CN109252097A - A kind of non-hardened and tempered steel and its continuous casting manufacturing technique of high intensity fractured connecting rod - Google Patents
A kind of non-hardened and tempered steel and its continuous casting manufacturing technique of high intensity fractured connecting rod Download PDFInfo
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- CN109252097A CN109252097A CN201811175895.7A CN201811175895A CN109252097A CN 109252097 A CN109252097 A CN 109252097A CN 201811175895 A CN201811175895 A CN 201811175895A CN 109252097 A CN109252097 A CN 109252097A
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- 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
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B22—CASTING; POWDER METALLURGY
- B22D—CASTING OF METALS; CASTING OF OTHER SUBSTANCES BY THE SAME PROCESSES OR DEVICES
- B22D11/00—Continuous casting of metals, i.e. casting in indefinite lengths
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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
- C21D8/065—Modifying the physical properties by deformation combined with, or followed by, heat treatment during manufacturing of rods or wires of ferrous alloys
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- C—CHEMISTRY; METALLURGY
- C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
- C22C—ALLOYS
- C22C33/00—Making ferrous alloys
- C22C33/04—Making ferrous alloys by melting
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- C22C38/04—Ferrous alloys, e.g. steel alloys containing manganese
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- C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
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- C22C38/06—Ferrous alloys, e.g. steel alloys containing aluminium
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- C22C38/08—Ferrous alloys, e.g. steel alloys containing nickel
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- C22C38/12—Ferrous alloys, e.g. steel alloys containing tungsten, tantalum, molybdenum, vanadium, or niobium
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- C22C38/14—Ferrous alloys, e.g. steel alloys containing titanium or zirconium
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- C22C38/00—Ferrous alloys, e.g. steel alloys
- C22C38/16—Ferrous alloys, e.g. steel alloys containing copper
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- 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
- C22C38/20—Ferrous alloys, e.g. steel alloys containing chromium with copper
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- 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
- C22C38/22—Ferrous alloys, e.g. steel alloys containing chromium with molybdenum or tungsten
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- C22C38/00—Ferrous alloys, e.g. steel alloys
- C22C38/18—Ferrous alloys, e.g. steel alloys containing chromium
- C22C38/24—Ferrous alloys, e.g. steel alloys containing chromium with vanadium
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- C22C—ALLOYS
- C22C38/00—Ferrous alloys, e.g. steel alloys
- C22C38/18—Ferrous alloys, e.g. steel alloys containing chromium
- C22C38/28—Ferrous alloys, e.g. steel alloys containing chromium with titanium or zirconium
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- 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
- C22C38/40—Ferrous alloys, e.g. steel alloys containing chromium with nickel
- C22C38/42—Ferrous alloys, e.g. steel alloys containing chromium with nickel with copper
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- 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
- C22C38/40—Ferrous alloys, e.g. steel alloys containing chromium with nickel
- C22C38/44—Ferrous alloys, e.g. steel alloys containing chromium with nickel with molybdenum or tungsten
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- 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
- C22C38/40—Ferrous alloys, e.g. steel alloys containing chromium with nickel
- C22C38/46—Ferrous alloys, e.g. steel alloys containing chromium with nickel with vanadium
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- 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
- C22C38/40—Ferrous alloys, e.g. steel alloys containing chromium with nickel
- C22C38/50—Ferrous alloys, e.g. steel alloys containing chromium with nickel with titanium or zirconium
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- C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
- C22C—ALLOYS
- C22C38/00—Ferrous alloys, e.g. steel alloys
- C22C38/60—Ferrous alloys, e.g. steel alloys containing lead, selenium, tellurium, or antimony, or more than 0.04% by weight of sulfur
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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
- C21D2211/00—Microstructure comprising significant phases
- C21D2211/005—Ferrite
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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
- C21D2211/00—Microstructure comprising significant phases
- C21D2211/009—Pearlite
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- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02P—CLIMATE CHANGE MITIGATION TECHNOLOGIES IN THE PRODUCTION OR PROCESSING OF GOODS
- Y02P10/00—Technologies related to metal processing
- Y02P10/20—Recycling
Abstract
The present invention relates to a kind of high-intensitive fractured connecting rod non-hardened and tempered steel and its continuous casting manufacturing techniques, the chemical component of the steel is calculated as C:0.32~0.40% by mass percentage, Si:0.90~1.25%, Mn:0.85~1.30%, P:0.008~0.045%, S:0.055~0.095%, Cr :≤0.35%, Ni :≤0.30%, Cu :≤0.25%, Mo :≤0.10%, Al :≤0.035%, Ti:0.030~0.070%, V:0.25~0.35%, N:0.009~0.022%, surplus are Fe and impurity element；Product form is hot rolled circular steel bar.Process flow is electric furnace or converter --- external refining --- VD or RH vacuum outgas --- continuous casting --- tandem rolling.The available uniform ferrite and pearlite of the steel, by being forged into fractured connecting rod, connecting rod mechanical property Rel >=900Mpa, Rm >=1100MPa, hardness: 305-360HBW.
Description
Technical field
The present invention relates to technical field of metal material, are related to a kind of for making the swollen disconnection of high intensity in automobile engine
The non-hardened and tempered steel and its manufacturing method of bar.
Background technique
A kind of novel link and Machining of Connecting Rod that fractured connecting rod and its manufacturing technology, which are the 1990s, is risen by Germany
New technology.Currently, many cars and commercial vehicle manufacturing enterprise engine all use fractured connecting rod both at home and abroad.
Fractured connecting rod is used exclusively for a kind of microalloying non-hardened and tempered steel of bulge-breaking process production engine link, steel with steel
Material is after being forged into connecting rod blank, then is machined out by fractured connecting rod processing line and is broken with swollen, and the manufacturing process of connecting rod is not required to
It is heat-treated, and connecting rod manufacturing process is simple, efficient.The steel is a kind of ferrite-pearlite type non-hardened and tempered steel, be can be used to
Instead of the quenched and tempered steel connecting rod such as 40Cr, 45,42CrMo；Importantly, carrying out separating connecting rod cap due to using bulge-breaking process, no
Need to carry out a series of machining processes such as millings, drawing, mill as conventional linkage manufacturing process, so that connecting rod manufacturing process becomes
It is very simple, and have many advantages, such as the high accuracy of manufacture, high-efficient, the saving energy, at low cost.
Fractured connecting rod is mainly the non-hardened and tempered steel of C70 series with steel at present, and there are also small part MnVS Series Steels.C70 series
The connecting rod strength performance indicator of steel making are as follows: Rel >=550Mpa, Rm >=900MPa；The connecting rod strength of MnVS series steel making
Energy index are as follows: Rel >=750Mpa, Rm >=950MPa.
" automobile connecting bar high-intensitive Micro Alloying automatic steel and its process " disclosed in application number 200810048807.7,
The present invention cuts the mechanism of hardness of steel from non-tempering easy is improved, and by quenched ingredient, Micro Alloying automatic steel connecting rod strength reaches
Rel >=750Mpa, Rm >=1000MPa
" non-hardened and tempered steel and non-hardened and tempered steel component " disclosed in application number 2012280024294.0, which passes through to chemistry
Ingredient design, can be hot-forged and be formed as being broken segmentation after regulation shape, be suitable as needing the automobile of high-fatigue strength
Engine link reaches Rel >=450Mpa.
" automobile engine fractured connecting rod steel " disclosed in application number 201510332645.X, which passes through to alloy body
It is scientific design, without making Important Adjustment to existing production technology, so that it may produce with high-intensitive, suitable brittleness and good
The automobile fractured connecting rod steel of machinability, connecting rod strength reach Rel >=800Mpa, Rm >=1100MPa.
As car is to energy conservation, the development in lightweight direction, the power-transmitting part engine link of automobile is proposed
Higher requirement, it is desirable that connecting rod has higher intensity.
Summary of the invention
It is a kind of for making engine link the technical problem to be solved by the present invention is to be provided for the above-mentioned prior art
The non-hardened and tempered steel and its manufacturing method of high intensity levels, connecting rod forging Rel >=900Mpa, Rm >=1100MPa, hardness 305-
360HBW, forging metallographic structure are that tiny ferrite adds pearlite, and grain size >=8 grade are conducive to automobile engine lightweight.
The present invention solves the above problems used technical solution are as follows: a kind of for making the non-tune of high-intensitive fractured connecting rod
The chemical component of matter steel, the non-hardened and tempered steel is calculated as C:0.32~0.40%, Si:0.90~1.25%, Mn by mass percentage:
0.85~1.30%, P:0.008~0.045%, S:0.055~0.095%, Cr :≤0.35%, Ni :≤0.30%, Cu :≤
0.25%, Mo :≤0.10%, Al :≤0.035%, Ti:0.030~0.070%, V:0.25~0.35%, N:0.009~
0.022%, surplus is Fe and impurity element；Product form is hot rolled circular steel bar.
Design of Chemical Composition of the present invention is according to as follows:
1) determination of C content
C is intensified element most economical, most basic in steel, can significantly improve the intensity of steel, as phosphorus content increases in steel,
Surrender and tensile strength increase, but plasticity and impact reduce.The range of C content of the present invention is determined as 0.32~0.40%, this
Invention is related to steel and belongs to medium carbon steel scope；
2) determination of Si content
Si is dissolved in ferrite the elastic limit, yield strength and tensile strength that can significantly improve steel in steel, reduces
Its plasticity, toughness, the effect that Si increases ferrite flow harden rate is very strong, keeps the cold working of steel difficult, improves to reach
The purpose of intensity, while guaranteeing the processing and swollen disconnected performance of engine link, the range of Si content of the present invention is determined as 0.90%
~1.25%.
3) determination of Mn content
Mn is to improve non-hardened and tempered steel intensity, improves the important alloying element of non-hardened and tempered steel toughness, Mn is that weak carbide is formed
Element mainly exists in the form of solid solution in steel, is solid-solution among ferrite at room temperature；The Mn of solid solution has stronger solid solution
Strengthening effect.The solution strengthening effect of Mn is only second to P and Si, and when Mn content is lower than 0.80%, strengthening effect is unobvious, and Mn contains
Amount more than 1.5% when, play the role of promotion steel bainite, and in steel bainite productivity, with the increase of Mn content
And it improves.And Mn forms MnS lesser to the performance hazards of steel in conjunction with the sulphur in steel, reduces or inhibit the generation of FeS, energy
Cutting ability and swollen disconnected performance are enough improved, the abrasion to cutter is reduced；The range of Mn content of the present invention is determined as 0.85~
1.30%
4) determination of P content
P energy reinforced ferrite phase, increases the intensity of steel, hardness, and inhibition of doing well in material processing becomes
The effect of shape ability, and plasticity, impact flexibility can be caused to significantly reduce, in order to improve swollen disconnected effect, need to add a small amount of
P, but cannot add excessively high, P content is more than 0.045%, and the continuous casting billet that circular-arc type continuous casting machine is produced is easy to occur in slab
Heart shake line, corner are split, and surface quality of continuously cast slab difference can only be using the production method of casting steel ingot；So the model of P content of the present invention
It encloses and determines 0.008~0.045%.
5) determination of S content
S is the element for improving the cutting ability of steel.S forms MnS field trash or duplex impurity in conjunction with the Mn in steel
Object, the machining to material are very favorable；But adding excessive S not only will lead to the mechanical property variation of steel, and
More serious segregation can be generated in steel also to the continuous casting and rolling generation adverse effect to steel.The range of S content of the present invention
It is determined as 0.055~0.095%.
6) determination of Cr content
Cr is carbide former, and the Cr that when heating dissolves in austenite can be such that C curve obviously moves to right, and can be significantly improved
Otherwise harden ability is easy to produce bainite structure to improve the intensity and hardness of steel, but content can not be excessive, reduce toughness.
The range of Cr content of the present invention is determined as≤0.35%.
7) determination of Ni content
Ni is non-carbide forming element.Ni is present in steel the effect for playing solution strengthening in the form being dissolved, but only
It is the weaker strengthening effect of display；When Ni and Cr are used cooperatively, it is remarkably improved harden ability.More Ni is easier to lead to steel
In there is bainite structure.The range of Ni content of the present invention is determined as≤0.30%.
8) determination of Cu content
Cu can improve the stability of austenite in steel, and play the role of reinforced ferrite, and amount containing Cu will lead to when higher
Steel has red brittleness, so that hot forging is rolled processing difficulties, the range of Cu content of the present invention is determined as≤0.25%.
9) determination of Mo content
Mo is present in the solid solution and carbide of steel, there is certain invigoration effect；But Mo can improve steel very significantly
Harden ability, Mo has significant retardation function to perlitic transformation, and the influence to bainite transformation is smaller, thus the steel containing Mo
It is readily available bainite structure, is had an adverse effect to the toughness of steel；Steel of the invention belongs to the non-tune of ferrite-pearlite type
Matter steel, so, steel of the invention has stringent control to Mo content, and the range of Mo content of the present invention is determined as≤0.10%.
10) determination of Al content
Al is deoxidation effective element, and Al content is excessively high, and Al is easily formed during molten steel2O3Equal brittle inclusions, reduce steel
The range of water degree of purity, Al content of the present invention is determined as≤0.035%.
11) determination of V, Ti, N content
V is the main alloy element that non-hardened and tempered steel is strengthened.Steel is mainly present in the compound state of the carbonitride of V
In, and the carbonitride of these V is distributed in pro-eutectoid ferrite with very tiny particle dispersion, and it is strong to generate precipitating
Change, to achieve the effect that improve ferrite-pearlite type non-hardened and tempered steel intensity, the surrender that can especially significantly improve steel is strong
Degree.In addition, the carbonitride of some V can play pinning because of strain induced precipitate in the rolling of steel or forging process
The effect of austenite grain boundary plays the effect of refinement crystal grain to inhibit the progress of austenite recrystallization and crystal grain is prevented to grow up,
Achieve the purpose that improve intensity and toughness simultaneously, when V content is higher, this effect is particularly evident.
The particles such as the TiN of stable small and dispersed, be precipitated by high temperature under solid-state, disperse point can be formed by addition Ti
The TiN of cloth, to preventing Austenite Grain Growth maximally efficient, non-hardened and tempered steel containing Ti is heated to 1250 DEG C, still has thinner Austria
Family name's body crystal grain, this makes the forging temperature of connecting rod higher, further increases the intensity of connecting rod.But Ti cannot be excessively high, because of Ti
Big with the affinity ratio V of N, excessively high Ti can consume more N, thus reduce the precipitating reinforcing effect of V.
N is one of the main intensified element in non-hardened and tempered steel, forms compound with strong nitride forming element (Ti, V etc.)
Play the role of improving intensity and refine crystal grain, but excessively high N content is unfavorable to continuous casting, easily forms continuous casting surfaces and splits
Line.
The range that the range of V content of the present invention is determined as 0.25~0.35%, Ti content is determined as 0.030~0.070%,
The range of N content is determined as 0.009~0.022%；Three's element must be strict controlled in aforementioned range simultaneously.
The manufacturing process of above-mentioned microalloying non-quenched/tempered connecting rod steel be electric furnace or converter --- external refining --- VD or
RH vacuum outgas --- continuous casting --- tandem rolling
Main production feature is as follows:
1) sorting: the high-quality steel scraps such as cutting head are selected, with addition of the level-one pig iron or high-quality molten iron, to reduce harmful element in steel.
2) smelting molten steel:
Steel grade belongs to steel containing P, it is more special to take off P technique, and produce difficult point, uses thin slag operation to the difficult point:
The lime content (reducing 10-35% compared with the lime content for using slag without P steel smelting molten steel) that slag is reduced when smelting, reduces
Basicity reduces oxidisability, and disposable P is de- in place during thin slag operation when smelting, by the control of 0.020%≤P≤0.045%
P content, and control tapping temperature not less than 1550 DEG C, provides prerequisite for subsequent smelting: i.e. tapping when P content >=
0.020%；Simultaneously when optimizing tapping alloy addition sequence: Al, Si, Mn, when being strict with control tapping terminal C, P at
Point, avoid bring peroxidating of re-blowing；Control tapping aim carbon >=0.05%, killing deoxidation when tapping, using eccentric-bottom
Tapping mode reduces steel slag and enters big packet.
Preceding drying is added to carburant, addition alloy, chemical component is accurately controlled, keeps the reducing atmosphere in furnace,
It is stirred using Argon, the non-metallic inclusion in steel is made sufficiently to float, guarantee Molten Steel Cleanliness.
The steel grade belongs to high Si, containing Ti, steel containing V, and there are rate of recovery problems more rambunctious, carry out science to this before smelting
Simulation is calculated and smelted, not only ensures the control purpose (oxygen content 6ppm) of low oxygen content, while by using narrow at sub-control
Technique processed (Si control in the control of target value ± 0.03%, Ti content in target value ± 0.01%, V content control target value ±
0.01%)
Vacuum outgas: since the steel grade belongs to high N steel, the time of RH strict control low vacuum, high vacuum (being less than 130Pa)
Ratio is not less than 2:1, and wherein high vacuum is not less than 10 minutes, avoids excessively de- N, it is ensured that the increasing N of molten steel is horizontal；
3) continuous casting: platform temperature is wrapped in strict control refining, it is ensured that molten steel overheat controls between 15~25 DEG C, and continuous casting is complete
Process takes anti-oxidation casting measure；
The steel grade belongs to high Si, containing P, high S non-hardened and tempered steel, and crack sensitivity is very strong, to this continuous casting process using completely new
Technological design: first use Continuous Casting Soft Reduction technique, secondly reduce pulling rate (0.40-0.6m/min), continuous casting process use M-
EMS (head end electromagnetic agitation) and F-EMS (electromagnetic agitation between stream) duplex, increase head end and stream between electromagnetic agitation ensure section at
Divide uniformity, then passes through the temperature ladder inside weak cold technique (the cooling water of secondary cooling zone water mist is 0.12L/kg) reduction slab
Degree, so as to avoid the generation of underbead crack；By implementing the offline retarded cooling process of high temperature when offline, temperature gradient is reduced, is avoided
The generation of underbead crack.It is effectively improved and reduces the component segregation of continuous casting billet, especially between increasing stream after electromagnetic agitation, slab is solidifying
Gu the consistency of tissue is improved, slab center porosity and shrinkage cavity have obtained effective control, and Models For Secondary Dendrite Arm spacing obtains
To being obviously improved, Center Equiaxial Crystal rate is significantly improved, and crystal grain is refined, to improve the quality of slab significantly, is reduced
Component segregation.
4) slab heats: strict control billet heating temperature (1150-1300 DEG C), heating time are greater than in the operation of rolling
0.71min/mm, furnace is interior using inert gas such as argon gas protection heating, makes steel surface without full decarburization, also guarantees decarburization not simultaneously
Exceeded, which helps to give full play to the effect of Ti and V, tiny grain size is obtained, to obtain high-intensity performance.
5) it tandem rolling: comes out of the stove after steel billet heat insulating and is handled through high-pressure water descaling；It is rolled into required specification subsequently into Continuous mill train,
Rolling reduction >=20, finishing temperature do not limit, air-cooled after the completion of rolling；
6) sawing；
7) heap is cold；
8) finishing.
Compared with the prior art, the advantages of the present invention are as follows:
1, the steel grade has the various advantages of non-hardened and tempered steel, and progress Tempering and Quenching is not needed after user's forging can be straight
It taps into row following process, use, forging mechanical property Rel >=900Mpa, Rm >=1100MPa, hardness 305-360HBW, metallographic
Tissue is tiny ferrite+pearlitic structrure, and grain size reaches 8 grades or more, mechanical property much higher than existing C70 series,
MnVS series fractured connecting rod, is conducive to automobile engine lightweight.
2, certain content Ti (0.030~0.070%) is added in the non-hardened and tempered steel of the application, forms stable small and dispersed
The particles such as TiN, further promote crystal grain refinement, keep connecting rod forging temperature higher, be more advantageous to raising connecting rod strength.
3, the steel contains a certain amount of S that can improve cutting ability and swollen disconnected performance, P element, improves connecting rod continuous casting manufacturing
Energy.
4, the application designs the ingredient of high-intensitive swollen disconnected steel, and without adding B, the content by designing P, S reaches
To the swollen disconnected performance of raising and mach effect.In addition, the content for improving Si while limiting the highest of Si to strengthen tensile strength
Additive amount hundred million reduces continuous casting difficulty, realizes the continuous casting of the steel product, and does not have to raw using production cycle longer casting steel ingot
Production mode.
Detailed description of the invention
Fig. 1 is hot rolled circular steel rod product tissue in the embodiment of the present invention.
Fig. 2 is the engine link mechanical curves figure of hot rolled circular steel rod product forging in the embodiment of the present invention.
Specific embodiment
Present invention is further described in detail with reference to embodiments.
The high-intensitive fractured connecting rod of embodiment 1-4 is that electric furnace or converter --- external refining --- vacuum are de- with steel making process
Gas (VD or RH) --- continuous casting --- tandem rolling --- sawing --- --- finishing --- surface and internal flaw detection --- packaging that heap is cold.
It is matched according to chemical component, the high-quality steel scraps such as cutting head is selected to have with addition of the level-one pig iron or high-quality molten iron to reduce in steel
Evil element；Smelting process flow slag operation controls terminal C >=0.15%, prevents Molten Steel over-oxidation, using thin slag operation: reducing slag
Lime content, reduce oxidisability, with without P steel smelting molten steel using slag lime content compared to reduction 10-35%, in thin slag
Disposable P is de- in place in operating process, controls P content by 0.020%≤P≤0.045%, and control tapping temperature and be not less than
1550 DEG C, prerequisite is provided for subsequent smelting: i.e. tapping P content >=0.020%；The addition sequence of control alloy: Al, Si,
Mn, killing deoxidation when tapping, eccentric bottom tapping reduce steel slag and reinforce diffusive deoxidation into big packet .LF furnace, keep furnace reduction
Atmosphere, Argon stirring, makes the non-metallic inclusion in steel sufficiently float, and guarantees Molten Steel Cleanliness；When vacuum drying oven guarantees high vacuum
Between (≤130Pa) be 15 minutes, strict control low vacuum, the time scale of high vacuum are not less than 2:1, avoid excessively de- N,
Change Morphology of Sulfide by sulfide deformation process.
Continuous casting process uses Prepared by Low Superheat Pouring, and the casting degree of superheat is no more than 25 DEG C, and is equipped with suitable pulling rate 0.4m/
Min and secondary cooling zone intensity of cooling: the cooling water 0.12L/kg of water mist, while continuous casting uses advanced M-EMS and F-EMS duplex
Measure effectively improves and reduces the component segregation of continuous casting billet.Steel rolling is by high temperature rolling, and 1160~1210 DEG C of heating temperature,
Heating time >=4h improves the precipitate of steel.
Tandem rolling: 1200-1300 DEG C of billet heating temperature will be set), heating time be greater than 4 hours, indifferent gas is used in furnace
Body such as argon gas protection heating, makes steel surface without full decarburization, also guarantees that decarburization is not exceeded simultaneously, which facilitates sufficiently
The effect for playing Ti and V, obtains tiny grain size, to obtain high-intensity performance.
5) it tandem rolling: comes out of the stove after steel billet heat insulating and is handled through high-pressure water descaling；It is rolled into required specification subsequently into Continuous mill train,
Rolling reduction >=20, finishing temperature do not limit, air-cooled after the completion of rolling.
1-4 of the embodiment of the present invention and serial, MnVS series fractured connecting rod steel chemical composition, connecting rod mechanical property than C70
Comparison, is shown in Table 1, table 2
1 chemical component of table (wt%)
2 connecting rod mechanical property of table
Embodiment 1-4 product metallographic structure is ferrite and pearlite, and grain size is not less than 8 grades, is higher by three comparative examples
Two-stage, from the point of view of hardness, the application still has preferable cutting ability.
The non-hardened and tempered steel of the application is forged into engine link mechanical property referring to fig. 2.
In addition to the implementation, all to use equivalent transformation or equivalent replacement the invention also includes there is an other embodiments
The technical solution that mode is formed should all be fallen within the scope of the hereto appended claims.
Claims (9)
1. a kind of non-hardened and tempered steel of high intensity fractured connecting rod, it is characterised in that: the chemical component of the non-hardened and tempered steel presses quality percentage
Content is calculated as C:0.32~0.40%, Si:0.90~1.25%, Mn:0.85~1.30%, P:0.008~0.045%, S:
0.055~0.095%, Cr :≤0.35%, Ni :≤0.30%, Cu :≤0.25%, Mo :≤0.10%, Al :≤0.035%,
Ti:0.030~0.070%, V:0.25~0.35%, N:0.009~0.022%, surplus are Fe and impurity element；Product form
For hot rolled circular steel bar.
2. the non-hardened and tempered steel of high intensity fractured connecting rod according to claim 1, it is characterised in that: Cr, Ni, Cu, Mo, Al make
For non-specifically addition element.
3. the non-hardened and tempered steel of high intensity fractured connecting rod according to claim 1, it is characterised in that: added by the non-hardened and tempered steel
Forging mechanical property Rel >=900Mpa made of work, Rm >=1100MPa, hardness 305-360HBW, metallographic structure are tiny
Ferrite+pearlitic structrure, grain size reach 8 grades or more.
4. a kind of continuous casting manufacturing technique of the non-hardened and tempered steel of manufacture high-intensitive fractured connecting rod as described in claim 1, feature
It is: the described method comprises the following steps:
1) high-quality steel scrap is selected, with addition of the level-one pig iron or high-quality molten iron；
2) smelt: for molten steel successively through refining-external refining-Fruit storage at the beginning of converter or electric furnace, steel aim carbon is just produced in control
>=0.05%, prevent Molten Steel over-oxidation, killing deoxidation when tapping, eccentric bottom tapping reduces steel slag and enters big packet；Accurate control
Chemical component when system refining, keeps furnace reduction atmosphere, and Argon stirring makes the non-metallic inclusion in steel sufficiently float, protects
Demonstrate,prove Molten Steel Cleanliness；
3) continuous casting: continuous casting process combines secondary cooling zone water using the technique that electromagnetic agitation combines between head end electromagnetic agitation and stream
Mist is cooling, and continuous casting overall process takes anti-oxidation casting；
4) slab heats: control billet heating temperature, 1150-1300 DEG C of heating temperature, heating time is greater than 7.9min/mm, furnace
It is interior to use inert gas shielding；
5) it tandem rolling: comes out of the stove after steel billet heat insulating and is handled through high-pressure water descaling；It is rolled into required specification subsequently into Continuous mill train, is rolled
Compression ratio >=20, finishing temperature do not limit, and carry out after the completion of rolling air-cooled；
6) sawing；
7) heap is cold；
8) finishing.
5. the continuous casting manufacturing technique of the non-hardened and tempered steel of high intensity fractured connecting rod according to claim 4, it is characterised in that: step
Using thin slag operation during the first refining of rapid 2 smelting molten steel: reducing the lime content of slag, use slag with without P steel smelting molten steel
Lime content compared to reduce 10-35%, during thin slag operation disposable P take off in place, by 0.020%≤P≤0.045%
P content is controlled, and controls tapping temperature not less than 1550 DEG C, provides prerequisite for subsequent smelting: P content of tapping >=
0.020%；Simultaneously when optimizing tapping alloy addition sequence: Al, Si, Mn, when being strict with control tapping terminal C, P at
Point, avoid bring peroxidating of re-blowing；Control tapping aim carbon >=0.05%, killing deoxidation when tapping, using eccentric-bottom
Tapping mode reduces steel slag and enters big packet.
6. the continuous casting manufacturing technique of the non-hardened and tempered steel of high intensity fractured connecting rod according to claim 4, it is characterised in that: step
During rapid 2 smelting molten steel, preceding drying is added to the alloy of carburant, addition.
7. the continuous casting manufacturing technique of the non-hardened and tempered steel of high intensity fractured connecting rod according to claim 4, it is characterised in that: step
The refining of rapid 2 smelting molten steel uses Narrow Composition Control technique: Si control is controlled in target value ± 0.03%, Ti content in target value
± 0.01%, V content is controlled in target value ± 0.01%.
8. the continuous casting manufacturing technique of the non-hardened and tempered steel of high intensity fractured connecting rod according to claim 4, it is characterised in that: step
In the Vacuum Degassing Process of rapid 2 smelting molten steel: control low vacuum, the time scale of high vacuum are not less than 2:1, and wherein high vacuum is not
Lower than 10 minutes, vacuum degree≤130Pa of high vacuum.
9. the continuous casting manufacturing technique of the non-hardened and tempered steel of high intensity fractured connecting rod according to claim 4, it is characterised in that: steel
The water degree of superheat controls between 15~25 DEG C, and continuous casting overall process takes anti-oxidation casting measure；Using Continuous Casting Soft Reduction technique, drop
Low pulling rate is to 0.40-0.6m/min, continuous casting process using electromagnetic agitation between head end electromagnetic agitation and stream) duplex, then pass through weak cold
Technique, the cooling water 0.12L/kg of setting secondary cooling zone water mist, reduces the temperature gradient inside slab, splits so as to avoid inside
The generation of line；Implement high temperature offline retarded cooling process when offline.
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