CN106350640A - Method for continuously quenching cold-rolled steel strip - Google Patents
Method for continuously quenching cold-rolled steel strip Download PDFInfo
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- CN106350640A CN106350640A CN201510422534.8A CN201510422534A CN106350640A CN 106350640 A CN106350640 A CN 106350640A CN 201510422534 A CN201510422534 A CN 201510422534A CN 106350640 A CN106350640 A CN 106350640A
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- steel strip
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- 238000010791 quenching Methods 0.000 title claims abstract description 42
- 230000000171 quenching effect Effects 0.000 title claims abstract description 38
- 238000000034 method Methods 0.000 title claims abstract description 36
- 239000010960 cold rolled steel Substances 0.000 title abstract 5
- 238000001816 cooling Methods 0.000 claims abstract description 61
- 229910000831 Steel Inorganic materials 0.000 claims abstract description 60
- 239000010959 steel Substances 0.000 claims abstract description 60
- 229910000734 martensite Inorganic materials 0.000 claims abstract description 24
- 239000000443 aerosol Substances 0.000 claims abstract description 17
- 229910001566 austenite Inorganic materials 0.000 claims abstract description 10
- 238000006243 chemical reaction Methods 0.000 claims abstract description 7
- 229910000859 α-Fe Inorganic materials 0.000 claims abstract description 7
- 238000009413 insulation Methods 0.000 claims description 2
- 238000010438 heat treatment Methods 0.000 abstract description 15
- 238000004519 manufacturing process Methods 0.000 abstract description 11
- 238000005496 tempering Methods 0.000 abstract description 3
- 230000009286 beneficial effect Effects 0.000 abstract description 2
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 description 16
- 230000008569 process Effects 0.000 description 10
- 230000035882 stress Effects 0.000 description 7
- 239000007789 gas Substances 0.000 description 5
- 230000009466 transformation Effects 0.000 description 5
- 229910000797 Ultra-high-strength steel Inorganic materials 0.000 description 4
- 238000009835 boiling Methods 0.000 description 4
- 229910001562 pearlite Inorganic materials 0.000 description 4
- 230000007704 transition Effects 0.000 description 4
- 238000000137 annealing Methods 0.000 description 3
- 238000005516 engineering process Methods 0.000 description 3
- 230000004907 flux Effects 0.000 description 3
- 208000037656 Respiratory Sounds Diseases 0.000 description 2
- 230000008901 benefit Effects 0.000 description 2
- 229910001339 C alloy Inorganic materials 0.000 description 1
- 229910000975 Carbon steel Inorganic materials 0.000 description 1
- FBPFZTCFMRRESA-JGWLITMVSA-N D-glucitol Chemical compound OC[C@H](O)[C@@H](O)[C@H](O)[C@H](O)CO FBPFZTCFMRRESA-JGWLITMVSA-N 0.000 description 1
- OAICVXFJPJFONN-UHFFFAOYSA-N Phosphorus Chemical compound [P] OAICVXFJPJFONN-UHFFFAOYSA-N 0.000 description 1
- 238000004458 analytical method Methods 0.000 description 1
- 229910001563 bainite Inorganic materials 0.000 description 1
- 229910052799 carbon Inorganic materials 0.000 description 1
- 239000010962 carbon steel Substances 0.000 description 1
- 230000008859 change Effects 0.000 description 1
- 238000010276 construction Methods 0.000 description 1
- 238000005336 cracking Methods 0.000 description 1
- 230000004069 differentiation Effects 0.000 description 1
- 238000010304 firing Methods 0.000 description 1
- 239000012530 fluid Substances 0.000 description 1
- 238000009776 industrial production Methods 0.000 description 1
- 238000011031 large-scale manufacturing process Methods 0.000 description 1
- 230000014759 maintenance of location Effects 0.000 description 1
- 239000000463 material Substances 0.000 description 1
- QMQXDJATSGGYDR-UHFFFAOYSA-N methylidyneiron Chemical compound [C].[Fe] QMQXDJATSGGYDR-UHFFFAOYSA-N 0.000 description 1
- 230000004048 modification Effects 0.000 description 1
- 238000012986 modification Methods 0.000 description 1
- 229910052698 phosphorus Inorganic materials 0.000 description 1
- 239000011574 phosphorus Substances 0.000 description 1
- 230000002265 prevention Effects 0.000 description 1
- 230000009467 reduction Effects 0.000 description 1
- 239000007787 solid Substances 0.000 description 1
- 238000005728 strengthening Methods 0.000 description 1
- 230000008646 thermal stress Effects 0.000 description 1
- 238000000844 transformation Methods 0.000 description 1
- 230000005514 two-phase flow Effects 0.000 description 1
- 238000010792 warming Methods 0.000 description 1
Landscapes
- Heat Treatment Of Sheet Steel (AREA)
- Heat Treatment Of Strip Materials And Filament Materials (AREA)
Abstract
The invention discloses a method for continuously quenching a cold-rolled steel strip. The method comprises the following steps: S1: heating the cold-rolled steel strip to the temperature which is 30-50 DEG C higher than the interconverting temperature of ferrite and austenite, and preserving heat for 50-100s; S2: cooling the cold-rolled steel strip to the temperature between the conversion starting temperature of martensite and the conversion finishing temperature of the martensite by an aerosol cooling method; S3: continuing cooling the cold-rolled steel strip to the room temperature by a high-speed air jetting method to obtain a 100% martensitic structure; S4: heating to the tempering temperature, and performing tempering treatment to obtain an ultrahigh-strength martensitic steel strip with an excellent strip shape. The method has the main beneficial effects as follows: by a stepped quenching cooling method provided by the invention, production of an ultrahigh-strength and small-deformation steel strip can be achieved, the follow-up strip shape flatting amount is reduced, and the production cost is reduced.
Description
Technical field
The invention provides a kind of continuous quenching method of ultrahigh-strength steel plates, belong to metallurgical and Material Field,
Particularly to the excellent martensite belt steel heat treatment manufacturing technique method of superhigh intensity, plate shape.
Background technology
The phasor of iron-carbon alloy shows, the carbon steel of any phosphorus content () taking the sub- steel for analysis as a example, in heating and
The critically weighted that Solid State Structure in cooling procedure changes, is that (pearlite is mutually turned with austenite by a1 line
Become) and a3 line (ferrite and austenite phase co-conversion) determine.In order to represent differentiation, generally represented with c
Heating process transition point, r represents cooling procedure transition point.Ac1 is pearlite turning to austenite during heating
Temperature, ac3 is the temperature that during cooling, ferrite is completely dissolved into austenite.
Quenching refers to for steel to be heated to critically weighted ac1 or more than ac3 uniform temperature, after insulation,
With the speed cooling more than critical cooling rate, obtain the Technology for Heating Processing of martensite or lower bainite tissue.
Generally steel plate is often deformed in quenching process, or even crackle, and this is mainly due to steel plate
Internal stress cause.Internal stress includes thermal stress that temperature decrease causes and the tissue that structural transformation produces should
Power, the deformation of steel plate depends on the comprehensive function of the two.When internal stress exceedes yield strength, generation is moulded
Property deformation；When quenching stress exceedes tensile strength, even crackle in steel plate.
Liu Zongchang (hardening break and prevention method, heat treatment, the 4th phase in 2010) points out, because heat should
Power and the superposition of structural stress, in steel plate quenching deformation and cracking main generation low-temperature martensite transition process.
This article actually indicates from theoretic, the temperature being deformed in steel quenching process and ftractureing
Region is low-temperature space, rather than high-temperature region.
Chinese patent (cn 102534423 a) discloses a kind of ultrahigh-strength steel plates system of 1500mpa rank
Make method, the steel plate direct water-cooling after austenitizing to room temperature carries out lonneal process immediately.Produce
Practice have shown that, this water hardening can obtain complete martensitic structure, and intensity is high, but due to the terminal that quenches
Temperature is uncontrollable, and cooling uniformity is poor, and after quenching, internal stress dramatically increases, and steel plate generally deforms serious.
The method that Chinese patent (cn 1624170a) realizes grade quench using gases at high pressure, this invention is led to
The method overregulating gas pressure obtains different cooling rate and realizes grade quench.This employing gas quenching
The precise control of temperature can be realized, and workpiece deformation is little.But because cooldown rate is limited, highest in theory
Workpiece strength be less than 1000mpa, on the other hand due to needing to use gases at high pressure, this cannot be extensive
Production in apply, be only suitable for small batch workpiece produce because large-scale production needs big flow without interruption
Gases at high pressure, this is technically difficult to realize, and cost intensive.
In sum, the common drawback of prior art be do not enable strip steel superhigh intensity with deform little good
In conjunction with.It is an advantage of the invention that in quenching process, carrying out sub-sectional cooling.High temperature section adopts aerosol to cool down, cold
But speed fast moreover it is possible to precise control rate of cooling and cooling outlet temperature；Low-temperature zone adopts high speed jet to cool down,
Cooling uniformly so that internal stress is little during martensite transfor mation, and then deforms little, then after temper
To the excellent superhigh intensity martensite strip steel of plate shape.
Content of the invention
The purpose of this patent is to invent a kind of quenching production method producing ultrahigh-strength steel plates.Using the present invention
The process for quenching introduced can produce the excellent martensite strip steel of superhigh intensity, plate shape.
To achieve these goals, technical scheme is as follows:
A kind of method carrying out continuous quenching to cold-strip steel, it comprises the steps:
S1: cold-strip steel is heated to 30～50 DEG C of more than the temperature that ferrite is with austenite phase co-conversion, protects
Warm 50～100s；
S2: by described cold-strip steel be cooled to Ms (martensite start) point and Mf point it
Between temperature；
S3: continue for described cold-strip steel to be cooled to room temperature, obtain 100% martensitic structure；
S4: temperature is quickly heated up to the speed of 20～50 DEG C/s and carries out temper, obtain plate shape
Excellent superelevation strong martensite strip steel.
Preferably, the rate of heat addition in step s1 is 15～60 DEG C/s.
Preferably, the type of cooling in step s2 is by the way of aerosol cooling.
Preferably, the cooldown rate in step s2 is 100～200 DEG C/s.
Preferably, the type of cooling in step s3 cools down for jet.
Preferably, the cooldown rate described in step s3 is 20～50 DEG C/s.
Preferably, the temperature of described temper is 200～280 DEG C.
The principle of the present invention is:
Structural transformation in continuous cooling process for the steel is as shown in Figure 1
In figure a represents austenite, and p represents pearlite, and f represents ferrite, and s represents sorbite, t table
Show troostite, m represents martensite.A1 represents that pearlite is represented with austenite phase co-conversion temperature and a3
Ferrite and austenite phase co-conversion temperature, ms represents Ms (martensite start) point, and mf represents martensite
Change final temperature,
Produce the required heating condition of high-strength steel sheet (martensite) and cooling condition be:
1. first it is warming up to completely austenitic state, be heated to more than a3 temperature；
2. rate of cooling is more than Critical cooling speed vk；
3. the temperature that final chilling temperature reaches is less than martensite start temperature ms.
Fig. 2 and Fig. 3 is the cooling curve using water quenching method gentle fog cooling lower steel plate respectively, and both is cold
But rate of cooling can be realized under mode and be more than Critical cooling speed vk.In actual industrial production, it is all independent
Cool down to produce high-strength steel sheet using water quenching cooling or aerosol.
Either water quenching or aerosol cooling, is all two phase flow cooling, and its cooling curve all assumes obvious boiling
Rise the feature of heat exchange.Steel plate, from high temperature to low temperature, experienced the film boiling area of a-b section successively, b-c section
Transition region, the nuclear boiling area of c-d section, d-e single-phase convection heat transfer zone.At b, corresponding minimum hot-fluid is close
Degree, i.e. leidenforst point, corresponding maximum heat flow density, i.e. critical heat flux density at c.
The common ground that water quenching is cooled down with aerosol:
1) what maximum rate of cooling and maximum cooled down heat flow density is not the high temperature occurring in a-b film boiling section
Area, is not the low-temperature space of d-e single-phase convection, but the temperature province between 250～400 DEG C, at this
Region occurs maximum critical heat flux, i.e. maximum cooling rate, and at a temperature of steel plate, reduction of speed rate is maximum, is also
It is easily caused that inhomogeneous cooling is even, the temperature province of deformed steel strip.Therefore it is used alone water quenching or aerosol cooling,
It is likely to make steel plate direct cool to the maximum region of cooldown rate, carry out causing deformed steel strip.
The difference from aerosol cooling for the water quenching:
1) experimental result as Fig. 4 understands, the level of the two heat flow density is different, and the heat flow density of water quenching will
Apparently higher than aerosol cooling, the heat flow density of water quenching cooling is usually several times of aerosol cooling.
2) cooling capacity of water quenching too strong it is impossible to control its cooling procedure, i.e. cooldown rate and cooling terminal temperature
Degree is uncontrollable.Simultaneously because the corresponding critical temperature of its critical heat flux is higher, during usual steel plate water quenching, no
Can experience rate of cooling region the fastest with avoiding, that is, experience maximum cooling speed point, i.e. c point, be also
It is easiest to the point deforming upon.
3) exchange capability of heat of aerosol cooling is less than water quenching, but for martensite is formed, heat transfer intensity is also
Enough, that is, rate of cooling is more than the Critical cooling speed forming martensite.On the other hand, aerosol cooling has water quenching
The advantage not possessed, you can by adjusting gas-water ratio, to control cooldown rate and cooling outlet temperature, to make band
Steel does not suffer from the maximum region of cooldown rate in cooling procedure.So can avoid based on phase transformation strengthening
Ultrahigh-strength steel plates, because rate of cooling is fast in quenching process, cooling outlet temperature and uniformity controlling are stranded
The deformed steel strip problem that the factors such as difficulty cause.
Therefore, the beneficial effects are mainly as follows: grade quench cooling means proposed by the present invention can
Realize superhigh intensity, deform little strip steel production, reduce the smooth amount of follow-up plate shape, reduce production cost.Suitable
For horizontally disposed or be arranged vertically continuous annealing production line or cyclical heat treatment furnace, it is simultaneously applicable to it
The heat treatment occasion that it needs high intensity and deforms little steel plate or workpiece.
Brief description
Fig. 1 is structural transformation figure in continuous cooling process for the steel；
Fig. 2 is the water quenching cooling curve of steel；
Fig. 3 is the aerosol cooling curve of steel；
Fig. 4 is the water quenching gentle fog cooling heat flow density contrast of steel；
Fig. 5 is the heat treatment cycle curve of the present invention.
Specific embodiment
Embodiment 1
25mntib is heated to 850 DEG C with 30 DEG C/s of firing rate, temperature retention time 50s；Cold using aerosol
But to 400 DEG C, cooldown rate is about 80 DEG C/s；High speed jet is cooled to room temperature immediately, is again heated to 200
DEG C temper.Steel plate yield strength б s after quenched, temper is about 1250mpa, and tension is strong
Degree б b is about 1450mpa, and elongation percentage is about 15%, and plate shape is good.
Embodiment 2
20cr is heated to 900 DEG C with 50 DEG C/s of the rate of heat addition, is incubated 80s；It is cooled to 420 using aerosol
DEG C, cooldown rate is about 60 DEG C/s；High speed jet is cooled to room temperature immediately, is again heated at 230 DEG C of tempering
Reason.Steel plate yield strength б s after quenched, temper is about 1100mpa, and tensile strength б b is about
For 1350mpa, elongation percentage is about 12%, and steel plate does not almost deform.
Embodiment 3
25simn2mov is heated to 900 DEG C with 60 DEG C/s of the rate of heat addition, is incubated 100s；Using aerosol
It is cooled to 450 DEG C, cooldown rate is about 50 DEG C/s；High speed jet is cooled to room temperature immediately, is again heated to 250
DEG C temper.Workpiece yield strength б s after quenched, temper is about 1300mpa, and tension is strong
Degree б b is about 1500mpa, and elongation percentage is about 13%, and workpiece deformation is little.
High-strength product made from steel has started in the industries such as household electrical appliances, electrical equipment, automobile making, ship and building progressively
It is applied, with the raising of user's request, also more and more higher is required to the plate shape of strip steel.Band steel heat treatment
In production particularly in the continuous annealing treatment of high-intensity band steel, suitable Technology for Heating Processing and belt plate shape
Fine or not relation is very big.
Grade quench cooling means proposed by the present invention can achieve that the little strip steel of superhigh intensity, deformation produces, and subtracts
Few smooth amount of follow-up plate shape, reduces production cost.It is applied to horizontally disposed or be arranged vertically continuous annealing production
Line or cyclical heat treatment furnace, are simultaneously applicable to the heat that other needs high intensity and deforms little steel plate or workpiece
Process occasion.
In sum, only presently preferred embodiments of the present invention, is not used for limiting the model of present invention enforcement
Enclose, all impartial changes done according to the shape described in scope of the invention as claimed, construction, feature and spirit
With modification, all should be included in scope of the presently claimed invention.
Claims (7)
1. a kind of the method for continuous quenching is carried out it is characterised in that comprising the steps: to cold-strip steel
S1: cold-strip steel is heated to 30～50 DEG C of more than the temperature that ferrite is with austenite phase co-conversion, insulation
50～100s；
S2: by described cold-strip steel be cooled to Ms (martensite start) point and Mf point it
Between temperature；
S3: continue for described cold-strip steel to be cooled to room temperature, obtain 100% martensitic structure；
S4: temperature is heated to the speed of 20～50 DEG C/s and carries out temper, obtain plate shape excellent
Superelevation strong martensite strip steel.
2. the method that cold-strip steel is carried out with continuous quenching as claimed in claim 1 is it is characterised in that walk
The rate of heat addition in rapid s1 is 15～60 DEG C/s.
3. the method that cold-strip steel is carried out with continuous quenching as claimed in claim 1 is it is characterised in that walk
The type of cooling in rapid s2 is by the way of aerosol cooling.
4. the method that cold-strip steel is carried out with continuous quenching as described in claim 1 or 3 it is characterised in that
Cooldown rate in step s2 is 100～200 DEG C/s.
5. the method that cold-strip steel is carried out with continuous quenching as claimed in claim 1 is it is characterised in that walk
The type of cooling in rapid s3 cools down for jet.
6. the method that cold-strip steel is carried out with continuous quenching as described in claim 1 or 5 it is characterised in that
Cooldown rate in described step s3 is 20～50 DEG C/s.
7. the as claimed in claim 1 method that cold-strip steel is carried out with continuous quenching is it is characterised in that institute
State 200～280 DEG C of temperature.
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| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201510422534.8A CN106350640A (en) | 2015-07-17 | 2015-07-17 | Method for continuously quenching cold-rolled steel strip |
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| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201510422534.8A CN106350640A (en) | 2015-07-17 | 2015-07-17 | Method for continuously quenching cold-rolled steel strip |
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| CN106350640A true CN106350640A (en) | 2017-01-25 |
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Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN113862432A (en) * | 2021-08-31 | 2021-12-31 | 大连环新精密特钢股份有限公司 | Carbon steel wire air quenching method and device |
Citations (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN101812578A (en) * | 2009-02-25 | 2010-08-25 | 宝山钢铁股份有限公司 | Flexible strip processing line suitable for producing various high-strength steel |
| CN101871078A (en) * | 2009-04-24 | 2010-10-27 | 宝山钢铁股份有限公司 | Super-high strength cold rolled steel and manufacturing method thereof |
| CN103826771A (en) * | 2011-09-30 | 2014-05-28 | 株式会社神户制钢所 | Method for manufacturing press-molded article and press molding equipment |
-
2015
- 2015-07-17 CN CN201510422534.8A patent/CN106350640A/en active Pending
Patent Citations (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN101812578A (en) * | 2009-02-25 | 2010-08-25 | 宝山钢铁股份有限公司 | Flexible strip processing line suitable for producing various high-strength steel |
| CN101871078A (en) * | 2009-04-24 | 2010-10-27 | 宝山钢铁股份有限公司 | Super-high strength cold rolled steel and manufacturing method thereof |
| CN103826771A (en) * | 2011-09-30 | 2014-05-28 | 株式会社神户制钢所 | Method for manufacturing press-molded article and press molding equipment |
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN113862432A (en) * | 2021-08-31 | 2021-12-31 | 大连环新精密特钢股份有限公司 | Carbon steel wire air quenching method and device |
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Application publication date: 20170125 |