CN102808136B - Manufacturing method for filter net body material of ultra-supercritical turbine in megawatt unit - Google Patents

Abstract

The invention provides a manufacturing method for a filter net body material of a bypass valve in a 1,000 megawatt ultra-supercritical turbine, and belongs to the field of metal materials. Alloy components are further designed and optimized on the basis of 1Cr13 and 10Cr9Mo1VNb alloys, a new alloy component is designed by adding a proper amount of W elements and controlling the W-to-Mo ratio and the contents of C, V and Cr in the alloys, and corresponding key manufacturing steps of smelting, electroslag treatment, forging and heat treatment and the like are determined. The performance of the filter net body material manufactured by the manufacturing method is improved at both room temperature and high temperature, so that the performance requirements of the ultra-supercritical turbine in a megawatt unit on the filter net body material can be met, and the safety and the reliability of the bypass valve of the turbine and the whole turbine are effectively guaranteed.

Description

A kind of manufacture method of 1,000,000 unit supercritical turbine strainer body materials

Technical field

The invention belongs to metal material field, relate to a kind of manufacture method of preparing 1,000,000 unit supercritical turbine strainer body materials.

Background technology

In power industry, thermal power generation is at dominate worldwide still from now on and for a long time, and unit is constantly towards large capacity, high-parameters, energy-efficient future development.China's Eleventh Five-Year Plan and later also attaching most importance to development 600MW, 1000MW above supercritical turbine.Continuing to increase of unit capacity proposed continual high request to the performance of associated materials.Valve one of forms as most critical in steam turbine, along with improving constantly of working temperature and pressure, the processing of the performance of intraware material and assembly, assembly precision is also had higher requirement.Therefore, ultra supercritical technical development the most important thing is the research and development of high strength at high temperature novel material.Can the special metal material moving under the severe rugged environments such as High Temperature High Pressure is provided, be the key factor that ultra supercritical fired power generating unit is applied.Development of Ultra-Supercritical unit has many key technical problems in design profit is manufactured, and wherein develops that hot strength is high, the oxidation corrosion of high temperature resistance flue gas and high temperature carbonated drink dielectric corrosion, weldability and good, the cheap material of manufacturability be the problem of most critical.

The Main Function of supercritical turbine by-pass valve (comprising septum valve, control valve, middle pressure control valve, variable valve etc.) is that dynamic adjustments and the pressure of controlling vapour gas in the jar keep constant, to guarantee the stable output power of generator.Therefore can steady operation in order to ensure steam turbine, valve must have high working reliability, and this just requires the associated component of valve to have excellent performance.Variable valve or control valve are normally comprised of several large key components such as valve rod, valve seat, valve disc, steam filter screens, wherein steam filter screen mainly works to prevent that the impurity such as outer solid particle from entering steam turbine inside from live steam piping, it is positioned at the top in stop valve chamber, surround valve and valve seat, while installing in valve casing, it and top and valve seat are running fit.Steam filter screen is mainly comprised of three parts: smart net, perforated plate and strainer body.Wherein the Main Function of strainer body is to support smart net and perforated plate, requires in ultra supercritical working order, and internal vapor pressure surpasses 30MPa, temperature surpasses 600 ℃, still has certain intensity and toughness, has good resistance to steam corrosion simultaneously.In subcritical pressure turbine, the work condition environment of strainer body is vapor pressure 17MPa, 540 ℃ of vapor temperatures, and the material of strainer body extensively adopts 1Cr13 steel, 1Cr13 has higher hardness, toughness, good rotproofness, heat resistance and cold deformation performance, damping property is also fine, its room temperature tensile strength >=540MPa, yield strength >=345MPa, ballistic work >=78J.In supercritical pressure turbine, the working temperature of strainer body is 567 ℃, vapor pressure is 25.5MPa, adopts 1Cr13 steel not meet the demands, and passes through suitably to reduce C content on the basis of 1Cr13 steel, and add the elements such as V, Nb, Mo, can improve stability and the hot strength of tissue, the 10Cr9Mo1VNb steel adopting at present is extensively as supercritical pressure turbine strainer body material, its room temperature tensile strength >=580MPa, yield strength >=415MPa, ballistic work >=68J.For supercritical turbine, the working temperature of strainer body reaches 600 ℃, and pressure reaches 30MPa, requires strainer body to have higher creep rupture strength, and under 600 ℃, 100h condition, creep rupture strength should, higher than 200MPa, have excellent corrosion resistance simultaneously.10Cr9Mo1VNb steel creep rupture strength in the time of 600 ℃ is 175MPa (100h), 95MPa (1000h), therefore adopts 10Cr9Mo1VNb steel can not meet Steam Turbine Technologies for Ultra Supercritical requirement, must develop and have more high performance strainer body material.

Summary of the invention

The object of the invention is to provide a kind of dependable performance, lower-cost strainer body material and preparation method thereof.Be mainly to take alloy 10Cr9Mo1VNb as basis, by improving C content, add appropriate W element, and adjust the ratio value of W and Mo, form the strengthening of W-Mo compound solid solution and WC precipitation strength, and eliminate the red brittleness that single Mo element brings, increase high temperature and creep resistance intensity and the creep rupture strength of alloy; In addition the content of Cr and V is adjusted, and formulated rational thermal treatment process, can fully utilize the high-temperature behavior that the strengthening mechanisms such as lath martensite strengthening, grain-boundary strengthening, particle dispersion precipitation strength and solution strengthening increase substantially alloy, especially do not affecting under the precondition of corrosion resistance, carry heavy alloyed high temperature endurance performance, meet the job requirement of supercritical turbine.

A kind of 1,000,000 in a watt manufacture method for supercritical turbine by-pass valve strainer body material, it is characterized in that having added appropriate W element on the basis of 1Cr13 and 10Cr9Mo1VNb alloy, and control the content of C, V and Cr in the ratio of W and Mo and alloy, and mate corresponding smelting, electroslag, forging and thermal treatment process, content comprises:

1) the composition weight percent of strainer body material is:

C:0.2～0.25%, Si:0.25～0.5%, Mn:0.25～0.7%, Cr:11～13%, Ni:0.3～0.7%, Mo:0.8～1.6%, V:0.2～0.35%, W:0.4～0.8%, Nb:0.02～0.05%, P and S are less than 0.02%, surplus is Fe, and wherein the ratio of Mo and W content is 2: 1;

2) alloy smelting: according to above-mentioned alloying constituent requirement, choose starting material, then carry out melting; The melting of this alloy adopts vacuum metling, then carries out esr refining.The slag system formula of esr refining is (weight percent): Al ₂o ₃for 35-45%; CaO is 40-55%; MgO is 5-10%; SiO ₂for 10-15%;

3) alloy forging: during alloy forging, it is 1180～1200 ℃ that workpiece enters stove holding temperature, soaking time is determined according to the standard of 0.2h/cm and in conjunction with the actual (real) thickness of forging; During One-time forging, the deflection of alloy is controlled at 15～20% scopes; It is 40～60% that the second fire starts each forging deformation amount span of control, and pier pulls out forging stock 2～3 times repeatedly, and forging ratio is reached more than 4, and the final forging temperature of last fiery alloy is 870 ℃, and it is 30% that deflection is controlled;

4) forge postheat treatment system: after forging and molding finishes, forging is entered to stove and in 950～970 ℃ of insulations, carry out annealing recrystallization, eliminate forging stress simultaneously, soaking time is determined according to the standard of 0.5h/cm and in conjunction with the actual (real) thickness of forging; After insulation finishes, workpiece is chilled to 300 ℃ of air coolings of coming out of the stove below with stove;

5) forging performance thermal treatment: after the workpiece surface that forges annealing is rough turn, carry out UT (Ultrasonic Testing), remove all defect that surface exists, after qualified, carry out property heat treatment, be that quenching+tempering is processed, quenching temperature is 950～970 ℃ and carries out oil cooling, and it is 7～10 ℃/min that temperature rise rate is controlled, and soaking time establishing criteria is 1h/cm; 700～720 ℃ of air coolings of tempering temperature, it is 7～10 ℃/min that temperature rise rate is controlled, soaking time establishing criteria is 1.5h/cm.

In a word, the strainer body material that adopts manufacturing process of the present invention to manufacture, owing to having added appropriate W element, and the ratio of W and Mo is controlled, the electroslag slag system of alloy is, the forging ratio of forging process and thermal treatment process etc. are carried out priority control simultaneously, further improve creep rupture strength and the impact property of alloy, met the performance requriements of 1,000,000 supercritical turbine units to strainer body material, guaranteed the safety and reliability of turbine bypass valve work.

Embodiment:

(1) manufacturing specification is the strainer body of Φ 581 (external diameter)/Φ 479 (internal diameter) * 522mm (length), and weight is about 100kg

First according to dimensional requirement, design blank dimension specification, is Φ 585 (external diameter)/Φ 475 (internal diameter) * 528mm, and blank weight is about 110kg.According to blank weight, and require to prepare burden in conjunction with the composition of concrete alloying element, adopt vacuum medium frequency induction furnace to carry out melting, then carry out esr, the specification of electric slag refusion ingot is Φ 300 * 200mm, and slag system formula is Al ₂o ₃be 35%; CaO is 50%; MgO is 5%; SiO ₂be 10%.Table 1 is the actual measurement composition of alloy after electroslag, and contrasts with the composition of the present invention's design, can find out that all alloying elements all within the scope of the present invention.

Table 1 chemical composition (weight percent %)

When resmelting ingot forges, first enter stove and heat, Heating temperature is 1190 ℃, and soaking time is 4h, makes the abundant heat penetration of steel billet, and realizes the further diffusion of inner alloying element, makes internal component more even.After insulation, carry out One-time forging, the first fiery deflection is controlled at 15%, makes coarse grain and precipitate obtain preliminary fragmentation; The second fire starts to increase the deflection of forging stock, and pier pulls out alloy 3 times repeatedly, and controls every fiery deflection and reach 40%, and final forging ratio reaches more than 4, and the final forging temperature of last fiery alloy is 900 ℃, and it is 40% that deflection is controlled.After forging finishes, workpiece is put into 970 ℃ of electric furnaces and be incubated 3h (thickness of workpiece is 55mm), and cool to 300 ℃ of air coolings of coming out of the stove below with the furnace.Work-piece cools is carried out roughing to room temperature, and carries out ultrasonic surface flaw detection, after ultrasonic inspection is qualified, carries out property heat treatment.Property heat treatment process is: first the qualified workpiece of flaw detection is entered to stove (furnace temperature is less than 300 ℃) and by the speed of 10 ℃/min, is warming up to 950 ℃ with stove, then be incubated 5h, the oil cooling of coming out of the stove, after quenching, again workpiece being entered to stove (furnace temperature is less than 300 ℃) is warming up to 720 ℃ with stove by the speed of 10 ℃/min and carries out tempering, tempering insulation time 8.25h, is then chilled to room temperature with stove.

The material of manufacturing by above-mentioned technique, carries out room temperature and mechanical behavior under high temperature test, and the mechanical performance index reaching is with as shown in table 2 below, and table 2 has listed file names with the performance that standard-required value and 1Cr13 and 10Cr9Mo1VNb can reach.Visible, the material composition and the manufacturing process that adopt the present invention to design, the performance that the performance of prepared material is all above standard and requires.

Table 2 measured performance value with require performance index

Claims (1)

1. the manufacture method of a gigawatt supercritical turbine by-pass valve strainer body material, it is characterized in that having added appropriate W element on the basis of 1Cr13 and 10Cr9MolVNb alloy, and control the content of C, V and Cr in the ratio of W and Mo and alloy, and mate corresponding smelting, electroslag, forging and thermal treatment process, content comprises:

1) the composition weight percent of strainer body material is:

C:0.2～0.25%, Si:0.25～0.5%, Mn:0.25～0.7%, Cr:11～13%, Ni:0.3～0.7%, Mo:0.8～1.6%, V:0.2～0.35%, W:0.4～0.8%, Nb:0.02～0.05%, P is less than 0.02%, S is less than 0.02%, surplus is Fe, and wherein the ratio of Mo and W content is 2:1;

2) alloy smelting: according to above-mentioned alloying constituent requirement, choose starting material, then carry out melting; The melting of this alloy adopts vacuum metling, then carries out esr refining; The slag system formula of esr refining is (weight percent): Al ₂o ₃for 35-45%; CaO is 40-55%; MgO is 5-10%; SiO ₂for 10-15%; In slag system, each raw material sum equals 100%;

3) alloy forging: during alloy forging, it is 1180～1200 ℃ that workpiece enters stove holding temperature, soaking time is determined according to the standard of 0.2h/cm and in conjunction with the actual (real) thickness of forging; During One-time forging, the deflection of alloy is controlled at 15～20% scopes; It is 40～60% that the second fire starts each forging deformation amount span of control, and pier pulls out forging stock 2～3 times repeatedly, and forging ratio is reached more than 4, and the final forging temperature of last fiery alloy is 870 ℃, and it is 30% that deflection is controlled;

4) forge postheat treatment system: after forging and molding finishes, forging is entered to stove and in 950～970 ℃ of insulations, carry out annealing recrystallization, eliminate forging stress simultaneously, soaking time is determined according to the standard of 0.5h/cm and in conjunction with the actual (real) thickness of forging; After insulation finishes, workpiece is chilled to 300 ℃ of air coolings of coming out of the stove below with stove;

5) forging performance thermal treatment: after the workpiece surface that forges annealing is rough turn, carry out UT (Ultrasonic Testing), remove all defect that surface exists, after qualified, carry out property heat treatment, be that quenching+tempering is processed, quenching temperature is 950～970 ℃ and carries out oil cooling, and it is 7～10 ℃/min that temperature rise rate is controlled, and soaking time establishing criteria is 1h/cm; 700～720 ℃ of air coolings of tempering temperature, it is 7～10 ℃/min that temperature rise rate is controlled, soaking time establishing criteria is 1.5h/cm.