CN106191389B - A kind of two-step method tempering process improving nuclear power heavy forging impact flexibility - Google Patents
A kind of two-step method tempering process improving nuclear power heavy forging impact flexibility Download PDFInfo
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- CN106191389B CN106191389B CN201610741540.4A CN201610741540A CN106191389B CN 106191389 B CN106191389 B CN 106191389B CN 201610741540 A CN201610741540 A CN 201610741540A CN 106191389 B CN106191389 B CN 106191389B
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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
- C21D1/18—Hardening; Quenching with or without subsequent tempering
-
- 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
- C21D9/0068—Heat treatment, e.g. annealing, hardening, quenching or tempering, adapted for particular articles; Furnaces therefor for particular articles not mentioned below
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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
- C21D2211/00—Microstructure comprising significant phases
- C21D2211/002—Bainite
-
- 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
- C21D2211/004—Dispersions; Precipitations
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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
- C21D2211/00—Microstructure comprising significant phases
- C21D2211/005—Ferrite
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- Engineering & Computer Science (AREA)
- Physics & Mathematics (AREA)
- Thermal Sciences (AREA)
- Crystallography & Structural Chemistry (AREA)
- Mechanical Engineering (AREA)
- Materials Engineering (AREA)
- Metallurgy (AREA)
- Organic Chemistry (AREA)
- Heat Treatment Of Steel (AREA)
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Abstract
The present invention relates to a kind of two-step method tempering process for improving nuclear power heavy forging impact flexibility, include the following steps：(1) by quenched nuclear power heating of Large Forgings to 300-450 DEG C, heat preservation；(2) heating forging is further continued for 600-660 DEG C, heat preservation, later forging furnace cooling is completed.Compared with prior art, the present invention reaches 100J or so using the impact absorbing energy average value of steel after the processing of two-step method tempering process, impact flexibility compared to the nuclear power heavy forging of traditional tempering process processing is improved significantly, and simple process, and operation is easily achieved.
Description
Technical field
The present invention relates to metal heating processing technology fields, more particularly, to a kind of raising SA508Gr.3 steel nuclear power heavy forging
The two-step method tempering process of impact flexibility.
Background technique
SA508Gr.3 steel is widely used in manufacturing nuclear pressure container, tube sheet, cylinder as a kind of common structural material
The nuclear power stations critical component such as body.For this steel, it is most important that provide high-intensitive enough and high impact toughness to overcome
Contingency causes security risk caused by temporary impact.It is worth noting that, crisp due to irradiating in nuclear power station operational process
Change, the impact flexibility of steel can run down, so steel initial impact toughness with higher is made to be by heat-treating methods
Guarantee that nuclear plant safety runs vital factor.
By literature search, Nuclear engineering and design magazine (1997, Vol.174 (1), P51-
58) Kim J T et al. writes articles " Improvement of impact toughness of the SA 508class on
3steel for nuclear pressure vessel through steel-making and heat-treatment
Practices is (tough come the impact for improving nuclear pressure container SA508Gr.3 steel by improving production and heat treatment process
Property) ", this article proposes that nuclear power pressure vessel forging can be significantly improved by improved vacuum carbon deoxidization technology and reduction Si content
Impact flexibility, but still it is not sufficient to ensure that the qualification of impact property 100%.
It is quilt in actual production that the SA508Gr.3 forging of quenching state, which is directly heated to 600-660 DEG C of tempering heat preservation 4-12h,
The tempering process generally used, but this traditional tempering process often leads to retained austenite and is decomposed into the larger strip of size
Shape carbide and ferritic line and staff control, so that impact absorbing energy is often unable to reach 48J required by technical specification.
Summary of the invention
It is an object of the present invention to overcome the above-mentioned drawbacks of the prior art and provide a kind of SA508Gr.3 steel cores
The two-step method tempering process of TV university forging makes the disadvantage that impact flexibility is relatively low after being heat-treated which overcome traditional handicraft.
The purpose of the present invention can be achieved through the following technical solutions：
A kind of two-step method tempering process improving nuclear power heavy forging impact flexibility, includes the following steps：
(1) quenched forging is heated to 300-450 DEG C, heat preservation；
(2) heating forging is further continued for 600-660 DEG C, heat preservation, later steel workpiece furnace cooling is completed.
The time that forging is kept the temperature at 300-450 DEG C in step (1) is 2-6h.
The time that forging is kept the temperature at 600-660 DEG C in step (2) is 4-12h.
Forging material in step (1) is SA508Gr.3 steel.
Quenched forging in step (1) is the nuclear power of water hardening processing after 890 ± 10 DEG C of austenitizings are kept the temperature
Heavy forging, tissue signature are bainite+residual austenite body tissue.
After common process heat treatment, often occurs larger-size strip carbide in nuclear power heavy forging, lead to steel
Impact flexibility is relatively low, and this strip carbide is by the retained austenite in steel after quenching at higher temperature (500-650 DEG C)
It is decomposed when tempering.
Compared with prior art, the present invention is tempered quenched nuclear power heavy forging using two-step method, after quenching first
Forging kept the temperature in 300-450 DEG C of tempering, so that retained austenite is completely transformed into the carbide of ferrite+tiny, then again plus
Heat eliminates quenching stress, and disperse educt carbide particle in the base to 600-660 DEG C of tempering heat preservation, meet hardness with
In the case where intensity requirement, promotes the impact absorbing energy of workpiece and arrive 100J or so.And after traditional tempering process will directly quench
Forging be heated to 600-660 DEG C of tempering heat preservation, cause retained austenite to be decomposed into larger-size strip carbide+iron element
The line and staff control of body, this larger-size strip distribution of carbides are serious broken between matrix bainite ferrite lath
It is broken the continuity of matrix, the impact absorbing energy of workpiece is caused there was only 40J or so, and two-step method tempering is used to be remarkably improved punching
Hit toughness.
Detailed description of the invention
Fig. 1 is process curve figure of the invention；
Fig. 2 is the microstructure evolution figure for the nuclear power heavy forging that two-step method tempering process of the invention is handled；
Fig. 3 is the microstructure evolution figure of the nuclear power heavy forging of conventional tempering process processing.
Specific embodiment
The present invention is described in detail with specific embodiment below in conjunction with the accompanying drawings.
Embodiment 1
Nuclear power heavy forging is handled using two-step method tempering process as shown in Figure 1.The specific steps are：
Lower shell forging, outer circle φ 4417mm, wall thickness 113mm, long 4267mm, it is desirable that hardness is higher than after tempering heat treatment
HB180, -21 DEG C of impact absorbing energies are greater than 48J.Workpiece is after 890 DEG C of austenitizings are kept the temperature, water hardening processing；Tempering uses
Two-step method tempering process：First in 400 DEG C of heat preservation 2h, then 650 DEG C of heat preservation 4h are warming up to, cool to room temperature with the furnace.In specified position
Its hardness of sample detection and impact flexibility, measuring hardness is HB202, and impact absorbing energy is respectively 79,95,118J, and average value is
97.33J reaching technical requirements.
Tissue before and after the forging tempering is detected, as shown in Figure 2.Wherein, it before Fig. 2 a is tempering, that is, quenches
The microstructure of state；Fig. 2 b is to keep the temperature 2h in 400 DEG C of tempering, the microstructure after 650 DEG C of heat preservation 4h.It is found that quenching state
Retained austenite in forging resolves into tiny ferrite and carbide particle, to effectively increase impact flexibility.
Comparative example 1
Lower shell forging, outer circle φ 4417mm, wall thickness 113mm, long 4267mm, it is desirable that hardness is higher than after tempering heat treatment
HB180, -21 DEG C of impact absorbing energies are greater than 48J.Workpiece is after 890 DEG C of austenitizings are kept the temperature, water hardening processing；Tempering uses
Conventional tempering process：It directly heats to 650 DEG C of heat preservation 4h, cools to room temperature with the furnace.In specified position, its impact of sample detection is tough
Property, measuring impact absorbing energy is respectively 41J, 37J, 51J, and average value only has 43J.
Tissue before and after the forging tempering is detected, as shown in Figure 3.Wherein, it before Fig. 3 a is tempering, that is, quenches
The microstructure of state；Fig. 3 b is the microstructure after 650 DEG C of heat preservation tempering 4h.In comparative example 1, due to quenching state lower shell
Retained austenite in forging is decomposed into larger-size strip carbide+ferritic line and staff control, and it is tough to result in impact
Technical requirements are not achieved in property.
Embodiment 2
Lower shell forging, outer circle φ 4417mm, wall thickness 113mm, long 4267mm want hardness after tempering heat treatment to be higher than
HB180, -21 DEG C of impact absorbing energies are greater than 48J.Workpiece is after 890 DEG C of austenitizings are kept the temperature, water hardening processing；Tempering uses
Two-step method tempering process：First in 350 DEG C of heat preservation 2h, then 650 DEG C of heat preservation 4h are warming up to, cool to room temperature with the furnace.In specified position
Its hardness of sample detection and impact flexibility, measuring hardness is HB200, and impact absorbing energy is respectively 72,90,128J, and average value is
96.67J reaching technical requirements.
Embodiment 3
Cone forging, one end outer circle φ 5626mm, other end outer circle φ 4467mm, wall thickness 168mm, long 3187mm, it is desirable that
Hardness is higher than HB180 after tempering heat treatment, and -21 DEG C of impact absorbing energies are greater than 48J.Workpiece is after 890 DEG C of austenitizings are kept the temperature, water
Cold quenching processing；Tempering uses two-step method tempering process：First in 450 DEG C of heat preservation 2h, then 660 DEG C of heat preservation 6h are warming up to, it is cold with furnace
But to room temperature.Its hardness of sample detection and impact flexibility in specified position, measuring hardness is HB193, and impact absorbing energy is respectively
97,105,86J, average value 96J, reach technical requirements.
Embodiment 4
Lower shell forging, outer circle φ 4417mm, wall thickness 113mm, long 4267mm, it is desirable that hardness is higher than after tempering heat treatment
HB180, -21 DEG C of impact absorbing energies are greater than 48J.Workpiece is after 880 DEG C of austenitizings are kept the temperature, water hardening processing；Tempering uses
Two-step method tempering process：First in 420 DEG C of heat preservation 4h, then 650 DEG C of heat preservation 8h are warming up to, cool to room temperature with the furnace.In specified position
Its hardness of sample detection and impact flexibility, measuring hardness is HB192, and impact absorbing energy is respectively 95,91,120J, and average value is
102J reaches technical requirements.
Embodiment 5
Lower shell forging, outer circle φ 4417mm, wall thickness 113mm, long 4267mm, it is desirable that hardness is higher than after tempering heat treatment
HB180, -21 DEG C of impact absorbing energies are greater than 48J.Workpiece is after 900 DEG C of austenitizings are kept the temperature, water hardening processing；Tempering uses
Two-step method tempering process：First in 300 DEG C of heat preservation 6h, then 600 DEG C of heat preservation 12h are warming up to, cool to room temperature with the furnace.In specified position
Its hardness of sample detection and impact flexibility, measuring hardness is HB190, and impact absorbing energy is respectively 98,75,85J, and average value is
86J reaches technical requirements.
Embodiment 6
Lower shell forging, outer circle φ 4417mm, wall thickness 113mm, long 4267mm, it is desirable that hardness is higher than after tempering heat treatment
HB180, -21 DEG C of impact absorbing energies are greater than 48J.Workpiece is after 890 DEG C of austenitizings are kept the temperature, water hardening processing；Tempering uses
Two-step method tempering process：First in 380 DEG C of heat preservation 3.5h, then 635 DEG C of heat preservation 10h are warming up to, cool to room temperature with the furnace.In predetermined bits
Its hardness of sample detection and impact flexibility are set, measuring hardness is HB193, and impact absorbing energy is respectively 88,95,110J, average value
For 97.67J, reach technical requirements.
The above description of the embodiments is intended to facilitate ordinary skill in the art to understand and use the invention.
Person skilled in the art obviously easily can make various modifications to these embodiments, and described herein general
Principle is applied in other embodiments without having to go through creative labor.Therefore, the present invention is not limited to the above embodiments, ability
Field technique personnel announcement according to the present invention, improvement and modification made without departing from the scope of the present invention all should be of the invention
Within protection scope.
Claims (2)
1. a kind of two-step method tempering process for improving nuclear power heavy forging impact flexibility, which is characterized in that include the following steps：
Quenched forging is heated to 300-450 DEG C, heat preservation；The tissue signature of the nuclear power heavy forging of water hardening processing is shellfish
Family name's body+residual austenite body tissue；Quenched nuclear power heavy forging is tempered using two-step method, quenched forging exists first
300-450 DEG C of tempering heat preservation makes retained austenite be completely transformed into the carbide of ferrite+tiny, is then heated to 600-
660 DEG C of tempering heat preservations, eliminate quenching stress, and disperse educt carbide particle in the base, are meeting hardness and strength requirement
In the case where, promote the impact absorbing energy of workpiece to 100J；Forging furnace cooling later is completed；
The material of forging in step (1) is SA508Gr.3 steel；
Quenched forging in step (1) is the nuclear power heavy forging of water hardening processing after 880~900 DEG C of austenitizings.
2. a kind of two-step method tempering process for improving nuclear power heavy forging impact flexibility according to claim 1, feature exist
In tempering process is specially：
Quenched lower shell forging first in 400 DEG C of heat preservation 2h, then is warming up to 650 DEG C of heat preservation 4h, cools to room temperature with the furnace；Or
Quenched lower shell forging is first in 350 DEG C of heat preservation 2h, then is warming up to 650 DEG C of heat preservation 4h, cools to room temperature with the furnace；Or after quenching
Lower shell forging first in 420 DEG C of heat preservation 4h, then be warming up to 650 DEG C of heat preservation 8h, cool to room temperature with the furnace；Or quenched lower cylinder
Body forging is first in 300 DEG C of heat preservation 6h, then is warming up to 600 DEG C of heat preservation 12h, cools to room temperature with the furnace；Or quenched lower shell forging
Part is first in 380 DEG C of heat preservation 3.5h, then is warming up to 635 DEG C of heat preservation 10h, cools to room temperature with the furnace；Or quenched cone forging is first
In 450 DEG C of heat preservation 2h, then 660 DEG C of heat preservation 6h are warming up to, cool to room temperature with the furnace.
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| CN102021304A (en) * | 2010-12-07 | 2011-04-20 | 无锡宏达重型锻压有限公司 | Heat processing technology for super-standard large-section pressure vessel tube plate |
| CN102115809A (en) * | 2011-03-04 | 2011-07-06 | 河南科技大学 | Environment-friendly heat treatment process for large shaft forgings |
| CN103820610B (en) * | 2012-11-19 | 2016-04-06 | 上海重型机器厂有限公司 | Improve the property heat treatment method of nuclear power container heavy froging obdurability |
| CN103820705B (en) * | 2012-11-19 | 2016-01-06 | 上海重型机器厂有限公司 | The nuclear power container property heat treatment method of SA508-3 heavy froging |
| CN103290192B (en) * | 2013-06-27 | 2015-05-06 | 洛阳中创重型机械有限公司 | Thermal treatment process of spliced-welding type large tube plate forging of pressure container |
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