CN104907335B - Supercooling austenite rolling method suitable for carbon-manganese medium steel plate - Google Patents
Supercooling austenite rolling method suitable for carbon-manganese medium steel plate Download PDFInfo
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- CN104907335B CN104907335B CN201510356138.XA CN201510356138A CN104907335B CN 104907335 B CN104907335 B CN 104907335B CN 201510356138 A CN201510356138 A CN 201510356138A CN 104907335 B CN104907335 B CN 104907335B
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Abstract
The invention relates to a super-cooling austenite rolling method suitable for a carbon-manganese medium steel plate, wherein a continuous casting billet is heated to 1170 DEG to 1250 DEG; on a medium plate rolling machine, the continuous casting billet is rolled through two stages of austenite recrystallization area and super-cooling austenite; the finished temperature of rolling at the austenite recrystallization area is within 1000 DEG to 1080 DEG; the thickness of the middle billet is more than 1.8 times that of the finished steel plate; during the process of the steel plate to be warmed, the steel plate is delivered into an ACC device for cooling and then the steel plate is sent back to the medium plate rolling machine; the starting temperature of the super-cooling austenite rolling is within 780 to 820 DEG; after the super-cooling austenite rolling is completed, the steel plate is delivered again to the ACC device for cooling; the finished temperature of cooling is within 600 to 700 DEG; and at last the steel plate is cooled in the air. By adopting the super-cooling austenite rolling method, the temperature to be warm is greatly reduced; the cost is lowered; the austenite is deformed under super-cooling; the nuclear formation rate of the ferrite during the phase-changing process is increased; and the fine crystalline structure on the steel plate surface is produced.
Description
Technical field
The invention belongs to the Bar Rolling Process field that steel plate is smelted, and in particular to one kind is applied to carbon/manganese medium plate
Overcooling austenite milling method.
Background technology
In all multipaths for improving Strength of Metallic Materials, grain refining intensificatiom can be in the premise for not reducing toughness of material
The lower intensity for improving material, thermo-mechanical processi (TMCP) can effectively crystal grain thinning, and then improve the mechanical property of material.It is right
In mild steel, TMCP crystal grain thinnings it is limited in one's ability, the crystal grain thinning dimension limit to be reached is only 10 μm or so, although
Addition alloying element can further crystal grain thinning, but significantly improve production cost.In recent years, deformation-induced ferrite transformation
(deformation induced ferrite transformation, DIFT) is with its significant grain refining effect and relatively
Low production cost, has obtained people widely concern and in-depth study.Current DIFT industrial applications, due to crystal grain mistake
Carefully, there is yield tensile ratio height, and the problem of room-temperature aging, popularization and application are not notable.At present, in conventional products production, still preferentially
From TMCP rollings, TMCP rollings are rolled laggard generally by austenite recrystallization area and the non-recrystallization zone rolling of austenite
Row section cooling accelerates cooling（Accelerated cooling, ACC）.Even so, people are seeking stable ultra-fine
But make great efforts all the time on brilliant road.There is research and utilization in laboratory by carrying out on the thermal simulation experiment machines of Gleeble 1500
Simulation, by experimental design, makes supercooling reach 200K, and true strain reaches 0.9, and Ultra-fine Grained top layer group is obtained in C-Mn steel plates
Knit.The method is not further applied in industrialization trial-production, but the thinking of high undercooling, it is expected on thin plate more use.And it is right
In cut deal, because cut deal not only needs high undercooling, big strain is also required, thus can not possibly be applied in Heavy Plate Production.
The content of the invention
The technical problem to be solved is to provide a kind of overcooling austenite milling method for above-mentioned prior art,
Suitable for the rolling of carbon/manganese medium plate, fine grained texture can be obtained on steel plate top layer, crystal grain is tiny at the thickness of steel plate 1/4, carries
The mechanical property of high steel plate, reduces the time of staying temperature during plate rolling, reduces steel plate smelting cost, improves production effect
Rate.
The present invention the adopted technical scheme that solves the above problems is：A kind of supercooling suitable for carbon/manganese medium plate is difficult to understand
Family name's body milling method, by continuous casting billet 1170 DEG C～1250 DEG C are heated to, on heavy and medium plate mill, using austenite recrystallization area and
Overcooling austenite two-phase control rolling：The finishing temperature of austenite recrystallization area rolling is base in the middle of 1000～1080 DEG C, gained
Thickness for 1.8 times of finished steel plate thickness and more than；Treating after steel plate austenite recrystallization area rolls during temperature, steel plate is sent
Enter ACC devices to be cooled down, it is 760～820 DEG C that steel plate goes out the temperature of ACC devices, and steel plate top layer cooling velocity is controlled to 8～15
℃/s；Then steel plate foldback is returned carries out overcooling austenite rolling on heavy and medium plate mill, the start rolling temperature of overcooling austenite rolling
For 780～820 DEG C, the temperature range again sends into steel plate after the completion of overcooling austenite rolling less than the Ae3 temperature of carbon/manganese steel
ACC devices are cooled down, and the final cooling temperature of cooling is 600～700 DEG C, last air cooling.
The top layer average grain size of the rolling method gained carbon/manganese steel plate finished product is between 3～5 μm.
C in the carbon/manganese medium plate that the rolling method is suitable for：0.05～0.15wt%, Mn：0.60～1.50wt%,
Steel plate austenite ferrite equilibrium phase change point Ae3 temperature >=820 DEG C.
Because Elements C, Mn are the Chief elements of impact austenite ferrite equilibrium phase change point Ae3 temperature in steel, this
Invention in order that carbon/manganese medium plate realize overcooling austenite roll, the chemical composition of steel is defined：
C：The essential element of steel mechanical property is affected, when carbon content is less than 0.05% low intensity, carbon content is higher, Ae3 temperature
Degree is lower, and when content is higher than 0.15%, Ae3 temperature is easy to less than 820 DEG C, is difficult to realize overcooling austenite rolling, the present invention
C content interval is set in into 0.05～0.15wt%.
Mn：Austenite can be postponed to ferritic transformation, finishing temperature window can be increased, fining ferrite is improved
Intensity and toughness.Yield strength between 235MPa level carbon/manganese medium plates manganese content generally >=0.60wt%.With carbon to Ae3 temperature
Degree affects the same, and manganese content is higher, and Ae3 temperature is lower, and when the content of manganese is higher than 1.50wt%, Ae3 temperature is easy to be less than
820 DEG C, it is unfavorable for the enforcement of the inventive method.Therefore, milling method of the present invention is more suitable for manganese content in 0.60～1.50wt%
In the range of cut deal.
Cut deal is such as：Structural steel, ship steel, bridge steel, wind-powered electricity generation steel, bridge steel major part steel grade C content between
0.05～0.15wt%, Mn content is between 0.60～1.50wt%, and this kind of steel grade accounts for 70% or so of whole cut deal yield, because
And the inventive method has wider use range.
The present invention is subcooled milling method by a kind of austenite, is rolled with overcooling austenite two benches using austenite recrystallization
System, and the time of staying temperature of steel plate is greatly reduced using cooling water cooling between rolling twice（Usual cut deal time of staying temperature
Between 5～15min）, gained C-Mn steel finished products obtain steel plate top layer fine grain, top layer average grain size between 3～5 μm, steel
Intralamellar part fine microstructures are uniform, and strength character is stable, and impact flexibility is excellent（Akv, -40℃）>=100J, intensity declines after normalizing
Not substantially, impact flexibility is improved.
Jing is tested, and the thick high-intensity high-tenacity EH36 ship steels of 38mm have successfully been rolled out, can popularization and application it is low to other
Rank and the bridge with intensity rank, construction(al)steel, improve production efficiency and reduction production cost.It is equal due to top layer steel plate
Even property, fine grain can also lift product up-gradation application, for the manufacture of wear-resisting Steel Used for Pressure Retaining Components plate.
The invention has the advantages that：
1st, rapid cooling zerolling is carried out before overcooling austenite rolling, to guarantee that austenite is become under big supercooling degree
Shape, increases Gibbs free energys, plastic work done, phase driving force, so as to increase ferrite nucleation rate during phase transformation, produces steel plate top layer
Fine grained texture.
2nd, rolled using overcooling austenite, greatly reduce time of staying temperature, reduces cost.
3rd, the DIFT of the production fine grained texture of mesh first two industrial applications and the TMCP side for combining increase microalloy element
Method milling method, the former large deformation rolling, it is bent with aggravation roll wear to be easily caused steel plate wooden dipper, equivalent to increased Plate Production into
This.The latter, increasing microalloy element can dramatically increase production cost.Obviously, entered by arranging cooling water between rolling twice
The quick cooling of row is most economical with a kind of effective mode reaching the purpose of overcooling austenite.
4th, milling method of the invention can popularization and application to other low levels and the bridge with intensity rank, it is for building
Steel.Due to the uniformity of top layer steel plate, fine grain, also product can be lifted and be applied in wear-resisting, Steel Used for Pressure Retaining Components plate manufacture.
5th, the present invention can be carried out equally to other rolling producing lines in popularization and application, such as cut deal steekle mill, thin
Slab continuous casting rolling machine line, thin plate hoop mill etc..
Description of the drawings
Fig. 1 is the light plate of embodiment 1 typical organization at thickness direction near surface；
Fig. 2 is the light plate of embodiment 1 typical organization at thickness direction 1/4.
Specific embodiment
The present invention is described in further detail below in conjunction with accompanying drawing embodiment.
On heavy and medium plate mill, by taking EH36 steel grades as an example, two pieces of thickness are selected for the C-Mn continuous casting billets of 370mm, respective steel
Chemical composition by weight percentage include C：0.11%, Si：0.25%, Mn：1.50%, P：0.007%, S：0.002%, Al:
0.030%, Ti:0.012%, balance of Fe and inevitable impurity element.Two pieces are calculated by Thermo-calc softwares
Steel Ae3829 DEG C of temperature.By in continuous blank heating temperature to 1170 DEG C～1250 DEG C temperature ranges, austenite recrystallization area is taken
And overcooling austenite（Less than steel plate austenite ferrite equilibrium phase change point Ae3）Two-phase control rolling：Austenite recrystallization area rolls
Finishing temperature control at 1000～1080 DEG C, in the middle of gained the THICKNESS CONTROL of base for 1.8 times of finished steel plate thickness and more than,
Treating during temperature after steel plate austenite recrystallization area rolls, sends steel plate into the cooling of ACC devices, when steel plate goes out ACC devices, steel
Plate skin temperature is controlled to 760～820 DEG C, and steel plate top layer cooling velocity is controlled to 8～15 DEG C/s；Then return again to cut deal to roll
Machine carries out overcooling austenite finish rolling, and finish rolling start rolling temperature is 780～820 DEG C, afterwards, again carries out in steel plate feeding ACC devices
Roller repairing, the final cooling temperature of cooling is controlled in the range of 600～660 DEG C, subsequent air cooling.
Specifically, the rolling technological parameter of two blocks of continuous casting billets is shown in Table 1,
Table 1
The rolling method obtains the performance of finished steel plate as shown in table 2, from the point of view of the tensile property of embodiment, steel
Plate yield strength transverse tensile property between 410～430MPa, between 560～580 MPa, fit tensile strength by intensity
In, yield tensile ratio is relatively low≤and 0.76, elongation percentage is moderate, -40 DEG C of impact of collision toughness value >=100 J.
Table 2
Jing after further normalized treatment, normalizing process is 880～910 DEG C of process to finished steel plate, is incubated 1.8min/mm.Just
The corresponding mechanical property of each embodiment steel plate is as shown in table 3 after fire.By contrast, passed through using the steel plate of overcooling austenite finish rolling
After normalized treatment, armor plate strength hydraulic performance decline is not obvious, and surrender declines 10～15MPa, and tensile strength only declines 20～30MPa,
And Jing after normalizing, impact property, elongation percentage are obviously improved, it follows that the steel plate not shadow after overcooling austenite is rolled
Ring user's high-temperature service performance.
Table 3
To sum up, the steel plate for being obtained according to rolling mill practice in embodiment, its mechanical property fully meet classification society rule and
EH36 steel mechanical properties are required in GB712.And property indices surplus capacity is larger, Jing after normalized treatment, intensity declines not
Substantially, impact property, elongation percentage are obviously improved.Rolled by overcooling austenite, steel plate does not affect user's high-temperature service performance.Obtain
The tissue for obtaining is excellent, and Fig. 1 is the correspondence steel plate of embodiment 1 typical organization at thickness direction near surface, by ferrite, pearlite group
Knit composition, uniform small grains, average grain size is between 3～5 μm.Fig. 2 is the correspondence steel plate of embodiment 1 in thickness direction 1/4
Typical organization of place, is made up of, uniform small grains ferrite, pearlitic structrure, and average grain size is between 5～8 μm.Performance shows
Write, and low production cost.The milling method is also stable with controlling of production process, it is easy to the features such as mass production.
Claims (2)
1. a kind of overcooling austenite milling method suitable for carbon/manganese medium plate, it is characterised in that：Continuous casting billet is heated to
1170 DEG C～1250 DEG C, on heavy and medium plate mill, using austenite recrystallization area and overcooling austenite two-phase control rolling：Austenite
The finishing temperature of recrystallization zone rolling is 1000～1080 DEG C, in the middle of gained the thickness of base for 1.8 times of finished steel plate thickness and
More than；Treating during temperature after steel plate austenite recrystallization area rolls, steel plate feeding ACC devices are cooled down, and steel plate goes out ACC
During device, the skin temperature of steel plate is controlled to 760～820 DEG C, and steel plate top layer cooling velocity is controlled to 8～15 DEG C/s；Then will
Steel plate foldback returns and overcooling austenite rolling is carried out on heavy and medium plate mill, and the start rolling temperature of overcooling austenite rolling is 780～820
DEG C, steel plate is sent into ACC devices cold by the temperature range again less than the Ae3 temperature of carbon/manganese steel after the completion of overcooling austenite rolling
But, the final cooling temperature of cooling is 600～700 DEG C, last air cooling；
The C of the carbon/manganese medium plate：0.05～0.15wt%, Mn：0.60～1.50wt%, steel plate austenite ferrite balance
Transformation temperature Ae3 temperature >=820 DEG C.
2. the overcooling austenite milling method suitable for carbon/manganese medium plate according to claim 1, it is characterised in that：
The top layer average grain size of gained carbon/manganese steel plate finished product is between 3～5 μm.
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| CN102465235A (en) * | 2010-11-11 | 2012-05-23 | 北京科技大学 | X100 large deformation resistant pipeline steel and manufacturing process thereof |
| CN104404377A (en) * | 2014-11-28 | 2015-03-11 | 内蒙古包钢钢联股份有限公司 | High-strength steel plate with excellent cold forming property and manufacturing method of high-strength steel plate |
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| SG43918A1 (en) * | 1993-04-26 | 1997-11-14 | Nippon Steel Corp | Thin steel sheet having excellent stretch-flange ability and process for producing the same |
| JPH09268323A (en) * | 1996-03-29 | 1997-10-14 | Nisshin Steel Co Ltd | Hot rolled austenitic stainless steel plate excellent in recrystallization softening characteristic, and its production |
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| WO2008096394A1 (en) * | 2007-02-02 | 2008-08-14 | Sumitomo Metal Industries, Ltd. | Process for producing hot-rolled steel sheet having fine ferrite structure and hot-rolled steel sheet |
| CN101153370B (en) * | 2006-09-27 | 2012-06-13 | 鞍钢股份有限公司 | Low-alloy high-strength steel plate capable of being welded at high heat input and manufacturing method thereof |
| CN101109037A (en) * | 2007-08-20 | 2008-01-23 | 重庆汽车研究所 | Method of producing high undercooling control rolling fine grain high-strength C-Mn steel plate |
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Patent Citations (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN1814845A (en) * | 2005-02-06 | 2006-08-09 | 宝山钢铁股份有限公司 | 1000Mpa-grade high-strength hot-rolled anti-bullet steel plate and making method |
| CN102465235A (en) * | 2010-11-11 | 2012-05-23 | 北京科技大学 | X100 large deformation resistant pipeline steel and manufacturing process thereof |
| CN104404377A (en) * | 2014-11-28 | 2015-03-11 | 内蒙古包钢钢联股份有限公司 | High-strength steel plate with excellent cold forming property and manufacturing method of high-strength steel plate |
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