CN108070785A - The excellent high-carbon wire rod of ductility and its manufacturing method - Google Patents

The excellent high-carbon wire rod of ductility and its manufacturing method Download PDF

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Publication number
CN108070785A
CN108070785A CN201711081233.9A CN201711081233A CN108070785A CN 108070785 A CN108070785 A CN 108070785A CN 201711081233 A CN201711081233 A CN 201711081233A CN 108070785 A CN108070785 A CN 108070785A
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wire rod
ductility
cooling
excellent high
carbon
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CN108070785B (en
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朴焌学
崔锡欢
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Posco Holdings Inc
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Posco Co Ltd
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    • C—CHEMISTRY; METALLURGY
    • C21—METALLURGY OF IRON
    • C21D—MODIFYING 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
    • C21D8/00—Modifying the physical properties by deformation combined with, or followed by, heat treatment
    • C21D8/06—Modifying the physical properties by deformation combined with, or followed by, heat treatment during manufacturing of rods or wires
    • C—CHEMISTRY; METALLURGY
    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22C—ALLOYS
    • C22C38/00—Ferrous alloys, e.g. steel alloys
    • C22C38/02—Ferrous alloys, e.g. steel alloys containing silicon
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B21—MECHANICAL METAL-WORKING WITHOUT ESSENTIALLY REMOVING MATERIAL; PUNCHING METAL
    • B21B—ROLLING OF METAL
    • B21B1/00—Metal-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
    • B21B1/16—Metal-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 wire rods, bars, merchant bars, rounds wire or material of like small cross-section
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B21—MECHANICAL METAL-WORKING WITHOUT ESSENTIALLY REMOVING MATERIAL; PUNCHING METAL
    • B21B—ROLLING OF METAL
    • B21B3/00—Rolling 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
    • B21B3/02—Rolling special iron alloys, e.g. stainless steel
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B21—MECHANICAL METAL-WORKING WITHOUT ESSENTIALLY REMOVING MATERIAL; PUNCHING METAL
    • B21B—ROLLING OF METAL
    • B21B37/00—Control devices or methods specially adapted for metal-rolling mills or the work produced thereby
    • B21B37/74—Temperature control, e.g. by cooling or heating the rolls or the product
    • C—CHEMISTRY; METALLURGY
    • C21—METALLURGY OF IRON
    • C21D—MODIFYING 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
    • C21D8/00—Modifying the physical properties by deformation combined with, or followed by, heat treatment
    • C21D8/06—Modifying the physical properties by deformation combined with, or followed by, heat treatment during manufacturing of rods or wires
    • C21D8/065—Modifying the physical properties by deformation combined with, or followed by, heat treatment during manufacturing of rods or wires of ferrous alloys
    • C—CHEMISTRY; METALLURGY
    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22C—ALLOYS
    • C22C38/00—Ferrous alloys, e.g. steel alloys
    • C22C38/04—Ferrous alloys, e.g. steel alloys containing manganese
    • C—CHEMISTRY; METALLURGY
    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22C—ALLOYS
    • C22C38/00—Ferrous alloys, e.g. steel alloys
    • C22C38/06—Ferrous alloys, e.g. steel alloys containing aluminium
    • C—CHEMISTRY; METALLURGY
    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22C—ALLOYS
    • C22C38/00—Ferrous alloys, e.g. steel alloys
    • C22C38/18—Ferrous alloys, e.g. steel alloys containing chromium
    • C—CHEMISTRY; METALLURGY
    • C21—METALLURGY OF IRON
    • C21D—MODIFYING 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
    • C21D2211/00—Microstructure comprising significant phases
    • C21D2211/001—Austenite
    • C—CHEMISTRY; METALLURGY
    • C21—METALLURGY OF IRON
    • C21D—MODIFYING 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
    • C21D2211/00—Microstructure comprising significant phases
    • C21D2211/009—Pearlite

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  • Chemical & Material Sciences (AREA)
  • Engineering & Computer Science (AREA)
  • Mechanical Engineering (AREA)
  • Materials Engineering (AREA)
  • Metallurgy (AREA)
  • Organic Chemistry (AREA)
  • Manufacturing & Machinery (AREA)
  • Physics & Mathematics (AREA)
  • Thermal Sciences (AREA)
  • Crystallography & Structural Chemistry (AREA)
  • Heat Treatment Of Steel (AREA)
  • Heat Treatment Of Strip Materials And Filament Materials (AREA)

Abstract

The present invention provides the high-carbon wire rod for also having the ductility of excellent ductility excellent under the conditions of a kind of high alloy and its manufacturing method.

Description

The excellent high-carbon wire rod of ductility and its manufacturing method
Technical field
The present invention relates to a kind of excellent high-carbon wire rod of ductility and its manufacturing methods.
Background technology
The height that the high-strength wire material that line footpath is 10mm~20mm is below 10mm by being heat-treated and fabricating into line footpath Intensity steel wire, high-tensile steel wires are loaded in a variety of manners for entire industry with supporting.
Typical form is useful for the steel wire rope of the bridges such as suspension bridge, cable-stayed bridge, is mixed for concrete pier etc. with reinforcement Coagulate soil PC steel wires, for building or works steel wire rope, be used to support the anchor of offshore oilfield or various works Rope (Anchor rope) etc..
In addition, high-strength wire material is processed into steel wire will pass through excellent drawing (drawing) technique of drawing hardening effect, At this time if the ductility (ductility) of material is excellent, it is very beneficial for ensuring drawing processability.
Before drawing process, in order to improve the intensity and work hardening rate at drawing initial stage, after usual influence of high austenizing temp Lead bath constant temperature heat treatment (LP heat treatments) is carried out, but before heat treatment as progress, if the ductility of material is poor, is just difficult to Ductility is ensured after heat treatment.
Therefore, the ductility of original material is critically important, especially for omission direct-on-line patenting (Direct-Line- Patenting, DLP) etc. heat treatments material, the ductility of original material is more important.
Recently, for the high intensity of steel wire, it is intended to increase the content of the alloying elements such as C, Si, Mn, Cr, but these are closed Center segregation caused by gold element aggravates, so as to encourage the formation for the proeutectoid cementite for hindering ductility.
In addition, when material in itself by high intensity when, can generate in Microamounts of Hydrogen present in wire rod and cooling procedure residual Stress etc. is stayed to cause embrittlement-sensitive sexual orientation, and in increase, this, which can also become, causes the factor that the ductility of original material is deteriorated.
Therefore, in order to obtain the excellent high-strength wire material of ductility, it is necessary to inhibit under the high alloy condition such as C, Si, Mn, Cr The generation of proeutectoid cementite, to be formed it is advantageously ensured that the microstructure of ductility, while by residual hydrogen amount, the residual in material Stress etc. minimizes.
The content of the invention
Technical problem
The object of the present invention is to provide a kind of high-carbon wire rods and its system also under the conditions of high alloy with excellent ductility Make method.
Technical solution
One aspect of the present invention provides a kind of ductility excellent high-carbon wire rod, and the meters of % by weight include carbon (C)：0.9%~ 1.1%th, silicon (Si)：0.6%~1.5%, manganese (Mn)：0.2%~0.8%, chromium (Cr)：0.2%~0.8%, aluminium (Al)： Less than 0.08%, surplus is Fe and other inevitable impurity, and the size that head (open region) is broken during tension failure is More than 1.4mm, the ductile fracture fraction of the fracture head (open region) is more than 35%.
Another aspect of the present invention provides a kind of manufacturing method of the excellent high-carbon wire rod of ductility, and it includes following steps：System Make the wire rod for meeting the alloy compositions；The wire rod is batched at 580 DEG C~750 DEG C；The wire rod batched is carried out pre- Cooling；After the temperature of the wire surface of the precooling rises, 500 are once cooled to the cooling velocity of 3 DEG C/s~10 DEG C/s ℃；And after the once cooling, with the cooling velocity secondary cooling of 1.2 DEG C/below s to 400 DEG C~500 DEG C.
Invention effect
According to the present invention it is possible to provide the contraction percentage of area be that more than 15% ductility is excellent and residual hydrogen content be 1.2ppm with The excellent wire rod of lower hydrogen embrittlement sensibility.
Description of the drawings
Fig. 1 is the stretching with the micro- sem observation invention material 1 of stereoptics and contrast material 1 in an embodiment of the present invention The photo of head is broken after fracture.
Fig. 2 is the fracture with scanning electron microscope observation invention material 2 and contrast material 2 in an embodiment of the present invention The photo on head point.
Specific embodiment
In order to improve the intensity of wire rod, the present inventors is had extensively studied containing a certain amount of above as alloying component C, Si, Mn, Cr etc., it may also be ensured that the scheme of excellent ductility.It turns out that pass through optimized alloy ingredient and manufacturing condition Ensure the microstructure it is advantageously ensured that ductility, it is possible to the contraction percentage of area is provided as the excellent wire rod of more than 15% ductility, from And complete the present invention.
The present invention is described below in detail.
The excellent high-carbon wire rod of ductility according to an aspect of the present invention, preferably by weight % meters include carbon (C)： 0.9%~1.1%, silicon (Si)：0.6%~1.5%, manganese (Mn)：0.2%~0.8%, chromium (Cr)：0.2%~0.8%, aluminium (Al)：Less than 0.08%.
The reasons why alloy compositions of steel wire provided by the present invention is controlled as described above in detailed hereafter.Do not saying especially In the case of bright, the content of each element represents weight %.
C：0.9%~1.1%
Carbon (C) is the element that cementite is formed in steel wire, and the cementite forms layer structure together with ferrite Pearlite.The pearlite has high intensity with ferritic phase ratio, therefore the intensity of the higher material of fraction of cementite more increases. In addition, the more uniform small intensity that can more further improve material of the spacing of layer structure.
When increasing the content of C, the fraction of cementite can increase, and piece interlamellar spacing becomes small, therefore to improving wire rod Intensity is highly effective.For this purpose, in the present invention, the content of the C is preferably more than 0.9%.But if the content of the C is high In 1.1%, then the fraction change of proeutectoid cementite is too much, there are problems that ductility reduction.
Therefore, in the present invention, the content of the C is preferably controlled in 0.9%~1.1%.
Si：0.6%~1.5%
Silicon (Si) is to be solid-solution in the element that substrate microstructure ferrite makes steel be strengthened, and is that wire rod is processed into steel wire When ensure element necessary to final strength.Because the Si forms Silicon-rich on ferrite/cementite interface in pearlite Layer, so as to play the role of inhibit drawing when cementite avalanche (decomposition).
In order to fully obtain above-mentioned effect, the content of the Si is preferably more than 0.6%.If the content of the Si is excessive More than 1.5%, then hardenability is greatly increased, carry out that during continuous coo1ing technique martensite may be generated after wire rod rolling.
Therefore, in the present invention, the content of the Si is preferably controlled in 0.6%~1.5%.
Mn：0.2%~0.8%
Manganese (Mn) is the element for postponing pearlitic transformation, and fine pearl can also be made under slightly slow cooling velocity by having The effect that body of light easily generates.
For above-mentioned effect, the content of the Mn is preferably more than 0.2%.But if the content of the Mn is higher than 0.8%, then hardenability can greatly increase, martensite may be generated in continuous coo1ing technique.
Therefore, in the present invention, the content of the Mn is preferably controlled in 0.2%~0.8%.
Cr：0.2%~0.8%
Chromium (Cr) makes the piece interlamellar spacing of pearlite become small, and Cr as the Si have drawing when inhibit carburizing The division (fragmentation) of body makes intensity decline reduce to minimum effect.
In order to fully obtain above-mentioned effect, it is necessary to add in more than 0.2% Cr, but if the content of the Cr is high In 0.8%, hardenability will be greatly increased, martensite may be generated in continuous cooling process.In addition, chromium is high price bit Element there are problems that manufacturing cost increase.
Therefore, in the present invention, the content of the Cr is preferably controlled in 0.2%~0.8%.
As described above, in order to ensure ensuring work hardening rate when the intensity of original material and drawing are processed, in the present invention In be preferably added to a certain amount of above C, Si, Mn and Cr, wherein Si and Cr have the effect for inhibiting cementite division, preferably distinguish Add in more than 0.6%, more than 0.2%.
Al：Less than 0.08% (except 0%)
Aluminium (Al) easily reacts with oxygen, is the typical element of the deoxygenation for steel-making.But when existing in steel During Al as far as possible, it is possible to encourage the formation of field trash, therefore be controlled preferably in steel to remain.In addition, the Al is in high temperature It is lower participation Carbon diffusion reaction, so as to inhibit austenitizing heat and keep high temperature when C from dissolution to ferrite Reaction, it is possible to the phenomenon that encouraging undissolved cementite residual.
In view of this, in the present invention, the Al is preferably added to less than 0.08%, but except 0%.
The surplus ingredient of the present invention is iron (Fe).It is but miscellaneous from raw material or ambient enviroment in conventional manufacturing process Matter can be inevitably mixed into unintentionally, therefore cannot be excluded these impurity and be mixed into.As long as the common skill of fields Anyone can know these impurity to art personnel, therefore repeat no more in the present specification.
Its microstructure of high-carbon wire rod for meeting the present invention of the alloy compositions is mutually used as substrate microstructure for pearlite. At this point, preferably satisfy austenite grain size in central part be 15 μm~45 μm, pearlite colony (Nodule) size be 5 μm~ 15μm。
In the present invention, central part refers to when the line footpath of wire rod is D (diameter) at the 1/2D of the D (region).
In general, the size of wire rod medium pearlite group is small to be just unfavorable for crack propagation, therefore be conducive to improve prolonging for wire rod Property.
The size of this pearlite colony is related with austenite grain size, when original austenite grains size is small, pearl Body of light group is also small.
However, when the size of austenite in hypereutectoid steel (hyper eutectoid steel) is excessively small, in crystal boundary The formation of proeutectoid cementite can be encouraged, there are problems that the phenomenon that occurring to hinder ductility.
Therefore, in the present invention, it is preferred to by austenite grain size and the size of pearlite colony control respectively 15 μm with Above, 5 μm or more.If austenite grain size and the size of pearlite colony are respectively smaller than 15 μm, less than 5 μm, can encourage instead There is being difficult to ensure that more than 15% contraction percentage of area in the formation of proeutectoid cementite.If the on the contrary, Ovshinsky Body grain size and the size of pearlite colony are respectively greater than 45 μm, more than 15 μm, then the crack propagation based on granularity refinement inhibits It has little effect, can not also ensure the ductility that the contraction percentage of area is more than 15%.
As described above, the wire rod for the present invention that austenite grain size and pearlite colony size are controlled may insure to draw The size that head (open region) is broken when stretching fracture is more than 1.4mm, the ductile fracture fraction of the fracture head (open region) For more than 35%.
The fracture head is the region being broken at first when stretching, and the region is compared with other regions, due to stress Pore aggregation ductile fracture fraction is relatively high caused by concentration.That is, the ductility for being broken the larger expression material of size of head is higher.
In the present invention, when the size of the fracture head is more than 1.4mm, the ductile fracture fraction on the entire plane of disruption For more than 35% higher, it can provide ductility excellent wire rod.
If the ductile fracture fraction of the fracture head is less than 35%, even if the size of fracture head is more than 1.4mm, to material The percentage contribution of the ductility of material is also little, and the contraction percentage of area of wire rod may be less than 15%.
In addition, the wire rod of the present invention has the tensile strength of 1200MPa~1600MPa, it is ensured that remaining hydrogen content is Below 1.2ppm, so as to ensure desirable high intensity and high ductility.
When wire rod is processed into steel wire, in order to ensure sufficient intensity, preferably ensure that the intensity of the i.e. wire rod of original material is protected Hold certain level.
Therefore, in the present invention, it is preferred to ensure tensile strength for more than 1200MPa, but during more than 1600MPa, because of intensity It is excessively high and to there are problems that being difficult to ensure that the contraction percentage of area be more than 15%.
Hydrogen additionally, there are Yu Gangzhong is to trigger brittle latency, preferably reduces the hydrogen content in steel as far as possible.
In the present invention, by hydrogen content control in wire rod in below 1.2ppm, therefore hydrogen embrittlement sensibility is low, it can be ensured that Sound tissue, and may insure excellent ductility.If the hydrogen content is higher than 1.2ppm, also can even if tissue is sound Trigger hydrogen embrittlement, there are problems that being difficult to ensure that the contraction percentage of area is more than 15%.
The method of the excellent wire rod of the manufacture ductility of detailed hereafter according to another aspect of the present invention.
The wire rod of the present invention can manufacture as follows：Meet the wire rod of the alloy compositions by series of process manufacture Afterwards, batched under the temperature conditionss controlled, then the technique by being cooled down stage by stage.
The wire rod can be manufactured by known various wire rod manufacturing technologies in technical field, it is preferred that through Cross following series of process.
First, after manufacture meets the blank of the alloy compositions, preferably through the heating process to homogenize to it.
By the heating process, the microstructure of blank is preferably made to become austenite one phase.
For this purpose, it is preferred that is heated in 950 DEG C~1100 DEG C of temperature range.If the heating temperature is less than 950 DEG C, In subsequent wire rod rolling, temperature region ensures to become difficult, if the heating temperature is higher than 1100 DEG C, generates oxidation , there is poor surface quality in skin (scale) and decarburization phenomenon aggravation.
Preferably, wire rod rolling postcooling is carried out to the blank heated according to the technique and wire rod is made.
At this point, wire rod rolling preferably carries out finish to gauge in 900 DEG C~1000 DEG C of temperature range.If finishing temperature is less than 900 DEG C, then since rolls damage may occur for rolling load, if finishing temperature is higher than 1000 DEG C, austenite grain is thicker, deposits Be difficult to ensure that desirable intensity the problem of.
After the wire rod rolling, the temperature range of subsequent coiling technique is preferably cooled to by conventional water-cooling method.
For the wire rod so manufactured, finally it is manufactured into cooling technique with desirable fine group preferably through batching Knit the wire rod of transitivity.
In the present invention, the coiling technique preferably carries out under 580 DEG C~750 DEG C of temperature range, wherein batching temperature Degree is accurate with the temperature of wire surface.
When being batched after wire rod rolling, temperature range is an important factor for controlling austenite size.It is it is well known that logical The austenite size of normal wire rod keeps nucleation state after rolling, and can grow up in cooling procedure after batching.Therefore, if volume Take temperature high, then the temperature region that austenite can grow up is relatively-high temperature, so austenite also can be thicker.
In the present invention, austenite grain size should control into 15 μm~45 μm in wire rod central part, therefore preferably exist 580 DEG C~750 DEG C of temperature range is batched, and more has the temperature range for being selected in 590 DEG C~730 DEG C to be batched.
If coiling temperature is less than 580 DEG C, become excessively small in wire rod central part austenite grain size, it will The formation of proeutectoid cementite is encouraged, and causes to generate cryo tissue in part decarburization region, exists and is difficult to ensure that section is received The problem of shrinkage is more than 15% ductility.If on the contrary, the coiling temperature is higher than 750 DEG C, in wire rod central part Middle austenite thinning effect is little.
After completing the coiling technique, preferably phase in cools down.
The technique cooled down to wire rod is pearlite uniform and small in order to obtain, the surface of wire rod when usually cooling down (surface portion) adjoint can cause cooling rear surface temperature increased due to the backheat from wire internal and phase transformation fever phenomenon Phenomenon.I.e., in the present invention, when implementing to precool to the wire rod as above batched, temperature can be generated in wire surface as described above Increase phenomenon.At this point, the precooling can be implemented by conventional cooling technique, its condition is not particularly limited, example The methods of air-cooled, air-cooled, misting cooling such as can be used.
For this purpose, the present inventors in wire surface to generating the cooling technique after temperature increases phenomenon as described above Cooling velocity and cooling end temp are controlled, so as to have technical feature in terms of small pearlite is ensured.
Specifically, after the temperature of the wire surface as above batched rises, the temperature of the preferred wire surface rises To after 600 DEG C~820 DEG C of temperature ranges, implementing cooling with the cooling velocity of 3 DEG C/s~10 DEG C/s makes the wire surface Temperature is down to 500 DEG C from the temperature range.It is highly preferred that cooling is implemented with the cooling velocity of 3.5 DEG C/s~9.5 DEG C/s.By this When cooling be defined as the present invention a cooling step.
When the cooling velocity of a cooling step is less than 3 DEG C/s, since wire rod central part cooling velocity is inadequate Soon, it is possible to can not ensure small pearlite, and the intensity ensured may be less than 1200MPa.On the contrary, when described When cooling velocity is more than 10 DEG C/s, since wire rod central part cooling velocity becomes too fast, it is impossible to uniform pearlite is obtained, it is all Such as pearlite is generated with the shape divided.In addition, to ensuring that ductility is also unfavorable, possibility of the contraction percentage of area less than 15% compared with It is high.
After completing a cooling step, preferably it is by the cooling velocity control under 400 DEG C~500 DEG C of temperature range 1.2 DEG C/below s are cooled down (except 0 DEG C/s).Cooling at this time is defined as to the secondary cooling step of the present invention, the temperature Degree scope is subject to wire surface temperature.
In the present invention, the secondary cooling is that hydrogen content is remained in wire rod in order to reduce, after once being cooled down described in completion, Cooling velocity controls slower during secondary cooling, to extend the time for resting on high temperature so that hydrogen is easily spread in wire rod, finally It can reduce and hydrogen content is remained in wire rod.
If the cooling velocity is more than 1.2 DEG C/s, hydrogen content is remained in wire rod can be higher than 1.2ppm, can not ensure to break Face shrinking percentage is more than 15%.
The present invention is more specifically described below by embodiment.But following embodiments are only intended to be more fully described The present invention is not intended to limit the interest field of the present invention.The interest field of the present invention is depended on as described in claims The content rationally derived of content.
(embodiment)
Cast meet the following table 1 alloy compositions ingot casting (70Kg) after, heated in 1100 DEG C of heating furnace about 2 it is small when, It is taken out again from the heating furnace and carries out wire rod rolling at a temperature of 900 DEG C or more, be rolled into line footpath as 13mm.Then, it is right The wire rod of rolling carries out water cooling and is cooled to the coiling temperature shown in table 1.Thereafter, the wire rod batched is stood in stelmor (stelmor) on line, the surface temperature of the wire rod, and the cooling speed shown in following table 1 are then controlled by adjusting air output Degree is once cooled to 500 DEG C, then implements secondary cooling.At this point, the secondary cooling speed of the temperature section at 400 DEG C~500 DEG C It is adjusted using air output, insulation cover controls.At this point, once cooling and the secondary cooling are stood in the stelmor The surface temperature of the wire rod batched on line rises to what is implemented after 620 DEG C~800 DEG C due to phase transformation is generated heat.
For each wire rod cooled down stage by stage described in completion, after confirming microstructure and making tensile sample, drawing is determined Intensity is stretched, and determines the fracture size of head and ductile fracture fraction.In addition, determine residual hydrogen content after manufacture wire rod.
The tension test is after each wire rod that line footpath is 13mm is fabricated to sample with the length cutting of 400mm, with folder The speed that tool spacing is 130mm and 20mm/min is implemented at normal temperatures.In the plane of disruption Site Determination when tension failure face is docked The line footpath of material is Di, the line footpath before experiment is D0When, the contraction percentage of area=100 × (Di/D0)2。
Then, using stereoptics microscope and scanning electron microscope determine after tension test the fracture head of sample and Ductile fracture fraction.
In addition, it observes the section microstructure of 5mm parts below the plane of disruption with scanning electron microscope and determines crystal grain Size.For pearlite colony (nodule) size, EBSD (Electron Backscatter are used in the section Diffraction after) measuring apparatus goes out the crystalline orientation of ferritic structure, by the misorientation of adjacent ferrite crystallization (misorientation) pearlite colony (nodule) border is defined as 7 ° or more of situation, and shows to measure what is marked at this time The value of the size on border (Boundary).
For remaining hydrogen amount, use quality analyzer (Quadrupole mass analyzer) is to scale removal foreign matter When material determine and be heated to 800 DEG C when the hydrogen amount that releases.
【Table 1】
In table 1, contrast material 1 to 12 is that alloy compositions meet the present invention, but manufacturing process does not meet the feelings of the present invention Shape is materials show as a comparison.
【Table 2】
In table 2, γ represents austenite, and P represents pearlite.
As shown in upper table 1 and 2, alloy compositions and manufacturing condition are satisfied by invention material 1 to 17 of the invention, stretch strong Degree meets 1200MPa~1600MPa, and the austenite size of wire rod central part and pearlite colony size and ductile fracture Fraction and the contraction percentage of area meet the scope proposed in the present invention, therefore can provide ductility excellent wire rod.In addition, described Hydrogen content is remained in its steel of the wire rod of invention less than 1.2ppm, can confirm that hydrogen embrittlement sensibility is excellent.
In contrast, temperature is higher than 750 DEG C of contrast material 1 to 3, austenite and pearlite colony size difference when batching The size of head is broken more than 45 μm, 15 μm, therefore during tension failure less than 1.4mm, and the ductile fracture fraction for being broken head is less than 35%, the contraction percentage of area is poor less than 15% ductility.
In addition, temperature is less than 580 DEG C of contrast material 4 to 6 when batching, austenite and pearlite colony size are excessively micro- It is small, therefore encourage the generation of proeutectoid cementite in wire rod central part.The size deficiency of head is broken during tension failure as a result, 1.4mm, and the ductile fracture fraction for being broken head is less than 35%, the contraction percentage of area is poor less than 15% ductility.
In addition, being more than the contrast material 7 and 8 of 10 DEG C/s for a cooling velocity, the intensity of wire rod is more than 1600MPa, The size of head is broken during tension failure and ductile fracture fraction exceeds the present invention, therefore the contraction percentage of area is poor less than 15% ductility.
In addition, being less than the contrast material 9 and 10 of 3 DEG C/s for a cooling velocity, the intensity of wire rod is less than 1200MPa, It can not ensure desirable high intensity.
Its secondary cooling velocity of contrast material 11 and 12 is more than 1.2 DEG C/s, therefore hydrogen content is remained in wire rod and is higher than 1.2ppm, be broken during tension failure head size and ductile fracture fraction beyond the present invention, therefore the contraction percentage of area is less than 15% Ductility is poor.
Fig. 1 is with the photograph that head is broken after the tension failure of the micro- sem observation invention material 1 of stereoptics and contrast material 1 Piece, Fig. 2 are the photos on the fracture head point with scanning electron microscope observation invention material 2 and contrast material 2.
As shown in Figure 1, the fracture head of invention material 1 is than 1 bigger of contrast material.
In addition, as shown in Fig. 2, 2 higher of ductile fracture score ratio contrast material of invention material 2.

Claims (6)

1. a kind of excellent high-carbon wire rod of ductility, the meters of % by weight include carbon (C)：0.9%~1.1%, silicon (Si)：0.6% ~1.5%, manganese (Mn)：0.2%~0.8%, chromium (Cr)：0.2%~0.8%, aluminium (A1)：It is remaining except less than 0.08% but 0% It measures as Fe and other inevitable impurity,
Microstructure includes pearlite mutually as substrate microstructure, and austenite grain size is 15 μm~45 μm in central part, The size of the pearlite colony is 5 μm~15 μm.
2. the excellent high-carbon wire rod of ductility according to claim 1, when tension failure, is broken the big of head (open region) Small is more than 1.4mm, and the ductile fracture fraction of the fracture head (open region) is more than 35%.
3. the excellent high-carbon wire rod of ductility according to claim 1, the tensile strength with 1200MPa~1600MPa, The contraction percentage of area is more than 15%, and residual hydrogen content is 1.2ppm.
4. a kind of manufacturing method of the excellent high-carbon wire rod of ductility, it includes following steps：
Wire rod is manufactured, wire rod % by weight meters include carbon (C)：0.9%~1.1%, silicon (Si)：0.6%~1.5%, manganese (Mn)：0.2%~0.8%, chromium (Cr)：0.2%~0.8%, aluminium (Al)：Except less than 0.08% but 0%, surplus is Fe and its Its inevitable impurity；
The wire rod is batched at 580 DEG C~750 DEG C；
The wire rod batched is precooled；
After the temperature of the wire surface of the precooling rises, 500 are once cooled to the cooling velocity of 3 DEG C/s~10 DEG C/s ℃；And
After the once cooling, with the cooling velocity secondary cooling of 1.2 DEG C/below s to 400 DEG C~500 DEG C.
5. the manufacturing method of the excellent high-carbon wire rod of ductility according to claim 4, wherein,
The once cooling is implemented after the wire surface of the precooling rises to 600 DEG C~820 DEG C of temperature range.
6. the manufacturing method of the excellent high-carbon wire rod of ductility according to claim 4, wherein,
The step of manufacture wire rod, comprises the steps of：Manufacture blank；The blank is added at 950 DEG C~1100 DEG C Heat；Final wire rod rolling is carried out to manufacture wire rod at 900 DEG C~1000 DEG C to the blank after heating；And to the wire rod into Row water cooling is to be cooled to coiling temperature.
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