CN1766147A - Two-link smelting process for centrifugal casting high alloy boiler tube - Google Patents
Two-link smelting process for centrifugal casting high alloy boiler tube Download PDFInfo
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- CN1766147A CN1766147A CN 200510095772 CN200510095772A CN1766147A CN 1766147 A CN1766147 A CN 1766147A CN 200510095772 CN200510095772 CN 200510095772 CN 200510095772 A CN200510095772 A CN 200510095772A CN 1766147 A CN1766147 A CN 1766147A
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Abstract
The invention discloses a preparation method to centrifugal cast high-alloy furnace tube used in nuclear power plant. Wherein, the method comprises: selecting high carbon ferro-chrome, 2-nickel, ferromolybdenum, and ferrosilicon as material; heating the ferromanganese and scrap steel by medium-frequency furnace to supply liquid semisteel by steel-tapping temperature as 1600~1650Deg; conveying said liquid with pouring ladle to AOD furnace; using three-steps to refine and provide pure liquid steel. This method reduces cost and Cr consumption, increases steel purity, and can decrease impurity of oxide and sulfide in product.
Description
Technical field: the present invention relates to a kind of centrifugal casting furnace tube, particularly relate to the manufacture craft of a kind of nuclear power plant with centrifugal casting high-alloy furnace pipe.
Technical background: along with rapid economic development, living standards of the people improve constantly.Need for electricity is increasing, but domestic coal storage capacity is fewer and feweri.And the thermal power generation environmental pollution is also very big, and this just must have a kind of new forms of energy to replace---nuclear power development.Nuclear energy power generation country formulates long term growth planning (2005～the year two thousand twenty).At present, pressurized-water reactor nuclear power plant is at present domestic built or in one of main nuclear power plant that builds, and pressurized-water reactor refrigerant main pipe line is one of key equipment of pressurized-water reactor nuclear power plant.In recent years, the hot rolling technology has been made significant headway, domesticly develop high performance alloy furnace tubes by adopting with the production method of centrifugal casting roll, to satisfy the needs of nuclear power, the centrifugal casting roll production method is compared with continuous casting composite algorithm (Chinese patent CN1280042), esr process (Chinese patent CN1157192) etc., and it is few to have a facility investment, and production cost is low, working method is easy, advantages such as constant product quality.But, nuclear power is with containing alloying elements such as more W, Cr, Mo, V in the alloy furnace tubes by adopting, and the carbide density difference of these elements and formation thereof is very big, under common rotary casting condition, alloy furnace tubes by adopting interalloy element segregation is serious, and outer V content is low, and W, Mo content height, internal layer is just in time opposite, has had a strong impact on the wear resistance of boiler tube like this; The raw materials cost height; The clarity of product is lower; Oxygen in the product, sulfide inclusion are more.
Summary of the invention: the object of the present invention is to provide a kind of segregation-free, wear resistance good, reduce raw materials cost simultaneously, make the manufacture method of the rotary casting alloy furnace tubes by adopting that the clarity of product is improved.
The present invention is achieved in that and adopts duplex rotary casting smelting technology to make the rotary casting alloy furnace tubes by adopting, provide half steel water by intermediate frequency furnace, transporting half steel water with casting ladle gives the AOD stove, carries out refining with three-step approach then, provide purified molten steel to spun cast pipe and sand mold casting, thereby guarantee that product performance reach the requirement of main pipe line product technology condition defined.
1. intermediate frequency furnace furnace charge: high carbon ferro-chrome; No. 2 nickel; Molybdenum-iron; Ferrosilicon; Ferromanganese; Steel scrap, tapping temperature: 1600～1650 ℃;
2.AOD stove one step decarburization;
3.AOD stove two steps reduction;
4.AOD stove three steps are made into branch, AOD stove tapping temperature: 1600-1630 ℃.
The target of two-link smelting process: materials A SME SA-451 CPF8M Modf, its chemical ingredients is: C≤0.04%; Mn≤1.50%; Si≤1.00%; S≤0.020%; P≤0.030%; Cr 18.00～20.00%; Ni 9.00～12.00%; Mo 2.00～3.00%; Cu≤0.10%; Co≤0.08%; All the other are Fe.
The present invention compared with prior art has following advantage:
1. two-link smelting process can use more economical raw material: do not use extra low carbon ferrochromium and even chromium metal, and carbon or high carbon ferro-chrome in can using; Do not use No. 1 metallic nickel (99.99% nickel) and can be with 2, No. 3 nickel or ferronickel; Do not use little carbon pure iron to produce Ultralow Carbon Stainless Steel.
2. but two-link smelting process smelting ultralow-carbon stainless steel can reduce the loss of chromium simultaneously;
3. two-link smelting process can improve stainless clarity:
A. two-link smelting process can be produced the stainless steel of low (S＜0.030%), thereby avoids the generation of hot tearing when welding for thick-walled tube;
B. two-link smelting process can reduce oxygen, sulfide inclusion.C. can to reduce the oxygen level in the steel be 40～70ppm to two-link smelting process.
D. two-link smelting process can reduce hydrogen richness in the steel between 2～4ppm, avoids spun cast pipe, foundry goods goods needle pore defect to occur effectively.
E. the controlled stainless nitrogen content of two-link smelting process: when needs were produced controlled nitrogen stainless steel, its nitrogen content was controlled at 0.01～0.025%; When requiring to produce nitrogen-contained stainless steel, can produce almost is the stainless steel product of supersaturation nitrogen content.
Adopt the main pipe line straight tube product performance index of duplex cast:
1. safe class: Nuclear safety one-level;
2. quality grade: QA1 level;
3. antidetonation classification: I class;
4. operating pressure: P=15.2Mpa;
5. operating temperature: T=315 ℃;
6. design temperature: T=350 ℃;
7. design pressure: P=17.15Mpa;
8. hydraulic test pressure: P=21.5Mpa;
9. life: Y=40
10. select materials: the performance test result of the main pipe line straight length of ASME SA-451 CPF8M Modf duplex cast:
1. the main pipe line straight length is manufactured experimently the chemical composition analysis of part specification Φ 840 * 72.5 * 2000 (mm):
Regulation by technical qualification, the chemical composition analysis of pipeline section, comprise that the chemical composition analysis of taking a sample from casting ladle reaches the chemical analysis that will ask for 0 °, 90 °, 180 °, 270 ° orientation 1/4 a thickness finished product sample of finished product by charter, analytical results meets technical qualification (seeing Table 1).
Table 1 casting ladle and finished product chemical composition analysis result
| Project | Chemical element Wt% | |||||||||
| C | Si | Mn | S | P | Cr | Ni | Mo | Cu | Co | |
| Requirement | ≤ 0.04 | ≤ 1.00 | ≤ 1.50 | ≤ 0.020 | ≤ 0.030 | 18.00～ 21.00 | 9.00～ 12.00 | 2.00～ 3.00 | ≤ 0.10 | ≤ 0.08 |
| Casting ladle | 0.03 | 0.84 | 0.82 | 0.013 | 0.026 | 20.18 | 10.41 | 2.12 | 0.02 | 0.01 |
| Finished product 1 | 0.03 | 0.84 | 0.82 | 0.011 | 0.026 | 20.04 | 10.52 | 2.10 | 0.02 | 0.01 |
| Finished product 2 | 0.03 | 0.84 | 0.82 | 0.013 | 0.026 | 20.18 | 10.41 | 2.12 | 0.02 | 0.01 |
| Finished product 3 | 0.02 | 0.82 | 0.80 | 0.010 | 0.024 | 19.96 | 10.40 | 2.05 | 0.02 | 0.01 |
| Finished product 4 | 0.03 | 0.84 | 0.83 | 0.014 | 0.026 | 20.02 | 10.55 | 2.09 | 0.02 | 0.01 |
2. the mensuration of the delta ferrite of main pipe line straight length
By the technical qualification regulation, with casting ladle chemical ingredients and finished product chemical composition analysis result, calculate chromium equivalent Creq and nickel equivalent Nieq respectively, try to achieve the delta ferrite level value, the gained result meets and requires ferrite content to should be 15～20% in the technical qualification all in 16～18% scopes.
Nickel and chromium equivalent formula are respectively:
Nieq＝％Ni+30×％C+0.5×％Mn；
Creq＝％Cr+％Mo+1.5×％Si+0.5×％Nb。
The sample analysis result all contains 0.02%Nb
1. casting ladle is analyzed Nieq=10.41+30 * 0.03+0.5 * 0.82=11.7
Creq＝20.18+2.12+1.5×0.84+0.5×0.02＝23.6
Getting ferrite content is: 17%
2. from the 1# finished product sample analysis result of 0 ° of position of goods, 1/4 thickness sampling
Nieq＝10.52+30×0.03+0.5×0.82＝11.8
Creq＝20.04+2.10+1.5×0.84+0.5×0.02＝23.4
Getting ferrite content is: 17%
3. the 2# finished product sample analysis result from the sampling of 90 ° of positions of goods, 1/4 thickness gets
Nieq＝10.41+30×0.03+0.5×0.80＝11.7
Creq＝20.18+2.12+1.5×0.84+0.5×0.02＝23.6
Getting ferrite content is: 17%
4. the 3# finished product sample analysis result from the sampling of 180 ° of positions of goods, 1/4 thickness gets
Nieq＝10.40+30×0.03+0.5×0.80＝11.7
Creq＝19.96+2.05+1.5×0.82+0.5×0.02＝23.3
Getting ferrite content is: 16%
5. the 4# finished product sample analysis result from the sampling of 270 ° of positions of goods, 1/4 thickness gets
Nieq＝10.55+30×0.03+0.5×0.83＝11.9
Creq＝20.02+2.09+1.5×0.84+0.5×0.02＝23.4
Getting ferrite content is: 16%
By analysis, The above results all meets the regulation of technical qualification
3. the main pipe line straight length intercepts the mechanical property of sample
The mechanical property sample presses the master drawing intercepting by the technical qualification requirement on the goods of solution heat treatment, press ASTM E8 and ASTM E21 standard, adopts the sample in Φ 10mm cross section to test, and its test-results meets the prescribed value (seeing Table 2) of technical qualification.
Table 2 normal temperature and high temperature (350 ℃) stretch test result
| Sample | Test temperature | σ bMPa | σ 0.2MPa | δ％ | φ％ |
| Prescribed value | Normal temperature | ≥210 | ≥485 | ≥35 | ≥45 |
| HA-TS-1 | Normal temperature | 270 | 530 | 45.3 | 65.8 |
| HA-TS-2 | Normal temperature | 265 | 538 | 56.0 | 73.7 |
| HC-TS-1 | Normal temperature | 260 | 524 | 54.6 | 62.1 |
| HC-TS-2 | Normal temperature | 269 | 542 | 48.0 | 58.4 |
| CB-TS-1 | Normal temperature | 261 | 523 | 52.2 | 71.1 |
| CB-TS-2 | Normal temperature | 259 | 535 | 52.4 | 65.1 |
| CD-TS-1 | Normal temperature | 271 | 531 | 47.6 | 65.1 |
| CD-TS-2 | Normal temperature | 277 | 559 | 45.7 | 56.7 |
| Prescribed value | 350℃ | ≥125 | ≥355 | ≥25 | ≥40 |
| HA-ETS-1 | 350℃ | 152 | 392 | 44 | 72 |
| HA-ETS-2 | 350℃ | 147 | 385 | 36 | 54 |
| HC-ETS-1 | 350℃ | 148 | 393 | 40 | 60 |
| HC-ETS-2 | 350℃ | 154 | 396 | 40 | 62 |
| HB-ETS-1 | 350℃ | 149 | 382 | 38 | 55 |
| HB-ETS-2 | 350℃ | 147 | 379 | 38 | 58 |
| HD-ETS-1 | 350℃ | 150 | 387 | 42 | 62 |
| HD-ETS-2 | 350℃ | 151 | 380 | 44 | 67 |
4. the summer of main pipe line straight length intercepting sample is than impacting toughness
Summer tests by ASTM A370 than impacting the used sample of toughness test by the straight length intercepting of technical qualification after the solution heat treatment, and test-results meets the mean value AK of three tests of regulation of technical qualification
VThe single Schwellenwert AK of 〉=80J
V〉=60J (seeing Table 3)
Table 3 Charpy impact test result
| Sample | C1-1 | C1-2 | C1-3 | C3-1 | C3-2 | C3-3 | H2-1 | H2-2 | H2-3 | H4-1 | H4-2 | H4-3 |
| AK(J) | 204 | 198 | 224 | 218 | 220 | 190 | 188 | 210 | 241 | 226 | 226 | 190 |
| Mean value (J) | 208 | 209 | 213 | 219 | ||||||||
| Single minimum value (J) | 198 | 190 | 188 | 190 | ||||||||
5. the intergranular corrosion sensitivity test of main pipe line straight length sample
Sample slowly cooling in luxuriant good fortune stove behind 30 minutes constant temperature of 725 ℃ of insulations by the technical qualification intercepting, through milled processed, purified rinse water is arranged after acetone deoils, dry up, boiled 24 hours in the triangle of taking back flow condenser burns by ASTM A262 E method, sample through Huey test, clod wash is 180 ° on trier, does not find cracking phenomena.
6. the macroetching of main pipe line straight length cross section ring-shaped sample test
Get the ring-shaped sample of a cross section from straight length one end of process solution treatment by the technical qualification requirement, carried out macroetching by ASTM E340, cross section tissue is even, defectives such as any shrinkage cavity, bubble and even crackle are not found in densification, meets the requirement of technical qualification.The performance test result of 90 ° of elbows of main pipe line of duplex cast:
1.90 ° elbow technical parameter:
1. safe class: Nuclear safety one-level
2. quality grade: QAI level
3. antidetonation classification: I class
4. operating pressure: P=15.2Mpa
5. operating temperature: T=316 ℃
6. design pressure: P=17.15Mpa
7. design temperature: T=350 ℃
8. hydraulic test pressure: Pt=21.5Mpa
9. life: Y=40
10. elbow external diameter: =893mm, elbow internal diameter: =695mm, eccentric (outside) δ=11mm of interior circle, elbow radius-of-curvature: R=1300mm
2. elbow material selection: ASME SA-351 CF8M Modf, the chemical composition analysis of elbow:
Carried out the chemical analysis of casting ladle and finished product by the regulation of technical qualification, analytical results meets the regulation of technical qualification, the results are shown in Table 4.
The chemical composition analysis result of table 4 elbow
| Project | Chemical ingredients (Wt%) | |||||||||
| C | Mn | Si | P | S | Cr | Ni | Mo | Cu | Co | |
| Standard | ≤0.04 | ≤ 1.50 | ≤ 1.00 | ≤0.030 | ≤0.020 | 18.00- 21.00 | 9.00- 12.00 | 2.00- 3.00 | ≤0.10 | ≤0.080 |
| Casting ladle | 0.02 | 0.93 | 0.85 | 0.010 | 0.013 | 19.40 | 10.45 | 2.23 | 0.01 | 0.014 |
| Finished product 01 | 0.02 | 0.76 | 0.84 | 0.024 | 0.012 | 19.78 | 10.20 | 2.07 | 0.02 | 0.010 |
| Finished product 02 | 0.03 | 0.79 | 0.83 | 0.025 | 0.011 | 19.77 | 10.42 | 2.04 | 0.02 | 0.010 |
| Finished product 03 | 0.03 | 0.77 | 0.83 | 0.024 | 0.011 | 19.80 | 10.22 | 2.09 | 0.02 | 0.010 |
| Finished product 04 | 0.025 | 0.84 | 0.81 | 0.022 | 0.010 | 20.10 | 10.38 | 2.08 | ＜0.05 | 0.014 |
Finished product 01-04 is the sample of 0 °, 90 °, 180 °, 270 ° sample position T * T/4 of 90 ° of elbows.
3.90 the delta ferrite level of ° elbow is measured
By the regulation of technical qualification, measure delta ferrite level with the chemical analysis of casting ladle and finished product, its delta ferrite level is 15%～18%.The result meets the regulation of technical qualification.
Cr and Ni content are respectively;
Nieq＝％Ni+30％C+0.5％Mn
Creq＝％Cr+％Mo+1.5％×％Si+0.5×％Nb
(1) casting ladle analytical results, the chromium of calculating and nickel equivalent are
Nieq＝10.45+30×0.02+0.5×0.93＝11.5
Creq＝19.40+2.23+1.5×0.85＝22.9
Getting the delta ferrite amount is 15%
(2) finished product 01
Nieq＝10.20+30×0.02+0.5×0.76＝11.2
Creq＝19.78+2.07+1.5×0.84＝23.1
Getting the delta ferrite amount is 18%
(3) finished product 02
Nieq＝10.42+30×0.03+0.5×0.79＝11.7
Creq＝19.77+2.04+1.5×0.83＝23.1
Getting the delta ferrite amount is 16%
(4) finished product 03
Nieq＝10.22+30×0.03+0.5×0.77＝11.5
Creq＝19.80+2.09+1.5×0.83＝23.1
Getting the delta ferrite amount is 17%
(5) finished product 04
Nieq＝10.38+30×0.025+0.5×0.84＝11.6
Creq＝20.10+2.08+1.5×0.81＝23.4
Getting the delta ferrite amount is 18%
4. intercept the normal temperature and the high temperature tension test of samples from 90 ° of elbows
By the regulation of technical qualification, carried out normal temperature and high temperature tension test, its result meets the requirement (seeing Table 5) of technical qualification
5. the summer ratio from 90 ° of elbow intercepting samples impacts toughness test
By the regulation of technical qualification, carried out Charpy impact test from elbow intercepting sample, test-results meets the regulation (seeing Table 6) of technical qualification
6. test from the macroetching of elbow intercepting cross section ring-shaped sample
End that is defined in elbow by technical qualification has intercepted the cross section ring-shaped sample, has carried out the macroetching test by the ASTME340 regulation.
Corrosion is a microprocess, and in macro-scope, by the cast structure of etch goods, defectives such as the inner slag inclusion thing that exists of goods, shrinkage porosite, tiny crack, pore all can show by the image after corroding.The ununiformity and the anisotropic of tissue, and the vestige after the repair welding can also be manifested by erosion., visual inspection even, fine and close from the whole as can be seen plane of the cross section ring-shaped sample macro-erosion macrostructure of elbow ends intercepting do not have any defective.
7. intercept the Huey test of sample from elbow:
By technical qualification regulations, from the sample of goods intercepting through 725 ± 10 ℃ after sensitization handles, undertaken by ASMEA-262 E method.Huey test, the result finds intergranular corrosion in the end, meets the regulation of technical qualification.
Table 5 normal temperature and high temperature tension test result
| Project | Temperature | σ bMPa | σ 0.2MPa | δ％ | ％ |
| Prescribed value | Room temperature | ≥485 | ≥210 | ≥35 | 45 |
| CB-TS-1 | Room temperature | 512 | 255 | 48 | 63 |
| CB-TS-2 | Room temperature | 515 | 248 | 49 | 71.8 |
| CD-TS-1 | Room temperature | 531 | 255 | 49 | 63.9 |
| CD-TS-2 | Room temperature | 517 | 236 | 37 | 57.8 |
| 01 | Room temperature | 515 | 270 | 47.5 | 76.0 |
| 02 | Room temperature | 531 | 280 | 50.5 | 67.0 |
| 03 | Room temperature | 510 | 260 | 48.5 | 71.0 |
| Prescribed value | 350℃ | ≥355 | ≥125 | ≥25 | ≥40 |
| HA-ETS-1 | 350℃ | 373 | 160 | 40 | 62.6 |
| HA-ETS-2 | 350℃ | 391 | 164 | 40 | 72.9 |
| HC-ETS-1 | 350℃ | 371 | 159 | 35 | 51.3 |
| HC-ETS-2 | 350℃ | 376 | 162 | 38 | 63.4 |
| 04 | 350℃ | 380 | 143 | 39 | 59 |
| 05 | 350℃ | 370 | 141 | 31 | 55 |
| 06 | 350℃ | 385 | 133 | 42 | 59 |
Table 6 summer is than impacting the toughness test result
| Sample | AK V(J) | Mean value (J) | Single Schwellenwert (J) |
| Prescribed value | AK V(J) | MV≥70J | SV≥60J |
| C1-1 | 224 | 230 | 224 |
| C1-2 | 238 | ||
| C1-3 | 230 | ||
| C2-1 | 210 | 215 | 210 |
| C2-2 | 216 | ||
| C2-3 | 220 | ||
| 01 | 168 | 179 | 168 |
| 02 | 217 | ||
| 03 | 207 |
Claims (2)
1. two-link smelting process for centrifugal casting high alloy boiler tube, it is characterized in that: raw material is with high carbon ferro-chrome; No. 2 nickel; Molybdenum-iron; Ferrosilicon; Ferromanganese and steel scrap are heated by intermediate frequency furnace and are provided half steel water, tapping temperature: 1600～1650 ℃; Transport half steel water with casting ladle and give the AOD stove, carry out refining with three-step approach then, provide purified molten steel to spun cast pipe and sand mold casting.
2. the high-alloy furnace pipe that two-link smelting process for centrifugal casting high alloy boiler tube according to claim 1 is made, it is characterized in that: its chemical ingredients is: C≤0.04%; Mn≤1.50%; Si≤1.00%; S≤0.020%; P≤0.030%; Cr 18.00～20.00%; Ni 9.00～12.00%; Mo 2.00～3.00%; Cu≤0.10%; Co≤0.08%, all the other are Fe.
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Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN102876966A (en) * | 2012-10-09 | 2013-01-16 | 西安交通大学 | Preparation method of as-cast high manganese steel through forging processing |
| CN114196865A (en) * | 2021-12-01 | 2022-03-18 | 浙江中达新材料股份有限公司 | NS1104 furnace tube for petroleum refining |
-
2005
- 2005-11-22 CN CN 200510095772 patent/CN1766147A/en active Pending
Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN102876966A (en) * | 2012-10-09 | 2013-01-16 | 西安交通大学 | Preparation method of as-cast high manganese steel through forging processing |
| CN114196865A (en) * | 2021-12-01 | 2022-03-18 | 浙江中达新材料股份有限公司 | NS1104 furnace tube for petroleum refining |
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