CN118326283A - Ultrahigh-temperature high-strength turbine rotor forging and preparation process - Google Patents
Ultrahigh-temperature high-strength turbine rotor forging and preparation process Download PDFInfo
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- CN118326283A CN118326283A CN202410362987.5A CN202410362987A CN118326283A CN 118326283 A CN118326283 A CN 118326283A CN 202410362987 A CN202410362987 A CN 202410362987A CN 118326283 A CN118326283 A CN 118326283A
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- 238000005242 forging Methods 0.000 title claims abstract description 70
- 238000002360 preparation method Methods 0.000 title claims abstract description 16
- 238000004519 manufacturing process Methods 0.000 claims abstract description 14
- 239000012535 impurity Substances 0.000 claims abstract description 5
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 claims description 149
- 229910000831 Steel Inorganic materials 0.000 claims description 123
- 239000010959 steel Substances 0.000 claims description 123
- 238000001816 cooling Methods 0.000 claims description 76
- 239000002893 slag Substances 0.000 claims description 39
- 238000010438 heat treatment Methods 0.000 claims description 25
- 238000007670 refining Methods 0.000 claims description 21
- 238000007664 blowing Methods 0.000 claims description 19
- 239000000843 powder Substances 0.000 claims description 19
- 238000000137 annealing Methods 0.000 claims description 18
- 239000000463 material Substances 0.000 claims description 18
- 238000005496 tempering Methods 0.000 claims description 16
- 238000009849 vacuum degassing Methods 0.000 claims description 9
- 238000004140 cleaning Methods 0.000 claims description 7
- 238000010891 electric arc Methods 0.000 claims description 6
- 210000004907 gland Anatomy 0.000 claims description 6
- 238000004321 preservation Methods 0.000 claims description 6
- 239000006104 solid solution Substances 0.000 claims description 6
- 238000000034 method Methods 0.000 claims description 5
- 239000000243 solution Substances 0.000 claims description 4
- 238000004220 aggregation Methods 0.000 claims description 3
- 230000002776 aggregation Effects 0.000 claims description 3
- 238000003754 machining Methods 0.000 claims description 3
- 239000003595 mist Substances 0.000 claims description 3
- 239000007921 spray Substances 0.000 claims description 3
- 238000007514 turning Methods 0.000 claims description 3
- 230000000149 penetrating effect Effects 0.000 claims description 2
- 239000007788 liquid Substances 0.000 description 21
- 229910045601 alloy Inorganic materials 0.000 description 12
- 239000000956 alloy Substances 0.000 description 12
- 238000005728 strengthening Methods 0.000 description 11
- 230000000694 effects Effects 0.000 description 10
- 229910052721 tungsten Inorganic materials 0.000 description 7
- 229910052720 vanadium Inorganic materials 0.000 description 7
- 239000006185 dispersion Substances 0.000 description 6
- 229910000734 martensite Inorganic materials 0.000 description 6
- 230000006872 improvement Effects 0.000 description 4
- 238000003825 pressing Methods 0.000 description 4
- 230000015572 biosynthetic process Effects 0.000 description 3
- 230000000903 blocking effect Effects 0.000 description 3
- 230000002301 combined effect Effects 0.000 description 3
- 229910052750 molybdenum Inorganic materials 0.000 description 3
- 229910052758 niobium Inorganic materials 0.000 description 3
- 239000002245 particle Substances 0.000 description 3
- 238000004663 powder metallurgy Methods 0.000 description 3
- 238000001556 precipitation Methods 0.000 description 3
- 230000008569 process Effects 0.000 description 3
- 230000000630 rising effect Effects 0.000 description 3
- 229910000859 α-Fe Inorganic materials 0.000 description 3
- 230000009471 action Effects 0.000 description 2
- 239000000498 cooling water Substances 0.000 description 2
- 238000010586 diagram Methods 0.000 description 2
- 230000007246 mechanism Effects 0.000 description 2
- 238000012986 modification Methods 0.000 description 2
- 230000004048 modification Effects 0.000 description 2
- 230000001681 protective effect Effects 0.000 description 2
- 238000005245 sintering Methods 0.000 description 2
- 239000013589 supplement Substances 0.000 description 2
- 230000001502 supplementing effect Effects 0.000 description 2
- 238000010521 absorption reaction Methods 0.000 description 1
- 230000009286 beneficial effect Effects 0.000 description 1
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- 230000007613 environmental effect Effects 0.000 description 1
- 238000000465 moulding Methods 0.000 description 1
- 238000010248 power generation Methods 0.000 description 1
- 238000003303 reheating Methods 0.000 description 1
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Abstract
The invention relates to the technical field of manufacturing of turbine rotors, in particular to an ultrahigh-temperature high-strength turbine rotor forging and a preparation process thereof. The turbine rotor forging comprises, by mass, 0.08-0.15% of C, less than or equal to 1.0% of Si, 0.6-1.0% of Mn, 9.0-12.0% of Cr, 4-6% of Ni, 2.0-4.0% of Mo, 0.15-0.25% of Nb, 1.5-2.5% of Co, 2-5% of W, 0.05-0.25% of Ti, 1.3-2.5% of V, less than or equal to 0.25% of Cu, less than or equal to 0.004% of P, less than or equal to 0.0008% of S, less than or equal to 0.020% of Al, less than or equal to 0.8PPm of [ H ], less than or equal to 10PPm of [ O ], less than or equal to 150PPm of [ N ], and the balance of Fe and unavoidable impurities. The invention improves the performance of the turbine rotor forging, thereby being more suitable for the use requirement of high temperature and high pressure resistance.
Description
Technical Field
The invention relates to the technical field of manufacturing of turbine rotors, in particular to an ultrahigh-temperature high-strength turbine rotor forging and a preparation process thereof.
Background
Along with the increasing severity of energy pressure and environmental pressure, the national requirements on the thermal power generation industry are higher and higher parameters, secondary reheating and cleaning efficiency are pursued. The highest working temperature of the ultra-supercritical rotor used on the steam turbine is 630 ℃, and the higher steam temperature and pressure parameters are realized in stages later so as to improve the thermal efficiency of high-temperature steam, but the higher design and use temperature presents no challenges to materials before, and no reliable materials are selected. Aiming at the gap in China, development of novel high-temperature-resistant rotor materials is very urgent.
Disclosure of Invention
In order to solve the problems, the invention provides an ultrahigh-temperature high-strength turbine rotor forging and a preparation process thereof, and aims to improve the performance of the turbine rotor forging so as to be more suitable for the use requirements of high temperature resistance and high pressure resistance. The specific technical scheme is as follows:
An ultra-high temperature high strength turbine rotor forging comprises, by mass, 0.08-0.15% of C, less than or equal to 1.0% of Si, 0.6-1.0% of Mn, 9.0-12.0% of Cr, 4-6% of Ni, 2.0-4.0% of Mo, 0.15-0.25% of Nb, 1.5-2.5% of Co, 2-5% of W, 0.05-0.25% of Ti, 1.3-2.5% of V, less than or equal to 0.25% of Cu, less than or equal to 0.004% of P, less than or equal to 0.0008% of S, less than or equal to 0.020% of Al, less than or equal to 0.8PPm of [ H ], less than or equal to 10PPm of [ O ], less than or equal to 150PPm of [ N ], and the balance of Fe and unavoidable impurities.
According to the ultrahigh-temperature high-strength turbine rotor forging material, alloy strengthening is mainly carried out by adding W, mo and Co in the material proportion, W and Mo are solid solution strengthening elements, and the combined effect of the two elements is better, so that the ultrahigh-temperature high-strength turbine rotor forging material has extremely high heat resistance and red hardness, and can increase tempering stability; co and V are further strengthened, and Co can inhibit the formation and precipitation of delta-ferrite; the addition of trace Nb, ti and V can play a role in refining grains. The shell obtains lath tempered martensite with uniform microstructure and fine dispersion alloy precipitated phases, so that the performance of the rotor forging of the ultra-temperature high-strength steam turbine is improved, and the use requirements of the rotor forging of the ultra-temperature high-strength steam turbine on high temperature and high pressure resistance are met.
A preparation process of an ultrahigh-temperature high-strength turbine rotor forging comprises the following steps:
(1) Refining molten steel in an arc furnace: after the steel material is proportioned, an electric arc furnace is adopted to roughen molten steel;
(2) Refining molten steel outside a furnace: adopting a ladle refining furnace, adding molten steel after the electric arc furnace roughing into the ladle refining furnace, and refining the molten steel;
(3) Vacuum degassing: the ladle is hung into a vacuum furnace, and vacuum degassing treatment is carried out on molten steel;
(4) Pouring a consumable electrode: after the molten steel is subjected to vacuum degassing treatment, pouring the steel into a consumable electrode mold of a consumable electrode pouring station by a ladle to pour the consumable electrode, and cooling and demolding to obtain the consumable electrode; the self-consumption electrode die adopts a water-cooling electrode die under the protection of Ar gas to improve the cooling speed, reduce carbide and inclusion aggregation and grow up, and the riser feeding control is performed during pouring to avoid riser shrinkage cavity;
(5) Annealing the consumable electrode; annealing the consumable electrode; cleaning the surface of the electrode after annealing treatment;
(6) Electroslag remelting to prepare a steel ingot of the steam turbine rotor: adopting an electroslag remelting furnace and a specially designed turbine rotor steel ingot crystallizer, inserting a consumable electrode into the turbine rotor steel ingot crystallizer of the Ar gas protection electroslag remelting furnace for secondary refining, cooling in the turbine rotor steel ingot crystallizer, and demoulding to obtain a turbine rotor steel ingot;
(6) Annealing of steel ingots of steam turbine rotors: annealing the steel ingot of the turbine rotor; cleaning the surface of a steel ingot of the steam turbine rotor after annealing treatment;
(7) Forging: heating a steel ingot of a steam turbine rotor and forging;
(8) Heat treatment after forging: normalizing, spheroidizing and tempering the forged turbine rotor steel ingot;
(9) Rough machining: rough turning is carried out on the steel ingot of the turbine rotor after the heat treatment after forging;
(10) Final heat treatment: and sequentially carrying out solution treatment and twice tempering treatment on the rough-turned turbine rotor steel ingot to obtain the ultrahigh-temperature high-strength turbine rotor forging.
Preferably, in the forging of the step (7), the initial forging temperature is 1120-1200 ℃ and the final forging temperature is 900-950 ℃.
Preferably, in the final heat treatment of (10), the solid solution treatment is to place the steel ingot of the steam turbine rotor into a heating furnace, heat the steel ingot to 1050-1100 ℃ at room temperature, keep the temperature, and then spray water mist for cooling; the first tempering is to place the steel ingot of the turbine rotor into a heating furnace, heat the steel ingot to 720-820 ℃ at room temperature, and air cool the steel ingot after heat preservation; and the second tempering is to place the steel ingot of the turbine rotor into a heating furnace, heat the steel ingot to 710-810 ℃ at room temperature, and air-cool the steel ingot after heat preservation.
After the forging is positively tempered, uniform lath tempered martensite and fine dispersed alloy precipitated phases are obtained, and the dispersed alloy precipitated phases are second-phase strengthening particles, so that the dispersion strengthening effect is achieved, the effects of pinning dislocation and blocking dislocation movement are achieved at high temperature, and the high-temperature toughness of the turbine rotor forging is remarkably improved.
The steel ingot crystallizer of the steam turbine rotor comprises a water cooling chassis and an annular crystallizer arranged on the water cooling chassis, wherein a water cooling chamber is arranged in the water cooling chassis, an annular water cooling cavity is arranged on the annular crystallizer, a water inlet and a water outlet are respectively arranged on the water cooling chamber and the annular water cooling cavity, the water inlet is connected with a water inlet pipe, and the water outlet is connected with a water outlet pipe.
As a further improvement of the invention, the crystallizer internal water temperature dynamic peak clipping device is arranged on the steel ingot crystallizer of the steam turbine rotor and comprises an annular water receiving tank connected to the lower part of the outer wall of the annular crystallizer, a water outlet arranged on the annular water receiving tank, a water drain pipe connected to the water outlet, and a plurality of bimetallic strip type high-temperature drain valves which are arranged on the outer circular surface of the annular crystallizer and distributed in a mode of being arranged at intervals and communicated with the annular water cooling cavity of the annular crystallizer; when the temperature of a local node area in an annular water cooling cavity of the annular crystallizer exceeds a preset threshold value, the bimetallic strip type high-temperature drain valve positioned at the local node area is automatically opened, and the ultra-warm water positioned at the local node area overflows into the annular water receiving tank and is discharged through the drain pipe, so that the uniform setting of the temperature of each area in the annular water cooling cavity of the annular crystallizer is realized.
The opening degree of the bimetallic strip type high-temperature drain valve is automatically adjusted according to the water temperature contacted in the bimetallic strip type high-temperature drain valve. Under the condition of overtemperature, the opening degree of the bimetallic strip type high-temperature drain valve is larger as the water temperature is higher, and the overflow amount of the overtemperature water is larger.
Preferably, a water inlet of an annular water cooling cavity of the annular crystallizer is connected with a variable-frequency cold water pump through the water inlet pipe, and a pressure sensor is arranged in the annular water cooling cavity of the annular crystallizer; the variable-frequency cold water pump and the pressure sensor are respectively connected with the controller, and the controller dynamically adjusts the rotating speed of the variable-frequency cold water pump in real time according to the internal water pressure of the annular water cooling cavity detected by the pressure sensor, so that the internal water pressure of the annular water cooling cavity is kept constant.
When the temperature of a local node area in an annular water cooling cavity of the annular crystallizer is too high, high-temperature water can overflow and be discharged from the bimetallic strip type high-temperature drain valve, so that the water pressure in the annular water cooling cavity is reduced, and at the moment, the rotating speed of the variable-frequency cold water pump can be increased, the flow rate is increased to supplement the pressure loss caused by overflow of the high-temperature water from the bimetallic strip type high-temperature drain valve, so that the dynamic balance of the water pressure in the annular water cooling cavity is maintained. When the temperature of the local node area in the annular water cooling cavity of the annular crystallizer is too high, the bimetallic strip type high-temperature drain valve at the local node area is automatically closed, so that the water pressure in the annular water cooling cavity is increased, and at the moment, the variable-frequency cold water pump can reduce the rotating speed and the flow rate, so that the water pressure in the annular water cooling cavity is recovered to be normal, and the dynamic balance of the water pressure in the annular water cooling cavity is maintained.
During electroslag remelting, a high-temperature area is usually formed in the crystallizer near slag liquid and a molten pool, and the high-temperature area in the crystallizer moves upwards along with the rising of the slag liquid level along with the gradual rising of the slag liquid level in the steel ingot crystallizer of the steam turbine rotor. According to the invention, the bimetallic strip type high-temperature drain valves with a large number are arranged on the annular crystallizer at intervals, so that the bimetallic strip type high-temperature drain valves arranged at intervals can always act at the highest temperature of which the positions are continuously and dynamically changed, and a dynamic peak clipping effect of the internal temperature of the crystallizer is achieved, thereby improving the uniformity of the internal cooling water temperature of the crystallizer and further improving the preparation quality of the steel ingot of the turbine rotor.
In the invention, a dummy electrode disc is arranged on the electroslag remelting furnace above the steel ingot crystallizer of the steam turbine rotor, and the consumable electrode is connected to the lower end of the dummy electrode disc.
The false electrode disc is arranged on a lifting mechanism of the electroslag remelting furnace, which is positioned above the steel ingot crystallizer of the steam turbine rotor, so as to meet the lifting requirement of a consumable electrode during electroslag remelting.
As a further improvement of the invention, the upper part of the steel ingot crystallizer of the turbine rotor is provided with an electroslag remelting Ar gas protection device, the electroslag remelting Ar gas protection device comprises a protection cover arranged at the upper end of the steel ingot crystallizer of the turbine rotor, a through hole arranged at the central part of the upper part of the protection cover and used for penetrating through a consumable electrode, and an annular protection gas supply chamber circumferentially arranged on the protection cover, the annular protection gas supply chamber is externally connected with an Ar gas supply source through a pipeline, a plurality of air supply pipes extending to the upper part of the inner part of the steel ingot crystallizer of the turbine rotor are circumferentially arranged on the annular protection gas supply chamber, and the front end of each air supply pipe is vertically connected with an air blowing pipe communicated with the air supply pipe.
Preferably, the gas blowing pipe is a slag powder pipe formed by pressing electroslag remelting slag powder materials through a special die for forming a pipe body.
Preferably, the special die for forming the pipe body comprises an upper die, a lower die, a guide column, a feed inlet, a feed gland and a conical core rod, wherein the upper die and the lower die are oppositely combined up and down, the guide column is arranged between the upper die and the lower die, the feed inlet is arranged at the upper end of the upper die, the feed gland is arranged on the feed inlet of the upper die, the conical core rod is arranged between the upper die and the lower die and is provided with a demoulding inclination, the upper die and the lower die are oppositely combined to form a die cavity, and the conical core rod penetrates between the die cavities formed by the upper die and the lower die.
Preferably, a connecting screw is further arranged between the upper die and the lower die.
Preferably, positioning cylinders are arranged at two ends of the conical core rod, semicircular holes for positioning are respectively arranged at two ends of the cavity of the upper die and the lower die, the semicircular holes on the upper die and the lower die are paired to form a circular hole after the upper die and the lower die are paired, and the positioning cylinders are positioned on the circular hole.
Preferably, the left end and the right end of the upper die and the lower die are respectively provided with a demoulding hole, and the demoulding holes are arranged along the up-down direction and penetrate through to the positioning cylinder.
During demolding, a jacking column can be placed in the demolding hole, and the tapered core rod is ejected out together with the upper air blowing pipe by applying acting force to the positioning column through the jacking column; and then separating the air blowing pipe from the conical core rod by utilizing the demoulding inclination of the conical core rod.
When the slag powder tube is used, the special die for tube body forming is arranged on a powder metallurgy forming press, electroslag remelting slag powder materials which are uniformly mixed after being mixed are added into a die cavity of the special die for tube body forming for pressing, slag powder is combined into a whole under high pressure, and a slag powder tube is formed after demoulding. The slag powder pipe after compression molding is directly used as an air blowing pipe without sintering and is connected with the air blowing pipe through a special connector.
During electroslag remelting, a plurality of blowing pipes distributed along the circumferential direction blow Ar gas into the steel ingot crystallizer of the turbine rotor simultaneously in a blowing mode from top to bottom, and the Ar gas forms a protective atmosphere above slag liquid in the steel ingot crystallizer of the turbine rotor. With the process of electroslag remelting, slag liquid in the steel ingot crystallizer of the turbine rotor gradually rises, and the part, close to the slag liquid, of the lower part of the slag powder pipe is gradually melted under the action of high temperature, so that Ar gas protection is realized, meanwhile, the effect of supplementing the slag liquid in the crystallizer can be also realized, the stability of liquid slag quality is favorably maintained, and the quality of the steel ingot of the turbine rotor after the electroslag remelting is improved.
The beneficial effects of the invention are as follows:
Firstly, according to the ultrahigh-temperature high-strength turbine rotor forging and the preparation process, W, mo and Co are added in the material proportion to perform alloy strengthening, W and Mo are solid solution strengthening elements, and the combined effect of the two elements is better, so that the ultrahigh-temperature high-strength turbine rotor forging has extremely high heat resistance and red hardness, and the tempering stability can be improved; co and V are further strengthened, and Co can inhibit the formation and precipitation of delta-ferrite; the addition of trace Nb, ti and V can play a role in refining grains. The shell obtains lath tempered martensite with uniform microstructure and fine dispersion alloy precipitated phases, so that the performance of the ultrahigh-temperature high-strength turbine rotor forging is improved.
Secondly, according to the ultrahigh-temperature high-strength turbine rotor forging and the preparation process, solution treatment and twice tempering treatment are adopted for final heat treatment after fracture, uniform lath tempered martensite and fine dispersed alloy precipitated phases are obtained by the shell, and the dispersed alloy precipitated phases are second-phase reinforced particles, so that the dispersion strengthening effect is achieved, the effects of pinning dislocation and blocking dislocation movement are achieved at high temperature, and the high-temperature toughness of the turbine rotor forging is remarkably improved.
Thirdly, the ultrahigh-temperature high-strength turbine rotor forging and the preparation process adopt an electroslag remelting technology to manufacture the turbine rotor steel ingot, so that internal inclusions can be effectively removed, an ultra-clean turbine rotor steel ingot is formed, the internal primary carbide structure is thinned, the reticular structure is eliminated, and the strength of molten steel after cooling is improved. Thereby further improving the workability of the cold-rolled work rolls.
Fourth, according to the ultrahigh-temperature high-strength turbine rotor forging and the preparation process, the turbine rotor steel ingot crystallizer is provided with the annular crystallizer internal water temperature dynamic peak clipping device, bimetallic strip type high-temperature drain valves are arranged on the outer cylindrical surface of the annular crystallizer at intervals, and the temperature of the high-temperature part dynamically changing on the turbine rotor steel ingot crystallizer can be dynamically adjusted in a targeted manner, so that the dynamic adjustment of the temperature of the turbine rotor steel ingot crystallizer in electroslag remelting is maintained. Thereby further improving the preparation quality of the steel ingot of the turbine rotor.
Fifth, according to the ultrahigh-temperature high-strength turbine rotor forging and the preparation process, the special manufactured slag powder pipe is used as the Ar gas blowing pipe by the electroslag remelting Ar gas protection device, so that the slag liquid continuously melted at the lower end of the slag powder pipe can be timely supplemented into the slag liquid layer in the crystallizer while the Ar gas protection atmosphere is formed, the stability of the liquid slag quality in the crystallizer is maintained, the continuous absorption capacity of the slag liquid in the crystallizer for impurities is enhanced, and the quality of the turbine rotor steel ingot after electroslag remelting is further improved.
Drawings
FIG. 1 is a schematic flow diagram of a process for preparing a rotor forging of an ultra-high temperature high strength steam turbine according to the present invention;
FIG. 2 is a schematic structural view of a turbine rotor ingot mold used in the process for manufacturing a turbine rotor forging with ultra-high temperature and high strength according to the present invention;
Fig. 3 is a schematic structural diagram of a special mold for forming a pipe body used in the process for preparing the ultra-high temperature high strength turbine rotor forging of the present invention.
In the figure: 1. the device comprises a consumable electrode, 2, a turbine rotor steel ingot crystallizer, 3, a water cooling chassis, 4, an annular crystallizer, 5, a water cooling chamber, 6, an annular water cooling cavity, 7, a water inlet pipe, 8, a water outlet pipe, 9, an annular water receiving tank, 10, a water outlet pipe, 11, a bimetallic strip type high-temperature drain valve, 12, a pressure sensor, 13, a false electrode disc, 14, an electroslag remelting Ar gas protection device, 15, a protection cover, 16, an annular protection gas supply chamber, 17, an air supply pipe, 18, a gas blowing pipe, 19, a special pipe body forming die, 20, an upper die, 21, a lower die, 22, a guide post, 23, a feed inlet, 24, a feed gland, 25, a conical core rod, 26, a positioning cylinder, 27 and a demoulding hole.
Detailed Description
The following describes the embodiments of the present invention further with reference to the drawings and examples. The following examples are only for more clearly illustrating the technical aspects of the present invention, and are not intended to limit the scope of the present invention.
Example 1:
As shown in FIGS. 1 to 3, an embodiment of the ultra-high temperature high strength turbine rotor forging of the present invention comprises, in mass proportions, C in an amount of 0.08 to 0.15%, si in an amount of 1.0%, mn in an amount of 0.6 to 1.0%, cr in an amount of 9.0 to 12.0%, ni in an amount of 4 to 6%, mo in an amount of 2.0 to 4.0%, nb in an amount of 0.15 to 0.25%, co in an amount of 1.5 to 2.5%, W in an amount of 2 to 5%, ti in an amount of 0.05 to 0.25%, V in an amount of 1.3 to 2.5%, cu in an amount of 0.25%, P in an amount of 0.004%, S in an amount of 0.0008%, al in an amount of 0.020%, H in an amount of 0.8PPm, O in an amount of 10PPm, N in an amount of 150PPm, fe and unavoidable impurities.
According to the ultrahigh-temperature high-strength turbine rotor forging material, alloy strengthening is mainly carried out by adding W, mo and Co in the material proportion, W and Mo are solid solution strengthening elements, and the combined effect of the two elements is better, so that the ultrahigh-temperature high-strength turbine rotor forging material has extremely high heat resistance and red hardness, and can increase tempering stability; co and V are further strengthened, and Co can inhibit the formation and precipitation of delta-ferrite; the addition of trace Nb, ti and V can play a role in refining grains. The shell obtains lath tempered martensite with uniform microstructure and fine dispersion alloy precipitated phases, so that the performance of the rotor forging of the ultra-temperature high-strength steam turbine is improved, and the use requirements of the rotor forging of the ultra-temperature high-strength steam turbine on high temperature and high pressure resistance are met.
Example 2:
a preparation process of a rotor forging of an ultra-high temperature high-strength steam turbine adopting the embodiment 1 comprises the following steps:
(1) Refining molten steel in an arc furnace: after the steel material is proportioned, an electric arc furnace is adopted to roughen molten steel;
(2) Refining molten steel outside a furnace: adopting a ladle refining furnace, adding molten steel after the electric arc furnace roughing into the ladle refining furnace, and refining the molten steel;
(3) Vacuum degassing: the ladle is hung into a vacuum furnace, and vacuum degassing treatment is carried out on molten steel;
(4) Pouring a consumable electrode: after the molten steel is subjected to vacuum degassing treatment, pouring the steel into a consumable electrode mold of a consumable electrode pouring station by a crane ladle to pour the consumable electrode, and cooling and demolding to obtain the consumable electrode 1; the self-consumption electrode die adopts a water-cooling electrode die under the protection of Ar gas to improve the cooling speed, reduce carbide and inclusion aggregation and grow up, and the riser feeding control is performed during pouring to avoid riser shrinkage cavity;
(5) Annealing the consumable electrode; annealing the consumable electrode; cleaning the surface of the electrode after annealing treatment;
(6) Electroslag remelting to prepare a steel ingot of the steam turbine rotor: adopting an electroslag remelting furnace and a specially designed turbine rotor steel ingot crystallizer 2, inserting a consumable electrode 1 into the turbine rotor steel ingot crystallizer 2 of the Ar gas protection electroslag remelting furnace for secondary refining, cooling in the turbine rotor steel ingot crystallizer 2, and demoulding to obtain a turbine rotor steel ingot;
(6) Annealing of steel ingots of steam turbine rotors: annealing the steel ingot of the turbine rotor; cleaning the surface of a steel ingot of the steam turbine rotor after annealing treatment;
(7) Forging: heating a steel ingot of a steam turbine rotor and forging;
(8) Heat treatment after forging: normalizing, spheroidizing and tempering the forged turbine rotor steel ingot;
(9) Rough machining: rough turning is carried out on the steel ingot of the turbine rotor after the heat treatment after forging;
(10) Final heat treatment: and sequentially carrying out solution treatment and twice tempering treatment on the rough-turned turbine rotor steel ingot to obtain the ultrahigh-temperature high-strength turbine rotor forging.
Preferably, in the forging of the step (7), the initial forging temperature is 1120-1200 ℃ and the final forging temperature is 900-950 ℃.
Preferably, in the final heat treatment of (10), the solid solution treatment is to place the steel ingot of the steam turbine rotor into a heating furnace, heat the steel ingot to 1050-1100 ℃ at room temperature, keep the temperature, and then spray water mist for cooling; the first tempering is to place the steel ingot of the turbine rotor into a heating furnace, heat the steel ingot to 720-820 ℃ at room temperature, and air cool the steel ingot after heat preservation; and the second tempering is to place the steel ingot of the turbine rotor into a heating furnace, heat the steel ingot to 710-810 ℃ at room temperature, and air-cool the steel ingot after heat preservation.
After the forging is positively tempered, uniform lath tempered martensite and fine dispersed alloy precipitated phases are obtained, and the dispersed alloy precipitated phases are second-phase strengthening particles, so that the dispersion strengthening effect is achieved, the effects of pinning dislocation and blocking dislocation movement are achieved at high temperature, and the high-temperature toughness of the turbine rotor forging is remarkably improved.
In this embodiment, the turbine rotor steel ingot crystallizer 2 includes a water cooling chassis 3 and an annular crystallizer 4 disposed on the water cooling chassis 3, a water cooling chamber 5 is disposed in the water cooling chassis 3, an annular water cooling cavity 6 is disposed on the annular crystallizer 4, a water inlet and a water outlet are respectively disposed on the water cooling chamber 5 and the annular water cooling cavity 6, a water inlet pipe 7 is connected to the water inlet, and a water outlet pipe 8 is connected to the water outlet.
As a further improvement of the embodiment, the crystallizer 2 is provided with a dynamic peak clipping device for the internal water temperature of the crystallizer, and the dynamic peak clipping device for the internal water temperature of the crystallizer comprises an annular water receiving tank 9 connected to the lower part of the outer wall of the annular crystallizer 4, a water outlet arranged on the annular water receiving tank 9, a water drain pipe 10 connected to the water outlet, and a plurality of bimetallic strip type high-temperature drain valves 11 which are arranged on the outer circular surface of the annular crystallizer 4 and distributed in a mode of being arranged at intervals and communicated with the annular water cooling cavity 6 of the annular crystallizer 4; when the temperature of a local node area in the annular water cooling cavity 6 of the annular crystallizer 4 exceeds a preset threshold value, the bimetallic strip type high-temperature drain valve 11 positioned at the local node area is automatically opened, and the ultra-warm water positioned at the local node area overflows into the annular water receiving tank 9 and is discharged through the drain pipe 10, so that the uniform setting of the temperature of each area in the annular water cooling cavity 6 of the annular crystallizer 4 is realized.
Wherein, the opening degree of the bimetallic strip type high temperature drain valve 11 is automatically adjusted according to the water temperature contacted in the bimetallic strip type high temperature drain valve 11. Under the condition of over-temperature, the opening degree of the bimetallic high-temperature drain valve 11 is larger as the water temperature is higher, and the overflow amount of the over-temperature water is larger.
Preferably, a water inlet of the annular water cooling cavity 6 of the annular crystallizer 4 is connected with a variable-frequency cold water pump (not shown in the figure) through the water inlet pipe, and a pressure sensor 12 is arranged in the annular water cooling cavity 6 of the annular crystallizer 4; the variable-frequency cold water pump and the pressure sensor 12 are respectively connected with a controller, and the controller dynamically adjusts the rotating speed of the variable-frequency cold water pump in real time according to the internal water pressure of the annular water cooling cavity 6 detected by the pressure sensor 12, so that the internal water pressure of the annular water cooling cavity is kept constant.
Preferably, the internal water pressure of the annular water cooling cavity 6 is set to be 1.1-1.5 atm.
When the temperature of the local node area in the annular water cooling cavity 6 of the annular crystallizer 4 is too high, high-temperature water can overflow and be discharged from the bimetallic strip type high-temperature drain valve 11, so that the water pressure in the annular water cooling cavity 6 is reduced, and at the moment, the variable-frequency cold water pump can increase the rotating speed and increase the flow rate to supplement the pressure loss caused by the overflow of the high-temperature water from the bimetallic strip type high-temperature drain valve 11, so that the dynamic balance of the water pressure in the annular water cooling cavity is maintained. When the temperature of the local node area in the annular water cooling cavity 6 of the annular crystallizer 4 is recovered to the normal temperature at the position with overhigh temperature, the bimetallic strip type high-temperature drain valve is automatically closed, so that the water pressure in the annular water cooling cavity 6 is increased, at the moment, the variable-frequency cold water pump can reduce the rotating speed and the flow rate, so that the water pressure in the annular water cooling cavity 6 is recovered to be normal, and the dynamic balance of the water pressure in the annular water cooling cavity 6 is maintained.
During electroslag remelting, a high-temperature area is usually formed in the crystallizer near slag liquid and a molten pool, and the high-temperature area in the crystallizer moves upwards along with the rising of the slag liquid level as the liquid level of the slag liquid in the steel ingot crystallizer 2 of the steam turbine rotor gradually rises. According to the embodiment, the bimetallic strip type high-temperature drain valves 11 with a large number are arranged on the annular crystallizer 4 in the interval array mode, so that the bimetallic strip type high-temperature drain valves 11 arranged in the interval array mode can always act at the highest temperature position where the positions are continuously and dynamically changed, the dynamic peak clipping effect of the internal temperature of the crystallizer is achieved, the uniformity of the internal cooling water temperature of the crystallizer is improved, and the preparation quality of the steel ingots of the steam turbine rotor is improved.
In this embodiment, a dummy electrode plate 13 is disposed above the steel ingot crystallizer 2 of the steam turbine rotor on the electroslag remelting furnace, and the consumable electrode 1 is connected to the lower end of the dummy electrode plate 13.
The dummy electrode plate 13 is arranged on a lifting mechanism (not shown in the figure) of the electroslag remelting furnace above the steel ingot crystallizer 2 of the steam turbine rotor, so as to meet the lifting requirement of the consumable electrode 1 during electroslag remelting.
As a further improvement of the present embodiment, the upper portion of the turbine rotor ingot mold 2 is provided with an electroslag remelting Ar gas protection device 14, the electroslag remelting Ar gas protection device 14 includes a protection cover 15 disposed at the upper end of the turbine rotor ingot mold 2, a through hole disposed at the upper center of the protection cover 14 and used for passing through the consumable electrode 1, and an annular protection gas supply chamber 16 circumferentially disposed on the protection cover 14, the annular protection gas supply chamber 16 is externally connected with an Ar gas supply source through a pipeline, a plurality of gas supply pipes 17 extending to the upper portion of the turbine rotor ingot mold 2 are circumferentially disposed on the annular protection gas supply chamber 16, and a gas blowing pipe 18 communicating with the gas supply pipes 17 is vertically connected with the front end of the gas supply pipes 17.
Preferably, the gas blowing pipe 18 is a slag powder pipe formed by pressing an electroslag remelting slag powder material with a special pipe body forming die 19.
Preferably, the special pipe body forming mold 19 includes an upper mold 20 and a lower mold 21 which are vertically combined, a guide post 22 arranged between the upper mold 20 and the lower mold 21, a feed inlet 23 arranged at the upper end of the upper mold 20, a feed gland 24 arranged on the feed inlet 23 of the upper mold, and a conical core rod 25 with a demoulding inclination arranged between the upper mold 20 and the lower mold 21, wherein the upper mold 20 and the lower mold 21 are combined to form a mold cavity, and the conical core rod 25 penetrates between the mold cavities formed by the upper mold 20 and the lower mold 21.
Preferably, a connecting screw is further provided between the upper die 20 and the lower die 21.
Preferably, positioning cylinders 26 are disposed at two ends of the conical core rod 25, positioning semicircular holes are disposed at two ends of the cavity of the upper die 20 and the lower die 21, the semicircular holes of the upper die 20 and the lower die 21 are paired to form a circular hole, and the positioning cylinders 26 are positioned on the circular hole.
Preferably, the left and right end portions of the upper die 210 and the lower die 21 are respectively provided with a stripping hole 27, and the stripping holes 27 are arranged along the up-down direction and penetrate to the positioning cylinder 26.
During demoulding, a jacking column can be placed in the demoulding hole 27, and the conical core rod 25 and the upper air blowing pipe 18 are ejected together by applying force to the positioning column 26 through the jacking column; the blowpipe 18 is then separated from the tapered mandrel 25 by the draft angle of the tapered mandrel 25.
When the powder metallurgy forming machine is used, the special pipe body forming die 19 is installed on the powder metallurgy forming press, electroslag remelting slag powder materials which are uniformly mixed after being mixed are added into a die cavity of the special pipe body forming die 19 for pressing, slag powder is combined into a whole under high pressure, and a slag powder pipe is formed after demoulding. The slag powder pipe after the press molding is directly used as the air blowing pipe 18 without sintering, and is connected with the air blowing pipe 18 through a special joint.
During electroslag remelting, a plurality of blowing pipes 18 distributed along the circumferential direction blow Ar gas into the inside of the steel ingot crystallizer 2 of the turbine rotor simultaneously in a blowing mode from top to bottom, and the Ar gas forms a protective atmosphere above slag liquid in the steel ingot crystallizer 2 of the turbine rotor. With the process of electroslag remelting, slag liquid in the steel ingot crystallizer 2 of the steam turbine rotor gradually rises, and the part, close to the slag liquid, of the lower part of the slag powder pipe is gradually melted under the action of high temperature, so that Ar gas protection is realized, meanwhile, the effect of supplementing the slag liquid in the crystallizer can be achieved, the stability of liquid slag quality is maintained, and the quality of the steel ingot of the steam turbine rotor after the electroslag remelting is improved.
The foregoing is merely a preferred embodiment of the present invention, and it should be noted that it will be apparent to those skilled in the art that several modifications and variations can be made without departing from the technical principle of the present invention, and these modifications and variations should also be regarded as the scope of the invention.
Claims (10)
1. An ultra-high temperature high strength turbine rotor forging, characterized in that the forging comprises, by mass, 0.08-0.15% of C, 1.0% or less of Si, 0.6-1.0% of Mn, 9.0-12.0% of Cr, 4-6% of Ni, 2.0-4.0% of Mo, 0.15-0.25% of Nb, 1.5-2.5% of Co, 2-5% of W, 0.05-0.25% of Ti, 1.3-2.5% of V, 0.25% or less of Cu, 0.004% or less of P, 0.0008% or less of S, 0.020% or less of Al, 0.8PPm or less of [ H ], 10PPm or less of [ O ], 150PPm or less of [ N, and the balance Fe and unavoidable impurities.
2. A process for preparing a rotor forging of a super-temperature high-strength steam turbine according to claim 1, which is characterized by comprising the following steps:
(1) Refining molten steel in an arc furnace: after the steel material is proportioned, an electric arc furnace is adopted to roughen molten steel;
(2) Refining molten steel outside a furnace: adopting a ladle refining furnace, adding molten steel after the electric arc furnace roughing into the ladle refining furnace, and refining the molten steel;
(3) Vacuum degassing: the ladle is hung into a vacuum furnace, and vacuum degassing treatment is carried out on molten steel;
(4) Pouring a consumable electrode: after the molten steel is subjected to vacuum degassing treatment, pouring the steel into a consumable electrode mold of a consumable electrode pouring station by a ladle to pour the consumable electrode, and cooling and demolding to obtain the consumable electrode; the self-consumption electrode die adopts a water-cooling electrode die under the protection of Ar gas to improve the cooling speed, reduce carbide and inclusion aggregation and grow up, and the riser feeding control is performed during pouring to avoid riser shrinkage cavity;
(5) Annealing the consumable electrode; annealing the consumable electrode; cleaning the surface of the electrode after annealing treatment;
(6) Electroslag remelting to prepare a steel ingot of the steam turbine rotor: adopting an electroslag remelting furnace and a specially designed turbine rotor steel ingot crystallizer, inserting a consumable electrode into the turbine rotor steel ingot crystallizer of the Ar gas protection electroslag remelting furnace for secondary refining, cooling in the turbine rotor steel ingot crystallizer, and demoulding to obtain a turbine rotor steel ingot;
(6) Annealing of steel ingots of steam turbine rotors: annealing the steel ingot of the turbine rotor; cleaning the surface of a steel ingot of the steam turbine rotor after annealing treatment;
(7) Forging: heating a steel ingot of a steam turbine rotor and forging;
(8) Heat treatment after forging: normalizing, spheroidizing and tempering the forged turbine rotor steel ingot;
(9) Rough machining: rough turning is carried out on the steel ingot of the turbine rotor after the heat treatment after forging;
(10) Final heat treatment: and sequentially carrying out solution treatment and twice tempering treatment on the rough-turned turbine rotor steel ingot to obtain the ultrahigh-temperature high-strength turbine rotor forging.
3. A process for preparing a rotor forging of a super-temperature high-strength steam turbine according to claim 2, wherein in the forging of the step (7), the initial forging temperature is 1120-1200 ℃ and the final forging temperature is 900-950 ℃.
4. A process for preparing a high-temperature and high-strength turbine rotor forging according to claim 2, wherein in the final heat treatment of (10), the solid solution treatment is to place a turbine rotor steel ingot into a heating furnace, heat the steel ingot to 1050-1100 ℃ at room temperature, preserve heat and then spray mist for cooling; the first tempering is to place the steel ingot of the turbine rotor into a heating furnace, heat the steel ingot to 720-820 ℃ at room temperature, and air cool the steel ingot after heat preservation; and the second tempering is to place the steel ingot of the turbine rotor into a heating furnace, heat the steel ingot to 710-810 ℃ at room temperature, and air-cool the steel ingot after heat preservation.
5. The process for preparing the ultrahigh-temperature high-strength turbine rotor forging is characterized in that the turbine rotor steel ingot crystallizer comprises a water-cooling chassis and an annular crystallizer arranged on the water-cooling chassis, a water-cooling chamber is arranged in the water-cooling chassis, an annular water-cooling cavity is arranged on the annular crystallizer, a water inlet and a water outlet are respectively arranged on the water-cooling chamber and the annular water-cooling cavity, a water inlet pipe is connected to the water inlet, and a water outlet pipe is connected to the water outlet.
6. The preparation process of the ultra-temperature high-strength turbine rotor forging is characterized in that a crystallizer internal water temperature dynamic peak clipping device is arranged on a turbine rotor steel ingot crystallizer, and comprises an annular water receiving groove connected to the lower part of the outer wall of the annular crystallizer, a water outlet arranged on the annular water receiving groove, a water drain pipe connected to the water outlet, and a plurality of bimetallic strip type high-temperature drain valves which are arranged on the outer circular surface of the annular crystallizer and distributed in a mode of being arranged at intervals and communicated with an annular water cooling cavity of the annular crystallizer; when the temperature of a local node area in an annular water cooling cavity of the annular crystallizer exceeds a preset threshold value, the bimetallic strip type high-temperature drain valve positioned at the local node area is automatically opened, and the ultra-warm water positioned at the local node area overflows into the annular water receiving tank and is discharged through the drain pipe, so that the uniform setting of the temperature of each area in the annular water cooling cavity of the annular crystallizer is realized.
7. A process for preparing a rotor forging of an ultra-temperature high-strength steam turbine by adopting the method disclosed by claim 6, which is characterized in that a water inlet of an annular water cooling cavity of the annular crystallizer is connected with a variable-frequency cold water pump through the water inlet pipe, and a pressure sensor is arranged in the annular water cooling cavity of the annular crystallizer; the variable-frequency cold water pump and the pressure sensor are respectively connected with the controller, and the controller dynamically adjusts the rotating speed of the variable-frequency cold water pump in real time according to the internal water pressure of the annular water cooling cavity detected by the pressure sensor, so that the internal water pressure of the annular water cooling cavity is kept constant.
8. The process for preparing the ultrahigh-temperature high-strength turbine rotor forging is characterized in that an electroslag remelting Ar gas protection device is arranged at the upper part of a turbine rotor steel ingot crystallizer, the electroslag remelting Ar gas protection device comprises a protection cover arranged at the upper end of the turbine rotor steel ingot crystallizer, a through hole arranged at the central part of the upper part of the protection cover and used for penetrating through a consumable electrode, and an annular protection gas supply chamber circumferentially arranged on the protection cover, wherein the annular protection gas supply chamber is externally connected with an Ar gas supply source through a pipeline, a plurality of gas supply pipes extending to the position above the inside of the turbine rotor steel ingot crystallizer are circumferentially arranged on the annular protection gas supply chamber, and the front end of the gas supply pipe is vertically connected with a gas blowing pipe communicated with the gas supply pipe.
9. A process for preparing a rotor forging of an ultra-temperature high-strength steam turbine by adopting the method disclosed in claim 8, which is characterized in that the gas blowing pipe is a slag powder pipe formed by adopting electroslag remelting slag powder material through a special die for forming a pipe body.
10. The process for preparing the rotor forging of the ultra-temperature high-strength steam turbine is characterized in that the special die for forming the pipe body comprises an upper die, a lower die, a guide post, a feeding port, a feeding gland and a conical core rod, wherein the upper die and the lower die are combined up and down, the guide post is arranged between the upper die and the lower die, the feeding port is arranged at the upper end of the upper die, the feeding gland is arranged on the feeding port of the upper die, the conical core rod is arranged between the upper die and the lower die and is provided with a demoulding inclination, the upper die and the lower die are combined to form a die cavity, and the conical core rod penetrates between the die cavities formed by the upper die and the lower die.
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| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202410362987.5A CN118326283A (en) | 2024-03-28 | 2024-03-28 | Ultrahigh-temperature high-strength turbine rotor forging and preparation process |
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| Application Number | Priority Date | Filing Date | Title |
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| CN202410362987.5A CN118326283A (en) | 2024-03-28 | 2024-03-28 | Ultrahigh-temperature high-strength turbine rotor forging and preparation process |
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