A kind of Ultra-fine Grained milling method of 45 steel bar of large scale
Technical field
The present invention relates to field of machining, and in particular to a kind of Ultra-fine Grained milling method of 45 steel bar of large scale.
Background technique
Ultra-fine Grained/nanocrystalline material and technology of preparing are one of the research hotspots of present material scientific domain.This direction
Research embodied a concentrated reflection of people by persistently refinement crystal grain be continuously improved polycrystalline material Strengthening and Toughening level effort.Wherein, especially
It is attracted people's attention with the research achievement of severe plastic deformation (Severe Plastic Deformation, abbreviation SPD) technology.
Now, the SPD technique of mainstream include high pressure torsion (HPT), equal channel angular squeeze (ECAP), accumulation pack rolling (ARB),
Multiway forging (MF) and torsion squeeze (TE) five kinds of methods, in which:
(1) high pressure torsion deforms: while loading the pressure of several GPa on material thickness, lower die or low punch rotation are logical
The rubbing action for crossing active applies torque on material cross-section, promotes material to generate and is compressed axially and tangential shear-deformable modeling
Property shape technique, the characteristics of high pressure torsion, is that workpiece is plate-like, and size is smaller, and diameter is generally 10-20mm, with a thickness of
0.2-0.5mm。
(2) miter angle extruding deforming: sample passes through the corner of two same channels under the pressure effect of formed punch, generates
Large plastometric set is sheared, and the shape of sample cross and area remain unchanged, therefore pass through that repeatedly repeatedly extrude can will be each
The dependent variable of passage is accumulated.
(3) accumulate pack rolling method: plate is handled by surface degreasing steel brush to expose its fresh surface, then by two boards
Material is superimposed together and rolling is carried out under room temperature or certain heating temperature makes two pieces of plate material be combined into one piece of plate, this
The plate of Rolling compund is cut off from centre afterwards, to obtain size two pieces of composite plates identical with original veneer material size, so
Obtain two pieces of composite plate materials are carried out to the processing of a new round afterwards.
(4) torsion squeezes: Beygelzime etc. proposes the technique.The method be also by it is shear-deformable refinement crystal grain at
Column blank is pressed through torsion mould by type technology, and similar with HPT, there are deformation problem of non-uniform, grain refinement effect is lower than
ECAP and HPT.
(5) multiway forging: the direction different to material carries out repeatedly upset and pulling, big plastic deformation is introduced, with this
To realize the refinement of crystal grain and the raising of material property.But this method is there are apparent strain gradient, strain uniformity compared with
Other SPD methods are poor, and actually active drastic deformation area size is also far from the requirement for meeting technical grade.Thus crystal grain refinement effect
Fruit will be significantly lower than ECAP and HPT.
(6) the isometric helix milling method (201810172304 .4 of application number) of a kind of 45 steel ultra fine grained steel bar of large scale,
Using positive cone roller, to circular blank carries out etc., roll spacings are rolled, and technical parameter in the forming process: feed angle is 15 ~ 17 °, roll off
Angle is 19 ~ 21 °, roll rotational speed n is 30 ~ 60r/min, diameter reduction ratio 5% ~ 15.5%, pass ovality are 1.25-1.5 etc., real
The preparation of large scale ultra fine grained steel bar is showed.But there is the deficiencies of deformation is uneven in this method, remain to be further improved.
It is relatively fewer for the patent report of 45 steel Ultra-fine Grained techniques both at home and abroad.Since ultra-fine grain steel has excellent resist
The advantages that fatigue behaviour, good weldability, higher intensity and good low-temperature flexibility, has obtained extensively in manufacture field
General application.Iron and Steel Research Geueral Institute Wang Ruizhen et al. is referred to a kind of surface layer ultra fine grain iron in patent [106676240 B of CN]
The preparation method of ferritic low-alloy steel slab.It cools down using acceleration after roughing plus returns warm rolling mill practice and be prepared for average grain size
≤ 3 μm of ultra-fine grained ferrite, is limited to deformed area volume in the operation of rolling, and this method can not achieve blocks of large Ultra-fine Grained
The preparation of material.
Once week Radiance-of-fire et al. is referred to low-alloy steel in patent [103572023 B of CN] for Nanjing Steel stock Co., Ltd
Slab/special heavy plate surface layer ultra fine grain manufacturing method.This method uses multiple controlled rolling and controlled cooling, makes surface layer Austenite Grain Refinement,
It is quickly cooled down the thick steel plate for obtaining and there is surface layer fine grained texture.But the degree of refinement of its crystallite dimension is limited, is unable to satisfy work
Industry demand.
It is double that Xi'an Communications University Sun person of outstanding talent et al. is referred to a kind of stratiform Ultra-fine Grained in patent [108018503 A of CN]
Phase ferrite/martensite steel and preparation method thereof.Through two-phase section heat treatment and multi- pass rolling, it is double Ultra-fine Grained has been prepared
Xiang Gang, the thickness direction size using the super fine crystal material of this method preparation is smaller, and the thickness of plate is usually in 10mm or less.Cause
This, this method can not achieve the preparation of blocks of large super fine crystal material.
Shandong steel enterprise sunshine Co., Ltd Li Canming et al. is referred to one kind in patent [108070789 A of CN]
The special thick steel of not less than 480MPa grades Ultra-fine Graineds of yield strength and preparation method, although excellent product performance, its rolling mill practice
It is required that extremely stringent, industrialized production still difficulties.
The shortcomings that prior art:
(1) in ECAP deformation process, blank and mold Full connected, frictional force is big, thus molding load is big, and finished size is small, and
Stock utilization is low, and production efficiency is low, it is difficult to realize the preparation of the ultra-fine-grained material of industrialization demand.
(2) HPT shaping load is huge, and it is more than tens that existing former, which does not have industrialization large scale product generally,
The load capability of GPa is only applicable to the forming of ultra-thin product such as film, and blank is Φ 10-15 × 1-10mm's before usually deforming
Cylindrical body.
(3) ARB technique is limited to the influence of deformed area volume and deformation uniformity, and deformed area thickness is only mm rank.
Simultaneously as prepared Ultra-fine Grained is the elongation crystal grain of pie, the more three-dimensional equi-axed crystal of mechanical property is poor.Therefore, by
The limitation of load capability and deformation degree of irregularity, ARB are only capable of preparing ultra-thin sheet material.
(4) MF and TE due to unhomogeneity of deformation it is serious, cause crystal particle scale uneven, grain structure stability is poor, property
It can reduce, and can not equally prepare large scale forging.
(5) the isometric helix milling method (201810172304 .4 of application number) of a kind of 45 steel ultra fine grained steel bar of large scale,
Existing major defect:
1) roll shape of original technology is regular conical, after blank enters roll, because roller diameter gradually increases, and roll and base
Material contact area speed gradually increases, and the deformation velocity difference that will lead to blank center portion and edge increases, so that it is uneven to aggravate deformation
Property.
2) roll spacing is equidistant, and diameter reduction ratio gradually decreases, and deformation is smaller, thus grain refining effect can be gradually
Weaken.
Known to comprehensive analysis: the 45 steel Ultra-fine Grained techniques referred in existing patent or paper are all made of traditional multi- pass rolling side
Method is only capable of preparation small size super fine crystal material, it is difficult to prepare the large scale of technical grade entirety Ultra-fine Grained by deformed area volumetric constraint
(60 ~ Φ of Φ 500mm) material.
Summary of the invention
It is an object of that present invention to provide one kind can obviously reduce transverse spreading deformation, reduces center portion tensile stress, while can also
Increase screw pitch, reduce the roll off number repeatedly of screw rolling, to inhibit Mans effect, reduce crackle occurrence probability and improve change
Shape uniformity, grain refining effect can gradually be reinforced, a kind of better Ultra-fine Grained of 45 steel bar of large scale of grain refining effect
Milling method.
A kind of Ultra-fine Grained milling method of 45 steel bar of large scale of the present invention, comprising the following steps:
1) rolling tool designs, and specifically includes Roller Design and guide plate design, sets hyperbolic noodles truncated cone-shaped for roll and roll
Roller, specifically: the bus of roll is connected by two curves to be formed;It sets curved surface on one side by guide plate;
2) structural deformation area: described two guide plate curved surfaces are staggered relatively, and two rolls are placed between the guide plate, and two are led
The region that plate and two rolls surround is deformed area;
The direction at the roll small end face center is directed toward by the large end face center of the roll on a roll in two rolls
For first direction;Being directed toward the direction at the roll small end face center by the large end face center of the roll on another roll is second
Direction;
Angle between the first direction and second direction is acute angle;
3) the ovalitys deformed area such as construction: ovality remains unchanged in deformed area;
4) it chooses rolling feeding manner: pouring formula rolling mode into, i.e., blank enters deformed area from the big end of roll in the operation of rolling;
5) diameter of phi 60-500mm, 45 steel blanks of length 300-15000mm selection: are chosen;
6) roll: two rolls are rotated rotating around center axis thereof, by blank after heating, according to the rolling feeding manner
Blank after heating is sent into deformed area, blank advances in deformed area inside spin, and exports from roll small end, realizes that variable cross-section rolls
After completing the operation of rolling, it is cooling to carry out blank for system.
It preferably, is the first curve close to the curve of roll big end on roll bus, the line between the first curve both ends
It close to the curve of small end is the second curve on roll bus, the line between the second curve both ends is in second for the first middle line
Line;
The maximum distance of point the first middle line of distance on first curve is not more than 5mm, point the second middle line of distance on the second curve
Maximum distance be not more than 2.5mm;
Angle between first middle line and the second middle line is 4-7 degree.
Preferably, the first curve rotates the region in the curved surface corresponding deformation area to be formed around the roll axis as rolling on roll
Area, it is circle area that the second curve, which rotates the region in the curved surface corresponding deformation area to be formed around the roll axis, on roll;Roll the head of district
Degree is 2.5-5 times of circle area length.
Preferably, roll outside diameter is 3-6 times of blank diameter, and roll end diameter is 2.5-4 times of blank diameter.
Preferably, ovality is the maximum distance D between two guide plates in the same cross section in deformed areadxWith two rolls
The distance between DgxThe ratio between, the ovality in deformed area at arbitrary cross section is equal, ovality 1.0-1.03.
Preferably, blank heating is that blank heats in heating furnace, and the temperature of heating is 870-1020 degrees Celsius, when heating
Between T be T=Db× (0.6-0.8) min, wherein DbFor blank diameter;
Roll surface cone angle gradient α is 4-5 degree in deformed area, and the roll surface cone angle gradient α is the first middle line and roll line angle, is sent into
Angle beta is 18.5-20.5 degree, and the feed angle is during the rolling process that roll axis and roll line are in the level comprising roll line
The angle projected on face;Roll off angle γ is 20-22 degree, and roll off angle γ is during the rolling process that roll axis and roll line are wrapping
The angle projected on vertical plane containing roll line;Roll rotational speed n is 42-70 r/min, and diameter reduction ratio ε is 30-48%, directly
Diameter reduction ratio ε is blank diameter and the difference and the ratio of blank diameter for rolling rear diameter of rod;
Blank is cooled to that blank is air-cooled or blank water cooling is to room temperature.
The invention has the following beneficial effects:
(1) a kind of Ultra-fine Grained milling method of 45 steel bar of large scale of the present invention, by design hyperbolic noodles truncated cone-shaped roll and
Curved form guide plate, the ovalitys deformed area such as construction, can generate acutely under the premise of significantly inhibiting center portion Mannesmann effect
Plastic deformation.
(2) by rationally designing special feed angle, roll off angle, roll rotational speed, ovality warp tool and technical parameter,
It not only can obviously reduce transverse spreading deformation, reduce center portion tensile stress, while screw pitch can also be increased, reduce screw rolling repeatedly
Roll off number, to inhibit Mans effect, reduce crackle occurrence probability and improve deformation uniformity.
(3) this preparation method is to pour formula rolling into, and roll is hyperbolic noodles truncated cone-shaped roll, and blank is maximum from roller diameter
One end enters roll off deformed area, is plastically deformed after being bitten;After blank enters the roll off deformed area between roll, with connecing
Touching roll off deformed area roller diameter is gradually reduced, and roll gradually decreases along the component velocity of rolled piece direction of advance, rolled piece advance by
Resistance reduces metal along axial deformation unevenness, to improve deformation uniformity.
Angle, that is, roll hyperboloid angle theta between (4) first middle lines and the second middle line is 4-7 degree, be can be effectively controlled
The ratio of rolling zone and circle area length improves the surface quality and deformation uniformity for rolling rear workpiece.Rolling zone is between roll
Away from the single taper acutely reduced, roll surface cone angle gradient α is 4-5 degree, for 1.1-2.5 times of conventional graceful formula oblique milling, it can be achieved that doubling
The deformation of unit time diameter, deformation extent can remain that large plastometric set, i.e. grain refining effect can gradually add
By force, grain refining effect is more preferable.
Detailed description of the invention
Fig. 1 is hyperbolic noodles truncated cone-shaped roll and deformed area schematic diagram.
Fig. 2 is operation of rolling main view.
Fig. 3 is Section A-A schematic diagram in Fig. 2.
Fig. 4 is operation of rolling top view.
Fig. 5 is 45 steel starting microstructure figures.
Fig. 6 is 45 steel microscopic structure figures after the completion of rolling in embodiment one.
Appended drawing reference: 1- roll, 2- guide plate, 3- blank.
Specific embodiment
A kind of Ultra-fine Grained milling method of 45 steel bar of large scale of the present invention, comprising the following steps:
1) rolling tool designs, and specifically includes the design of roll 1 and guide plate 2 designs, set hyperbolic noodles truncated cone-shaped for roll 1 and roll
Roller 1, specifically: the bus of roll 1 is connected by two curves to be formed;It sets curved surface on one side by guide plate 2;
2) structural deformation area: described two 2 curved surfaces of guide plate are staggered relatively, and two rolls 1 are placed between the guide plate 2, and two
The region that a guide plate 2 and two rolls 1 surround is deformed area;
3) the ovalitys deformed area such as construction: ovality remains unchanged in deformed area;
4) it chooses rolling feeding manner: pouring formula rolling mode into, i.e., blank 3 enters deformation from the big end of roll 1 in the operation of rolling
Area;
5) diameter of phi 60-500mm, 45 steel blanks 3 of length 300-15000mm selection: are chosen;
6) roll: two rolls 1 are rotated rotating around center axis thereof, by blank 3 after heating, according to the rolling charging side
Blank 3 after heating is sent into deformed area by formula, and blank 3 advances in deformed area inside spin, and exports from 1 small end of roll, is realized and is become
After completing the operation of rolling, it is cooling to carry out blank 3 for section rolling.
The curve of close 1 big end of roll is the first curve on 1 bus of roll, and the line between the first curve both ends is first
Middle line close to the curve of small end is the second curve on 1 bus of roll, and the line between the second curve both ends is the second middle line;
The maximum distance of point the first middle line of distance on first curve is not more than 5mm, point the second middle line of distance on the second curve
Maximum distance be not more than 2.5mm;
Angle between first middle line and the second middle line is 4-7 degree.
First curve is rolling zone around the region that 1 axis of roll rotates the curved surface corresponding deformation area to be formed on roll 1, is rolled
Second curve is circle area around the region that 1 axis of roll rotates the curved surface corresponding deformation area to be formed on roller 1;Rolling section length is
2.5-5 times of circle area length.
1 outside diameter of roll is 3-6 times of 3 diameter of blank, and 1 end diameter of roll is 2.5-4 times of 3 diameter of blank.
Ovality be the same cross section in deformed area in, between the maximum distance and two rolls 1 between two guide plates 2 away from
The ratio between from, the ovality in deformed area at arbitrary cross section is equal, ovality 1.0-1.03.
Blank 3 is heated to be blank 3 and heats in heating furnace, and the temperature of heating is 870-1020 degrees Celsius, and heating time, T was
T=Db× (0.6-0.8) min, wherein DbFor 3 diameter of blank;
Roll surface cone angle gradient α is 4-5 degree in deformed area, and feed angle β is 18.5-20.5 degree, roll off angleFor 20-22 degree, roll 1
Revolving speed n is 42-70 r/min, diameter reduction ratio ε is 30-48%;
Blank 3 is cooled to that blank 3 is air-cooled or 3 water cooling of blank is to room temperature.
Embodiment one:
Below by the specific example exemplary embodiment that the present invention will be described in detail.Following example is with 3 specification of blank for Φ 82
For × 400 45 steel bars, however, the invention is not limited thereto, the 45 of other specifications can also be produced by means of the present invention
Steel bar.
1) rolling tool designs, and specifically includes the design of roll 1 and guide plate 2 designs, set hyperbolic noodles rotary table for roll 1
Shape roll 1, specifically: the bus of roll 1 by two curves be connected forms, as shown in Figure 1, one of curve be curve m and
Any one curve between curve p, the line between the curve both ends are the first middle line n, and another curve is curve q and curve t
Between any one curve, the line between the curve both ends is the second middle line s;It sets curved surface on one side by guide plate 2;Roll
1 outside diameter D is 410mm, and 1 end diameter d of roll is 260mm;
2) structural deformation area: being oppositely arranged on one side for curved surface is set by described two guide plates 2, and two settings of guide plate 2 are existed
Between the roll 1, the region that two guide plates 2 and two rolls 1 surround is deformed area;
First curve is rolling zone, roll 1 around the region that 1 axis of roll rotates the curved surface corresponding deformation area to be formed on roll 1
Upper second curve is circle area around the region that 1 axis of roll rotates the curved surface corresponding deformation area to be formed;Roll section length L1For
Circle area length L24 times;
3) the ovalitys deformed area such as construction: ovality remains unchanged in deformed area;Ovality is in the same cross section in deformed area two
Maximum distance D between a guide platedxThe distance between two rolls DgxThe ratio between, as shown in figure 3, any transversal in deformed area
Ovality at face is equal, ovality 1.0;
4) it chooses rolling feeding manner: pouring formula rolling mode into, i.e., blank 3 enters deformation from the big end of roll 1 in the operation of rolling
Area;
5) selection, 45 steel bars for purchasing 82 × 400mm of Φ are that manufacturer adds through vacuum consumable electrode arc furnace melting, forging and machine
Work obtains, and quality meets rolling requirements, and each site tissue of 45 steel bars is evenly distributed, do not find to be mingled with, stomata the defects of;
6) roll: two rolls 1 are rotated rotating around center axis thereof, blank 3 are heated in heating furnace, the temperature of heating is
910 degrees Celsius, heating time T is 48min, and 45 steel bars that would be heated to temperature are transported in milling train deflector chute from heating furnace, is turned
The fortune time is 8s.Wherein, the technological parameter of the operation of rolling are as follows: roll surface cone angle gradient α is 4 degree in deformed area, and feed angle β is 20
Degree, roll off angle γ are 22 degree, diameter reduction ratio ε is 45%, and 1 revolving speed n of roll is 42 r/min, and blank 3 is between 1 big end of roll
Deformed area enter, and start to be rolled, blank 3 is advanced until in deformed area inside spin from the deformation between 1 small end of roll
Area's output realizes variable cross-section rolling, completes the operation of rolling.It carries out the blank 3 after the completion of rolling to be air-cooled to room temperature;
Initial tissu is as shown in figure 5, average grain size is 111 μm in figure;Using the method for the present invention, Fig. 6 is after the completion of rolling
45 steel microscopic structures, wherein crystallite dimension is 2.1 μm or so, degree of grain refinement 98.1%.
The curve of close 1 big end of roll is the first curve on 1 bus of roll, and the line between the first curve both ends is first
Middle line close to the curve of small end is the second curve on 1 bus of roll, and the line between the second curve both ends is the second middle line;
The maximum distance of point the first middle line of distance on first curve is 5mm, and the second middle line of point distance on the second curve is most
Big distance is 2.5mm;
1 hyperboloid angle theta of angle, that is, roll between first middle line and the second middle line is 4 degree.