CN1458867A - Hot rooling mill and method - Google Patents

Hot rooling mill and method Download PDF

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Publication number
CN1458867A
CN1458867A CN02800719A CN02800719A CN1458867A CN 1458867 A CN1458867 A CN 1458867A CN 02800719 A CN02800719 A CN 02800719A CN 02800719 A CN02800719 A CN 02800719A CN 1458867 A CN1458867 A CN 1458867A
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CN
China
Prior art keywords
rolling
rolled piece
equipment
hot
milling train
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Granted
Application number
CN02800719A
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Chinese (zh)
Other versions
CN1275711C (en
Inventor
竹士伊知郎
仓桥隆郎
森本敬治
大谷崇
箱守一昭
高冈真司
高桥昌范
足立明夫
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Nakayama Steel Works Ltd
Kawasaki Heavy Industries Co Ltd
Original Assignee
Nakayama Steel Works Ltd
Kawasaki Heavy Industries Co Ltd
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Priority to JP2001077293A priority Critical patent/JP3418738B2/en
Priority to JP77293/2001 priority
Priority to JP77293/01 priority
Priority to JP287428/2001 priority
Priority to JP2001287428A priority patent/JP3413184B2/en
Priority to JP2001287427A priority patent/JP3413183B2/en
Priority to JP287427/2001 priority
Priority to JP287427/01 priority
Priority to JP287428/01 priority
Application filed by Nakayama Steel Works Ltd, Kawasaki Heavy Industries Co Ltd filed Critical Nakayama Steel Works Ltd
Publication of CN1458867A publication Critical patent/CN1458867A/en
Application granted granted Critical
Publication of CN1275711C publication Critical patent/CN1275711C/en
Expired - Fee Related legal-status Critical Current
Anticipated expiration legal-status Critical

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Classifications

    • BPERFORMING OPERATIONS; TRANSPORTING
    • B21MECHANICAL METAL-WORKING WITHOUT ESSENTIALLY REMOVING MATERIAL; PUNCHING METAL
    • B21BROLLING OF METAL
    • B21B1/00Metal-rolling methods or mills for making semi-finished products of solid or profiled cross-section; Sequence of operations in milling trains; Layout of rolling-mill plant, e.g. grouping of stands; Succession of passes or of sectional pass alternations
    • B21B1/22Metal-rolling methods or mills for making semi-finished products of solid or profiled cross-section; Sequence of operations in milling trains; Layout of rolling-mill plant, e.g. grouping of stands; Succession of passes or of sectional pass alternations for rolling plates, strips, bands or sheets of indefinite length
    • B21B1/24Metal-rolling methods or mills for making semi-finished products of solid or profiled cross-section; Sequence of operations in milling trains; Layout of rolling-mill plant, e.g. grouping of stands; Succession of passes or of sectional pass alternations for rolling plates, strips, bands or sheets of indefinite length in a continuous or semi-continuous process
    • B21B1/26Metal-rolling methods or mills for making semi-finished products of solid or profiled cross-section; Sequence of operations in milling trains; Layout of rolling-mill plant, e.g. grouping of stands; Succession of passes or of sectional pass alternations for rolling plates, strips, bands or sheets of indefinite length in a continuous or semi-continuous process by hot-rolling, e.g. Steckel hot mill
    • BPERFORMING OPERATIONS; TRANSPORTING
    • B21MECHANICAL METAL-WORKING WITHOUT ESSENTIALLY REMOVING MATERIAL; PUNCHING METAL
    • B21BROLLING OF METAL
    • B21B45/00Devices for surface or other treatment of work, specially combined with or arranged in, or specially adapted for use in connection with, metal-rolling mills
    • B21B45/02Devices for surface or other treatment of work, specially combined with or arranged in, or specially adapted for use in connection with, metal-rolling mills for lubricating, cooling, or cleaning
    • B21B45/0203Cooling
    • B21B45/0209Cooling devices, e.g. using gaseous coolants
    • B21B45/0215Cooling devices, e.g. using gaseous coolants using liquid coolants, e.g. for sections, for tubes
    • B21B45/0218Cooling devices, e.g. using gaseous coolants using liquid coolants, e.g. for sections, for tubes for strips, sheets, or plates
    • BPERFORMING OPERATIONS; TRANSPORTING
    • B21MECHANICAL METAL-WORKING WITHOUT ESSENTIALLY REMOVING MATERIAL; PUNCHING METAL
    • B21BROLLING OF METAL
    • B21B13/00Metal-rolling stands, i.e. an assembly composed of a stand frame, rolls, and accessories
    • B21B13/14Metal-rolling stands, i.e. an assembly composed of a stand frame, rolls, and accessories having counter-pressure devices acting on rolls to inhibit deflection of same under load; Back-up rolls
    • B21B13/142Metal-rolling stands, i.e. an assembly composed of a stand frame, rolls, and accessories having counter-pressure devices acting on rolls to inhibit deflection of same under load; Back-up rolls by axially shifting the rolls, e.g. rolls with tapered ends or with a curved contour for continuously-variable crown CVC
    • BPERFORMING OPERATIONS; TRANSPORTING
    • B21MECHANICAL METAL-WORKING WITHOUT ESSENTIALLY REMOVING MATERIAL; PUNCHING METAL
    • B21BROLLING OF METAL
    • B21B2267/00Roll parameters
    • B21B2267/02Roll dimensions
    • B21B2267/06Roll diameter
    • B21B2267/065Top and bottom roll have different diameters; Asymmetrical rolling
    • BPERFORMING OPERATIONS; TRANSPORTING
    • B21MECHANICAL METAL-WORKING WITHOUT ESSENTIALLY REMOVING MATERIAL; PUNCHING METAL
    • B21BROLLING OF METAL
    • B21B2269/00Roll bending or shifting
    • B21B2269/02Roll bending; vertical bending of rolls
    • B21B2269/04Work roll bending
    • BPERFORMING OPERATIONS; TRANSPORTING
    • B21MECHANICAL METAL-WORKING WITHOUT ESSENTIALLY REMOVING MATERIAL; PUNCHING METAL
    • B21BROLLING OF METAL
    • B21B2269/00Roll bending or shifting
    • B21B2269/12Axial shifting the rolls
    • B21B2269/14Work rolls
    • BPERFORMING OPERATIONS; TRANSPORTING
    • B21MECHANICAL METAL-WORKING WITHOUT ESSENTIALLY REMOVING MATERIAL; PUNCHING METAL
    • B21BROLLING OF METAL
    • B21B27/00Rolls, roll alloys or roll fabrication; Lubricating, cooling or heating rolls while in use
    • B21B27/06Lubricating, cooling or heating rolls
    • B21B27/10Lubricating, cooling or heating rolls externally
    • BPERFORMING OPERATIONS; TRANSPORTING
    • B21MECHANICAL METAL-WORKING WITHOUT ESSENTIALLY REMOVING MATERIAL; PUNCHING METAL
    • B21BROLLING OF METAL
    • B21B3/00Rolling materials of special alloys so far as the composition of the alloy requires or permits special rolling methods or sequences Rolling of aluminium, copper, zinc or other non-ferrous metals
    • B21B3/02Rolling special iron alloys, e.g. stainless steel
    • BPERFORMING OPERATIONS; TRANSPORTING
    • B21MECHANICAL METAL-WORKING WITHOUT ESSENTIALLY REMOVING MATERIAL; PUNCHING METAL
    • B21BROLLING OF METAL
    • B21B37/00Control devices or methods specially adapted for metal-rolling mills or the work produced thereby
    • B21B37/74Temperature control, e.g. by cooling or heating the rolls or the product
    • BPERFORMING OPERATIONS; TRANSPORTING
    • B21MECHANICAL METAL-WORKING WITHOUT ESSENTIALLY REMOVING MATERIAL; PUNCHING METAL
    • B21BROLLING OF METAL
    • B21B45/00Devices for surface or other treatment of work, specially combined with or arranged in, or specially adapted for use in connection with, metal-rolling mills
    • B21B45/002Increasing friction between work and working rolls by using friction increasing substance
    • BPERFORMING OPERATIONS; TRANSPORTING
    • B21MECHANICAL METAL-WORKING WITHOUT ESSENTIALLY REMOVING MATERIAL; PUNCHING METAL
    • B21BROLLING OF METAL
    • B21B45/00Devices for surface or other treatment of work, specially combined with or arranged in, or specially adapted for use in connection with, metal-rolling mills
    • B21B45/02Devices for surface or other treatment of work, specially combined with or arranged in, or specially adapted for use in connection with, metal-rolling mills for lubricating, cooling, or cleaning
    • B21B45/0239Lubricating
    • B21B45/0242Lubricants
    • BPERFORMING OPERATIONS; TRANSPORTING
    • B21MECHANICAL METAL-WORKING WITHOUT ESSENTIALLY REMOVING MATERIAL; PUNCHING METAL
    • B21BROLLING OF METAL
    • B21B45/00Devices for surface or other treatment of work, specially combined with or arranged in, or specially adapted for use in connection with, metal-rolling mills
    • B21B45/02Devices for surface or other treatment of work, specially combined with or arranged in, or specially adapted for use in connection with, metal-rolling mills for lubricating, cooling, or cleaning
    • B21B45/0239Lubricating
    • B21B45/0245Lubricating devices
    • B21B45/0248Lubricating devices using liquid lubricants, e.g. for sections, for tubes
    • B21B45/0251Lubricating devices using liquid lubricants, e.g. for sections, for tubes for strips, sheets, or plates
    • BPERFORMING OPERATIONS; TRANSPORTING
    • B21MECHANICAL METAL-WORKING WITHOUT ESSENTIALLY REMOVING MATERIAL; PUNCHING METAL
    • B21BROLLING OF METAL
    • B21B45/00Devices for surface or other treatment of work, specially combined with or arranged in, or specially adapted for use in connection with, metal-rolling mills
    • B21B45/02Devices for surface or other treatment of work, specially combined with or arranged in, or specially adapted for use in connection with, metal-rolling mills for lubricating, cooling, or cleaning
    • B21B45/0239Lubricating
    • B21B45/0245Lubricating devices
    • B21B45/0263Lubricating devices using solid lubricants
    • BPERFORMING OPERATIONS; TRANSPORTING
    • B21MECHANICAL METAL-WORKING WITHOUT ESSENTIALLY REMOVING MATERIAL; PUNCHING METAL
    • B21BROLLING OF METAL
    • B21B45/00Devices for surface or other treatment of work, specially combined with or arranged in, or specially adapted for use in connection with, metal-rolling mills
    • B21B45/02Devices for surface or other treatment of work, specially combined with or arranged in, or specially adapted for use in connection with, metal-rolling mills for lubricating, cooling, or cleaning
    • B21B45/0269Cleaning
    • B21B45/0275Cleaning devices
    • B21B45/0278Cleaning devices removing liquids
    • B21B45/0281Cleaning devices removing liquids removing coolants
    • CCHEMISTRY; METALLURGY
    • C21METALLURGY OF IRON
    • C21DMODIFYING 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
    • C21D8/00Modifying the physical properties by deformation combined with, or followed by, heat treatment
    • C21D8/02Modifying the physical properties by deformation combined with, or followed by, heat treatment during manufacturing of plates or strips
    • C21D8/0221Modifying the physical properties by deformation combined with, or followed by, heat treatment during manufacturing of plates or strips characterised by the working steps
    • C21D8/0226Hot rolling

Abstract

The hot rolling apparatus of the present invention has a mill arranged on the preceding stage, mills of a plurality of stands arranged on the later stage which are different-diameter roll mills including a pair of different-diameter work rolls having an equivalent roll diameter of less than 600 mm or minimum-diameter roll mills including a pair of work rolls having a diameter of less than 600 mm, and a cooling unit for cooling steel to be rolled which is arranged on each exit side of the mills of at least two stands on the later stage. The hot rolling apparatus can smoothly manufacture hot rolled plates of fine-particle steel.

Description

Equipment of hot rolling and method
Technical field
The present invention relates to equipment of hot rolling and hot-rolling method, especially make the equipment of hot rolling and the hot-rolling method of the steel plate have mainly the delicate tissues that constitutes by the thin crystalline substance of ferrite.
Background technology
Usually, as the method that improves the steel mechanical performance, the means that make steel organize granular have been known.If improved the steel mechanical performance, then bring as having realized many advantages of steel structure lightness.At present, the steel that has proposed many manufacturings and have delicate tissues is promptly made the method for the steel of trickle crystal grain, and its typical method is exactly that (1) depresses rolling and (2) controlled rolling method greatly.
Wherein, (1) is depressed rolling greatly and is recorded among clear 58-123823 of Japanese Unexamined Patent Publication No and the flat 3-65564 of Japanese Unexamined Patent Publication No.That is, this method applies heavy reduction to austenite crystal, to promote from austenite (γ) mutually to the strain phase transformation and the thinning microstructure of ferrite (α) phase.
In addition, (2) controlled rolling method is to realize the method for ferrite crystal grain refinement, carefully contain at ferrite crystal grain under the situation of Nb (niobium) and Ti (titanium), not only easy precipitation strength effect by Nb and Ti realizes high-tensionization, and the inhibition austenite crystal effect of crystallization again by Nb and Ti, when implementing zerolling (ferrite area is rolling), promote strain phase transformation from γ to the α phase.
Because implement finish rolling at low-temperature space (800 ℃ or lower), so the controlled rolling method has such shortcoming, i.e. the deformation drag of rolled piece is obviously increased, thereby the load that acts on rolling equipment is huge.On the other hand,, depress rolling greatly and can not be useful for industrially, must use special rolling equipment by common hot strip mill as ground as described in the flat 5-65564 of above-mentioned Japanese Unexamined Patent Publication No.Reason is, as described in above-mentioned patent application gazette, needs to implement continuously to be difficult to the rolling of the heavy reduction rate (as more than 40%) realized with the ordinary hot rolling plant.
When implementing to depress rolling ground greatly, except can not also having following point with the rolling equipment that becomes ordinary hot strip mill form at industry and commercial manufacturing fine-grained steel material.
1) because the enforcement of heavy reduction ground is rolling, so the shortcoming that frequent appearance is caused by rolling load.Promptly have such situation, promptly rolling load reaches the intrinsic limiting value (mill production restriction and mechanical strength) of rolling equipment and can't be rolled.In addition, concerning rolled piece, can't realize the reduction ratio be scheduled to, and cause the edge attenuate.The reason that can not obtain predetermined reduction ratio is that especially when the outlet side thickness of slab of rolling equipment was the reduction ratio of getting below the 2mm more than 40%, because rolling load height and deformation drag height, institute's roll flattening increased.Under this occasion, carry out heavy reduction rolling even if enhance big pressure ground, reduction ratio can not improve yet.Edge attenuate cause of increased is that high load capacity puts near the edge (width end) of rolled piece, and can not obtain good plate shape.
2) being difficult to keep the rolled piece temperature also is a serious problem.This be because, when carrying out heavy reduction rate with multi-set of rolling mill when rolling, obviously raise because of processing heat makes the rolled piece temperature, thus be not easy to remain on be suitable for finishing depress rolling greatly temperature (from Ar 3Transformation temperature is to Ar 3+ 50 ℃) under.When quickening rolled piece ground when improving transporting velocity, accelerate and increased processing heat in response to the speed change degree, make thus to keep the temperature more and more difficulty that becomes.
3) often cause the shortcoming relevant with the roll thermic load.When carrying out the high high load capacity of reduction ratio when rolling, also increased the processing heat and the corresponding thermic load that increases roll of rolled piece.As a result, the hot convexity that diameter increases at the center of each roll appears easily.Hot convexity size can't only be eliminated by cooling off each roll, and in this case, the shape of rolled piece worsens and also sheet material is difficult stably passes through.
4) roll wear aggravation and shape of rolling piece (the thick protuberance in center) further worsen easily.This is because big and load is high when rolling at reduction ratio, the thermic load or the mechanics load that put on roll are high, so roll is easy to wear.On the part at contact rolled piece edge, because of the high wearing and tearing especially easily of rolling load, making thus quality is that important rolled piece cross sectional shape worsens.In addition, when roll is easy to wear, be used for also increasing as the maintenance cost of roll grinding or roll change.
Summary of the invention
Therefore, the object of the present invention is to provide equipment of hot rolling and the fine-grained steel manufacture method that solves the problems referred to above relevant and can make this steel plate smoothly with making thin brilliant hot rolled steel plate.
In addition, another object of the present invention is to provide the continuous hot-rolling method that is suitable for making thin brilliant hot rolled steel plate, this hot-rolling method is very outstanding aspect cost effectiveness.
In addition, the equipment of hot rolling that another object of the present invention is to provide use can make thin plate is made the continuous hot-rolling method of slab smoothly.
The present invention relates to rolling rolled piece ground and make the equipment of hot rolling of steel plate, it comprises: be arranged on the milling train in the leading portion; Be arranged on the multi-set of rolling mill in the back segment, described multi-set of rolling mill has and has equivalent roller footpath less than the reducing roller mill of a pair of reducing working roll of 600mm or have separately diameter less than the ultra-fine roller mill of a pair of working roll of 600mm; Be arranged at least one the milling train outlet side and cooling device that cool off described rolled piece of described back segment.
Here, " equivalent roller footpath " refers to the diameter mean value of a pair of reducing working roll up and down with the reducing roller mill relevantly.
In addition, this cooling device curtain wall formula cooler preferably.
Here, " curtain wall formula cooler " refers to such cooling device, promptly by as curtain from upper and lower stratified flow shape the upper and lower surface that makes a large amount of flow of cooling water and in whole width range, impact rolled piece.
In addition, in the milling train in being arranged on leading portion and back segment, the milling train that is arranged at least in the leading portion preferably includes many CVC milling trains.
Here, " CVC milling train " be meant include external diameter on the axial length direction continually varying roll and roll can move the milling train of (CVC roll) along the axial length direction.
In addition, that of reducing roller mill directly is 550mm or littler to the roller of the described working roll of the equivalent roller footpath of reducing working roll or described ultra-fine roller mill.
In addition, the working roll of the working roll of reducing roller mill or ultra-fine roller mill is equipped with CVC function and roller function.
Here, " CVC function " refers to make its external diameter continually varying roll on the axial length direction carry out the function that roll gap shape changes control movably along the axial length direction.And " roller function " is to instigate bending roller force (bending moment) to act on the function that roll ground changes roll gap shape.
In addition, this equipment of hot rolling preferably also has the feeding lubricating device that lubricant is provided to the roll of described milling train, and described feeding lubricating device is arranged on any at least rolling mill in the described milling train in being arranged at described leading portion and back segment.
In addition, this feeding lubricating device preferably is provided at the lubricant that contains the fine-particle solid lubricant in the lubricating grease.
In addition, this equipment of hot rolling preferably is sprayed onto fluid on the described rolled piece in addition and removes the jet flow device of the cooling water on described rolled piece, and this jet flow device is arranged on the downstream of this cooling device of described rolled piece direction of travel at the outlet side of finish to gauge frame.
In addition, this jet flow device comprises a plurality of so the nozzle of high pressure water jets to this rolled piece, and promptly the upstream side that aims at this rolled piece direction of travel from this rolled piece top tiltedly down sprays, thereby water under high pressure is launched on this rolled piece width.
The present invention relates to rolling rolled piece ground and make the method for fine-grained steel, the described rolled piece of heating supplied with have the rolling equipment that is arranged on the milling train in the leading portion and is arranged on the milling train in the back segment, to have diameter be 550mm or littler working roll to the milling train in the back segment of being arranged on of this rolling equipment; On one side described rolled piece is cooled off in the front and back along this rolled piece direction of travel of the milling train in the described back segment of being arranged at of this rolling equipment, is 0.9 or the rolling described rolled piece in highland more Yi Bian make accumulation strain.
Here, " strain " refers to following value, and promptly this value is the rolled piece thickness h at each milling train entrance side 0Thickness h with outlet side 1Difference obtain divided by both mean values.
ε=(h 0-h 1)/{(h 0+h 1)/2)
In addition, " accumulation strain " refers to ε cPromptly considering influences many (for example 3 of the strong and weak ground of metal structure weight calculation back segment, also may be 2) milling train (because of its effect little, so ignore its upstream milling train) in strain and suppose finish to gauge frame, last of finish to gauge thus respectively and last again strain is ε n, ε N-1And ε N-2, obtain thus
ε c=ε nn-1/2+ε n-2/4
Fine-grained steel manufacture method of the present invention uses any aforesaid equipment of hot rolling to come rolling rolled piece like this, and promptly the accumulation strain of the rolled piece in the rolling equipment back segment is 0.9 or bigger.
In addition, with 20 ℃/s or higher cooling rate the rolled piece after leaving described finish to gauge frame is just cooled off.
In addition, rolled piece P preferably contains 0.5% or carbon content still less and 5% or alloying element content still less.
The present invention relates to continuously hot rolling rolled piece ground and make the method for steel plate, wherein the rolled piece supply with heating has the rolling equipment that is equipped with to tandem a plurality of rolling machine frames in leading portion and back segment; The accumulation strain that makes on one side this rolled piece be 0.6 or more the highland with rolling this rolled piece of described rolling equipment, one side the outlet side of a rolling machine frame in this rolling equipment back segment cool off described rolled piece.
In addition, the rolled piece finishing temperature preferably is decided to be from Ar 3More than the transformation temperature-50 ℃ to Ar 3Below transformation temperature+50 ℃.
Here, " finishing temperature " refers to the rolled piece surface temperature of the thermometer measure in the rolling equipment downstream (several meters far away place in finish to gauge frame downstream) by being arranged on the rolled piece direction of travel.
In addition, the inside ferrite average grain diameter of the steel plate that obtains by rolling rolled piece preferably is about 3 μ m-7 μ m.
The present invention relates to the rolling continuous hot-rolling method for the treatment of rolled material and making slab, wherein the rolled piece supply with heating has the rolling equipment that tandem like this is arranged on a plurality of rolling racks in leading portion and the back segment, and promptly it can make steel plate in rolling rolled piece ground; Outlet side in operational finish to gauge frame cools off described rolled piece on one side, do not use on one side being arranged at least a portion in many rolling mills in this back segment and using of described rolling equipment near at least three rolling machine frame ground of described rolling equipment entrance side rolling this rolled piece like this, promptly the accumulation strain of described rolled piece be 0.25 or reduction ratio bigger or in operational finish to gauge frame be 12% or higher.
Here, " thin plate " refers to the steel plate of thickness less than 6mm, and " slab " refers to what the steel plate of 6mm or thicker (less than 50mm) was mentioned.
In addition, the finishing temperature of rolled piece preferably is set at and is no more than Ar 3Transformation temperature+50 ℃.
Here, " finishing temperature " refers to the rolled piece surface temperature of the thermometer measure in the rolling equipment downstream (several meters far away place in finish to gauge frame downstream) by being contained in the rolled piece direction of travel.
In addition, the average ferrite particle diameter described slab that obtains by rolling this rolled piece, count 1/4 the inside that reaches thickness of slab deeply on the slave plate surface is about 3 μ m-10 μ m.
Description of drawings
Fig. 1 is the schematic side view of configured in one piece of the equipment of hot rolling of the expression embodiment of the invention.
Fig. 2 A, 2B and 2C respectively with the leading portion milling train 1 relevant ground illustrative CVC function of rolling equipment shown in Figure 1.
Fig. 3 is the detailed side view of final milling train 6 grades of expression rolling equipment shown in Figure 1.
Fig. 4 is expression about with the grain size of the ferritic structure crystal grain of the steel plate of rolling equipment shown in Figure 1 manufacturing and the graph of a relation between the yield point.
Fig. 5 A, 5B and 5C represent near the crystalline structure near near the upper surface, the thickness of slab center and bottom surface with the steel plate of rolling equipment manufacturing shown in Figure 1 respectively.
Fig. 6 is the curve map that concerns between the equivalent roller footpath of working roll of expression reducing roller mill and the rolling load.
Fig. 7 is expression alleviates the edge attenuate by the reducing roller mill a curve map.
Fig. 8 is illustrated in the curve map that roller surface wearing and tearing when making with lubricator alleviate effect.
Fig. 9 is the side view that schematically illustrates according to the configured in one piece of the equipment of hot rolling of modification embodiment illustrated in fig. 1.
Figure 10 schematically illustrates the side view of the configured in one piece of continuous hot-rolling equipment according to another embodiment of the present invention.
Figure 11 A, 11B and 11C schematically represent the CVC function of the leading portion milling train 10 of rolling equipment shown in Figure 10 respectively.
Figure 12 is the back segment milling train 40-60 of expression rolling equipment shown in Figure 10 and near the side view of details thereof.
Figure 13 is that expression is by the accumulation strain of the rolling various steel plates that obtain of test and the curve map of the relation between the ferrite particle diameter.
Figure 14 is that expression is by the end temp (finishing temperature) of the rolling various steel plates that obtain of test and the curve map of the relation between the ferrite particle diameter.
Figure 15 is that expression is by the ferrite particle diameter of the rolling various steel plates that obtain of test and the curve map of the relation between the tensile strength.
Figure 16 is that expression is by the ferrite particle diameter of the rolling various steel plates that obtain of test and the curve map of the relation between the percentage elongation.
Figure 17 is expression by the curve map that concerns between the ferrite particle diameter of testing the rolling various steel plates that obtain and the tensile strength * percentage elongation.
Figure 18 A, 18b and 18C represent respectively the steel plate that obtains by the milling method embodiment that adopts rolling equipment shown in Figure 10 near the end face, interior dark 1/4 thickness inboard near reach near the mid-depth crystalline structure.
Figure 19 A, 19B and 19C represent respectively the steel plate that obtains by embodiment of the invention D near end face, in stretch near 1/4 thickness inboard and near the crystalline structure the mid-depth.
Figure 20 is the curve map that concerns between ferrite particle diameter, tensile strength and the yield point of the steel plate made by the embodiment of the invention of expression.
Figure 21 is the curve map of variations in temperature of the pendulum impact value of the steel plate made by the embodiment of the invention of expression and general steel plate (non-fine-grained steel plate).
Figure 22 is the curve map of variations in temperature of the embrittlement rate of the steel plate made by the embodiment of the invention of expression.
The specific embodiment
Below, the fine-grained steel board fabrication method that the equipment of hot rolling of the embodiment of the invention is described with reference to the accompanying drawings and uses this equipment of hot rolling to implement.
According to equipment of hot rolling embodiment illustrated in fig. 1 is the upstream (not shown) that a finish rolling equipment and heating furnace and roughing equipment are positioned in rolled piece P direction of travel, and a runout table and a coiling machine are arranged on the downstream (not shown).So form this equipment of hot rolling, promptly pass through continuous rolling, produce thin brilliant hot rolled steel plate with meticulous ferritic structure at the rolled piece P of upstream process roughing.
At first, as constituting equipment of hot rolling leading portion 3 rolling mills, tandem is provided with so-called CVC milling train 1,2 and 3.The CVC milling train 1 of the most close equipment of hot rolling inlet constitutes the four-high mill of being made up of working roll 1a and 1b and backing roll 1c and 1d as shown in Figure 1, and this working roll 1a and 1b have the convexity (CVC, promptly diameter changes continuously) shown in Fig. 2 A.Working roll 1a shown in Fig. 2 B and 2C and 1b can be on the axial length direction relative motion (moving) simultaneously, therefore, can adjust the roll shop building position and concern to be roll gap.The diameter of working roll 1a and 1b is taken as 700mm, and the maximum amount of movement that reaches forward backward is set at 100mm.In addition two CVC milling trains 2,3 are identical with CVC milling train 1 on structure and function.
The reason that CVC milling train 1,2 and 3 is set at leading portion is to make the center convex thick part (shape) of rolled piece P keep suitable like this.In the reducing roller mill 4,5 and 6 (back is described) of back segment, form easily hot convexity that the processing heat by rolling generation causes etc., thus come the center convex thick part of rectification plate by the CVC milling train 1,2 and 3 that is installed in leading portion in advance and reduce rolled piece P in the middle of shrink.
Promptly, CVC milling train 1,2 and 3 is compared with the device that carries out roller simply has bigger roll gap shape changing capability, because rolled piece is thick and leading portion that easily carry out convexity control partly is arranged on the center, so at adjustable plate center convex thick part and apply and prevent on the back segment of big pressure that the plate instability is by being favourable.
In addition, as 3 frame continuous-rollings of the back segment of closelying follow leading portion, the so-called reducing roller mill 4,5 and 6 that has tandem according to the equipment of hot rolling of this embodiment.The frame spacing that comprises all 6 rolling mills of aforementioned CVC milling train 1,2 and 3 all equates, as is 5.5m.Counting from CVC milling train 1 is that the 4th reducing roller mill 4 is configured to as illustrated in fig. 1 the four-high mill be made up of working roll 4a and 4b and backing roll 4c and 4d, and working roll 4a and 4b have different-diameter as shown in figure.
And, have only the major diameter lower roll 4b of working roll 4a and 4b to be driven rotation by a motor (not shown), so constitute minor diameter top roll 4a, promptly it does not freely rotate with can having driving force.Working roll 4a and 4b are furnished with a roller mechanism (not shown) respectively, thereby can make working roll 4a and 4b bending.In addition, working roll 4a and 4b are endowed the CVC function and can make it in the mobile 100mm in front and back on the long axis direction.
Because working roll 4a and 4b have been composed roller function and CVC function, so improved the shape of rolling piece control ability and can obtain good steel plate profile.
The diameter of working roll 4a is that the diameter of 480mm and working roll 4b is 600mm, is that the equivalent roller of both mean values directly is 540mm.Aspect such 26S Proteasome Structure and Function, in addition two reducing roller mills 5 after leaning on and 6 and reducing roller mill 4 do not have difference.In addition, although the equivalent roller footpath of the working roll of reducing roller mill 4,5 and 6 can be for less than 540mm, from the viewpoint of intensity, it is 400mm or bigger preferably.
Because the equivalent roller footpath of these three reducing roller mills 4,5,6 is less and make shearing force act on rolled piece P because of having only a working roll (4b etc.) to be driven, so, even if rolling load is lower, also can carry out the rolling of heavy reduction rate (reduction ratio) as 50%.Therefore, it is rolling to carry out forming depressing greatly of meticulous ferritic structure in rolled piece P under the low situation of rolling load.In addition, because rolling load is low, so shortcoming flat by roll-in and that the edge attenuate causes also can not occur.
The curve map X3 of Fig. 6 shows such situation, promptly (composition is 0.16% C with the steel plate that equates the rolling thick 2.3mm of reduction ratio (48%), wide 730mm when the 6th reducing roller mill 6,0.22% Si and 0.82% Mn) time, how the equivalent roller footpath of working roll changes with rolling load.
In addition, curve X5 shown in Figure 7 represents that (diameter of working roll 5a and 5b is 480mm when certain reducing roller mill 5,6, the diameter of working roll 5c and 5d is 600mm, and the equivalent roller of each milling train is directly for 540mm) the edge attenuate that produced during rolling steel plate same as shown in Figure 6.In addition, in order to contrast, curve X4 shown in Figure 7 shows the edge attenuate when working roll is made into same thickness (intermediate diameters of 600mm) and rolling identical steel plate.
In addition, as the modified example of this embodiment, as shown in Figure 9, be arranged on milling train in the back segment and can replace reducing roller mill 4,5,6 ground to become comprising that a pair of diameter is less than the working roll 4a ' of 600mm and the ultra-fine roller mill 4 ', 5 ' and 6 ' of 4b '.
In addition, in the equipment of hot rolling of this embodiment, be each working roll outfit feeding lubricating device of all 6 rolling mill 1-6.This installs, and symbol 5e, 5f, 6e and 6f ground for example are made up of the spout and the lubricant supply pump of the roll surface of working towards each as shown in Figure 3.In addition, a modified example is not as an example directly supplied with lubricant each work roll surface, but by lubricant being supplied with rolled piece P surface, thereby the indirect supply roll surface.
In addition, in the equipment of hot rolling of this embodiment, lubricant is used for avoiding each roll surface wearing, rather than is used for reducing coefficient of friction.Therefore, the fine-particle solid lubricant can be used as lubricant as calcium phosphate, mica or the calcium carbonate that comprises grease.By mixing those solia particles, each working roll and the coefficientoffriction between the rolled piece P when making with lubricator become quite high, as 0.28 or higher.When guaranteeing high like this coefficient of friction, suitably prevented skidding of rolled piece P and roller.
When using above-mentioned lubricant, above-mentioned particulate can prevent that roll from directly contacting rolling stock between each roll surface and rolled piece P, thereby suppresses roll surface wearing, and is easy to keep well for a long time the shape of rolled piece P.In addition, comprise at the lubricating grease proxy mineral under the situation of solia particle oilyly, have such advantage, do not worry promptly that particulate can be deposited in the lubricant storage container and supply of lubricant like this, promptly solia particle always uniformly dispersing on roll surface.
Fig. 8 shows the effect that with lubricator alleviates roll wear because of making, and curve X6 represents not make situation with lubricator, and curve X7 represents to make situation with lubricator.In addition, the transverse axis of Fig. 8 is represented the working roll payload, and the longitudinal axis is represented the working roller abrasion amount.
In addition, in the equipment of hot rolling of this embodiment, curtain wall formula cooler 7A, 7B and 7C are set at the outlet side of reducing roller mill 4,5 and 6, are that example describes with cooler 7B.As shown in Figure 3, cooler 7B rushes on the whole plane of structure of rolled piece P a large amount of normal temperature cooling water laminar flow shapes (best is 16mm for curtain wall formula, thick 10mm or thicker) from last lower nozzle 7Ba and 7Bb, thereby cools off rolled piece P strongly.Cooling water inflow can be at 100m 3/ h-500m 3The temperature drop speed of adjusting and rolling stock P is 20 ℃/s or higher in/h/ rolled piece P unit width (1m) scope.In curtain wall formula cooler, use 350m usually 3The cooling water of/h/ unit width.When steel plate thickness and speed long-pending during for 1200mmmpm, the temperature drop speed of such rolled piece P reaches 60 ℃/s-80 ℃/s and (comprises the intensification that is caused by the processing heating, about 40 ℃/s).Other cooler 7A also has identical 26S Proteasome Structure and Function with 7C.
In addition, in the equipment of hot rolling of this embodiment, curtain wall formula cooler is arranged on the outlet side of back segment milling train 4,5 and 6.But, being provided with that quantity is not limited thereto and can changing along with the rolled piece kind fully of cooler.
By using curtain wall formula cooler 7A, 7B and 7C, the rolled piece P that has caused owing to the processing heating in having suppressed during rolling heats up and rolled piece P is remained on and is suitable for depressing greatly in the warm area of rolling or controlled rolling method, and has suppressed growing up of delicate tissues after rolling.
In addition, cool off rolled piece P by cooling water with 10 ℃/s or higher speed equally in the runout table (not shown) in equipment of hot rolling shown in Figure 1 downstream, to prevent grain growth.
In equipment of hot rolling shown in Figure 1, water jet 8 is arranged on the outlet side of final reducing roller mill 6 to 1 meter from the about hundreds of millimeter of curtain wall formula cooler 7C.This is in order to remove the cooling water of staying on the rolled piece P upper surface by cooler 7C.As shown in Figure 3, water jet 8 has a plurality of nozzle 8a (in this embodiment totally 4), and they are respectively with about 10kg/cm of 300 liters 2Water under high pressure the upstream side towards rolled piece P direction of travel tiltedly down is ejected on the rolled piece surface from rolled piece P top, the angle of cut of injection water and rolled piece P upper surface is 65 ° (or 50 °-80 °).As shown in Figure 3, on rolled piece P length direction, at regular intervals and at its width a plurality of nozzle 8a are set at regular intervals also.Nozzle 8a makes water spread out on rolled piece P width with brushing water, and the angle of spread on rolled piece P width preferably is made as 15 °-30 °, and the angle of spread in the longitudinal direction preferably is made as 1 °-10 ° (in this embodiment, they are made as 21 ° and 3 ° respectively).
Can stay cooling water on the rolled piece P by using such water jet 8 to remove smoothly because of cooling device 7 work, thus can suitably carry out by each measuring instrument that is installed in the downstream with rolling after rolled piece P be the relevant various measurements of finished product steel plate.Here,,, it obtains so easily being endowed kinetic energy and being easy to because water is heavier than air, so the suitable injection stream of doing of water.The reason that produces good action can be considered to, can prevent that by tiltedly down blowing water under high pressure cooling water from arriving downstream (measuring instrument side), and can in the whole width range of rolled piece P upper surface, remove cooling water by using the nozzle that launches at rolled piece P width towards the upstream.
In addition, be equipped with roll cooling water nozzle (as symbol 5i, 5j, 6i, 6j) as illustrated in fig. 3 for the working roll of each rolling mill and removed the drain bar (as symbol 5g, 5h, 6g, 6h) of resultant cooling water.
Then, the embodiment that uses above-mentioned equipment of hot rolling (Fig. 1) to carry out hot rolling is described.
About the steel (not comprising other important component) of the chemical composition of Mn with 0.16% C, 0.2% Si and 0.82%, the steel plate of thick 2.33mm, wide 730mm is that (embodiment 1-3) makes by rolling equipment shown in Figure 1 under three kinds of conditions.Following table 1-1 shows the passage program list (rolling condition) of embodiment 1, and table 1-2 shows the passage program list of embodiment 2 and 3.In addition, table 1-3 is illustrated in curtain wall formula cooler 7A, 7B among the embodiment 1-3 and the operating position of 7C, and table 1-4 is illustrated in the finishing temperature of the rolled piece P that measure in finish to gauge frame 6 backs among the embodiment 1-3.In each table, roughing equipment of " roughed bloom " expression, and " F1 "-" F6 " represents first to the 6th rolling mill 1-6.In addition, mill speed is not particularly limited, and adopts the mill speed (as 7m/s-9m/s) of the long usefulness of general tropocal wood milling train.
[table 1-1]
Embodiment 1: passage program list (accumulation strain=0.65)
Roughed bloom ????F1 ????F2 ????F3 ????F4 ????F5 ????F6
Thickness of slab Mm ??40 ????22.82 ????12.55 ????7.53 ????4.89 ????3.33 ????2.33
Reduction ratio ????43 ????45 ????40 ????35 ????32 ????30
Strain - ????0.55 ????0.58 ????0.50 ????0.42 ????0.38 ????0.35
Accumulation strain - ????????????????????????????????????????????????????????????????????????????????0.65
[table 1-2]
Embodiment 2,3: passage program list (accumulation strain=0.92)
Roughed bloom ????F1 ????F2 ????F3 ????F4 ????F5 ????F6
Thickness of slab Mm ???40 ????25.96 ????17.39 ????12.17 ????7.06 ????3.88 ????2.33
Reduction ratio ????35 ????33 ????30 ????42 ????45 ????40
Strain - ????0.42 ????0.40 ????0.35 ????0.53 ????0.58 ????0.50
Accumulation strain - ????????????????????????????????????????????????????????????????????????????????????0.92
[table 1-3]
Cooling condition (curtain wall)
Embodiment The F4 rear surface The F5 rear surface The F6 rear surface
????1 Do not use Do not use Use
????2 Do not use Do not use Use
????3 Use Use Use
[table 1-4]
Temperature conditions
Embodiment Finishing temperature, ℃
??1 ????800~850
??2 ????800~850
??3 ????750~780
Table 1-5 shows respectively the ferrite particle diameter and the mechanical performance of the hot rolled steel plate that is obtained by embodiment 1-3.In table 1-5, " TS " represents tensile strength, and " YP " represents yield point, and " EL " expression percentage elongation.In addition, in table 1-5, also write down as table 1-1 to the main rolling condition shown in the table 1-3.
[table 1-5]
Rolling condition and mechanical performance
Embodiment The curtain wall cooling Accumulation strain The ferrite particle diameter ??TS?kg/mm 2 ??YP?Kg/mm 2 ????EL%
?1 ????F6 ?0.65 ?6~9 ??45~50 ??30~40 ????25~30
?2 ????F6 ?0.92 ?4~4.5 ??55~65 ??45~55 ????25~30
?3 ????F4、F5、F6 ?0.92 ?3.5~4 ??57~65 ??49~57 ????26~30
TS: tensile strength, YP: yield point, EL: percentage elongation
As show shown in the 1-5, at accumulation strain (above-mentioned weight calculation value ε c) be among 0.92 the embodiment 2,3, can obtain to have ferritic structure and the outstanding steel plate of mechanical performance that particle diameter is about 4 μ m.Be used among the embodiment 3 of 3 (F4-F6) milling train outlet sides (rear surface) of back segment at curtain wall formula cooler 7A-7C, obtained to have diameter and be about 4 μ m or littler ferritic structure and the outstanding especially steel plate of mechanical performance.
Fig. 4 represents by the grain size (-1/2 power of particle diameter D (μ m)) of the ferritic structure crystal grain of the steel plate of embodiment 1-3 acquisition and the relation between the yield point.As shown in the figure, when the accumulation strain of 3 rolling mills of back segment is 0.65 (being shown in the group X2 of Fig. 4), grain size be 0.43 or littler (5.4 μ m or bigger particle diameter) and yield point not high enough.But when accumulation strain was 0.92, grain size became about 0.5 (particle diameters of about 4 μ m) and yield point is brought up to 45kg/mm 2Or it is higher.
And Fig. 5 A, 5B and 5C are presented near the crystalline structure near near the end face, the thickness of slab center and bottom surface of the steel plate that obtains among the embodiment 3 respectively.On any part in plate, form the meticulous ferritic structure that particle diameter is about 3 μ m.
As mentioned above, according to this embodiment, can successfully make and contain meticulous ferritic structure and comprise tensile strength, ductility, toughness and thin brilliant hot rolled steel plate that fatigue strength intensity is harmonious outstanding, this steel plate also can suitability for industrialized production, the reasons are as follows:
A) be arranged on 2 of back segment or more reducing roller mill 4,5 and 6 or ultra-fine roller mill 4 ', 5 ' and 6 ' because of equivalent roller footpath or working roll (to) diameter all little can be under low rolling load realization depress greatly rolling, i.e. high rolling of reduction ratio.This be because, along with work roll diameter diminishes, the rolling load under identical reduction ratio reduce and roughly with work roll diameter proportional (with reference to figure 6).When rolling load reduces, eliminated and to have carried out the high rolling phenomenon of reduction ratio because of roll-in is flat and reduce to have alleviated edge attenuate (with reference to figure 7) because of the flat deflection of roll.
B) being installed in curtain wall formula cooler 7A, 7B in the back segment and 7C has suppressed along with accumulation should be 0.9 or the rolling and intensification that is caused by rolled piece P processing heating that produces of bigger heavy reduction rate.Cooler 7A, 7B and 7C be by the strong cooling metal sheets P of above-mentioned mobile a large amount of cooling waters, so even rolled piece P is accelerated, cooler also can make steel P remain on to be suitable in the warm area of realizing depressing greatly rolling (as Ar 3Transformation temperature is to Ar 3Transformation temperature+50 ℃).By after rolling, cooling off rolled piece P immediately strongly, can stop the ferritic structure grain growth among the rolled piece P, and the diameter of the ferritic structure crystal grain in the finished product steel plate can carefully arrive 4 μ m or littler according to appointment.Because cooler 7A, 7B and 7C not only are arranged on the outlet side of final frame 6, and be arranged on the outlet side of at least 2 rolling mills of back segment, so the heat that when final frame 6 and this forebay rolling, produced and suitably keep temperature of having left effectively.Because cooler 7A, 7B and 7C are arranged on the outlet side of every rolling mill,, also guaranteed to stop growing up of delicate tissues crystal grain thus after rolling by every rolling mill so rolled piece P is cooled off immediately strongly.In addition, because cooler 7A, 7B and 7C are flushed to water in the whole width range of rolled piece P, do not lay particular stress on evenly cooling rolled piece P of ground so can on width, have.
As mentioned above, according to this embodiment, with implement to depress the relevant problem i of rolling greatly) and ii) obtained solution, and can successfully make the fine-grained steel plate and can realize the suitability for industrialized production of fine-grained steel plate by the rolling equipment of one-tenth ordinary hot band and strip rolling mill form.
In addition, when suitably using curtain wall formula cooler 7A, 7B and 7C that rolled piece P warm area is remained on 700 ℃-800 ℃ (warm area), the steel that contains Nb and Ti is used as rolled piece P, also can stably realize above-mentioned controlled rolling method (can make the fine-grained steel plate subsequently).
In addition, contain 0.5% or following carbon and 5% or during the rolled piece of following alloying element when rolling, because of mechanical performance equilibrium (is general from tensile strength and ductility equal angles) and Weldability strong etc., there is the fine-grained steel plate of such composition to be widely used, and because of relatively cheaply being easy to obtain, and owing to it can reclaim, so people can press for this material.Therefore, the steel plate that such component content arranged is big and produce very economical rationality to the contribution of society.
Usually, when carbon content increases, the steel that ferrite content reduces and obtains mainly to be made up of pearlite.But according to this embodiment, even carbon content is identical, ferrite content also can increase, and when carbon content less than 0.5% the time, can obtain the tissue that mainly constitutes by ferrite.
In addition, no matter whether de-carbon alloying element is in addition arranged in rolled piece P, this embodiment has also obtained excellent results.But for will be from Ar 3Transformation temperature is to Ar 3The warm area of transformation temperature+50 ℃ is set at 700 ℃-900 ℃, and this warm area is suitable as the warm area of hot rolling most, preferably adjusts phase point temperature according to the alloying element total amount.But when the alloying element total amount greater than 5% the time, Ar 3The transformation temperature very low and difficult acquisition that becomes is carefully brilliant.
Then, equipment of hot rolling and hot-rolling method according to another embodiment of the present invention are described.
According to the hot-rolling method of the foregoing description mainly by the back segment milling train depress strongly (that is, accumulation strain be 0.9 or bigger drafts) rolled piece and make steel plate remain under the proper temperature and produce the ferrite particle diameter thus to be about 4 μ m or littler high-quality fine-grained steel plate.For realizing this method, equipment of hot rolling shown in Figure 1 has adopted the structure of carrying out required drafts and strong cooling rolled piece by low rolling load.Thus one, if (temperature control) rolled piece is cooled off on the enough highlands of drafts strongly, then can industrially produce the very high thin brilliant hot rolled steel plate of quality by common tandem rolling equipment.
But exist in the above-described embodiments, about load or the most effective operation that alleviates the equipment of putting on and the room for improvement of making thin brilliant hot rolled steel plate.That is,, suppress quality (ferrite particle diameter etc.) as far as possible and descend, can relax the low-cost fine-grained steel plate of making in the ground of creating conditions thus by the influence of further research drafts and cooling condition to the rolled piece metal structure.
By improving rolling from such cost effectiveness aspect, industrially produce easily complete practicality but the lower slightly fine-grained steel plate of quality level (particle diameter etc.).Normally indispensable under the situation of not considering plate quality as said heavy reduction of above-mentioned embodiment etc., then improved production cost with rolling equipment structure and roll consumption relevantly, and by following the rolled piece processing heating of depressing greatly to cause, cooling device also needs higher equipment cost and operating cost.
Equipment of hot rolling and method according to this embodiment solve these problems.
According to continuous hot-rolling equipment embodiment illustrated in fig. 10 is to be used for the so-called finish rolling equipment of rolled piece P and to be provided with a heating furnace and a roughing equipment in the upstream (not shown) of rolled piece P direction of travel, is provided with a runout table and a coiling machine in the downstream (not shown).Equipment of hot rolling is respectively formed with the tandem mill 10-60 of roll by amounting to 6, and its continuous rolling is passed through the rolled piece P of roughing and produced the various hot rolled steel plates of common thick about 2mm-16mm in the upstream.In the steel plate of making ordinary internal tissue (average ferrite particle diameter be 10 μ m or bigger) smoothly common rolling, realize the rolling of fine-grained steel by suitable setting service condition, just, manufacturing has the thin brilliant hot rolled steel plate of meticulous ferritic structure, and the structure of rolling equipment shown in Figure 10 is as follows.
At first, as 3 frames of leading portion, tandem is provided with so-called CVC milling train 10,20 and 30.Near the form of 10 one-tenth in the CVC milling train of the equipment of hot rolling entrance side four-high mill of being made up of working roll 101a and 101b and backing roll 101c and 101d as shown in figure 10, working roll 101a and 101b have the convexity (CVC, diameter changes continuously) shown in Figure 11 A.Working roll 101a shown in Figure 11 B and 11C and 101b can be on the axial length direction relative motion (moving) simultaneously, the position that therefore can adjust between the roll concerns to be roll gap.The diameter of working roll 101a and 101b is decided to be 700mm and the maximum amount of moving forward and backward is decided to be 100mm.In addition two CVC milling trains 20 are identical with CVC milling train 10 on structure and function with 30.
At leading portion CVC milling train 10,20 and 30 being set like this is to make the center convex thick part (shape) of rolled piece P keep suitable.Afterwards in the reducing roller mill 40,50 and 60 of the back segment that will describe, when rolling fine-grained steel, form the hot convexity that causes by rolling processing heating easily, so come the center convex thick part of rectification plate and can reduce the middle of rolled piece P to shrink by the CVC milling train 10,20 and 30 that is contained in the leading portion in advance.CVC milling train 10,20 links to each other with the AC motor (not shown) that a speed-change control device is arranged by a reduction gear box and a universal-joint spindle (all not shown) respectively with 101b with 30 working roll 101a.
As three follow-up frames, tandem is provided with so-called reducing roller mill 40,50 and 60.The frame spacing that comprises all 6 rolling mills of aforementioned CVC milling train 10,20 and 30 all equates, as is 5.5m.The form of the four-high mill that 40 one-tenth of the 4th reducing roller mills of counting from CVC milling train 10 are made up of as shown in figure 10 working roll 104a and 104b and backing roll 104c and 104d, in this example, working roll 104a and 104b have different-diameter.The major diameter lower roll 104b that has only working roll 104a and 104b is (not shown by a motor that links to each other by reduction gearing chest (not shown) and universal-joint spindle, be the AC motor that speed-change control device is arranged) drive and rotate, so constitute minor diameter top roll 104a, promptly it does not rotate freely with can having driving force.Working roll 104a and 104b are furnished with a roller mechanism (not shown) respectively, so, can make working roll 104a and 104b bending.In addition, working roll 104a and 104b are endowed CVC function and can be before and after on the axial length direction in the mobile 100mm.The diameter of working roll 104a is 480mm, and the diameter of working roll 104b is 600mm, is that the equivalent roller footpath of both mean values is less, as is 540mm.In said structure and function aspects, in addition two the reducing roller mills 50 after leaning on are identical with 60 with reducing roller mill 40.
Less and shearing force is acted on the rolled piece P because of its equivalent roller footpath because of having only a working roll 104b to be driven, so, these three reducing roller mills 40,50 and 60 even can to carry out heavy reduction rate (reduction ratio as 50%) under quite low rolling load rolling.Therefore, rolling fine-grained steel depress rolling can under low-down rolling load, carrying out greatly, in addition, at this moment because rolling load is low, so even the thick thin plate of rolling about 2mm also can be avoided the shortcoming that causes because of roller flatness and edge attenuate.
Rolling for carrying out fine-grained steel continuously, need fully cooling rolled piece P and it is remained in the suitable warm area, so before every rolling mill 40,50 and 60 of the back segment of equipment of hot rolling and/or all be provided with as shown in figure 10 curtain wall formula cooler 107 (symbol 107A-107H shown in Figure 12) afterwards.Cooler 107 be into curtain (curtain wall shape) make to form a large amount of normal temperature cooling waters (laminar flow, symbol f as shown in figure 12) from top loading or below shower nozzle impact the whole athwartship plane of rolled piece P.Become the thickness (curtain thickness) of the cooling water of curtain shape to be necessary for 10mm or bigger, from the viewpoint of cooling effect, it preferably is about 16mm.The cooling water inflow of each cooler 107 can be at 100-500m 3Adjust in the scope of/h/ rolled piece unit width (1m), the temperature drop speed of the rolled piece P that is cooled is set at 20 ℃/s or higher.When increasing drafts, use 350m 3The cooling water of/h/ unit width.But when thickness of slab and speed long-pending during for 1200mmmpm, the temperature drop speed of rolled piece P reaches 60 ℃/s-80 ℃/s and (comprises the intensification that causes because of the processing heating, about 40 ℃/s).
The a plurality of coolers 107 that show among Figure 10 are arranged on the upper surface and bottom surface of rolled piece P as illustrated in fig. 12, on rolled piece P upper surface, cooler 107A, 107B, 107D, 107E and 107G are separately positioned on the back of milling train 40, the front and back of milling train 50 and the front and back of milling train 60, on the bottom surface of rolled piece P, cooler 107C, 107F and 107H are separately positioned on the back of milling train 40,50 and 60.Wherein, cooler 107H is installed at the rear portion of finish to gauge frame 60 on the support of roller-way T, and other cooler 107A-107G is fixed on the memorial archway of each rolling mill.
By using curtain wall formula cooler 7 at 3 rolling mills 40,50 of back segment and each outlet side of 60, even if that uses that the equipment of hot rolling of this embodiment realizes being attended by remarkable processing heating depresses rolling and controlled rolling method greatly, also suppressed the intensification of milling train 40,50 and 60 and rolled piece P is remained in the suitable warm area, and, can be at the grain growth of rolling back inhibition delicate tissues.In addition, even if on the runout table (not shown) in equipment of hot rolling downstream shown in Figure 10, the rolled piece P water cooling that is cooled equally is to prevent grain growth.
In addition, as shown in figure 10, in equipment of hot rolling, water jet 108 is arranged on the outlet side of last rolling mill 60 and apart from curtain wall formula cooler (107G, 107H) hundreds of millimeter-1 meter is arranged in the downstream.It is to remove the mechanism that stays the lip-deep cooling water of rolled piece P because of a plurality of cooler 107G and 107H, it tiltedly down thinks high pressure water jets the upper surface of rolled piece P from the rolled piece top towards the upstream of rolled piece direction of travel by a plurality of nozzle (not shown), thereby water is launched on the width of rolled piece P.By using water jet 108, can successfully remove because of cooling device 107 work and stay cooling water on the rolled piece P, thereby can pass through various measuring instruments (thermometer etc., not shown) suitably measure with rolling after relevant each value (finishing temperature etc.) of rolled piece P.When measuring accuracy is high, can wait the rolling condition of accurately controlling as finishing temperature by the control cooling water inflow.
That be contained in water jet 108 downstreams by one and measure the finishing temperature of steel P in the downstream apart from finish to gauge frame 60 about 2m thermometer far away and increase and decrease the cooling water inflow of each curtain wall formula cooler 107 (cooler 107E, the 107G and the 107H that especially keep finish to gauge frame 60) by a calculating operation device (not shown) that receives measurement result.Control finishing temperature and it is remained in the suitable scope by FEEDBACK CONTROL.
In the continuous hot-rolling equipment of above-mentioned structure is arranged, can guarantee that good productivity ground is with the thick good thin brilliant hot rolled steel plate of sufficiently high speed (as 7m/s-9m/s) the about 2mm-6mm of manufacturing.Specifically, by rolling acquisition 0.6 or higher accumulation strain (above-mentioned weight calculation value ε c) and cool off strongly by the curtain wall formula cooler 107 behind each back segment milling train 40,50 and 60, as rolled piece, can make the fine-grained steel plate that average ferrite particle diameter is about 3 μ m-7 μ m by the steel that phosphorus content and alloying element amount is low.Though the percentage elongation of some fine-grained steel is less, can eliminate such shortcoming.The example that the embodiment that the back will be described comes to this.
Can realize this excellent product be because, in having a strong impact on the back segment mill stand of metal structure, the curtain wall formula cooler 107 that higher cooling capacity is arranged by use, the temperature of rolled piece P is remained in the suitable scope, by minor diameter reducing roller mill 40,50 and 60, can realize that heavy reduction rate is rolling, thereby produce above-mentioned accumulation strain.In milling train 40,50 and 60, can avoid the flat and edge attenuate of roll-in, the center convex thick part can be controlled by the CVC function of milling train 10,60, so in the back segment of making steel plate thinner, also can suppress the curved and shape deterioration of snake of rolled piece P.Therefore, in this embodiment, can also can form the very accurate steel plate of shape by very successfully rolling fine-grained steel plate.
The inventor is by using equipment of hot rolling shown in Figure 10 and differently changing the cooling degree (finishing temperature) of rolled piece and many tests that drafts (accumulation strain) carries out and discovered and can produce satisfied fine-grained steel plate under these conditions.This test and research and data relevant with the embodiment that obtains satisfied fine-grained steel plate are as follows.
Continuous hot-rolling equipment by using this embodiment and differently change secondary program and table 2-1 shown in the finishing temperature of steel grade (not comprising other important composition), try rolling.But the steel plate of 60 outlet sides of finish to gauge frame in all cases, is thick is that 2mm-3mm and mill speed are 8m/s-9m/s.
[table 2-1]
The chemical composition of steel (weight %)
Transformation temperature (℃)
????C ????Si ????Mn ??Ar 3
Embodiment ????0.16 ????0.2 ????0.8 ??785
For by trying for the rolling many steel plates that obtain, measure the ferrite particle diameter of mid-depth and check accumulation strain during rolling and the relation between the end temp (finishing temperature).Relation between accumulation strain (transverse axis) and the ferrite particle diameter (longitudinal axis) as shown in figure 13.In the drawings, symbol ● the expression finishing temperature is at Ar 3Data in the time of in ℃ scope of transformation temperature ± 10, ▲ expression finishing temperature become and are lower than Ar 3Data during transformation temperature-10 ℃, ■ represents that finishing temperature becomes and is higher than Ar 3Data (Figure 13-17) during transformation temperature+10 ℃.
According to Figure 13, when finishing temperature is higher than Ar 3During transformation temperature+10 ℃, see that slightly the ferrite particle diameter increases the trend that reduces with accumulation strain, when finishing temperature not simultaneously, even accumulation strain increases, the ferrite particle diameter also reduces hardly.
On the other hand, Figure 14 is the relation of expression of transverse axis ground and ferrite particle diameter (longitudinal axis) with the finishing temperature.Figure 14 shows ferrite particle diameter footpath when finishing temperature reduces and obviously reduces.
In addition, the mechanical performance of checking each finished product steel plate and result thereof and ferrite particle diameter etc. relevant and be recorded among each figure among Figure 15-17, transverse axis is represented-1/2 side's value of particle diameter (μ m).
Figure 15 represents the relation between ferrite particle diameter and the tensile strength (MPa), and Figure 16 represents the relation between ferrite particle diameter and the percentage elongation (%).As shown in the figure, when the ferrite particle diameter reduced (transverse axis right side), tensile strength was tending towards improving, and was lower than Ar up to becoming when finishing temperature 3During transformation temperature-10 ℃ (among the figure ▲), ferrite particle diameter refinement and percentage elongation reduces.When finishing temperature is lower than Ar 3During transformation temperature-10 ℃, the same during with the refinement of ferrite particle diameter, the product of tensile strength and percentage elongation (MPa * %) also reduced as illustrated in fig. 17.
On these results' basis, can determine the following fact.That is:
A), lower finishing temperature is set than higher accumulation strain is set and more effectively obtains the tiny thin brilliant hot rolled steel plate of ferrite by the rolling equipment (Figure 10) of this embodiment.
B) but be starkly lower than Ar when finishing temperature 3During transformation temperature,, also can reduce percentage elongation, thereby reduce the advantage of intensity even carried out refinement.
C) consider structure and the roll wear cost related that has improved when increasing accumulation strain with rolling equipment when implementing to depress greatly, from the cost effectiveness viewpoint, preferably make accumulation strain not too high, as 0.6 (best 0.65) or bigger and less than 0.9, and accurately control finishing temperature, thereby obtain the fine-grained steel plate.By making finishing temperature remain on Ar 3In the scope of transformation temperature ± 50 ℃, can produce its ferrite particle diameter and be 4 μ m-6 μ m's and the harmonious outstanding fine-grained steel plate of mechanical strength.Especially by finishing temperature is set in as Ar 3Transformation temperature-50 is ℃ to Ar 3In the scope of transformation temperature+20 ℃, preferably be set in as Ar 3Transformation temperature-20 is ℃ to Ar 3In the scope of transformation temperature+50 ℃, obtain the also outstanding steel plate of tensile strength height and percentage elongation thus.But, preferably make finishing temperature remain on Ar from each intensity and balanced angle thereof 3In the scope of transformation temperature ± 10 ℃.
In table 2-2 to 2-4 and Figure 18, introduced the embodiment that makes good fine-grained steel plate based on the knowledge ground of acquisition like this.In addition, " F10 " shown in the table represents first respectively to the 6th rolling mill 10-60 to " F60 ".
It is wide that table 2-2 shows thickness of slab (thickness of slab of " roughed bloom thickness " expression roughing equipment outlet side), reduction ratio (%), strain, accumulation strain and the plate of milling train 10-60 outlet side, and table 2-3 shows operating position and end temp (finishing temperature) at each curtain wall formula cooler 7 of each milling train 40-60 back.Table 2-4 has shown at table 2-1 to the steel plate of the embodiment that shows to obtain under the condition shown in 2-3 ferrite particle diameter and the mechanical performance at the thickness of slab central part.The steel plate that Figure 18 A, 18B and 18C represent this embodiment respectively near the end face, interior dark 1/4 thickness inboard near reach near the mid-depth crystalline structure.In each part, all form the delicate tissues that average ferrite particle diameter is about 4 μ m-6 μ m.
In addition, the rolling rolling equipment by this embodiment (with reference to figure 10-12) that obtains rolling and this embodiment of data shown in Figure 13-17 is realized.But for using accumulation strain to be about the rolling of 0.6-0.9, can infer, need not use the reducing roller mill 40-60 of above-mentioned back segment.That is,, can infer that also they are enough even these milling trains have equivalent diameter as being about the upper and lower working roll of 600mm-700mm.In addition, if the accumulation strain of this degree is enough, then follow the hot convexity of processing heating to estimate it is not obvious, so think it unnecessary to give milling train 10-60 with CVC function and roller function.
[table 2-2]
Roughed bloom ????F10 ????F20 ????F30 ????F40 ????F50 ????F60 The wide mm of plate
Thickness of slab ????Mm ?40 ????22.28 ????13.19 ????7.78 ????4.52 ????2.85 ????2.07
Reduction ratio ????% ????44 ????41 ????41 ????42 ????37 ????28 ???670
Strain ????- ????0.56 ????0.51 ????0.52 ????0.53 ????0.45 ????0.32
Accumulation strain ????- ????????????????????????????????????????????????????????????????????????????0.68
[table 2-3]
The rear surface of F40 The rear surface of F50 The rear surface of F60 Finishing temperature, ℃
Embodiment Use Use Use ??782
[table 2-4]
Mechanical performance
The ferrite particle diameter, μ m ???TS?Mpa ??YP?MPa ????EL%
Embodiment ??4.5 ???519 ??431 ????34
TS: tensile strength, YP: yield point, EL: percentage elongation
According to the continuous hot-rolling method of this embodiment, can be under moderate condition make very at low cost enough little average ferrite particle diameter is arranged, outstanding mechanical performance and the sufficiently high thin brilliant hot rolled steel plate of practical quality.
Promptly, pass through a) to use multi-set of rolling mill to realize that accumulation strain is as being to depress rolling b greatly 0.6 or more) cool off rolled piece P strongly at each multi-set of rolling mill outlet side of back segment, thus effectively loose the processing heat in finally frame and this forebay, sent when rolling and keep suitable temperature (as to make finishing temperature remain on Ar 3In the scope of transformation temperature ± 50 ℃) and stop the grain growth of delicate tissues, average ferrite particle diameter be can make thus and 10 μ m or littler thin brilliant hot rolled steel plate are about.
By inventor's current research, known by above-mentioned processing to obtain the fine-grained steel plate.That is, confirmable is under the condition of depressing rolling rolled piece and strong cooling greatly, even the former condition is relaxed (that is, even accumulation strain increases to 0.9) slightly, also can produce the too thick high-quality fine-grained steel plate of ferrite crystal grain.Particularly, average exactly ferrite particle diameter can be reduced to about 3 μ m-7 μ m by aforesaid accumulation strain and cooling.
If 0.6 or higher accumulation strain just enough, then significantly reduced the especially required reduction ratio (about 30%) of back segment milling train of milling train, and required cost of the equipment that greatly reduces and operating cost.Therefore, can not be nipped the well skidding of any milling train of rolled piece P head end does not appear.
In addition, when average ferrite particle diameter be 10 μ m or more hour, the mechanical performance of fine-grained steel plate can be extensive use of significantly better than common (non-fine-grained steel) hot rolled steel plate and the expection of particle diameter greater than 10 μ m.That is, in the fine-grained steel plate with above-mentioned chemical composition and ferrite particle diameter, mechanical performance harmony (is general from the angle of tensile strength, percentage elongation and ductility) is good and Weldability is outstanding.Therefore, the fine-grained steel plate is widely used, and owing to low relatively price is easy to obtain, and it has good recovery, so people press for such material.Therefore, in making this embodiment milling method of this steel plate, big and economic rationality its production is also very high to the contribution of society.
The hot-rolling method of another embodiment of the present invention then, will be described.
The hot-rolling method of this embodiment relates to the method for using equipment of hot rolling embodiment illustrated in fig. 10 to make slab.
In the equipment of hot rolling of previous embodiment shown in Figure 10, CVC milling train 10,20 and 30 and reducing roller mill 40,50 and 60 in, consider when rolling carrying out, thickness of slab reduces and the mill speed raising, the speed reducing ratio of back segment milling train reduces and the maximum revolution of working roll increases, and sets low maximum output torque simultaneously.The permission maximum output torque value of milling train 10-60 is respectively 125.0,98.2,61.4,34.1,22.7 and 19.5 (unit is ton (tf) .m).
And all milling train 10-60 of the rolling equipment by using the foregoing description shown in Figure 10 under the speed (as 7m/s-9m/s) of sufficient to guarantee excellent product, can produce the good thin brilliant hot rolled steel plate of thick about 2mm-6mm.Specifically, by rolling obtain 0.6 or bigger accumulation strain (be above-mentioned weight calculation value ε c) and cool off strongly by the curtain wall formula cooler 107 in each back segment milling train 40,50 and 60 back, by phosphorus content and the low steel of alloying element amount are used as rolled piece P, can produce the preferred fine-grained steel plate that average ferrite particle diameter is about 4 μ m-6 μ m.Especially, when accumulation strain be 0.9 or when bigger, the average ferrite particle diameter of identical steel grade can be reduced to 4 μ m or littler.The Comparative examples A that the back will illustrate is that a relevant example (is worked as ε c=0.6 o'clock).The reason that can obtain this product is, in having a strong impact on the back segment mill stand of metal structure, the curtain wall formula cooler 107 that has high cooling capacity by use, the temperature of rolled piece P is remained in the suitable warm area, by minor diameter reducing roller mill 40,50 and 60, can realize depressing greatly rolling and produce aforementioned accumulation strain.In milling train 40,50 and 60, can avoid roll flattening and edge attenuate and control convexity by the CVC function of milling train 10-60, so steel plate is being made in the thinner back segment, can suppress the curved and shape of the snake of rolled piece P and worsen, this also is one of reason that can rolling this fine-grained steel.
But when same when replacing thin plate ground to make thick 6mm or thicker thick fine-grained steel plate with finish to gauge frame 60, output torque is not high enough in finish to gauge frame 60 (or also at before this milling train 50), and rolling possibility discontinuous (motor stops).Reason is, under the slab situation, even when reduction ratio no better than during (or less than) thin plate reduction ratio, therefore contact arc length need high roll torque greater than the contact arc length of thin plate.In the milling train 50 of finish to gauge frame 60 and front, allow low maximum output torque as described above, so load become and be higher than power, therefore rolling can not be continuous.This situation is shown in the following comparative example that will describe.
The back segment milling train can not realize that the reason of sufficiently high roll torque is as follows.At first, in the back segment milling train, the roll drive system should be corresponding to becoming the high speed form because of the mill speed that occurs along with rolling slab attenuate improves ground, and compare with the leading portion milling train, and the back segment milling train is configured to rotating speed height (being that reduction rate is low) but the low form of roll torque usually.On the other hand, when rolling slab, even reduction ratio is identical during with rolled sheet metal, the contact arc length (contact length) of entrance side is big (contact angle is big) also, so the moment of required moment during obviously greater than rolled sheet metal.Therefore, in the low milling train of back segment moment, although thin plate can be rolling smoothly, take the required pressurized measure of plant capacity, thereby be difficult to make thick fine-grained steel plate slab.
In addition, there are not to find to point out above-mentioned and the file of making the relevant problem of thick fine-grained steel plate by tandem multi-set of rolling mill equipment.Relate to the thick 3mm of manufacturing or 5mm or thinner thin fine-grained steel plate in the described prior art of in patent publication us, describing of specification as correlation technique ground, perhaps use the reversible rolling equipment to make.
Therefore, promptly make the continuous hot-rolling equipment of thin fine-grained steel plate for the continuous hot-rolling equipment that uses previous embodiment shown in Figure 10 and make thickness 6mm or thicker thick fine-grained steel plate, the inventor a)-d) operates rolling equipment under the situation following.That is:
A) do not use the finish to gauge frame 60 of hanging down output torque.When allowing maximum output torque, even do not use leading portion milling train 40 and 50 less than the required moment that calculates from thickness of slab, reduction ratio and deformation drag.Therefore, according to the road secondary program, from satisfying 3 of roll torque or the rolling mill that more manys than selection and use the milling train 10-50 of finish to gauge frame 60 more close rolling equipment inlets.
B) the road secondary program is like this decision, and promptly accumulation strain is made as 0.25 or bigger (preferably 0.29 or bigger), or by the finish to gauge frame in used 3 above milling trains reduction ratio is made as 12% or higher (preferably 14% or higher).Reason is, unless carry out under the rolling reduction ratio more than quantitatively that influences metal structure strongly in the downstream, otherwise be difficult to make the ferrite particle diameter to diminish.
C) use curtain wall formula cooler 107 strong cooling metal sheets (so that with surperficial temperature drop speed control to about 40 ℃/s).As for cooler 107, after the process finish to gauge frame of milling train, use immediately.Preferably use all coolers 107 (107A-107H) of the cooler that comprises that the finish to gauge frame is preceding.This is for making the ferrite particle diameter become littler, and key is fully to cool off rolled piece P immediately after rolling, so that it remains in the suitable warm area and accurately suppresses grain growth after rolling.
D) pass through c) cooling, control finishing temperature (by the surface temperature at the rolled piece P of the thermometer measure of more than 60 meters far away on free finishing rolling mill frame down) is no more than Ar 3Transformation temperature+50 ℃ (Ar preferably 3Transformation temperature or lower).Although also wishing has lower limit,, can not hinder fine-grained steel production even surface temperature significantly reduces yet.Playing reason may be, does not consider surface temperature, as long as rolling and make thick 6mm or thicker steel plate under the speed of about 2m/s-3m/s, the temperature at close rolled piece P thickness of slab center just is maintained at about Ar 3Transformation temperature.
By realizing the rolling, can produce the thin brilliant hot rolling steel plate that is 5 μ m-10 μ m at the dark average ferrite particle diameter that reaches the inboard of 1/4 thickness from the surface, its steel grade be carbon containing 0.5% below with contain alloying element below 5%.As Embodiment C and D show the data relevant with making this steel plate.
About the thin and thick thin brilliant hot rolled steel plate by the continuous hot-rolling equipment manufacturing, rolling data are as follows.In table, the manufacturing of Comparative examples A relates to as described above thin (thickness 2.07mm) steel plate, and comparative example B represents to use milling train 10-60 to make the steel plate example, this rolling can not be continuous.Embodiment C and D represent to use rolling equipment successfully to make thick (thick 12.2mm) fine-grained steel plate continuously.
At first, table 3-1 represents Ar among steel plate chemical composition (shown in the outer composition of composition be unessential) and the embodiment 3The temperature of transformation temperature, Comparative examples A-D and table 3-2 represent the wide operating position that reaches at the curtain wall formula cooler 107 of each milling train 40-60 back of plate of finishing temperature (finishing temperature), each steel plate.Table 3-3 represents the thickness of slab (thickness of slab of " roughed bloom thickness " expression roughing equipment outlet side) of every rolling mill 10-60 outlet side.Table 3-4,3-5 and 3-6 represent when applying the road secondary program of showing among the 3-3, the reduction ratio of milling train 10-60, strain, accumulation strain and required roll torque (ton.m).
[table 3-1]
The chemical composition of steel (weight %) transformation temperature
The embodiment comparative example Become score value C Become score value Si Become score value Mn Become score value P ????Ar3 ????[℃]
Comparative examples A ????0.16 ????0.2 ????0.8 ????0.014 ????785
Comparative example B ????0.15 ????0.18 ????0.77 ????0.02 ????795
Embodiment C ????0.17 ????0.21 ????0.8 ????0.014 ????785
Embodiment D ????0.17 ????0.21 ????0.8 ????0.014 ????785
[table 3-2]
Passage program list cooling condition (curtain wall)
The embodiment comparative example Finishing temperature [℃] Plane width [mm] The back of F40 The back of F50 The back of F60
Comparative examples A ????782 ????670 Use Use Use
Comparative example B ????757 ????660 Use Use Use
Embodiment C ????679 ????660 Use Use Use
Embodiment D ????676 ????660 Use Use Use
[table 3-3]
The embodiment comparative example Roughed bloom is thick The thickness of slab of F10 [mm] The thickness of slab of F20 [mm] The thickness of slab of F30 [mm] The thickness of slab of F40 [mm] The thickness of slab of F50 [mm] The thickness of slab of F60 [mm]
Comparative examples A ????40.0 ????22.28 ????13.19 ????7.78 ????4.52 ????2.85 ????2.07
Comparative example B ????39.8 ????39.8 ????31.1 ????24.5 ????19.2 ????15.0 ????12.2
Embodiment C ????32.2 ????21.2 ????16.6 ????14.1 ????12.2 ????12.2 ????12.2
Embodiment D ????36.1 ????23.4 ????18.2 ????15.4 ????12.2 ????12.2 ????12.2
[table 3-4]
The embodiment comparative example The reduction ratio of F10 [%] The reduction ratio of F20 [%] The reduction ratio of F30 [%] The reduction ratio of F40 [%] The reduction ratio of F50 [%] The reduction ratio of F60 [%]
Comparative examples A ???44 ????41 ????41 ????42 ????37 ????28
Comparative example B ????22 ????21 ????22 ????22 ????19
Embodiment C ???34 ????22 ????15 ????14
Embodiment D ???35 ????22 ????15 ????21
[table 3-5]
The embodiment comparative example The strain [-] of F10 The strain [-] of F20 The strain [-] of F30 The strain [-] of F40 The strain [-] of F50 The strain [-] of F60 Accumulation strain [-]
??A ??0.56 ??0.51 ????0.52 ????0.53 ???0.45 ??0.32 ????0.68
??B ??0.25 ????0.24 ????0.24 ???0.24 ??0.20 ????0.39
??C ??0.41 ??0.24 ????0.16 ????0.15 ????0.29
??D ??0.43 ??0.25 ????0.17 ????0.23 ????0.38
[table 3-6]
The embodiment comparative example The roll torque of F10 [ton.m] The roll torque of F20 [ton.m] The roll torque of F30 [ton.m] The roll torque of F40 [ton.m] The roll torque of F50 [ton.m] The roll torque of F60 [ton.m]
Comparative examples A ????112 ????59 ????48 ????31 ????19 ????16
Comparative example B ????38 ????36 ????25 ????23 ????23
Embodiment C ????73 ????28 ????14 ????18
Embodiment D ????85 ????33 ????17 ????30
According to table 3-6, in can not the comparative example B of continuous rolling, finish to gauge frame 60 required moments arrive 23ton.m greatly, and this surpasses above-mentioned milling train 60 permission maximum moments (19.5ton.m).In addition, in embodiment D, shown in table 3-5, be depressing greatly in the of 0.38 owing to carried out as accumulation strain, so shown in table 3-6, the finish to gauge frame 40 of used milling train need be up to the big moment of 30ton.m (i.e. the moment that can't realize in the milling train after more leaning on 50 or 60).
The steel plate that forms in each embodiment and Comparative examples A-D is carried out the investigation of ferrite particle diameter and mechanical performance, and it the results are shown among the table 3-7.But, the data of the temporary transient steel plate that obtains before can't be rolling have been shown in comparative example B.In Comparative examples A, shown in particle diameter record in thickness central authorities, and in comparative example B and Embodiment C and D, be that the dark place that reaches 1/4 thickness records from the surface.In table, " TS " represents tensile strength, and " YP " represents yield point, and " EL " expression percentage elongation, " L direction " expression length direction (mill length), and " C direction " expression width.In all cases, all find to obtain the steel plate that the ferrite particle diameter is enough little and mechanical performance is outstanding.
[table 3-7]
Mechanical features
TS: tensile strength, YP: yield point, EL: percentage elongation
The embodiment comparative example The particle diameter of L direction [μ m] The particle diameter of C direction [μ m] The TS[Mpa of L direction] The YP[Mpa of L direction] The EL[% of L direction] The TS[Mpa of C direction] The YP[Mpa of C direction] The EL[% of C direction]
??A ??4.5 ??4.5 ??519 ????431 ????34 ??528 ?495 ????34
??B ??7.6 ??8.0 ??487 ????345 ????29 ??489 ?368 ????29
??C ??6.6 ??6.7 ??519 ????387 ????26 ??530 ?419 ????25
??D ??6.6 ??6.7 ??530 ????394 ????24 ??537 ?444 ????22
Figure 19 A, 19B and 19C represent respectively the steel plate that obtains by embodiment D near end face, interior dark 1/4 thick place and the locational crystalline structure of mid-depth.Place thick 1/4 forms the delicate tissues that average grain diameter is 5 μ m-10 μ m and forms average grain diameter at mid-depth is 10 μ m or littler delicate tissues.
In addition, Figure 20-22 other mechanical performance of checking and having put out the steel plate of under the rolling condition of embodiment D, making in order.That is, at first, Figure 20 represents the relation between ferrite particle diameter, tensile strength and fine-grained steel plate (transverse axis is represented-1/2 power value of ferrite particle diameter d (μ the m)) yield point.And for same fine-grained steel plate, Figure 21 has shown the variations in temperature of pendulum impact value and the variation of ordinary steel (non-fine-grained steel plate), and Figure 22 has shown that the embrittlement rate is to dependence on temperature.In addition, a plurality of test films of the identical steel plate made are carried out joint straight draw test, joint bend test, joint impact test, microscopic test and hardness based on the welding point of JIS Z 3040 " the affirmation experimental technique of welding procedure method " to distribute and detects test, can determine that the Weldability of fine-grained steel plate is gratifying.
As mentioned above,, use the multi-set of rolling mill that is used for making thin plate is set, also can not cause the thick fine-grained steel plate of defective ground manufacturing that brings by the moment deficiency by the continuous hot-rolling method of this embodiment.Reason is, even if the moment of back segment milling trains such as finish to gauge frame is not high enough, if but do not use these frames and only use near having and to realize big roll torque but the milling train of the rolling equipment inlet of the drive system of driven at low speed, then when the slab of rolling contact radian length, also can avoid moment fully to depress insufficiently.Although, have such advantage equally, promptly because mill speed is slack-off, so guarantee because of being the required cool time that slab will prolong easily because of not using back segment milling train not improve mill speed.Reason that can rolling as described above fine-grained steel plate is, as accumulation strain be 0.25 or depressing greatly of bigger (or the reduction ratio of finish to gauge frame being 12% or higher) be applied to that rolled piece P goes up and fully cool off rolled piece P at the outlet side of the finish to gauge frame of used milling train.As mentioned above, the cooling of milling train outlet side becomes stronger, can obtain the thinner fine-grained steel of ferrite crystal grain.In addition, on the meaning of strengthening cooling, also implement cooling before being preferably in the milling train that back segment uses, perhaps also implement cooling at the outlet side of every rolling mill of back segment.
The feature of the continuous hot-rolling method of this embodiment is that especially finishing temperature is set as and is no more than Ar 3Transformation temperature+50 ℃.
When above-mentioned cooling capacity is controlled and as described above finishing temperature is set, at least steel plate (as contain 0.5% or still less carbon and 5% or the steel of still less alloying element) near surface formed the ferrite particle diameter less than 10 μ m or littler delicate tissues.The warm area that is suitable for depressing greatly rolling is assumed to from Ar 3Transformation temperature is to Ar 3Transformation temperature+50 ℃.But according to the test that the inventor did, finishing temperature is being no more than above-mentioned Ar 3Just enough in the scope of transformation temperature+50 ℃.Reason can think that under the situation of slab, even surface temperature is low, internal temperature also keeps near Ar 3Transformation temperature.
In addition, the continuous hot-rolling method of this embodiment cools off rolled piece P strongly by curtain wall formula cooler 107, so, can make the thin especially fine-grained steel plate of particle diameter smoothly.Because can realize even cooling, so exist the advantage that in whole steel plate width scope, can make even tissueization.
The feature of the continuous hot-rolling method of this embodiment especially is, rollingly contains 0.5% or carbon still less and 5% or the rolled piece P of alloying element still less and can obtain the slab that average ferrite particle diameter in the inboard that reaches 1/4 thickness in the surface deeply is about 3 μ m-10 μ m.
Fine-grained steel plate with above-mentioned chemical composition and ferrite particle diameter has high mechanical performance harmony (is general from aspects such as tensile strength and ductility), and its low-temperature flexibility and Weldability strong (as with reference to figure 20-22).Therefore, this fine-grained steel plate is widely used, the easy acquisition because price comparison is low, and in addition, it has good recovery, so people can press for this material.Therefore, this steel plate is big to contribution to society and economic rationality its production is also very high.

Claims (19)

1, the equipment of hot rolling of rolling rolled piece ground manufacturing steel plate, it comprises: be arranged on the milling train in the leading portion; Be arranged on the multi-set of rolling mill in the back segment, described multi-set of rolling mill has and has equivalent roller footpath less than the reducing roller mill of a pair of reducing working roll of 600mm or have separately diameter less than the ultra-fine roller mill of a pair of working roll of 600mm; Be arranged at least one the milling train outlet side and cooling device that cool off described rolled piece of described back segment.
2, equipment of hot rolling as claimed in claim 1 is characterized in that, described cooling device is a curtain wall formula cooler.
3, equipment of hot rolling as claimed in claim 1 or 2 is characterized in that, in the milling train in being arranged at described leading portion and back segment, the milling train that is arranged at least in this leading portion comprises many CVC milling trains.
As the described equipment of hot rolling of one of claim 1-3, it is characterized in that 4, that of described reducing roller mill directly is 550mm or littler to the roller of the described working roll of the equivalent roller footpath of reducing working roll or described ultra-fine roller mill.
As the described equipment of hot rolling of one of claim 1-4, it is characterized in that 5, the working roll of described reducing roller mill or the working roll of described ultra-fine roller mill have CVC function and roller function.
6, as the described equipment of hot rolling of one of claim 1-5, it also comprises: the feeding lubricating device of lubricant being provided for the roll of described milling train, described feeding lubricating device are arranged on any at least rolling mill in the described milling train in being arranged at described leading portion and back segment.
7, equipment of hot rolling as claimed in claim 6 is characterized in that, described feeding lubricating device is provided at the lubricant that contains the fine-particle solid lubricant in the grease.
8, as the described equipment of hot rolling of one of claim 1-7, it also comprises: be sprayed onto fluid on the described rolled piece and remove the jet flow device of the cooling water on described rolled piece, this jet flow device is arranged on the downstream of this cooling device of described rolled piece direction of travel at the outlet side of finish to gauge frame.
9, equipment of hot rolling as claimed in claim 8, it is characterized in that, this jet flow device comprises a plurality of so the nozzle of high pressure water jets to this rolled piece, and promptly the upstream side that aims at this rolled piece direction of travel from this rolled piece top tiltedly down sprays, thereby water under high pressure is launched on this rolled piece width.
10, the method for rolling rolled piece ground manufacturing fine-grained steel, it comprises: the described rolled piece of heating is supplied with had the rolling equipment that is arranged on the milling train in the leading portion and is arranged on the milling train in the back segment, to have diameter be 550mm or littler working roll to the milling train in the back segment of being arranged on of this rolling equipment; On one side described rolled piece is cooled off in the front and back along this rolled piece direction of travel of the milling train in the described back segment of being arranged at of this rolling equipment, is 0.9 or the rolling described rolled piece in highland more Yi Bian make accumulation strain.
11, the manufacture method of fine-grained steel is characterized in that, use as the described equipment of hot rolling of one of claim 1-9 come so rolling as described in rolled piece, promptly the accumulation strain of the described rolled piece in the back segment of described rolling equipment is 0.9 or bigger.
12, as claim 10 or 11 described fine-grained steel autofrettages, it is characterized in that, the rolled piece after leaving described finish to gauge frame is just cooled off with 20 ℃/s or higher cooling rate.
13, as the described fine-grained steel autofrettage of one of claim 10-12, it is characterized in that, the carbon content of described rolled piece be 0.5% or lower and its alloying element content be 5% or lower.
14, the continuous hot-rolling method of steel plate is made on continuously hot rolling rolled piece ground, it is characterized in that, the described rolled piece of heating is supplied with have the rolling equipment that is equipped with to tandem a plurality of rolling machine frames in leading portion and back segment; The accumulation strain that makes on one side this rolled piece be 0.6 or more the highland with rolling this rolled piece of described rolling equipment, one side the outlet side of a rolling machine frame in this rolling equipment back segment cool off described rolled piece.
15, continuous hot-rolling method as claimed in claim 14 is characterized in that, the finishing temperature of this rolled piece is got and is decided to be from Ar 3More than the transformation temperature-50 ℃ to Ar 3Below transformation temperature+50 ℃.
16, as claim 14 or 15 described continuous hot-rolling methods, it is characterized in that rolling described rolled piece and the average ferrite particle diameter in inside of the described steel plate that obtains is about 3 μ m-7 μ m.
17, the continuous hot-rolling method of rolling rolled piece ground manufacturing steel plate is characterized in that, this rolled piece of heating is supplied with have the rolling equipment that tandem like this is arranged on a plurality of rolling racks in leading portion and the back segment, and promptly it can make steel plate in rolling rolled piece ground; Outlet side in operational finish to gauge frame cools off described rolled piece on one side, do not use on one side being arranged at least a portion in many rolling mills in this back segment and using of described rolling equipment near at least three rolling machine frame ground of described rolling equipment entrance side rolling this rolled piece like this, promptly the accumulation strain of described rolled piece be 0.25 or reduction ratio bigger or in operational finish to gauge frame be 12% or higher.
18, continuous hot-rolling method as claimed in claim 17 is characterized in that, the finishing temperature of described rolled piece is established and is no more than Ar 3Transformation temperature+50 ℃.
As claim 17 or 18 described continuous hot-rolling methods, it is characterized in that 19, the average ferrite particle diameter described slab that obtains by rolling this rolled piece, count 1/4 the inside that reaches thickness of slab deeply on the slave plate surface is about 3 μ m-10 μ m.
CNB028007190A 2001-03-16 2002-01-29 Hot rooling mill and method Expired - Fee Related CN1275711C (en)

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Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN102834191A (en) * 2010-03-31 2012-12-19 住友金属工业株式会社 Method for producing and device for producing hot-rolled steel sheet
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CN102834191A (en) * 2010-03-31 2012-12-19 住友金属工业株式会社 Method for producing and device for producing hot-rolled steel sheet
CN102834191B (en) * 2010-03-31 2017-03-29 新日铁住金株式会社 The manufacture device and manufacture method of hot rolled steel plate
CN105916603A (en) * 2013-12-24 2016-08-31 安赛乐米塔尔公司 Hot rolling method
CN105916603B (en) * 2013-12-24 2018-09-07 安赛乐米塔尔公司 Hot-rolling method
US10870138B2 (en) 2013-12-24 2020-12-22 Arcelormittal Hot rolling method

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