CN113667807A - Heat-resistant steel, heat treatment method and application - Google Patents
Heat-resistant steel, heat treatment method and application Download PDFInfo
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- CN113667807A CN113667807A CN202010411361.0A CN202010411361A CN113667807A CN 113667807 A CN113667807 A CN 113667807A CN 202010411361 A CN202010411361 A CN 202010411361A CN 113667807 A CN113667807 A CN 113667807A
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- 238000000034 method Methods 0.000 title claims abstract description 44
- 229910000831 Steel Inorganic materials 0.000 title claims abstract description 34
- 238000010438 heat treatment Methods 0.000 title claims abstract description 34
- 239000010959 steel Substances 0.000 title claims abstract description 34
- 238000005242 forging Methods 0.000 claims abstract description 87
- 238000001816 cooling Methods 0.000 claims abstract description 46
- 238000000137 annealing Methods 0.000 claims description 17
- 229910000859 α-Fe Inorganic materials 0.000 claims description 16
- 229910052804 chromium Inorganic materials 0.000 claims description 11
- 238000004321 preservation Methods 0.000 claims description 11
- 239000013078 crystal Substances 0.000 abstract description 15
- 238000007670 refining Methods 0.000 abstract description 5
- 229910001566 austenite Inorganic materials 0.000 description 18
- 239000000463 material Substances 0.000 description 13
- 230000008569 process Effects 0.000 description 13
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- 238000005728 strengthening Methods 0.000 description 5
- 238000010248 power generation Methods 0.000 description 4
- OKTJSMMVPCPJKN-UHFFFAOYSA-N Carbon Chemical compound [C] OKTJSMMVPCPJKN-UHFFFAOYSA-N 0.000 description 3
- ZOKXTWBITQBERF-UHFFFAOYSA-N Molybdenum Chemical compound [Mo] ZOKXTWBITQBERF-UHFFFAOYSA-N 0.000 description 3
- 229910052799 carbon Inorganic materials 0.000 description 3
- 239000010941 cobalt Substances 0.000 description 3
- 229910017052 cobalt Inorganic materials 0.000 description 3
- GUTLYIVDDKVIGB-UHFFFAOYSA-N cobalt atom Chemical compound [Co] GUTLYIVDDKVIGB-UHFFFAOYSA-N 0.000 description 3
- 238000011161 development Methods 0.000 description 3
- 238000009826 distribution Methods 0.000 description 3
- 229910052750 molybdenum Inorganic materials 0.000 description 3
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- 238000001556 precipitation Methods 0.000 description 3
- 230000009467 reduction Effects 0.000 description 3
- IJGRMHOSHXDMSA-UHFFFAOYSA-N Atomic nitrogen Chemical compound N#N IJGRMHOSHXDMSA-UHFFFAOYSA-N 0.000 description 2
- ZOXJGFHDIHLPTG-UHFFFAOYSA-N Boron Chemical compound [B] ZOXJGFHDIHLPTG-UHFFFAOYSA-N 0.000 description 2
- VYZAMTAEIAYCRO-UHFFFAOYSA-N Chromium Chemical compound [Cr] VYZAMTAEIAYCRO-UHFFFAOYSA-N 0.000 description 2
- 229910052796 boron Inorganic materials 0.000 description 2
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- 238000005260 corrosion Methods 0.000 description 2
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- 238000010583 slow cooling Methods 0.000 description 2
- 239000006104 solid solution Substances 0.000 description 2
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- WFKWXMTUELFFGS-UHFFFAOYSA-N tungsten Chemical compound [W] WFKWXMTUELFFGS-UHFFFAOYSA-N 0.000 description 2
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- GUCVJGMIXFAOAE-UHFFFAOYSA-N niobium atom Chemical compound [Nb] GUCVJGMIXFAOAE-UHFFFAOYSA-N 0.000 description 1
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- 229910052720 vanadium Inorganic materials 0.000 description 1
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Images
Classifications
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- 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
- C21D1/26—Methods of annealing
-
- 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
- C21D6/007—Heat treatment of ferrous alloys containing Co
-
- 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
- C21D9/00—Heat treatment, e.g. annealing, hardening, quenching or tempering, adapted for particular articles; Furnaces therefor
- C21D9/40—Heat treatment, e.g. annealing, hardening, quenching or tempering, adapted for particular articles; Furnaces therefor for rings; for bearing races
-
- 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
- C21D2211/00—Microstructure comprising significant phases
- C21D2211/001—Austenite
Abstract
The invention provides heat-resistant steel, a heat treatment method and application, wherein the heat treatment method comprises the following steps: austenitizing the forging, cooling the austenitized forging to 680-800 ℃, preserving heat for 2-50 h, and then cooling to room temperature. After the heat treatment method disclosed by the invention is adopted, the crystal grains of the forged piece after the thermal refining treatment are more uniform and obviously refined.
Description
Technical Field
The invention belongs to the technical field of steam turbines, relates to a heat treatment method, and particularly relates to heat-resistant steel, a heat treatment method and application.
Background
The power industry is one of the basic industries of national economy, the development level of the power industry directly influences the development of various industries, and the power production is an important index for measuring the national economic level. At present, more than 80% of world electricity is produced by a steam turbine as a prime mover, so the steam turbine plays an important role in national economy.
In recent years, as global environmental issues have become more prominent, it has become more and more important to improve the efficiency of thermal power stations. It is known that in thermal power generation, a steam turbine can obtain higher thermal efficiency by increasing steam parameters (temperature and pressure). However, the improvement of steam parameters means that a hot component of the steam turbine needs to reliably bear a high-strength forging material with high temperature, the forging material of the steam turbine in use at present mainly comprises 9% -12% Cr ferrite heat-resistant steel, and the ferrite heat-resistant steel is prepared by utilizing the traditional annealing process after forging, so that the grain size of the ferrite heat-resistant steel is larger, the metallographic structure is quite uneven, and the application performance of the material is seriously influenced. In order to improve the microstructure of coarse grains and mixed grains, the traditional annealing process after forging needs to be improved so as to obtain a forging microstructure with refined and uniform grains.
Disclosure of Invention
In view of the above-mentioned disadvantages of the prior art, the present invention aims to provide a heat-resistant steel, a heat treatment method and a use thereof, which are used for solving the problem of serious mixed crystal of the prior heat-resistant steel in the prior art.
In order to achieve the above objects and other related objects, the present invention provides a heat treatment method for heat-resistant steel, applied to a forging of ferrite heat-resistant steel of 9% -12% Cr, the heat treatment method comprising:
austenitizing the forging;
and cooling the austenitized forging to 680-800 ℃, preserving heat for 2-50 h, and then cooling to room temperature.
In an embodiment of the present invention, the forging is austenitized by: and (3) placing the forge piece in an annealing furnace, heating to 900-1100 ℃ along with the furnace, and preserving heat.
In an embodiment of the invention, the heat preservation time is 1-6 hours.
In an embodiment of the present invention, the forging is austenitized by: directly placing the forged piece subjected to final fire forging into an annealing furnace;
and cooling the austenitized forging to 680-800 ℃, preserving heat, and then cooling to room temperature.
In one embodiment of the invention, the austenitized forging is cooled to 680-800 ℃ and kept warm for 10-20 hours.
In an embodiment of the present invention, the cooling manner is air cooling or furnace cooling.
A heat-resistant steel obtained by any one of the heat treatment methods.
The invention also provides heat-resistant steel which is applied to a steam turbine.
As described above, after the heat treatment method of the invention, the crystal grains of the metallographic structure of the forged piece are obviously refined compared with those before the heat treatment method, and the non-uniformity degree of the metallographic structure is also obviously improved.
Drawings
FIG. 1 is a flow chart illustrating a thermal processing method according to an embodiment of the present invention.
FIG. 2 shows a grain size microstructure diagram of a 12Cr10Co3W2MoVNbNB steam turbine ring forging using the present invention.
FIG. 3 is a grain size microstructure diagram of a 12Cr10Mo1W1NiVNbN steam turbine ring forging using the present invention.
FIG. 4 shows the grain size microstructure of sample A.
FIG. 5 is a grain size microstructure of sample B.
FIG. 6 is a grain size microstructure of sample C.
FIG. 7 is a grain size microstructure of sample D.
FIG. 8 is a grain size distribution diagram of sample E.
FIG. 9 is a grain size microstructure of sample F.
FIG. 10 is a grain size distribution diagram of sample G.
FIG. 11 is a grain size distribution diagram of sample H.
Detailed Description
The following description of the embodiments of the present invention is provided for illustrative purposes, and other advantages and effects of the present invention will become apparent to those skilled in the art from the present disclosure.
It should be understood that the structures, ratios, sizes, and the like shown in the drawings and described in the specification are only used for matching with the disclosure of the specification, so as to be understood and read by those skilled in the art, and are not used to limit the conditions under which the present invention can be implemented, so that the present invention has no technical significance, and any structural modification, ratio relationship change, or size adjustment should still fall within the scope of the present invention without affecting the efficacy and the achievable purpose of the present invention. In addition, the terms "upper", "lower", "left", "right", "middle" and "one" used in the present specification are for clarity of description, and are not intended to limit the scope of the present invention, and the relative relationship between the terms and the terms is not to be construed as a scope of the present invention.
The steam turbine is a rotating mechanical device which takes steam as power and converts the heat energy of the steam into mechanical power, and is mainly widely applied to power plants. The steam turbine is the heart of thermal power generation, and the whole quality of steam turbine is more than tens tons, and the inside high temperature of steam turbine, high pressure super supercritical water steam environment that is in, especially the rotor of steam turbine is in the steam environment and is high-speed rotatory, and along with the steam parameter of steam turbine improves gradually at present, original low alloy steam turbine forging material can not satisfy operation requirement yet.
According to the prediction of 2012 world energy prospect issued by energy agency (IEA), coal is still an important power generation fuel, which indicates that the coal-fired power generation technology is still the main development direction of the world electric power industry, and under the large background of energy conservation, emission reduction and cost reduction, the ultra-supercritical technology with the maximum construction cost can effectively relieve energy shortage and reduce carbon emission. At present, 9-12% Cr ferrite steel is mainly used as a forging material of an ultra supercritical steam turbine.
The 9% -12% Cr ferrite heat-resistant steel is based on Cr-Mo steel, V, Nb and N are added to improve creep strength, wherein the 9% -12% Cr heat-resistant steel has high-temperature oxidation resistance, and the effect of alloy elements in the heat-resistant steel is as follows:
carbon (C) may beThe high-temperature strength of the steel is improved, the solubility in austenite is high, the solubility in ferrite is low, and M with dispersion strengthening effect can be formed in the treatment process23C6A type carbide.
Nitrogen (N) changes creep strength of heat-resistant steel and promotes M23C6Precipitation of carbide.
Chromium (Cr) to give steel sufficient high-temperature strength and corrosion resistance, M23C6The carbide is mainly generated by the reaction of chromium and carbon and is the main precipitate of 9% -12% Cr ferrite heat-resistant steel.
Molybdenum (Mo), solid solution strengthening and precipitation strengthening elements.
Tungsten (W), an element that is more effective at improving creep rupture strength at high temperatures than molybdenum.
Cobalt (Co) is effective in enlarging the austenite phase region and suppressing the δ ferrite element. Below the curie temperature, cobalt may improve the stability of the alloy structure. However, cobalt can lower the solid solution limit of molybdenum and tungsten.
Vanadium (V) and niobium (Nb) form MX type nanometer precipitation strengthening phase, thereby improving the creep rupture strength of the material.
Boron (B) and trace boron can obviously improve creep property, improve grain boundary binding force, prevent grain boundary carbide from coarsening and effectively improve alloy welding performance.
When the 9-12% Cr ferrite forged piece is used as a main forged piece material of a steam turbine, in the use process of the steam turbine, particularly, a rotor forged piece needs to bear severe working conditions such as high temperature, high profit, steam oxidation corrosion and the like, and higher requirements are provided for the structure performance of the forged piece. Meanwhile, the forging has large crystal grains and serious mixed crystal, so that the performance is poor, and the detection sensitivity during ultrasonic detection cannot meet the requirement, so that the internal quality of the workpiece cannot be judged through ultrasonic detection.
The invention provides a heat treatment method of heat-resistant steel for forgings, and crystal grains of the forgings are refined.
In an embodiment, referring to fig. 1, the heat treatment method of the embodiment mainly includes the following steps:
s1, placing the forging into an annealing furnace for heating, and heating the forging to a first temperature along with the furnace until the metallographic structure of the forging is transformed into austenite (A)3) I.e., austenitizing the forging. Wherein the rate of temperature rise of the forgings along with the furnace can be determined according to experience or tests on each forging.
The forging is very sensitive to the applied temperature and the heat preservation time in the austenitizing process, and in the embodiment, the first temperature is further limited to 900-1100 ℃, and the heat preservation time is 1-6 hours. In the process that the temperature of the forging is increased to 900-1100 ℃, the grain size of austenite in the forging is slowly increased, the normal growth of the grain size of austenite is ensured, the growth speed of the grain size of austenite is faster when the selected temperature is higher in the range of 900-1100 ℃, and when the temperature exceeds 1100 ℃, the growth speed of the austenite grains in the forging is gradually reduced, and at the moment, the austenite grains are abnormally grown. Meanwhile, when the furnace temperature is at the first temperature, the heat preservation time is set to be 1-6 h for heat preservation, and ferrite of the forge piece is completely transformed into austenite. Note that the grain structure of the forging is still in a mixed crystal state (coarse crystal and fine crystal exist) in this temperature raising stage. On one hand, if the heat preservation time is less than 1h, the forged piece is not austenitized; on the other hand, if the heat preservation time exceeds 6 hours, the proportion of coarse grains in the forge piece is increased continuously, and fine grains are consumed continuously, which is against the original intention of refining grains. In addition, in step S1, there may be some alloy carbides that are not dissolved into the austenite in the forging, and the alloy carbides are dispersed and distributed on the austenite matrix.
Further, the first temperature was defined as 1090 ℃ and kept for 5 h. When the forging piece is at 1090 ℃, the growth speed of austenite grains reaches the maximum, and meanwhile, the dispersion strengthening effect of an alloy compound is enhanced and the hardness of the forging piece is improved within the heat preservation time of 5 hours.
And S2, taking the forge piece out of the annealing furnace for air cooling or furnace cooling until the temperature of the forge piece is cooled to 680-800 ℃, and preserving heat for 2-50 h. In the process of cooling the austenitized forging to 680-800 ℃ in air or along with a furnace, the austenite in the forging begins to transform to pearlite, and at the moment, the heat is preserved for 2-50 h, so that the austenite in the forging can be transformed in sufficient time.
And further, the forging is cooled to 680-800 ℃ in air or with a furnace, and the temperature is kept for 10-20 hours. The pearlite transformation rate of the forge piece is highest when the forge piece is in 10-20 hours. The forging air cooling and furnace cooling have low cooling rate, the cooling rate is approximately 0-3 ℃/s, the slow cooling of the forging is ensured, cracks caused by overlarge internal stress are avoided in the slow cooling process, and meanwhile, the grain enlargement of transformed pearlite is also avoided in the transformation process of austenite in pearlite.
In another embodiment, in the process of preparing the forging piece, the forging piece subjected to final fire forging is directly cooled to 680-800 ℃, is subjected to heat preservation for 10-20 hours, and is then cooled to room temperature in a furnace. Wherein the ferrite of the forging is completely transformed into austenite in the final fire forging process.
Because the austenitizing temperature is not completely dissolved compared with the alloy carbide, the temperature and the heat preservation time of the forging at the step S2 are long, and the austenite in the forging is recrystallized into fine and uniform grains by taking the undissolved alloy carbide as nucleation particles in the process of transforming the austenite to pearlite, so that the purpose of grain refinement is achieved, and the structure is more uniform.
Further, in the austenitized forged piece, the forged piece is cooled to 700-750 ℃ in air or with a furnace, and the temperature is kept for 20 h. The grain size grade of the obtained forge piece reaches 6.0 grade at most. At 700-750 ℃, the number of effective nucleation particles reaches the maximum, the grain refining effect is further improved, the inclusion content in the forging is reduced, and the material purity is improved.
In this embodiment, taking an annular forging of two types of ferrite, 12Cr10Co3W2 movnbb and 12Cr10Mo1W1NiVNbN as an example, the microstructure of the forging includes single-phase ferrite and precipitated phase, the untreated heat-resistant steel is mixed with crystals seriously, and the grain size cannot be judged, and the metallographic structure diagram is shown in fig. 2 and 3, and the heat treatment method of the present invention is used for treatment.
[ 12Cr10Co3W2MoVNbNB ] annular forging
And (3) placing the 12Cr10Co3W2MoVNbNB annular forging in an annealing furnace at 910 ℃, preserving heat for 1h, cooling to 680 ℃ along with the furnace, preserving heat for 10h, then cooling to room temperature to obtain a sample A, and carrying out metallographic structure shooting, wherein the grain size is 2.0 grade with reference to fig. 4.
Placing the 12Cr10Co3W2MoVNbNB annular forging material in an annealing furnace at 910 ℃, preserving heat for 6h, cooling to 800 ℃ along with the furnace, preserving heat for 10h, then cooling to room temperature to obtain a sample B, and carrying out metallographic structure shooting, wherein the grain size is 3.0 grade with reference to FIG. 5.
And (3) placing the 12Cr10Co3W2MoVNbNB annular forging in an annealing furnace at 1090 ℃, preserving heat for 5h, cooling to 750 ℃ along with the furnace, preserving heat for 20h, cooling to 200 ℃ along with the furnace, taking out of the furnace, air-cooling to room temperature to obtain a sample C, and shooting a metallographic structure, wherein the grain size is 2.0 grade with reference to fig. 6, so that fine grains are obtained.
Placing the 12Cr10Co3W2MoVNbNB annular forging in an annealing furnace at 1100 ℃, preserving heat for 6h, cooling to 680 ℃ along with the furnace, preserving heat for 20h, then cooling to room temperature to obtain a sample D, and carrying out metallographic structure shooting, wherein the grain size is 2.0 grade with reference to FIG. 7.
And (3) placing the 12Cr10Co3W2MoVNbNB annular forging material in an annealing furnace at 1100 ℃, preserving heat for 1-6 h, cooling to 800 ℃ along with the furnace, preserving heat for 20h, then cooling to room temperature to obtain a sample E, and shooting a metallographic structure, wherein the grain size is 1.5 grade with reference to the figure 8.
[ 12Cr10Mo1W1NiVNbN annular forging ]
And (3) directly air-cooling the 12Cr10Mo1W1NiVNbN annular forging to 700 ℃ after the end fire forging is finished, preserving the heat for 10 hours, cooling to 200 ℃ along with the furnace, taking out the annular forging from the furnace, air-cooling to room temperature to obtain a sample F, and shooting the metallographic structure, wherein the grain size is 4.5 grade, please refer to FIG. 9.
After the 12Cr10Mo1W1NiVNbN annular forging piece is subjected to final fire forging, the annular forging piece is cooled to 800 ℃, the temperature is kept for 20 hours, the annular forging piece is cooled to 200 ℃ along with the furnace, the annular forging piece is taken out of the furnace and cooled to room temperature in an air cooling mode to obtain a sample G, and metallographic structure shooting is carried out, please refer to FIG. 10, and the grain size is 2.5 grade.
And (3) placing the 12Cr10Mo1W1NiVNbN annular forging in an annealing furnace at 1090 ℃, preserving heat for 5H, cooling to 700 ℃ along with the furnace, preserving heat for 20H, then cooling to room temperature to obtain a sample H, and shooting a metallographic structure, wherein the grain size is 6.0 grade with reference to fig. 11, so that fine grains are obtained.
The metallographic structures of the obtained samples A to H were photographed, respectively, as shown in FIGS. 4 to 11. In fig. 2 and fig. 3, coarse crystals and fine crystals are included in the structural diagram of the forged piece before unrefined forging, and the mixed crystal phenomenon is very serious, and after the heat treatment method of the invention is carried out, as can be seen from fig. 4 to fig. 11, the forged piece after the heat treatment method of the invention is obviously refined compared with the grains of the metallographic structure before the heat treatment method, and the non-uniformity degree of the metallographic structure is also obviously improved.
In order to further obtain the performance of the forged piece after the heat treatment method, the performance of the forged piece under two thinning conditions is selected below and detected and compared with the forged piece before thinning, and tables 1 and 2 are obtained.
Taking a forging material as a 12Cr10Co3W2MoVNbNB annular forging, and refining the forging material: placing a 12Cr10Co3W2MoVNbNB annular forging in an annealing furnace at 1090 ℃, preserving heat for 5 hours, cooling to 750 ℃ along with the furnace, preserving heat for 20 hours, cooling to 200 ℃ along with the furnace, taking out of the furnace, air-cooling to room temperature to obtain a sample C, shooting a metallographic structure, referring to fig. 6, wherein the grain size is 2.0 grade to obtain fine grains, detecting the mechanical properties of the sample C to obtain a table 1, respectively detecting the yield strength R of the forgingp0.2Tensile strength RmElongation after fracture A5Z reduction of area, HBW hardness, and KV impact absorption energy2。
| Rp0.2/MPa | Rm/MPa | A5/％ | Z/％ | HBW | KV2/J | |
| Before using the invention | 770 | 909 | 17.8 | 60.4 | 282 | 46/56/48 |
| After the invention is used | 772 | 913 | 18.8 | 64.1 | 285 | 49/66/48 |
Taking a forging material as a 12Cr10Mo1W1NiVNbN annular forging, and refining: and (3) placing the 12Cr10Mo1W1NiVNbN annular forging in an annealing furnace at 1090 ℃, preserving heat for 5H, cooling to 700 ℃ along with the furnace, preserving heat for 20H, then cooling to room temperature to obtain a sample H, carrying out metallographic structure shooting, obtaining fine grains with the grain size of 6.0 grade by referring to a graph 11, and carrying out mechanical property detection on the sample H to obtain a table 2.
| Rp0.2/MPa | Rm/MPa | A/％ | Z/％ | HBW | KV2/J | |
| Before using the invention | 800 | 931 | 17.0 | 65.3 | 282 | 98/94/105 |
| After the invention is used | 801 | 932 | 18.8 | 65.2 | 275 | 74/64/71 |
It can be found from tables 1 and 2 that the mechanical properties of the original forged piece are not affected and the original mechanical properties of the forged piece are maintained by using the heat treatment method of the invention.
Aiming at the heat treatment method of 9% -12% Cr ferrite heat-resistant steel, compared with the traditional annealing process, the method can convert the forging with serious mixed crystal into the forging with uniform structure, and in the heat treatment process, the structure crystal grains are refined, thereby facilitating the later ultrasonic detection.
In conclusion, the present invention effectively overcomes various disadvantages of the prior art and has high industrial utilization value.
The foregoing embodiments are merely illustrative of the principles and utilities of the present invention and are not intended to limit the invention. Any person skilled in the art can modify or change the above-mentioned embodiments without departing from the spirit and scope of the present invention. Accordingly, it is intended that all equivalent modifications or changes which can be made by those skilled in the art without departing from the spirit and technical spirit of the present invention be covered by the claims of the present invention.
Claims (8)
1. A heat treatment method of heat-resistant steel is applied to a forging piece of 9% -12% Cr ferrite heat-resistant steel, and is characterized by comprising the following steps:
austenitizing the forging;
and cooling the austenitized forging to 680-800 ℃, preserving heat for 2-50 h, and then cooling to room temperature.
2. The heat treatment method of heat-resistant steel according to claim 1, characterized in that: the forging is austenitized into: and (3) placing the forge piece in an annealing furnace, heating to 900-1100 ℃ along with the furnace, and preserving heat.
3. A heat treatment method of heat-resistant steel according to claim 2, characterized in that: the heat preservation time is 1-6 h.
4. The heat treatment method of heat-resistant steel according to claim 1, characterized in that: the forging is austenitized into: directly placing the forged piece subjected to final fire forging into an annealing furnace;
and cooling the austenitized forging to 680-800 ℃, preserving heat, and then cooling to room temperature.
5. A heat treatment method of heat-resistant steel according to claim 2 or 4, characterized in that: and cooling the austenitized forging to 680-800 ℃ and preserving heat for 10-20 h.
6. The heat treatment method of heat-resistant steel according to claim 1 or 4, characterized in that: the cooling mode adopts air cooling or furnace cooling.
7. A heat-resistant steel obtained by the heat treatment method according to any one of claims 1 to 6.
8. A heat-resistant steel as claimed in claim 7, which is used in a steam turbine.
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| CN107400761A (en) * | 2016-05-20 | 2017-11-28 | 上海电气上重铸锻有限公司 | The heat treatment method of advanced ultra supercritical rotor forging |
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| Publication number | Priority date | Publication date | Assignee | Title |
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| CN107400761A (en) * | 2016-05-20 | 2017-11-28 | 上海电气上重铸锻有限公司 | The heat treatment method of advanced ultra supercritical rotor forging |
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| Title |
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| 王晓芳: "620℃汽轮机转子锻件用钢晶粒细化热处理工艺研究", 《大型铸锻件》 * |
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