0.069 0.0170 0.532 0.0064 0.045
实施例12 0.084 0.26 0.75 0.020 0.0000 9.86 2.24 2.36 0.284 0.028 0.0131 0.711 0.0043 0.059
实施例13 0.100 0.20 0.57 0.018 0.0011 9.66 3.14 2.14 0.103 0.081 0.0166 0.295 0.0035 0.047
实施例14 0.101 0.34 0.92 0.001 0.0063 9.91 3.11 2.38 0.273 0.019 0.0087 0.369 0.0035 0.019
实施例15 0.094 0.55 0.47 0.003 0.0100 9.36 2.88 2.90 0.198 0.097 0.0163 0.761 0.0087 0.029
实施例16 0.106 0.54 0.34 0.011 0.0080 10.00 2.00 2.47 0.160 0.071 0.0101 0.794 0.0094 0.050
实施例17 0.099 0.21 0.77 0.020 0.0054 9.68 3.12 3.48 0.120 0.081 0.0081 0.808 0.0043 0.032
实施例18 0.117 0.69 0.26 0.007 0.0089 9.41 2.63 2.89 0.252 0.019 0.0138 0.725 0.0050 0.010
实施例19 0.089 0.33 0.36 0.003 0.0054 8.71 2.97 3.51 0.105 0.093 0.0065 0.464 0.0068 0.064
实施例20 0.103 0.23 0.79 0.014 0.0011 8.26 2.39 3.93 0.152 0.018 0.0142 0.377 0.0075 0.073
对比例1 0.049 0.32 1.46 0.001 0.0039 6.11 3.32 3.27 0.420 0.287 0.0370 2.60 0.0354 0.028
对比例2 0.141 1.26 0.32 0.024 0.0094 10.30 0.85 5.11 0.462 0.351 0.0432 2.70 0.0030 0.005
对比例3 0.072 0.99 0.04 0.008 0.0118 11.74 3.62 2.29 0.437 0.048 0.0188 0.78 0.0361 0.085
对比例4 0.156 1.08 0.24 0.022 0.0176 12.06 4.82 0.13 0.310 0.388 0.0169 0.45 0.0241 0.097
对比例5 0.164 0.25 0.86 0.011 0.0055 11.21 1.36 2.07 0.568 0.193 0.0419 1.32 0.0307 0.090
对比例6 0.123 1.15 0.82 0.021 0.0145 7.66 4.65 7.34 0.782 0.434 0.0408 1.13 0.0471 0.001
对比例7 0.104 0.33 0.55 0.020 0.0092 10.87 4.53 6.16 0.696 0.032 0.0215 0.44 0.0015 0.064
对比例8 0.165 1.12 0.15 0.026 0.0055 12.61 3.81 7.33 0.557 0.401 0.0239 1.85 0.0011 0.015
对比例9 0.102 0.25 1.47 0.026 0.0189 6.60 0.74 0.11 0.296 0.023 0.0171 0.92 0.0061 0.003
对比例10 0.194 0.51 1.06 0.034 0.0089 11.80 4.13 4.35 0.020 0.060 0.0093 1.83 0.0340 0.082
表2
Figure PCTCN2018107521-appb-000001
Figure PCTCN2018107521-appb-000002
表3
Figure PCTCN2018107521-appb-000003
Figure PCTCN2018107521-appb-000004

Claims (17)

  1. 一种超超临界火电机组用钢，其化学成分质量百分比为：Cr：8.0～10.0％，W：2.0～3.2％，Co：2.0～4.0％，V：0.1～0.3％，Nb：0.01～0.1％，B：0.006～0.018％，Cu：0.2～1.0％，Mn：0.2～1.0％，Al：0.005～0.08％，Si：0.1～0.8％，C：0.06～0.12％，N：0.003～0.010％，P≤0.02％，S≤0.01％，Ni≤0.01％，Re≤0.01％，Ti≤0.01％，其余是Fe以及不可避免的杂质，不可避免的杂质总量≤0.015％，且上述元素需同时满足如下关系：1.6≤(Cr+1.4W+1.5Si+2Nb+2V)/(Co+Cu+0.3Mn+30C+20N)≤3.2，0.6≤B/N≤6。
  2. 根据权利要求1所述的超超临界火电机组用钢，其特征在于，所述超超临界火电机组用钢的化学成分中Cr：8.5～9.5％。
  3. 根据权利要求1或2所述的超超临界火电机组用钢，其特征在于，所述超超临界火电机组用钢的化学成分中W：2.5～3.0％。
  4. 根据权利要求1-3任一项所述的超超临界火电机组用钢，其特征在于，所述超超临界火电机组用钢的化学成分中Co：2.5～3.5％。
  5. 根据权利要求1-4任一项所述的超超临界火电机组用钢，其特征在于，所述超超临界火电机组用钢的化学成分中V：0.15～0.25％。
  6. 根据权利要求1-5任一项所述的超超临界火电机组用钢，其特征在于，所述超超临界火电机组用钢的化学成分中Nb：0.05～0.09％。
  7. 根据权利要求1-6任一项所述的超超临界火电机组用钢，其特征在于，所述超超临界火电机组用钢的化学成分中B：0.008～0.013％。
  8. 根据权利要求1-7任一项所述的超超临界火电机组用钢，其特征在于，所述超超临界火电机组用钢的化学成分中Cu：0.2～0.5％。
  9. 根据权利要求1-8任一项所述的超超临界火电机组用钢，其特征在于，所述超超临界火电机组用钢的化学成分中Mn：0.3～0.8％。
  10. 根据权利要求1-9任一项所述的超超临界火电机组用钢，其特征在于，所述超超临界火电机组用钢的化学成分中Al：0.01～0.05％。
  11. 根据权利要求1-10任一项所述的超超临界火电机组用钢，其特征在于，所述超超临界火电机组用钢的化学成分中Si：0.2～0.6％。
  12. 根据权利要求1-11任一项所述的超超临界火电机组用钢，其特征在于，所述超超临界火电机组用钢的化学成分中C：0.08～0.10％。
  13. 根据权利要求1-12任一项所述的超超临界火电机组用钢，其特征在于，所述超超临界火电机组用钢的化学成分中N：0.005～0.008％。
  14. 根据权利要求1-13所述的超超临界火电机组用钢，其特征在于，所述超超临界火电机组用钢的化学成分中：1≤B/N≤3。
  15. 根据权利要求1-14任一项所述的超超临界火电机组用钢，其特征在于，所述超超临界火电机组用钢在620～650℃外推10万小时持久强度≥100MPa，650℃蒸汽氧化腐蚀1000小时的增重≤18mg/cm 2。
  16. 如权利要求1-15任一项所述的超超临界火电机组用钢的制备方法，其包括如下步骤：
    1)按照权利要求1-14任一项所述的化学成分利用真空感应炉冶炼浇铸成铸锭，然后将铸锭在1000～1180℃保温1～6小时，再在920～1150℃之间进行高温变形，加工成所需尺寸；
    2)热处理
    正火处理：正火温度1000～1140℃，保温0.5～4小时，空冷至室温；
    回火处理：回火温度700～820℃，保温1～5小时，空冷至室温。
  17. 根据权利要求16所述的超超临界火电机组用钢的制备方法，其特征在于，所述超超临界火电机组用钢在620～650℃外推10万小时持久强度≥100MPa，650℃蒸汽氧化腐蚀1000小时的增重≤18mg/cm 2。
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