CN104630425B - A kind of eliminate the method for σ phase in Nuclear piping cast stainless steel - Google Patents
A kind of eliminate the method for σ phase in Nuclear piping cast stainless steel Download PDFInfo
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- CN104630425B CN104630425B CN201510046441.XA CN201510046441A CN104630425B CN 104630425 B CN104630425 B CN 104630425B CN 201510046441 A CN201510046441 A CN 201510046441A CN 104630425 B CN104630425 B CN 104630425B
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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
- C21D1/00—General methods or devices for heat treatment, e.g. annealing, hardening, quenching or tempering
- C21D1/26—Methods of annealing
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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
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Abstract
The invention discloses and a kind of eliminate the heat treatment method of σ phase in Nuclear piping cast stainless steel, belong to metal material Field of Heat-treatment.The present invention uses same Equipment for Heating Processing that the austenite ferrite type Nuclear piping cast stainless steel containing varying number σ phase carries out 900～1000 DEG C of isothermal annealings and processes, and annealing time 0.25～35h, after annealing, Water Quenching is to room temperature.Can be effectively eliminated the σ phase in Nuclear piping rustless steel by the method, the brittle phenomenon that material causes owing to σ phase separates out eliminates, and the mechanical property such as hardness, impact flexibility returns to the state without σ phase.
Description
Technical field
The invention belongs to metal material Field of Heat-treatment, relate to a kind of eliminating the side of fragility the second phase in rustless steel
Method, is specifically related to a kind of eliminate the heat treatment method of σ phase in Nuclear piping cast stainless steel.
Background technology
Pressurized-water reactor nuclear power plant primary Ioops main pipeline as the important component part on pressure bearing system border to nuclear power station
Safety plays important barrier action, generally use austenite-ferrite type duplex structure's rustless steel casting and
Become.In this material, ferritic phase plays raising intensity, reduces sweating heat fragility, raising anticorrosion stress-resistant
Deng effect；But, ferritic existence also bring heat ageing brittle, in heat-sensitized embrittlement issue, the latter
Main precipitation by σ phase causes ([1] R.N.Gunn.Cambridge England:Abington, 1997:175. [2]
K.H.Lo,et al.Materials Science and Engineering R,2009,65(4-6):39-104.[3]Y.Q.
Wang,et al.Nuclear Engineering and Design.2013,259:1-7.).The production of Nuclear piping,
Installation process inevitably carries out heat treatment and welding, and enterprise produces during reality proves this and can produce
Raw σ phase.Research show that σ phase is a kind of hard and crisp intermetallic compound, it not only increase stainless firmly
Degree, significantly reduce stainless toughness and make it become fragile, and reduce stainless spot corrosion and corrosion among crystalline grains,
So it has been generally acknowledged that material is had by its precipitation to do harm to very much ([4] Y.S.Ahn et al.Materials Science and
Technology,2000,16(4):382-388.[5]Y.Q.Wang,B.Yang,H.C.Wu,et al.Materials
Transactions.2013,54(5):839-843.[6]Park C J,et al.Corrosion,2005,61(1):
76-83.).The existence of σ phase reduces the military service performance of Nuclear piping, the safe operation of harm nuclear power station, therefore presses down
The precipitation of system or elimination σ phase is particularly important.
Generally, can effectively delay by the interpolation method such as suitable alloying element and pressure processing or suppress σ
The precipitation of phase ([7] O.Smuk, et al.Metallurgical and Materials Transactions A, 2004,
35 (7): 2103-2109. [8] C.C.Hsieh, et al.ISRN Metallurgy, 2012,2012:1-16.), but
Said method is preventive measure, and can not eliminate the σ phase separated out, and adjusts alloying component meeting shadow
Ring materials microstructure and performance, relate to multiple operations such as smelting, molding, be unfavorable for the strict of Nuclear piping
Production requirement.Production technology is fixed, alloy that material composition is certain, it is to disappear that annealing (solid solution) processes
Unique method except σ phase.There are some researches show, SAF2205 rustless steel is sent out when higher than 1050 DEG C of solution treatment
Raw σ → γ phase transformation, ([9] R.Badji, et al.Materials Science and in σ phased soln to austenitic matrix
Engineering A, 2008,496 (1 2): 447-454.), but the tissue of Nuclear piping cast stainless steel with become
Point all significantly different with SAF2205, need to explore new σ phase most preferably eliminates technique.Therefore, exploitation one
Plant and eliminate the heat treatment method of σ phase in Nuclear piping rustless steel targetedly, for improving pipeline material
, can ensure that nuclear plant safety has important actual application value.
Summary of the invention
It is an object of the invention to provide a kind of for the removing method of σ phase in Nuclear piping cast stainless steel,
Heat-sensitized fragility during Nuclear piping rustless steel causes can be eliminated owing to σ phase separates out to adopting said method
Phenomenon, makes material mechanical performance return to the level without σ phase, thus reaches to improve tube performance, prolongation
The purpose in service life.
In order to realize above-mentioned technical purpose, the present invention is achieved by the following technical programs.
The present invention is a kind of eliminates the method for σ phase in Nuclear piping cast stainless steel, uses isothermal annealing process side
Described cast stainless steel containing σ phase is processed by method, and concrete technology parameter is:
Annealing temperature: 900～1000 DEG C；Annealing time: 0.25～35h；The type of cooling: shrend is to room temperature.
Further, described annealing temperature is 950 DEG C, annealing time 0.5h.
The present invention specifically includes following steps:
(1) observe timeliness steel part tissue, measure the content of σ phase in timeliness steel part；
(2) steel part containing σ phase is carried out 900～1000 DEG C of annealings, the time 0.25～35h, measure σ
The content of phase；
(3) impact flexibility of steel part, microcell hardness after test annealing.
Described step (1), (2) use optical microscope (OM) or scanning electron microscope (SEM) to see
Examine tissue and shoot picture, 20 visual fields of the minimum shooting of each sample, use Metallographic Analysis software statistics σ phase
Quantity, replaces volume fraction with area fraction, so easy to be reliable.
The Charpy-V impact power of v-notch sample, specimen size: 10mm under described step (3) test room temperature
× 10mm × 55mm, surface roughness RaIt is better than 5 μm, except end.
Equipment for Heating Processing of annealing in the present invention is in chamber type electric resistance furnace, tube type resistance furnace or vacuum annealing furnace
Kind.It is the one in air, vacuum or noble gas that isothermal annealing of the present invention processes atmosphere.
Compared with prior art, the present invention has following technical effect that
1, the Nuclear piping cast stainless steel that the present invention is directed to particular tissues and composition proposes a kind of simple, high
Effect, economic its fragility σ phase method of elimination, compare the production process related to few, can carry with additive method
High enterprise productivity effect, the saving energy；
2, the present invention uses same Equipment for Heating Processing, organizes parallel sample more, can guarantee that measurement, test result
Accuracy.
Accompanying drawing explanation
Fig. 1 is the metallographic structure of steel part sample before and after annealing in the embodiment of the present invention 1,2,3；
Wherein: (a) is the tissue of 750 DEG C of timeliness 200h steel part samples；B (), (c), (d) are respectively
750 DEG C of timeliness 200h steel part sample 900 DEG C of annealings 35h, 950 DEG C of annealing in the inventive method
Process sample tissue after 0.5h, 1000 DEG C of annealing 0.25h.
Fig. 2 be in the embodiment of the present invention 2 annealing before and after impact specimen fracture apperance；
Wherein: (a), (d) are nonageing steel part sample impact fracture patterns；When (), (e) are 750 DEG C b
Effect 200h steel part sample impact fracture pattern；C (), (f) are that 750 DEG C of timeliness 200h steel parts are through side of the present invention
Sample impact fracture pattern after method 950 DEG C annealing 0.5h；(d), (e), (f) be respectively (a), (b),
The high power figure of (c).
Fig. 3 be in the embodiment of the present invention 2 annealing before and after sample microcell hardness.
Detailed description of the invention
By following embodiment further details of elaboration present disclosure, to it is better understood from,
But example is not limiting as protection scope of the present invention.
Embodiment 1
The present embodiment carries out 900 DEG C to 750 DEG C of certain main nuclear power pipeline cast stainless steel parts processing 200h and moves back
Fire processes, time 35h, and step is as follows:
The first step, steel part is processed into 10mm × 10mm × 10mm sample several.
Second step, 10mm × 10mm × 10mm sample is through sand papering to 2000#, 1.5 μm diamond
Ultrasonic waves for cleaning, then DC source electrolytic attack after abrasive pastes mechanical polishing, parameter is: voltage 3V, time
Between 10S, electrolyte is: 30g NaOH+120mL H2O, observes the metallographic structure of steel part, measures steel part
Middle σ phase content.
3rd step, puts in tube type resistance furnace to enter at 900 DEG C by Nuclear piping stainless steel part remaining after sampling
Row 35h makes annealing treatment, and selects argon as protective atmosphere, uses water quenching to be cooled to room temperature after annealing.
4th step, observes the metallographic structure of steel part after making annealing treatment, and measures σ phase content in steel part and (specifically grasps
Make with step one, two), contrast with the tissue without σ phase steel part.As shown in table 1, Fig. 1, use
After the method for annealing of the present invention processes, the tissue of Nuclear piping cast stainless steel has essentially returned to without σ
The state of phase.
Embodiment 2
The present embodiment carries out 950 DEG C of annealing to 750 DEG C of certain main nuclear power pipeline cast stainless steel parts processing 200h
Processing, time 0.5h, step is as follows:
The first step, is processed into 10mm × 10mm × 10mm and 10mm × 10mm × 55mm by steel part
Sample several, wherein 10mm × 10mm × 55mm specimen surface roughness RaIt is better than 5 μm, end
Except, v-notch is opened in centre.
Second step, 10mm × 10mm × 10mm sample is through sand papering to 2000#, 1.5 μm diamond
Ultrasonic waves for cleaning, then DC source electrolytic attack after abrasive pastes mechanical polishing, parameter is: voltage 3V, time
Between 10S, electrolyte is: 30g NaOH+120mL H2O, observes the metallographic structure of steel part, measures steel part
Middle σ phase content.
3rd step, after measuring polished electrolytic attack with microhardness testers, 10mm × 10mm × 10mm tries
The austenite of sample, the microcell hardness of ferritic phase.
4th step, tests 10mm × 10mm × 55mm sample room temperature with electronic type balance weight impact testing machine
Lower Charpy-V impact power, at least three parallel sample, take measurement result meansigma methods.
5th step, puts in chamber type electric resistance furnace to enter at 950 DEG C by Nuclear piping stainless steel part remaining after sampling
Row 0.5h makes annealing treatment, and atmosphere is air, uses water quenching to be cooled to room temperature after annealing.
6th step, observes the metallographic structure of steel part after making annealing treatment, measures σ phase content in steel part, and test is moved back
The Charpy-V impact power of steel part and austenite after fire, ferritic phase microcell hardness (concrete operations with step one, two,
Three, four), contrast with the tissue without σ phase steel part, impact flexibility, fracture apperance, microcell hardness etc..
As shown in table 1, table 2 and Fig. 1～Fig. 3, after using the method for annealing of the present invention to process, Nuclear piping casts
Stainless tissue and mechanical property have returned to the state without σ phase.
Embodiment 3
The present embodiment carries out 1000 DEG C to 750 DEG C of certain main nuclear power pipeline cast stainless steel parts processing 200h and moves back
Fire processes, time 0.25h, and step is as follows:
The first step, steel part is processed into 10mm × 10mm × 10mm sample several.
Second step, 10mm × 10mm × 10mm sample is through sand papering to 2000#, 1.5 μm diamond
Ultrasonic waves for cleaning, then DC source electrolytic attack after abrasive pastes mechanical polishing, parameter is: voltage 3V, time
Between 10S, electrolyte is: 30g NaOH+120mL H2O, observes the metallographic structure of steel part, measures steel part
Middle σ phase content.
3rd step, puts in vacuum annealing furnace to enter at 1000 DEG C by Nuclear piping stainless steel part remaining after sampling
Row 0.25h makes annealing treatment, and uses water quenching to be cooled to room temperature after annealing.
4th step, observes the metallographic structure of steel part after making annealing treatment, and measures σ phase content in steel part and (specifically grasps
Make with step one, two), contrast with the tissue without σ phase steel part.As shown in table 1, Fig. 1, use
After the method for annealing of the present invention processes, the organized renewing of Nuclear piping cast stainless steel has arrived the shape without σ phase
State.
Embodiment 4
The present embodiment carries out 950 DEG C of annealing to 750 DEG C of certain main nuclear power pipeline cast stainless steel parts processing 100h
Processing, time 0.5h step is as follows:
The first step, is processed into 10mm × 10mm × 10mm and 10mm × 10mm × 55mm by steel part
Sample several, wherein 10mm × 10mm × 55mm specimen surface roughness RaIt is better than 5 μm, end
Except, v-notch is opened in centre.
Second step, 10mm × 10mm × 10mm sample is through sand papering to 2000#, 1.5 μm diamond
Ultrasonic waves for cleaning, then DC source electrolytic attack after abrasive pastes mechanical polishing, parameter is: voltage 3V, time
Between 10S, electrolyte is: 30g NaOH+120mL H2O, observes the metallographic structure of steel part, measures steel part
Middle σ phase content.
3rd step, tests 10mm × 10mm × 55mm sample room temperature with electronic type balance weight impact testing machine
Lower Charpy-V impact power, at least three parallel sample, take measurement result meansigma methods.
4th step, puts in chamber type electric resistance furnace to enter at 950 DEG C by Nuclear piping stainless steel part remaining after sampling
Row 0.5h makes annealing treatment, and atmosphere is air, uses water quenching to be cooled to room temperature after annealing.
5th step, observes the metallographic structure of steel part after making annealing treatment, measures σ phase content in steel part, and test is moved back
The Charpy-V impact power (concrete operations with step one, two, three) of steel part after fire, with the tissue without σ phase steel part,
Impact flexibility contrasts.As shown in table 1, table 2, after using the method for annealing of the present invention to process, nuclear power pipe
The tissue of road cast stainless steel and mechanical property have returned to the state without σ phase.
Table 1, embodiment select the change of σ phase content (volume fraction) in main nuclear power pipeline cast stainless steel
| Nonageing | Sample after timeliness | Sample after annealing | |
| Embodiment 1 | 0% | 18.57 ± 0.65% | 0% |
| Embodiment 2 | 0% | 18.57 ± 0.65% | 0% |
| Embodiment 3 | 0% | 18.57 ± 0.65% | 0% |
| Embodiment 4 | 0% | 18.02 ± 1.84% | 0% |
Table 2, embodiment select the change of main nuclear power pipeline cast stainless steel ballistic work
| Nonageing | Sample after timeliness | Sample after annealing | |
| Embodiment 2 | 392.57±12.7J | 37.0±2.5J | 389.3±7.4J |
| Embodiment 4 | 392.25±11.3J | 54.5±14.15J | 385.7±9.2J |
Claims (2)
1. one kind eliminates the method for σ phase in Nuclear piping cast stainless steel, it is characterised in that use isothermal to move back
Described Nuclear piping cast stainless steel containing σ phase is processed by fire processing method, specifically includes following steps:
(1) observe Nuclear piping cast stainless steel steel part tissue after timeliness, measure containing of σ phase in this steel part tissue
Amount；
(2) the Nuclear piping cast stainless steel steel part that step (1) contains σ phase carries out 900～1000 DEG C of annealing
Process, the time 0.25～35h, use water quenching to be cooled to room temperature afterwards, measure the content of σ phase；
(3) impact flexibility of Nuclear piping cast stainless steel steel part, microcell after testing procedure (2) annealing
Hardness；
Described step (1), (2) use optical microscope or sem observation tissue and shoot figure
Sheet, 20 visual fields of the minimum shooting of each sample, use Metallographic Analysis software statistics σ phase amount, with Line Integral
Number replaces volume fraction.
The most as claimed in claim 1 a kind of eliminating the method for σ phase in Nuclear piping cast stainless steel, it is special
Levying and be, the annealing temperature of described step (2) is 950 DEG C, annealing time 0.5h.
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| SE1950909A1 (en) * | 2019-07-31 | 2021-02-01 | Ferritico Ab | Duplex steel with improved embrittlement properties and method of producing such |
| CN113832412B (en) * | 2021-09-09 | 2023-12-05 | 中车戚墅堰机车车辆工艺研究所有限公司 | Heat treatment method of Nb-containing Cr-Ni cast austenitic heat-resistant stainless steel |
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| CA2537506C (en) * | 2003-09-03 | 2009-12-15 | Fluor Technologies Corporation | Post weld heat treatment for chemically stabilized austenitic stainless steel |
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