CN106480306B - The control method of second segment cooling precision in laminar flow sub-sectional cooling technique - Google Patents
The control method of second segment cooling precision in laminar flow sub-sectional cooling technique Download PDFInfo
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- 238000001816 cooling Methods 0.000 title claims abstract description 177
- 238000000034 method Methods 0.000 title claims abstract description 68
- 230000009466 transformation Effects 0.000 claims abstract description 44
- 239000004615 ingredient Substances 0.000 claims abstract description 36
- 229910000885 Dual-phase steel Inorganic materials 0.000 claims abstract description 27
- 229910000734 martensite Inorganic materials 0.000 claims abstract description 23
- 229910000859 α-Fe Inorganic materials 0.000 claims abstract description 23
- 229910001563 bainite Inorganic materials 0.000 claims abstract description 17
- 239000000203 mixture Substances 0.000 claims abstract description 12
- 238000013461 design Methods 0.000 claims abstract description 11
- 229910001562 pearlite Inorganic materials 0.000 claims abstract description 11
- 238000005096 rolling process Methods 0.000 claims abstract description 11
- 238000012545 processing Methods 0.000 claims abstract description 4
- 229910020012 Nb—Ti Inorganic materials 0.000 claims description 23
- 229910001566 austenite Inorganic materials 0.000 claims description 13
- 239000000498 cooling water Substances 0.000 claims description 6
- 238000012360 testing method Methods 0.000 claims description 6
- 235000019628 coolness Nutrition 0.000 claims description 3
- 230000007704 transition Effects 0.000 claims description 3
- 238000011017 operating method Methods 0.000 claims description 2
- 238000009472 formulation Methods 0.000 abstract description 2
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 description 31
- 238000001514 detection method Methods 0.000 description 7
- 238000009835 boiling Methods 0.000 description 6
- 229910000831 Steel Inorganic materials 0.000 description 4
- 238000010583 slow cooling Methods 0.000 description 4
- 239000010959 steel Substances 0.000 description 4
- 239000000126 substance Substances 0.000 description 4
- XEEYBQQBJWHFJM-UHFFFAOYSA-N Iron Chemical compound [Fe] XEEYBQQBJWHFJM-UHFFFAOYSA-N 0.000 description 3
- 230000001133 acceleration Effects 0.000 description 3
- 238000005516 engineering process Methods 0.000 description 3
- 230000009123 feedback regulation Effects 0.000 description 3
- 238000010586 diagram Methods 0.000 description 2
- 238000007789 sealing Methods 0.000 description 2
- 238000000844 transformation Methods 0.000 description 2
- 238000000137 annealing Methods 0.000 description 1
- 230000008859 change Effects 0.000 description 1
- 230000009977 dual effect Effects 0.000 description 1
- 230000000694 effects Effects 0.000 description 1
- 238000005265 energy consumption Methods 0.000 description 1
- 238000009851 ferrous metallurgy Methods 0.000 description 1
- 238000010438 heat treatment Methods 0.000 description 1
- 238000005098 hot rolling Methods 0.000 description 1
- 238000004519 manufacturing process Methods 0.000 description 1
- 230000008569 process Effects 0.000 description 1
- 238000003672 processing method Methods 0.000 description 1
- 238000006467 substitution reaction Methods 0.000 description 1
- 238000005496 tempering Methods 0.000 description 1
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Abstract
The present invention provides a kind of control method of second segment cooling precision in laminar flow sub-sectional cooling technique.The method comprising the steps of：Draw the continuous cooling transformation (CCT) curve of two kinds of component systems；Determine the austenites of two kinds of ingredients, ferrite, pearlite, bainite, Martensite temperature transformation range, sub-sectional cooling " coiling technique window " range；Target temperature, the nearly method for control speed at the uniform velocity rolled soon are batched in sub-sectional cooling processing route, air-cooled target temperature and the air-cooled object time of determining two kinds of ingredients, second segment cooldown rate range, second segment cooling in " coiling technique window "；It calculates two kinds of ingredient second segments and cools down fixed starting valve location；Two kinds of ingredient second segment cooling closed-loop control systems of design, cooling control mode and the corresponding cooling control routine of formulation；To rolling the performance of latter two ingredient, tissue is detected, and cooling control parameter is cured or corrected.The present invention can obtain tissue, function admirable hot-rolled dual-phase steel product.
Description
Technical field：
The present invention relates to a kind of control methods of second segment cooling precision in laminar flow sub-sectional cooling technique, belong to Ferrous Metallurgy
The laminar flow sub-sectional cooling technical field of class.
Background technology：
The advantages that dual phase steel matches when excellent forming property with its good strong plasticity has obtained the extensive concern of people,
Its product can be widely applied to the moving link and safety member of automobile, such as wheel, chassis, bumper.Hot direct rolling process is given birth to
Dual phase steel is produced, additional heat-treatment and annealing device is not needed to, reduces working hour and energy consumption, it is at low cost.Its metallurgical control principle is：
（1）Enough ferrites need to be formed；（2）Pearlite and bainite is inhibited to generate；（3）Remaining austenite is completely transformed into geneva
Body.Corresponding difficult point is：（1）According to the characteristics of its austenite continuous cooling transformation, complicated laminar flow cooling technology is needed, generally
It is cooled down using laminar flow segmented, technology stability requirement is high；（2）For sub-sectional cooling technique, advanced cooling equipment, phase are needed
The detection instrument answered and model-controlled system etc..So-called sub-sectional cooling refers to cooling control dividing into leading portion and back segment Liang Ge areas
Domain, after finish to gauge strip enter first segment cooling zone carry out water cooling, the cold medium temperature of layer for reaching certain, then air-cooled one section when
Between, it enters back into second segment cooling zone and carries out a kind of complicated cooling technique that water cooling reaches the target coiling temperature of requirement, that is, pass through
First segment water cooling+air-cooled+second segment water cooling, control finished strip only obtain the cooling technique of ferrite+martensite duplex structure.
At present, some hot rolling producing lines have had been provided with the laminar cooling system of sub-sectional cooling requirement, but are controlled in control methods and model
There are different problems in precision, and if second segment cooling air cooling time, the setting of cooling path are unreasonable, cooling curve enters pearl
Body of light, bainite transformation area, laminar flow do not have complicated cooling technique model-controlled system or system function it is not perfect, tradition is rolled
Machine increasing speed rolling process second segment cooling water inflow is uneven etc. with speed increase overall length fluctuation strip overall length tissue, performance, these
The exploitation and marketing of hot-rolled dual-phase steel are affected, therefore, it is necessary to sub-sectional cooling particularly second segment cooling precision
Control method is optimized and is innovated.
Invention content
The purpose of the present invention is provide second segment in a kind of laminar flow sub-sectional cooling technique in view of the above problems to cool down
The control method of precision mainly solves Si-Mn-Cr-Mo systems medium temperature（500-600℃）With Si-Mn-Nb-Ti systems low temperature（100-
250℃）Batch hot-rolled dual-phase steel laminar flow sub-sectional cooling（First segment water cooling+air-cooled+second segment water cooling）Second segment cools down in technique
The design effectively in path and the problem of implementation of model control method, to respectively obtain the production of the hot-rolled dual-phase steel of tissue, function admirable
Product.
Above-mentioned purpose is achieved through the following technical solutions：
The control method of second segment cooling precision in laminar flow sub-sectional cooling technique, this method comprises the following steps：
（1）Draw two kinds of component systems（Si-Mn-Cr-Mo systems, Si-Mn-Nb-Ti systems）The continuous coo1ing of hot-rolled dual-phase steel
Transition curve（CCT curve）；
（2）Determine the austenites of two kinds of ingredients, ferrite, pearlite, bainite, Martensite temperature transformation range；
（3）Determine sub-sectional cooling " coiling technique window " range of two kinds of ingredients；
（4）The sub-sectional cooling processing route of two kinds of ingredients is determined in " coiling technique window "；
（5）Determine the air-cooled target temperature of two kinds of ingredients and air-cooled object time；
（6）Determine the second segment cooldown rate range of two kinds of ingredients；
（7）Determine that target temperature is batched in two kinds of ingredient second segment coolings；
（8）The method for control speed that two kinds of ingredients closely at the uniform velocity roll soon；
（9）Two kinds of ingredient second segments are calculated according to step 5 air-cooled object time, step 8 mill speed and cool down fixed
Beginning valve location；
（10）Two kinds of ingredient second segment cooling closed-loop control systems are designed according to step 5-9；
（11）Target temperature, step 10 closed-loop control system composition are batched according to step 7, design two kinds of ingredient cooling controls
Mode and the corresponding cooling control routine of formulation；
（12）Second segment cools down feedforward control；
（13）Second segment cools down feedback control；
（14）Feedback control goes temperature vacation point to handle；
（15）To rolling the performance of latter two ingredient, tissue is detected, and cooling control parameter is cured or corrected.
The control method of second segment cooling precision, step in the laminar flow sub-sectional cooling technique（1）Described in drafting
Two kinds of component systems（Si-Mn-Cr-Mo systems, Si-Mn-Nb-Ti systems）The continuous cooling transformation (CCT) curve of hot-rolled dual-phase steel（CCT is bent
Line）Operating method be：Using Gleeble3500 hot modeling test machines, carry out two kinds of component systems（Si-Mn-Cr-Mo systems,
Si-Mn-Nb-Ti systems）Hot-rolled dual-phase steel thermal modeling test measures its austenite Continuous Cooling Transformation Curve（CCT curve）.
The control method of second segment cooling precision, step in the laminar flow sub-sectional cooling technique（6）Described in two kinds
The second segment cooldown rate range of ingredient：Si-Mn-Cr-Mo systems 20-30 DEG C/s of cooling rate, Si-Mn-Nb-Ti systems cooling rate 50-60
℃/s。
The control method of second segment cooling precision, step in the laminar flow sub-sectional cooling technique（7）Described in second
Target temperature is batched in section cooling：500-600 DEG C of Si-Mn-Cr-Mo systems coiling temperature range takes 550 DEG C of desired value, Si-Mn-Nb-
100-250 DEG C of Ti systems coiling temperature range.
The control method of second segment cooling precision, step in the laminar flow sub-sectional cooling technique（8）Described in two kinds
The method for control speed that ingredient closely at the uniform velocity rolls soon：Hot-rolled dual-phase steel thickness range be 3.0-4.8mm, the finish to gauge of Si-Mn-Cr-Mo systems
880 DEG C of target temperature, 830 DEG C of Si-Mn-Nb-Ti systems target temperature, finishing speeds model calculate when, using respective 3.0mm thickness as
Benchmark calculates maximum threading speed using the method for thinned workpiece thickness speed governing, interstand cooling water control temperature.
Advantageous effect：
In " the coiling technique window " of two kinds of component system dual phase steels, develop air-cooled in region+second segment water cooling and adopt
The method designed with independent cooling path+coiling temperature；It is gradually increased for second segment cooling water inflow in former technique increasing speed rolling
Lead to the non-uniform problem of overall length performance, develop the nearly method for control speed at the uniform velocity rolled soon；For air cooling time requirement and closely
The characteristics of at the uniform velocity rolling, the method for developing the fixed starting valve location of second segment cooling, is not required to change with velocity variations；Needle
To the control of second segment cooldown rate requirement, on the configuration mode of existing cooling manifold, develop that be different from traditional back segment cold
But temperature detection vacation point is removed in thick cold collector, the setting of cold sperm collector and feedback and feedback control procedure
Processing method.
Description of the drawings
Attached drawing 1a is the austenite Continuous Cooling Transformation Curve schematic diagram of Si-Mn-Cr-Mo systems；
Attached drawing 1b is the austenite Continuous Cooling Transformation Curve schematic diagram of Si-Mn-Nb-Ti systems；
Attached drawing 2 is laminar flow second segment cooling control system layout drawing.
Specific embodiment
With reference to embodiment, the present invention is furture elucidated, it should be understood that following specific embodiments are only used for
It is bright the present invention rather than limit the scope of the invention.
The invention discloses a kind of control method of second segment cooling precision in laminar flow sub-sectional cooling technique, including following step
Suddenly：
1）Using Gleeble3500 hot modeling test machines, carry out two kinds of component systems（Si-Mn-Cr-Mo systems, Si-Mn-
Nb-Ti systems）Hot-rolled dual-phase steel thermal modeling test measures its austenite Continuous Cooling Transformation Curve（CCT curve）, see attached drawing 1；
2）In respective CCT curve, austenite, ferrite, pearlite, bainite, the martensite of two kinds of ingredients are determined
Temperature transformation ranges.It can will become apparent from from attached drawing 1：（1）Si-Mn-Cr-Mo systems（Attached drawing 1a）Dual phase steel perlitic transformation area
It moves to right strongly, the sealing of bainite transformation area right end, the Ovshinsky for having vertical temperature difference larger between ferrite and bainite transformation area
Body meta-stable area；（2）Si-Mn-Nb-Ti systems（Attached drawing 1b）Dual phase steel perlitic transformation area moves to right unobvious, ferritic transformation area
Right side links together in the longitudinal direction with pearlite, bainite transformation area；
3）Determine sub-sectional cooling " coiling technique window " range of two kinds of ingredients, the i.e. temperature of cooling procedure, time graph
Pearlite, bainite transformation area cannot be entered into, it can only be in ferrite, austenite, martensite range " walking ", to obtain
The duplex structure of ferrite+martensite；
4）The sub-sectional cooling processing route of two kinds of ingredients is determined in " coiling technique window ".It can be seen that from attached drawing 1：
（1）Si-Mn-Cr-Mo systems（Attached drawing 1a）After dual phase steel " finish to gauge " is shut out, by first segment water cooling（Into ferrite area）+ one
Long period it is air-cooled（Ferritic transformation occurs）+ second segment water cooling（Cooling ends in martensitic regions, subsequent process air cooler
Form martensite）, to obtain ferrite+martensitic structure；（2）Si-Mn-Nb-Ti systems（Attached drawing 1b）Dual phase steel " finish to gauge " is shut out
Afterwards, first segment water cooling is first passed through（Into ferrite area）+ one short period it is air-cooled（Ferritic transformation occurs）+ second segment is fast
Fast water cooling（Cooling curve avoids pearlite, Bainite Region, quickly enters martensitic regions）, to obtain ferrite+martensitic structure；
5）（1）The purpose of dual phase steel sub-sectional cooling first segment water cooling is that the strip after finish to gauge is made to enter iron element in a short time
Body transformation C curve " nose " and temperature, during ensureing air-cooled in ferrite area residence time longest, therefore will be near nose
Temperature be set to air-cooled target temperature；（2）Air-cooled purpose is during ensureing Slow cooling, to be formed in ferritic transformation area
A certain amount of ferritic structure, and before cooling curve reaches perlitic transformation, second segment water cooling slope is controlled, ensure second segment
Cooling curve does not enter pearlite, bainite transformation area, and the first segment water cooling end time to second segment water cooling time started is determined
For the air-cooled object time.It is empty as can be seen that Si-Mn-Cr-Mo systems dual phase steel is since " coiling technique window " is wider from attached drawing 1
The cold object time is longer, and " window " of Si-Mn-Nb-Ti systems is relatively narrow, and the air-cooled object time is shorter；
6）（1）Since Si-Mn-Cr-Mo systems " coiling technique window " are wider, second segment cooldown rate can be controlled slowly,
20-30 DEG C of cooling rate/s can be met the requirements；（2）Si-Mn-Nb-Ti systems window is relatively narrow, it is necessary to carry out intensive cooling in a short time
Pearlite, bainite transformation area can be just avoided, 50-60 DEG C of cooling rate/s can be only achieved requirement；
7）（1）Si-Mn-Cr-Mo systems（Attached drawing 1a）Martensitic structure, coiling temperature range can be formed during Slow cooling
500-600 DEG C, take 550 DEG C of desired value；（2）Si-Mn-Nb-Ti systems（Attached drawing 1b）Martensite point temperature be must be cooled to hereinafter, simultaneously
The self tempering of ferrite failure and martensite is prevented, 100-250 DEG C of coiling temperature range takes 180 DEG C of desired value；
8）Hot-rolled dual-phase steel thickness range be 3.0-4.8mm, 880 DEG C of Si-Mn-Cr-Mo systems finish to gauge target temperature, Si-Mn-
830 DEG C of Nb-Ti systems target temperature, when finishing speeds model calculates, on the basis of respective 3.0mm thickness, using thinned intermediate base
Thickness speed governing, the maximum threading speed of method calculating of interstand cooling water control temperature.Specially：The conventional intermediate base of the thickness range is thick
40mm is spent, the present invention is using minimum rolled thickness 30mm, while each group interstand cooling water calculates the finish to gauge by maximum minable water yield
At a temperature of threading speed, i.e. V3.0 threadings.Remaining thickness is a group away from benchmark threading speed designs as the following formula using 0.3mm：
VThreading=V3.0 threading- 0.3n, n=0,1,2,3,4,5,6.Due to finish rolling high speed threading, in Acceleration Control, 1 plus, 2 accelerations point
Not Wei 0.001m/s2,0.002m/s2, the 1/15 ~ 1/10 of only normal strip acceleration；
9）According to respectively air-cooled object time s requirements and specification mill speed VThreadingCalculate two kinds of ingredient second segment coolings
Originate valve location, i.e., air-cooled length L=VThreading* that of s arranges in a row pipe and cools down starting valve as second segment.Due to band in step 8
The mill speed design of steel is similar at the uniform velocity, this starting valve location be not required to as traditional increasing speed rolling with air cooling time with roll
Velocity variations processed（Secure second segment cooling starting valve location）, second segment is caused to cool down, and overall length inhomogeneous cooling is even to bring group
It knits uneven；
10）By attached drawing 2,（1）Second segment cooling manifold device is made of 5 groups of intensive thick cold collectors, 2 groups of cold sperm collectors, is examined
Survey instrument by the cold intermediate pyrometer of layer, batch entrance pyrometer and form；（2）The cooling system of this part belongs in tradition cools down
Back segment cools down, and the invention is designed to it " leading portion cooling " the pattern, by air-cooled target temperature as second segment cooling in region
" finishing temperature ", the closed-loop control system independent in compositing area together with coiling temperature target, can both participate in entirely point
Section cooling control, and independent presetting and feedback control can be carried out in the region；
11）（1）According to the requirement of step 6 cooldown rate and the successional requirement of second segment cooling curve, to two kinds into split
The cooling manifold of system is redesigned, and cold sperm collector uses few boiling water, thick cold using more boiling water strategies, i.e., is originated from step 9
Valve starts, cooling capacity integral forward lead, the water of cold sperm it is as much as possible be assigned to it is thick cold；（2）Si-Mn-Cr-Mo systems are cold
Fast 20-30 DEG C/s, in 2 groups of cold sperm collectors, Bank15 1-4 rows are pre- to open, and 5-8 rows are used as feedback regulation, remaining cold sperm collector is complete
Portion sets failure not boiling water, since being originated valve, 5 groups slightly cold collector use the sparse type of cooling（A row side is arranged every one
Formula）, it is M by this type of cooling Code Design；Si-Mn-Nb-Ti systems 50-60 DEG C/s of cooling rate, in 2 groups of cold sperm collectors, Bank14
1-4 rows are pre- to open, and 5-8 rows are used as feedback regulation, remaining cold sperm collector all sets failure not boiling water, since being originated valve, 5 groups
Thick cold collector is using the continuous intensive type of cooling（That is opening ways successively）, it is N by this type of cooling Code Design.The method is filled
Divide the characteristics of field device flexible configuration is utilized and effective combination with model cootrol；
12）Model carries out feedforward control, and the closed-loop control system of step 10 starts, in a step 11, type of cooling code
M, since the starting valve of step 9, " leading portion cooling " pattern starts, and every arranging, to open quantity be estimated to 5 groups of thick cold collection tube valves
Calculate the 4 row's cold sperms unlatching number for opening total number of rows-Bank15；Type of cooling code N, since being originated valve, " leading portion cooling " mould
Formula also begins to start, 5 groups it is thick it is cold integrate tube valve and continuously opens quantity opened as 4 row's cold sperms of the total number of rows-Bank14 of precomputation unlatching
Open number；
13）It batches entrance pyrometer and detects belt steel temperature actual temperature signal, the closed loop of coiling temperature is anti-in step 10
Feedback control starts, and Si-Mn-Cr-Mo systems cool down control mode code M, and Bank15 1-8 rows all participate in feedback tune in step 11
Section；Si-Mn-Nb-Ti systems type of cooling code N, Bank14 1-8 rows all participate in feedback regulations in step 11, respectively reach step
What two kinds of ingredients were set in rapid 7 batches target temperature；
14）In the feedback control of step 13 coiling temperature, for belt steel surface, there may be the influence temperature such as ponding or fog
The problem of degree detection authenticity, such as batches pyrometer and detects that the temperature value of certain point is less than preceding 5-30 DEG C of mean values, and judgement should
Point is the false point of detection, is not transferred to coiling temperature model and carries out feedback control（Go false point design）；
15）Performance, tissue detection are carried out to coiled latter two ingredient dual phase steel substitution table sample plate, as performance is qualified and obtains
Ferrite+martensitic structure fixes this second segment cooling technique, otherwise, compares CCT curve, second segment cooling parameter is carried out
It corrects.
Embodiment 1
By taking the Si-Mn-Cr-Mo systems dual phase steel DP600 for producing trimmed size 3.6*1150mm as an example, the cooling of laminar flow second segment
Step is as follows：
1. chemical composition is as shown in table 1, austenite Continuous Cooling Transformation Curve（CCT curve）As shown in 1 a of attached drawing；
1 Si-Mn-Cr-Mo systems dual phase steel DP600 chemical compositions of table（Mass fraction, %）
Surplus is Fe.
2. from attached drawing 1a it can be seen that perlitic transformation area moves to right strongly, bainite transformation area right end sealing, in ferrite
There is the austenite meta-stable area that vertical temperature difference is larger between bainite transformation area；
3. in ferrite, austenitic area, its cooling transformation curve is determined as shown in fig. la；
After 4. strip goes out " finish to gauge ", by first segment water cooling（Into ferrite area）+ one long period it is air-cooled（Occur
Ferritic transformation）+ second segment water cooling, cooling finishing temperature form martensite close to martensitic regions, subsequent Slow cooling；
5. by ferritic transformation C curve, " " neighbouring temperature is set to air-cooled target temperature to nose, is 710 DEG C；Air-cooled window compared with
Width, air-cooled object time are set to 6s；
6. second segment water cooling window is wider, cooldown rate is set to 20-30 DEG C/s；
7. Slow cooling can form martensitic structure after cooling ends, coiling temperature desired value can be in martensite transfor mation song
More than line, it is determined as 550 DEG C；
8. it is 8.4m/s by the benchmark threading speed of 880+30 DEG C of calculating, then during thickness 3.0mm 880 DEG C of finishing temperature
3.6mm threading speed is：VThreading=V3.0 threading-0.3n=8.4-0.3*2=7.8m/s；
9th, air-cooled length L=VThreading* s=7.8*7=46.8m, calculating the thick cold starting valve location of second segment cooling by model is
The 9th of Bank11 arranges the beginning；
10th, 710 DEG C of finishing temperature of second segment cooling（I.e. air-cooled target temperature）, 550 DEG C of coiling temperature, cooling manifold by
Intensive thick cold collector+Bank14, the 15 cold sperm collector composition of Bank9 ~ Bank13, detection instrument by the cold intermediate pyrometer of layer,
Entrance pyrometer composition is batched, it is designed to independent model-controlled system, sees attached drawing 2；
11st, second segment cooling required continuous coo1ing, to ensure water Forward, Bank15 1-4 rows are pre- to open, and 5-8 rows make anti-
Feedback, which is adjusted, to be used, remaining cold sperm collector all sets failure not boiling water.20-30 DEG C of cooldown rate/s, from the 9th of starting valve Bank11 the
The beginning is arranged, thick cold collector is used arranges row's mode toward the unlatching of coiling machine direction every one, is that M is supplied by this type of cooling Code Design
Model cootrol uses.The control parameter setting such as the following table 2 of second segment cooling are determined as a result,：
2 second segment of table cools down control parameter
12nd, strip starts to roll, into second segment cooling control system, before model is carried out by cooling control parameter and mode
Feedback, feedback control, as a result such as the following table 3：
3 second segment cooling jig control result of table
13rd, come into operation false point function in second segment cooling control；
14th, after rolling is coiled, take head, in, tail represent model and survey performance and tissue data such as the following table 4, meet DP600 mass
The requirement of uniformity.
The performance of strip, tissue result after the cooling of 4 second segment of table
Embodiment 2
By taking the Si-Mn-Nb-Ti systems dual phase steel 580DP for producing trimmed size 4.2*1250mm as an example, the cooling of laminar flow second segment
Step is as follows：
1st, chemical composition is as shown in table 5, austenite Continuous Cooling Transformation Curve（CCT curve）As shown in 1 b of attached drawing；
5 Si-Mn-Cr-Mo systems dual phase steel DP600 chemical compositions of table（Mass fraction, %）
| C | Si | Mn | P | S | Nb | Ti | Al |
| 0.085 | 0.20 | 1.25 | ≤0.020 | ≤0.0105 | 0.03 | 0.02 | 0.03 |
Surplus is Fe.
2nd, from attached drawing 1a it can be seen that perlitic transformation area moves to right seldom, bainite transformation area is under perlitic transformation area
Side, ferrite, austenite transition window are relatively narrow；
3rd, in ferrite, austenitic area, its cooling transformation curve is determined as shown in figure ib；
4th, after strip goes out " finish to gauge ", by first segment water cooling（Into ferrite area）+ one short period it is air-cooled（Occur
Ferritic transformation）The quick water cooling of+second segment can just avoid pearlite, Bainite Region, and quickly enter martensitic regions, can just obtain
Ferrite+martensitic structure；
5th, by ferritic transformation C curve, " " neighbouring temperature is set to air-cooled target temperature to nose, is 690 DEG C；Air-cooled window compared with
Narrow, the air-cooled object time is set to 4.5s；
6th, second segment water cooling window is relatively narrow, need to increase cooldown rate, and cooldown rate is set to 50-60 DEG C/s；
7th, second segment cooling need to be cooled fast to martensite transfor mation curve hereinafter, coiling temperature desired value is set to 180 DEG C；
8th, 830 DEG C of finishing temperature are 8.0m/s by the benchmark threading speed of 830+30 DEG C of calculating, then during thickness 3.0mm
4.2mm threading speed is：VThreading=V3.0 threading-0.3n=8.0-0.3*4=6.8m/s；
9th, air-cooled length L=VThreading* s=6.8*4.5=30.6m calculates the thick cold starting valve location of second segment cooling by model
The 8th for Bank9 arranges the beginning；
10th, 690 DEG C of finishing temperature of second segment cooling（I.e. air-cooled target temperature）, 180 DEG C of coiling temperature, cooling manifold by
Intensive thick cold collector+Bank14, the 15 cold sperm collector composition of Bank9 ~ Bank13, detection instrument by the cold intermediate pyrometer of layer,
Entrance pyrometer composition is batched, it is designed to independent model-controlled system, sees attached drawing 2；
11st, second segment cooling required continuous coo1ing, to ensure water Forward, Bank14 1-4 rows are pre- to open, and 5-8 rows make anti-
Feedback, which is adjusted, to be used, remaining cold sperm collector all sets failure not boiling water.50-60 DEG C of cooldown rate/s, from the 8th of starting valve Bank9 the
The beginning is arranged, thick cold collector is opened using the mode that continuously opens toward coiling machine direction, this type of cooling Code Design is supplied model for N
Control uses.The control parameter setting such as the following table 6 of second segment cooling are determined as a result,：
6 second segment of table cools down control parameter
12nd, strip starts to roll, into second segment cooling control system, before model is carried out by cooling control parameter and mode
Feedback, feedback control, as a result such as the following table 7：
7 second segment cooling jig control result of table
13rd, come into operation false point function in second segment cooling control；
14th, after rolling is coiled, take head, in, tail represent model and survey performance and tissue data such as the following table 8, meet 580DP mass
The requirement of uniformity.
The performance of strip, tissue result after the cooling of 8 second segment of table
Claims (4)
1. the control method of second segment cooling precision in a kind of laminar flow sub-sectional cooling technique, it is characterized in that：This method includes as follows
Step：
（1）Draw two kinds of component systems：Si-Mn-Cr-Mo systems, the continuous cooling transformation of Si-Mn-Nb-Ti systems hot-rolled dual-phase steel are bent
Line；
（2）Determine the austenites of two kinds of ingredients, ferrite, pearlite, bainite, Martensite temperature transformation range；
（3）Determine sub-sectional cooling " coiling technique window " range of two kinds of ingredients；
（4）The sub-sectional cooling processing route of two kinds of ingredients is determined in " coiling technique window "；
（5）Determine the air-cooled target temperature of two kinds of ingredients and air-cooled object time；
（6）Determine the second segment cooldown rate range of two kinds of ingredients；
（7）Determine that target temperature is batched in two kinds of ingredient second segment coolings；
（8）The method for control speed that two kinds of ingredients closely at the uniform velocity roll soon：Hot-rolled dual-phase steel thickness range is 3.0-4.8mm, Si-Mn-
880 DEG C of Cr-Mo systems finish to gauge target temperature, 830 DEG C of Si-Mn-Nb-Ti systems target temperature, when finishing speeds model calculates, with respective
On the basis of 3.0mm thickness, maximum threading speed is calculated using the method for thinned workpiece thickness speed governing, interstand cooling water control temperature
Degree；
（9）Two kinds of ingredient second segments are calculated according to step 5 air-cooled object time, step 8 mill speed and cool down fixed starting valve
Door position；
（10）Two kinds of ingredient second segment cooling closed-loop control systems are designed according to step 5-9；
（11）Target temperature, step 10 closed-loop control system composition are batched according to step 7, design two kinds of ingredient cooling control modes
And formulate corresponding cooling control routine；
（12）Second segment cools down feedforward control；
（13）Second segment cools down feedback control；
（14）Feedback control goes temperature vacation point to handle：Such as batch pyrometer detect the temperature value of certain point less than preceding 5 mean values-
30 DEG C, judge that the point to detect temperature vacation point, is not transferred to coiling temperature model and carries out feedback control；
（15）To rolling the performance of latter two ingredient, tissue is detected, and cooling control parameter is cured or corrected.
2. the control method of second segment cooling precision in laminar flow sub-sectional cooling technique according to claim 1, it is characterized in that：
Step（1）Described in two kinds of component systems of drafting：Si-Mn-Cr-Mo systems, the continuous cold of Si-Mn-Nb-Ti systems hot-rolled dual-phase steel
But the operating method of transition curve is：Using Gleeble3500 hot modeling test machines, carry out two kinds of component systems：Si-Mn-Cr-
Mo systems, Si-Mn-Nb-Ti systems hot-rolled dual-phase steel thermal modeling test, measure its austenite Continuous Cooling Transformation Curve.
3. the control method of second segment cooling precision in laminar flow sub-sectional cooling technique according to claim 1, it is characterized in that：
Step（6）Described in two kinds of ingredients second segment cooldown rate range：Si-Mn-Cr-Mo systems 20-30 DEG C/s of cooling rate, Si-
Mn-Nb-Ti systems 50-60 DEG C/s of cooling rate.
4. the control method of second segment cooling precision in laminar flow sub-sectional cooling technique according to claim 1, it is characterized in that：
Step（7）Described in second segment cooling batch target temperature：500-600 DEG C of Si-Mn-Cr-Mo systems coiling temperature range, takes mesh
550 DEG C of scale value, 100-250 DEG C of Si-Mn-Nb-Ti systems coiling temperature range.
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