CN111057827B - Method for regulating and controlling distribution state of boron element in 9Cr3W3CoB heat-resistant steel for ultra-supercritical unit - Google Patents
Method for regulating and controlling distribution state of boron element in 9Cr3W3CoB heat-resistant steel for ultra-supercritical unit Download PDFInfo
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- 239000010959 steel Substances 0.000 title claims abstract description 76
- 229910000831 Steel Inorganic materials 0.000 title claims abstract description 75
- 238000000034 method Methods 0.000 title claims abstract description 36
- 238000009826 distribution Methods 0.000 title claims abstract description 30
- ZOXJGFHDIHLPTG-UHFFFAOYSA-N Boron Chemical compound [B] ZOXJGFHDIHLPTG-UHFFFAOYSA-N 0.000 title claims abstract description 23
- 229910052796 boron Inorganic materials 0.000 title claims abstract description 23
- 230000001276 controlling effect Effects 0.000 title claims abstract description 23
- 230000001105 regulatory effect Effects 0.000 title claims abstract description 21
- 238000001816 cooling Methods 0.000 claims abstract description 18
- 238000010438 heat treatment Methods 0.000 claims abstract description 18
- 238000005496 tempering Methods 0.000 claims abstract description 11
- 238000011282 treatment Methods 0.000 claims abstract description 9
- 238000005096 rolling process Methods 0.000 claims abstract description 7
- 239000000126 substance Substances 0.000 claims description 9
- 239000013078 crystal Substances 0.000 claims description 5
- 239000012535 impurity Substances 0.000 claims description 4
- 239000000758 substrate Substances 0.000 claims 1
- 230000032683 aging Effects 0.000 abstract description 13
- 239000011159 matrix material Substances 0.000 abstract description 12
- 238000010899 nucleation Methods 0.000 abstract description 6
- 230000006911 nucleation Effects 0.000 abstract description 5
- 230000000930 thermomechanical effect Effects 0.000 abstract description 3
- 230000000052 comparative effect Effects 0.000 description 10
- 238000001556 precipitation Methods 0.000 description 5
- 239000007787 solid Substances 0.000 description 5
- 238000003723 Smelting Methods 0.000 description 3
- 229910001566 austenite Inorganic materials 0.000 description 3
- 229910000734 martensite Inorganic materials 0.000 description 3
- 238000005204 segregation Methods 0.000 description 3
- IJGRMHOSHXDMSA-UHFFFAOYSA-N Atomic nitrogen Chemical compound N#N IJGRMHOSHXDMSA-UHFFFAOYSA-N 0.000 description 2
- ATJFFYVFTNAWJD-UHFFFAOYSA-N Tin Chemical compound [Sn] ATJFFYVFTNAWJD-UHFFFAOYSA-N 0.000 description 2
- 230000009286 beneficial effect Effects 0.000 description 2
- 230000015572 biosynthetic process Effects 0.000 description 2
- 239000000463 material Substances 0.000 description 2
- 229910052758 niobium Inorganic materials 0.000 description 2
- 150000004767 nitrides Chemical class 0.000 description 2
- 239000006104 solid solution Substances 0.000 description 2
- 229910052720 vanadium Inorganic materials 0.000 description 2
- 229910000859 α-Fe Inorganic materials 0.000 description 2
- 238000005275 alloying Methods 0.000 description 1
- 229910052804 chromium Inorganic materials 0.000 description 1
- 230000002860 competitive effect Effects 0.000 description 1
- 150000001875 compounds Chemical class 0.000 description 1
- RKTYLMNFRDHKIL-UHFFFAOYSA-N copper;5,10,15,20-tetraphenylporphyrin-22,24-diide Chemical group [Cu+2].C1=CC(C(=C2C=CC([N-]2)=C(C=2C=CC=CC=2)C=2C=CC(N=2)=C(C=2C=CC=CC=2)C2=CC=C3[N-]2)C=2C=CC=CC=2)=NC1=C3C1=CC=CC=C1 RKTYLMNFRDHKIL-UHFFFAOYSA-N 0.000 description 1
- 239000006185 dispersion Substances 0.000 description 1
- 230000008030 elimination Effects 0.000 description 1
- 238000003379 elimination reaction Methods 0.000 description 1
- 238000005516 engineering process Methods 0.000 description 1
- 230000007613 environmental effect Effects 0.000 description 1
- 238000005242 forging Methods 0.000 description 1
- 230000006698 induction Effects 0.000 description 1
- 230000005764 inhibitory process Effects 0.000 description 1
- 229910001068 laves phase Inorganic materials 0.000 description 1
- 238000004519 manufacturing process Methods 0.000 description 1
- 239000000203 mixture Substances 0.000 description 1
- 229910052757 nitrogen Inorganic materials 0.000 description 1
- 238000004886 process control Methods 0.000 description 1
- 238000010791 quenching Methods 0.000 description 1
- 230000000171 quenching effect Effects 0.000 description 1
- 238000001953 recrystallisation Methods 0.000 description 1
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- 238000005728 strengthening Methods 0.000 description 1
- 230000001550 time effect Effects 0.000 description 1
- 229910052721 tungsten Inorganic materials 0.000 description 1
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- C21D8/00—Modifying the physical properties by deformation combined with, or followed by, heat treatment
- C21D8/005—Modifying the physical properties by deformation combined with, or followed by, heat treatment of ferrous alloys
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- C22C38/02—Ferrous alloys, e.g. steel alloys containing silicon
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- C22C38/04—Ferrous alloys, e.g. steel alloys containing manganese
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- C22C38/18—Ferrous alloys, e.g. steel alloys containing chromium
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Abstract
The invention belongs to the field of thermal deformation, and particularly relates to a method for regulating and controlling the distribution state of boron in 9Cr3W3CoB heat-resistant steel for an ultra-supercritical unit. The method mainly comprises the following steps: (1) heating the workpiece to 1150-1200 ℃, and preserving heat for 1.5-2 h; (2) rolling the workpiece for 5-7 times at 1150-1200 ℃, wherein the single-pass deformation is controlled to be below 20 percent, and the final deformation of the workpiece reaches 60-90 percent; (3) cooling the workpiece to room temperature in air; (4) tempering for 1-2 h at 750-780 ℃ and air cooling. The thermomechanical treatment method provided by the invention can effectively regulate and control the distribution of the B element of the steel grade, so that the boride is completely dissolved, the B element is re-dissolved in the matrix, and the mechanical property of the workpiece is improved; meanwhile, the nucleation growth of BN is inhibited in the subsequent high-temperature aging process, and the method is suitable for producing boron-containing heat-resistant steel.
Description
Technical Field
The invention belongs to the field of thermal deformation, and particularly relates to a method for regulating and controlling the distribution state of boron in 9Cr3W3CoB heat-resistant steel for an ultra-supercritical unit.
Background
Due to energy and environmental problems, it is a major need to improve the efficiency of thermal power generating units and develop ultra-supercritical units. Among them, G115 steel is a representative steel grade of novel 9Cr3W3CoB series of novel martensitic heat-resistant steel, and becomes an ideal material for a main steam pipeline of a 650 ℃ ultra-supercritical unit due to its more excellent high-temperature durability. The B element has low solid solubility in alpha-Fe and is easy to be partially polymerized to the grain boundary. The 9Cr3W3CoB series martensite heat-resistant steel is subjected to segregation at the prior austenite grain boundary and enters M by introducing trace B elements23C6Formation of carbide M23(CB)6Can suppress M in the vicinity of the prior austenite grain boundary23C6The carbide is cured under the condition of high temperature and long time aging, so that the pinning capability of the carbide to grain boundaries and dislocation is enhanced, the structure stability is improved, and the creep property of the steel is improved. However, the B element is a strong nitride-forming element. Comparing the solid solubility product formula of nitrides such as NbN, TiN, VN, AlN and BN in austenite, the solid solubility product of BN is the smallest, TiN times, NbN and AlN are the next, and VN is the largest. Because the steel inevitably contains a certain amount of N element, if the composition is not controlled properly, the B element in the steel is easy to form coarse micron-sized BN inclusions. Even if the content of N in the steel is less, no or only a small amount of BN is formed during smelting, a large amount of BN can be formed and grown in the subsequent high-temperature long-time aging process. In addition to the formation of BN, B also forms borides of more complex structure with other alloying elements. After tempering, B having a tetragonal structure is present in the steel0.38C0.62BC of triangular structure0.38Si0.04And M3B2((Mo0.66Cr0.34)2(Fe0.75V0.25)B2) A boride compound. The formation of BN inclusions and other borides consumes B element as a solid solution in steel, and since the amount of B element is insufficient, there is a possibility that B element does not cause effective segregation, and thus M inhibition cannot be sufficiently exerted23C6Carbide(s) and method of making the sameCuring and solid solution strengthening. The boride in the G115 steel is mainly BN and boride (W-rich inclusion) rich in W, V, Nb, Cr elements having a complex structure. The W-rich inclusions in the steel in the heat treated state are relatively high in content and extremely non-uniform in distribution. The existence of W-rich inclusions consumes B element dissolved in steel, so that the B element is difficult to exert the optimal distribution and the creep property is improved. In the high-temperature long-time aging process, BN rapidly nucleates and grows to micron-sized, and the mechanical property of the steel is greatly reduced. In order to fully exert the function of the B element in component design, the distribution of the B element in the steel needs to be regulated and controlled, and the nucleation and growth of boride are eliminated and inhibited.
At present, related patents for regulating and controlling the distribution of B element in heat-resistant steel are rare, such as: a heat treatment method (publication No. CN105695678A) for controlling the shape of BN phase in ultra-supercritical heat-resistant steel, which is a process control technology for controlling the shape of BN phase in novel ferrite heat-resistant steel through high-temperature quenching, high-temperature normalizing and one-time high-temperature tempering to obtain fine and dispersedly distributed BN phase. However, the method is suitable for being applied to heat-resistant steel with lower service temperature. For 9Cr3W3CoB heat-resistant steel, the heat treatment process does not completely dissolve all borides to the matrix, and can not inhibit the precipitation of BN in the subsequent aging process.
Disclosure of Invention
Aiming at the problem that boron-containing 9Cr3W3CoB heat-resistant steel contains a large amount of boride to hinder the preferential distribution of B element, the invention aims to provide a method for regulating and controlling the distribution state of the boron element in the 9Cr3W3CoB heat-resistant steel for an ultra-supercritical unit, under the premise of not changing the chemical components and smelting process of the existing 9Cr3W3CoB heat-resistant steel, uniform micron-sized crystal grains are obtained through a thermal mechanical treatment process, the boride in the steel is eliminated, and the B element is re-dissolved to a matrix.
The technical scheme of the invention is as follows:
a method for regulating and controlling the distribution state of boron elements in 9Cr3W3CoB heat-resistant steel for an ultra-supercritical unit comprises the following steps:
(1) heating the workpiece to 1150-1200 ℃, and preserving heat for 1.5-2 h;
(2) rolling the workpiece for 5-7 times at 1150-1200 ℃, wherein the single-pass deformation is controlled to be below 20 percent, and the final deformation of the workpiece reaches 60-90 percent;
(3) cooling the workpiece to room temperature in air;
(4) tempering for 1-2 h at 750-780 ℃ and air cooling.
The method for regulating and controlling the distribution state of boron elements in the 9Cr3W3CoB heat-resistant steel for the ultra-supercritical unit comprises the following chemical components in percentage by weight:
c: 0.06-0.12%; cr: 8.4-9.6%; w: 2.33 to 3.17 percent; co: 2.8-3.25%; cu: 0.4-1.2%; b: 0.01-0.022%; mn: 0.27-0.73%; nb: 0.03-0.1%; v: 0.13-0.27%; n: 0.005-0.015%; si: less than or equal to 0.55 percent; ti: less than or equal to 0.05 percent; al: less than or equal to 0.02 percent; the balance of Fe and inevitable impurity elements.
The method for regulating and controlling the distribution state of the boron element in the 9Cr3W3CoB heat-resistant steel for the ultra-supercritical unit comprises the following inevitable impurity elements: p: less than or equal to 0.02 percent; s: less than or equal to 0.01 percent; o: less than or equal to 0.004 percent.
Preferably, in the step (1), the workpiece is heated to 1150 ℃ at a speed of 400 ℃/h, and the temperature is kept for 1.5 h.
According to the method for regulating and controlling the distribution state of the boron element in the 9Cr3W3CoB heat-resistant steel for the ultra-supercritical unit, in the step (2), the final deformation of the workpiece is 60%, 70%, 80% or 90% respectively.
Preferably, in the step (2), the workpiece is rolled for 6 passes at 1150 ℃ until the deformation is 90% and the single-pass deformation is 15%.
Preferably, in the step (4), the workpiece is tempered at 750 ℃ for 1.5h and cooled in air.
The design idea of the invention is as follows:
the idea of the thermomechanical treatment method for regulating and controlling the distribution of the boron element in the 9Cr3W3CoB heat-resistant steel comes from the research of theories such as deformation induced precipitation, element grain boundary segregation, second-phase precipitation and precipitation order and the like. Under thermodynamic equilibrium conditions, the temperature at which BN of G115 steel begins to precipitate is about 1282 ℃, the temperature at which NbN begins to precipitate is about 1292 ℃, and the competitive power of the steel on N elements is very close. The solid solubility product formula of BN and NbN shows that the solid solubility of BN in steel is far lower than that of NbN, and the BN is more likely to be preferentially separated out. However, when the Nb element content in G115 steel is higher by one order of magnitude than that of B element, NbN is likely to precipitate thermodynamically in preference to BN. And remelting BN and other borides in the steel through higher heating temperature to ensure that the B element is re-dissolved to the matrix. The MX-phase nucleation point is increased through high-temperature deformation, the preferential precipitation of nitride (Nb, V) N in the steel is promoted, and the purposes of fixing nitrogen and retaining boron are achieved, so that the re-nucleation and growth of BN in the high-temperature time-effect process are inhibited. Fine martensite recrystallization structures can be obtained after high-temperature deformation, the number of small-angle crystal boundaries is greatly increased, and the ultra-supercritical main steam pipeline material which is high in strength and toughness and has a large amount of second phases in dispersed distribution is obtained by matching with high-temperature tempering.
The invention has the advantages and beneficial effects that:
1. the method for regulating and controlling the distribution state of the boron element in the 9Cr3W3CoB heat-resistant steel for the ultra-supercritical unit eliminates all BN and other borides with complex structures in the steel through thermal mechanical treatment. The B element is re-dissolved to the matrix, and a foundation is provided for the subsequent distribution and the improvement of creep property. There are large differences compared to the related patent documents relating to the elimination of borides in steel.
2. The thermal mechanical treatment method provided by the invention can effectively inhibit the nucleation and growth of BN in the subsequent high-temperature long-time aging process, and delay the toughness reduction condition of the workpiece in the aging process.
3. The ultra supercritical heat-resistant steel crystal grain obtained by the method is greatly refined, and the size of the crystal grain is 2-5 mu m. The increased grain boundaries are mostly small-angle grain boundaries, the number percentage of the total grain boundaries can reach 93.95%, and the small-angle grain boundaries are beneficial to improving the durability of the steel.
Drawings
FIG. 1 is a topographical view of the tissue of example 1.
FIG. 2 is a topographical map of the tissue of example 2.
FIG. 3 is a topographical map of the tissue of example 3.
FIG. 4 is a graph of the morphology of BN and other borides in comparative example 1.
FIG. 5 is a morphology of BN in comparative example 2.
Detailed Description
In the specific implementation process, the steel ingot is cast into a steel ingot after the vacuum induction furnace and the electroslag remelting smelting are adopted. The steel ingot is forged at 1180 deg.c and the final forging temperature is over 900 deg.c, and the hot rolled pipe is hot extruded to form industrial trial pipe of 254mm × 25mm phi.
The 9Cr3W3CoB heat-resistant steel comprises the following chemical components in percentage by weight: c: 0.06-0.1%; cr: 8.4-9.6%; w: 2.33 to 3.17 percent; co: 2.8-3.25%; cu: 0.4-1.2%; b: 0.01-0.022%; mn: 0.27-0.73%; nb: 0.03-0.1%; v: 0.13-0.27%; n: 0.005-0.015%; si: less than or equal to 0.55 percent; ti: less than or equal to 0.05 percent; al: less than or equal to 0.02 percent; p: less than or equal to 0.02 percent; s: less than or equal to 0.01 percent; o: less than or equal to 0.004 percent; the balance of Fe.
The following thermo-mechanical treatments were performed on the industrial pilot-manufactured pipe: (1) heating the workpiece to 1150 ℃, and preserving heat for 1.5-2 h; (2) rolling at 1150 deg.c to reach deformation of the workpiece of 60-90%; (3) cooling the workpiece to room temperature in air; (4) tempering at 750 deg.c for 1.5 hr and air cooling. After the thermal mechanical treatment, boride in the heat-resistant steel can be eliminated, and the B element is re-dissolved to the matrix, and the mechanical property index range is as follows: tensile Strength σB850-950 MPa, yield strength sigma0.2750 to 850MPa, the elongation A is 15 to 20%, the reduction of area Z is 55 to 60%, and the Vickers hardness is 360 to 385 HV.
The present invention will be described in further detail below with reference to specific examples.
Example 1:
in this embodiment, the 9Cr3W3CoB ultra-supercritical heat-resistant steel comprises the following chemical components in percentage by weight:
c: 0.11 percent; cr: 9.02 percent; w: 2.99 percent; co: 3.05 percent; cu: 0.88 percent; b: 0.015 percent; mn: 0.46 percent; nb: 0.073%; v: 0.19 percent; n: 0.006%; si: 0.27 percent; ti: 0.015 percent; al: 0.013%; p: 0.012%; s: 0.007%; o: 0.002%; the balance of Fe.
In this embodiment, the method for regulating and controlling the distribution state of boron in the 9Cr3W3CoB heat-resistant steel for the ultra-supercritical unit includes the following steps:
(1) heating the workpiece to 1150 ℃ at a speed of 400 ℃/h, and preserving heat for 1.5 h;
(2) rolling the workpiece for 6 times at 1150 ℃, wherein the single-pass deformation is controlled at 10 percent, and the final deformation of the workpiece reaches 60 percent;
(3) and cooling the workpiece to room temperature in air.
As shown in figure 1, BN and other borides are completely dissolved in the steel, and the B element is re-dissolved to the matrix.
The grain size of the ultra-supercritical heat-resistant steel of the embodiment is 50 μm, and the mechanical property indexes are as follows: tensile Strength σB1150MPa, yield strength sigma0.21072MPa, elongation A of 12.5%, reduction of area Z of 51%, Vickers hardness 377.5 HV.
Example 2:
in this embodiment, the 9Cr3W3CoB ultra-supercritical heat-resistant steel comprises the following chemical components in percentage by weight:
c: 0.11 percent; cr: 9.02 percent; w: 2.99 percent; co: 3.05 percent; cu: 0.88 percent; b: 0.015 percent; mn: 0.46 percent; nb: 0.073%; v: 0.19 percent; n: 0.006%; si: 0.27 percent; ti: 0.015 percent; al: 0.013%; p: 0.012%; s: 0.007%; o: 0.002%; the balance of Fe.
In this embodiment, the method for regulating and controlling the distribution state of boron in the 9Cr3W3CoB heat-resistant steel for the ultra-supercritical unit includes the following steps:
(1) heating the workpiece to 1150 ℃ at the speed of 400 ℃/h, and keeping the temperature for 2 h;
(2) rolling the workpiece for 6 times at 1150 ℃, wherein the single-pass deformation is controlled to be 15 percent, and the final deformation of the workpiece reaches 90 percent;
(3) cooling the workpiece to room temperature in air;
(4) tempering at 750 deg.c for 1.5 hr and air cooling to room temperature.
As shown in figure 2, BN and other borides are completely dissolved in the steel, and the B element is re-dissolved into the matrix, so that uniform and fine equiaxed grains are obtained.
The grain size of the ultra-supercritical heat-resistant steel is 2-5 μm, and the mechanical property indexes after tempering are as follows: tensile Strength σB930MPa, yield strength sigma0.2815MPa, elongation A16.5%, reduction of area Z58%, Vickers hardness before tempering 382HV, Vickers hardness after tempering 276.8 HV.
Example 3:
in this embodiment, the 9Cr3W3CoB ultra-supercritical heat-resistant steel comprises the following chemical components in percentage by weight:
c: 0.11 percent; cr: 9.02 percent; w: 2.99 percent; co: 3.05 percent; cu: 0.88 percent; b: 0.015 percent; mn: 0.46 percent; nb: 0.073%; v: 0.19 percent; n: 0.006%; si: 0.27 percent; ti: 0.015 percent; al: 0.013%; p: 0.012%; s: 0.007%; o: 0.002%; the balance of Fe.
In this embodiment, the method for regulating and controlling the distribution state of boron in the 9Cr3W3CoB heat-resistant steel for the ultra-supercritical unit includes the following steps:
(1) heating the workpiece to 1150 ℃ at a speed of 400 ℃/h, and preserving heat for 1.5 h;
(2) rolling the workpiece for 6 times at 1150 ℃, wherein the single-pass deformation is controlled to be 15 percent, and the final deformation of the workpiece reaches 90 percent;
(3) cooling the workpiece to room temperature in air;
(4) and (3) aging the workpiece at 800 ℃ for 300h, and cooling the workpiece to room temperature in air.
As shown in FIG. 3, BN does not re-nucleate and grow, and the Laves phase is in a fine dispersion distribution, and the curing rate is low.
The grain size of the ultra-supercritical heat-resistant steel is 10-15 μm, and the mechanical property indexes are as follows: tensile Strength σB885.6MPa, yield strength σ0.2719MPa, elongation A17.2%, reduction of area Z62.3%, Vickers hardness before aging 382HV, Vickers hardness after aging 287 HV.
Comparative example 1:
in the comparative example, the 9Cr3W3CoB ultra-supercritical heat-resistant steel comprises the following chemical components in percentage by weight:
c: 0.11 percent; cr: 9.02 percent; w: 2.99 percent; co: 3.05 percent; cu: 0.88 percent; b: 0.015 percent; mn: 0.46 percent; nb: 0.073%; v: 0.19 percent; n: 0.006%; si: 0.27 percent; ti: 0.015 percent; al: 0.013%; p: 0.012%; s: 0.007%; o: 0.002%; the balance of Fe.
In this comparative example, the following heat treatment process was employed:
(1) heating the workpiece to 1100 ℃, preserving heat for 1h, and cooling in air;
(2) heating the workpiece to 780 ℃; keeping the temperature for 3 hours and cooling in air.
As shown in fig. 4, the grains after heat treatment were relatively coarse, and borides having a complex structure were not completely re-dissolved into the matrix, while a small amount of BN was present in the steel.
The grain size of the comparative example ultra-supercritical heat-resistant steel is 55 μm, and the mechanical property indexes are as follows: tensile Strength σB805MPa, yield strength σ0.2642MPa, elongation A22%, reduction of area Z73.5%, Vickers hardness 225 HV.
Comparative example 2:
in the comparative example, the 9Cr3W3CoB ultra-supercritical heat-resistant steel comprises the following chemical components in percentage by weight:
c: 0.11 percent; cr: 9.02 percent; w: 2.99 percent; co: 3.05 percent; cu: 0.88 percent; b: 0.015 percent; mn: 0.46 percent; nb: 0.073%; v: 0.19 percent; n: 0.006%; si: 0.27 percent; ti: 0.015 percent; al: 0.013%; p: 0.012%; s: 0.007%; o: 0.002%; the balance of Fe.
In this comparative example, the following heat treatment process was employed:
(1) heating the workpiece to 1100 ℃, preserving heat for 1h, and cooling in air;
(2) heating the workpiece to 780 ℃; preserving heat for 3 hours, and cooling in air;
(3) and (3) aging the workpiece at 800 ℃ for 300h, and cooling in air.
As shown in FIG. 5, the grains after heat treatment were relatively coarse, and all of the borides having a complex structure were not dissolved back into the matrix. When aging at high temperature, BN rapidly nucleates and grows to micron level.
This comparative example is super supercriticalThe grain size of the boundary heat-resistant steel is 71 mu m, and the mechanical property indexes are as follows: tensile Strength σB762MPa, yield strength sigma0.2461MPa, 18.5% elongation A, 57% reduction of area Z, and 211HV Vickers hardness.
The embodiment result shows that the simple thermal mechanical treatment method for remelting boride into a matrix and refining grains can effectively regulate and control the distribution of B elements in steel, so that boride is completely dissolved, and the B elements are re-dissolved into the matrix, thereby improving the mechanical property of a workpiece; meanwhile, the nucleation and growth of BN are inhibited in the subsequent high-temperature aging process.
Claims (6)
1. A method for regulating and controlling the distribution state of boron elements in 9Cr3W3CoB heat-resistant steel for an ultra-supercritical unit is characterized by comprising the following steps:
(1) heating the workpiece to 1150-1200 ℃, and preserving heat for 1.5-2 h;
(2) rolling the workpiece for 5-7 times at 1150-1200 ℃, wherein the single-pass deformation is controlled to be below 20 percent, and the final deformation of the workpiece reaches 60-90 percent;
(3) cooling the workpiece to room temperature in air;
(4) tempering at 750-780 ℃ for 1-2 h, and air cooling;
in the 9Cr3W3CoB heat-resistant steel, BN and other borides are completely dissolved, the B element is re-dissolved to a substrate, uniform micron-sized crystal grains are obtained through a thermal mechanical treatment process, and the mechanical property index range is as follows: tensile Strength σB850-950 MPa, yield strength sigma0.2750 to 850MPa, the elongation A is 15 to 20 percent, the reduction of area Z is 55 to 60 percent, and the Vickers hardness is 360 to 385 HV;
the 9Cr3W3CoB heat-resistant steel comprises the following chemical components in percentage by weight:
c: 0.06-0.12%; cr: 8.4-9.6%; w: 2.33 to 3.17 percent; co: 2.8-3.25%; cu: 0.4-1.2%; b: 0.01-0.022%; mn: 0.27-0.73%; nb: 0.03-0.1%; v: 0.13-0.27%; n: 0.005-0.015%; si: less than or equal to 0.55 percent; ti: less than or equal to 0.05 percent; al: less than or equal to 0.02 percent; the balance of Fe and inevitable impurity elements.
2. The method for regulating and controlling the distribution state of boron in the 9Cr3W3CoB heat-resistant steel for the ultra-supercritical unit as claimed in claim 1, wherein the inevitable impurity elements comprise: p: less than or equal to 0.02 percent; s: less than or equal to 0.01 percent; o: less than or equal to 0.004 percent.
3. The method for regulating and controlling the distribution state of the boron element in the 9Cr3W3CoB heat-resistant steel for the ultra-supercritical unit according to claim 1, wherein preferably, in the step (1), the workpiece is heated to 1150 ℃ at the speed of 400 ℃/h, and the temperature is kept for 1.5 h.
4. The method for regulating and controlling the distribution state of the boron element in the 9Cr3W3CoB heat-resistant steel for the ultra-supercritical unit as claimed in claim 1, wherein in the step (2), the final deformation of the workpiece is 60%, 70%, 80% or 90% respectively.
5. The method for controlling the distribution of boron in the 9Cr3W3CoB heat-resistant steel for the ultra-supercritical unit as claimed in claim 1, wherein preferably, in the step (2), the workpiece is rolled at 1150 ℃ for 6 passes until the deformation is 90% and the single-pass deformation is 15%.
6. The method for regulating and controlling the distribution state of boron in 9Cr3W3CoB heat-resistant steel for an ultra-supercritical unit according to claim 1, wherein preferably, in the step (4), the workpiece is tempered at 750 ℃ for 1.5h and cooled in air.
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