CN107326257A - A kind of hi-strength nodular iron section bar and preparation method thereof - Google Patents
A kind of hi-strength nodular iron section bar and preparation method thereof Download PDFInfo
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- CN107326257A CN107326257A CN201710520868.8A CN201710520868A CN107326257A CN 107326257 A CN107326257 A CN 107326257A CN 201710520868 A CN201710520868 A CN 201710520868A CN 107326257 A CN107326257 A CN 107326257A
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- C—CHEMISTRY; METALLURGY
- C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
- C22C—ALLOYS
- C22C37/00—Cast-iron alloys
- C22C37/10—Cast-iron alloys containing aluminium or 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
- B22D1/00—Treatment of fused masses in the ladle or the supply runners before casting
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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
- B22D11/04—Continuous casting of metals, i.e. casting in indefinite lengths into open-ended moulds
- B22D11/045—Continuous casting of metals, i.e. casting in indefinite lengths into open-ended moulds for horizontal casting
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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
- C22C33/08—Making cast-iron alloys
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- C—CHEMISTRY; METALLURGY
- C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
- C22C—ALLOYS
- C22C37/00—Cast-iron alloys
- C22C37/04—Cast-iron alloys containing spheroidal graphite
Abstract
The invention discloses a kind of hi-strength nodular iron section bar, by weight percentage consisting of：C：3.0~3.3%, Si：2.2~3.0%, Mn：0.1~0.3%, P≤0.15%, S≤0.06%, Sb：0.01~0.015%, MgIt is residual>=0.05%, REIt is residual：0.015~0.018%, remaining is Fe, and composition described above percentage by weight sum is 100%.The invention also discloses the preparation method of above-mentioned hi-strength nodular iron section bar.The tensile strength of high-strength ductile cast iron section bar of the present invention is more than 600MPa, and hardness is uniform, surface quality is good, and dimensional accuracy is high, the casting flaw such as no burning into sand, slag inclusion, stomata, shrinkage cavity, with good machinability.Spheroidal graphite cast-iron section bar center portion the number of graphite improves more than 20% than common Ductile iron bar, and diameter of graphite ball is about 6~7 grades, without obvious 4~5 grades of major diameter graphite.
Description
Technical field
The invention belongs to cast iron materials casting technology field, it is related to a kind of hi-strength nodular iron section bar, the invention further relates to upper
State the preparation method of Ductile iron bar.
Background technology
Ductile iron bar is the high-quality spheroidal graphite cast-iron blank material produced using horizontal continuous-casting mode, because level connects
Continuous casting Ductile iron bar has a dense structure, the advantages of good product quality, comprehensive mechanical property are excellent, processing characteristics is excellent, because
This has been widely used in the numerous areas such as machinery, hydraulic pressure, metallurgy, weaving, printing or industry.
At present, the Ductile iron bar for directly producing more than tensile strength 600MPa using horizontal continuous-casting method is relatively stranded
Difficulty, the method typically used is that high performance ductile iron section bar is obtained by ADI isothermal hardening.Although can be obtained by ADI processing
More than 1000MPa, or even 1500MPa high tensile property Ductile iron bar, but heat treatment window it is narrower, stability contorting rise
Come extremely difficult, and cost is higher.In addition, higher by the hardness of the ADI Ductile iron bars handled, machining property is poor,
This also result in some difficulty to following process.
However, with the fast development of machining technique, requirement to Ductile iron bar mechanical property also more and more higher, and
In order to control production cost, user is not intended to add the noble metals such as Cu, Ni, Mo or Cr and is heat-treated to realize high-performance,
The hardness for also wanting to material simultaneously is not so high, and can carry out follow-up machining.This requires cast iron profile material in level
Links must be strictly controlled in continuously casting production process, to realize the requirement of low-cost and high-performance.
The content of the invention
It is an object of the invention to provide a kind of hi-strength nodular iron section bar, solve that existing Ductile iron bar mechanical property is low to ask
Topic.
It is a further object of the present invention to provide the preparation method of above-mentioned hi-strength nodular iron section bar.
The technical solution adopted in the present invention is, a kind of hi-strength nodular iron section bar, by weight percentage consisting of：C：
3.0~3.3%, Si：2.2~3.0%, Mn：0.1~0.3%, P≤0.15%, S≤0.06%, Sb：0.01~0.015%,
MgIt is residual>=0.05%, REIt is residual：0.015~0.018%, remaining is Fe.
Another technical scheme of the present invention is, a kind of preparation method of hi-strength nodular iron section bar, specifically by following
Step is implemented：
Step 1, cast iron melting：
According to the percentage by weight of setting, the silicon amount that inovulant is brought into is deducted, the casting magnesium iron needed for base iron is weighed
The pig iron, steel scrap, foundry returns, 75% ferrosilicon and SiC, are molten into molten iron in induction furnace, take base iron to carry out stokehold composition quick
The content of each element, wherein C in analysis, adjustment base iron：3.0~3.3%, Si：1.1~1.8%, Mn：0.1%~0.3%,
P≤0.15%, S≤0.06%, remaining is Fe, and composition described above percentage by weight sum is 100%, is tapped a blast furnace；
Step 2, molten iron step 1 obtained carries out spheroidising using dam-type molten ductile iron bag and bred；
Step 3, the molten iron casting that step 2 is obtained is entered into holding furnace, and carries out horizontal continuous-casting, that is, obtain high intensity ball
Swage material.
Feature of the present invention is also resided in,
Charging sequence is melted in step 1 to be followed successively by：The part casting magnesium iron pig iron is first put into, is advisable, treated with covering furnace bottom
SiC is added after this batch of pig iron fusing, the remaining pig iron, steel scrap and foundry returns is then added, and be pressed in above SiC.
SiC consumption is the 0.8~1.1% of weight of molten iron in step 1, and granularity is 3~10mm.
Fusion temperature is 1550~1580 DEG C, and tapping temperature is 1500~1550 DEG C, and pouring temperature is 1360~1420 DEG C.
Bred in step 2 to breed twice, breed carried out simultaneously with spheroidising for the first time, breed for the second time at nodularization
Reason is completed, and is carried out after skimming, and inovulant is placed in the upper surface of molten iron in ladle, treats to pour into holding furnace with stream.
Spheroidising is specially in step 2：In the ladle that molten iron is poured into pre- roasted mistake, Sb nodulizers will be contained and add dike
In dam, and it is covered on nodulizer, then is covered in inovulant used is once bred using low-sulfur iron filings on nodulizer, is consolidated
The thickness of iron filings coating is not less than 2~3cm afterwards, covers ladle lid rapidly after tapping a blast furnace, treats that spheroidizing reacion is finished, and removes iron
Water clad, skims.
The granularity of inovulant is 3~5mm, and the consumption of an inovulant is the 0.3~0.4% of molten iron gross weight；Two
The granularity of secondary inovulant is 1~3mm, and the consumption of post inoculant is the 0.4~0.5% of molten iron gross weight.
Nodulizer consumption is 1.1~1.6% in step 2, and granularity is 15~30mm；The consumption of inovulant is weight of molten iron
0.7~0.9%.
Horizontal continuous-casting uses the rotating speed of traction electric machine in " drawing~stopping~to draw " processing mode, casting process in step 3
For 800~1200rpm, the drawing time is 0.2~2.0s, and the residence time is 1~35s, and length of mould is 200~600mm, is entered
Coolant-temperature gage is room temperature, and leaving water temperature is 50~70 DEG C, and section bar crystallizer outlet temperature is controlled at 900~1050 DEG C.
The beneficial effects of the invention are as follows, the tensile strength of high-strength ductile cast iron profile material of the present invention is more than 550MPa,
Hardness is uniform, surface quality is good, and dimensional accuracy is high, the casting flaw such as no burning into sand, slag inclusion, stomata, shrinkage cavity.Spheroidal graphite cast-iron section bar material
Material center portion the number of graphite improves more than 20% than common Ductile iron bar, and diameter of graphite ball is about 6~7 grades, without obvious
4~5 grades of major diameter graphite；The Ductile iron bar hardness of the present invention is HB200~260, and the machinability of Ductile iron bar is good
Good, resistance to cutting is small, can be with High speed finish machining, and processed surface smoothness relative fluctuation is small.
Embodiment
With reference to embodiment, the present invention is described in detail.
The invention provides a kind of hi-strength nodular iron section bar, by weight percentage consisting of：C：3.0~3.3%, Si：
2.2~3.0%, Mn：0.1~0.3%, P≤0.15%, S≤0.06%, Sb：0.01~0.015%, MgIt is residual>=0.05%,
REIt is residual：0.015~0.018%, remaining is Fe, and composition described above percentage by weight sum is 100%.
The preparation method of above-mentioned hi-strength nodular iron section bar, specifically implements according to the following steps：
Step 1, cast iron melting：
Molten iron is melted using intermediate frequency furnace, according to the percentage by weight composition of setting, long-acting ferrosilicon is pregnant when deduction breeds
The silicon amount that agent is brought into is educated, the low manganese casting magnesium iron pig iron, steel scrap, foundry returns, 75% ferrosilicon and SiC etc. needed for weighing base iron is calculated
Amount, carry out cast iron melting.Fusing charging sequence is followed successively by：A part of low manganese casting magnesium iron pig iron is first put into, to cover furnace bottom
Be advisable, the SiC that granularity is 3~10mm added after disposable after the fusing of this batch of pig iron, its weight press per stove weight of molten iron 0.8~
1.1% calculates, and then adds the remaining pig iron, steel scrap and foundry returns, and is pressed in above SiC, treats that all furnace charges are complete in stove
Fusing；The ferroalloy added in intermediate frequency furnace is calculated according to 10% scaling loss amount；Treat that all ferroalloys melt to terminate
After take base iron to carry out stokehold fast analyzing constituent, it is determined that and supplementing 75% ferrosilicon or carburant, and the ball produced as needed
The content of each element, wherein C in the diameter of swage material, adjustment base iron：3.0~3.3%, Si：1.1~1.8%, Mn：
0.1~0.3%, P≤0.15%, S≤0.06%, remaining is Fe, prepares to come out of the stove.Fusion temperature is 1550~1580 DEG C, is tapped a blast furnace
Temperature is 1500~1550 DEG C.
Step 2, spheroidising and once breed：
Dam-type molten ductile iron bag is selected to carry out spheroidising, ladle requires height/diameter >=1.6.Before spheroidising first
Scald in bag processing, the ladle that molten iron is poured into pre- roasted mistake, then molten iron is toppled in telegram in reply stove, be repeated three times.
Then, molten iron gross weight 1.1~1.6%, granularity are added in dykes and dams for 15~30mm nodulizer containing Sb, and will once bred
Inovulant used is covered on nodulizer, and consumption is covered in nodularization for the 0.3~0.4% of the molten iron total amount low-sulfur iron filings of use again
In agent, the thickness of iron filings coating is not less than 2~3cm after tamping.Wherein, the granularity of an inovulant is 3~5mm.After tapping a blast furnace
Covered with special molten iron clad rapidly, Mg and RE absorptivity are ensured with this, with this indirect control MgIt is residual>=0.05%, REIt is residualFor
0.015~0.018%.Treat that spheroidizing reacion is finished, remove special molten iron clad, then skim again, in case late inoculation and pouring
Note.
Step 3, late inoculation：
According to the weight of every iron clad water, the long-acting silicon iron inoculator containing Sr and Ba, one are weighed according to the Si amounts of required supplement
The total amount of secondary and post inoculant is 0.7~0.9% of molten iron gross weight in ladle.The molten iron of spheroidising is after skimming, button
Except the amount of an inovulant, the consumption of remaining post inoculant is the 0.4~0.5% of molten iron total amount, the granularity of inovulant for 1~
3mm, is placed on the upper surface of molten iron in ladle, treats to pour into holding furnace with stream.
Step 4, pour into a mould：
Holding furnace internal protecting wall is toasted to shiny red by 30~40min using atomized diesel fuel nozzle before cast, in a crystallizer
Dummy bar head is inserted, dummy bar head is connected with dummy bar, and by drawing machine travel drawing.By pouring for the warm stove of the molten iron handled well
Mouth pours into holding furnace.
Step 5, horizontal continuous-casting：
Molten iron casting is entered after holding furnace and stopped 1~4 minute, the molten iron into crystallizer is wrapped dummy bar head, treats
Start dummy ingot traction after crystallization and freezing, with " drawing~stopping~to draw " technological level continuous casting.Wherein, during horizontal continuous-casting
The rotating speed of traction electric machine is 800~1200rpm, and the drawing time is 0.2~2.0s, and the residence time is 1~35s, length of mould
For 200~600mm, inflow temperature is room temperature, and leaving water temperature is 50~70 DEG C, the control of section bar crystallizer outlet temperature 900~
1050 DEG C, that is, obtain nodular cast iron type material material.
Drawing speed and section bar outlet temperature are controlled, runout is prevented, control molten iron casting interval is no more than 10 minutes, to prevent
Only liquid iron balling and inoculation fade and occur graphite form variation and carbide.
The spheroidal graphite cast-iron section bar material of the present invention, tensile property index has exceeded LZQT600-3 standards (JB/T 10854-
2008 horizontal continuous-casting cast iron profile materials, Chinese machinery industry standard) require.
The tensile strength of the hi-strength nodular iron profile material of the present invention is more than 550MPa, and hardness is uniform, surface quality is good, chi
Very little precision is high, the casting flaw such as no burning into sand, slag inclusion, stomata, shrinkage cavity.Spheroidal graphite cast-iron section bar material center portion the number of graphite is than common
Ductile iron bar improves more than 20%, and diameter of graphite ball is about 6~7 grades, without obvious 4~5 grades of major diameter graphite；This hair
The hardness of bright Ductile iron bar is HB200~260, and the machinability of Ductile iron bar is good, and resistance to cutting is small, can be at a high speed
Finishing, processed surface smoothness relative fluctuation is small.
The preparation method of ball cast iron profile material material of the present invention, is mainly characterized by：Added during cast iron melting in electric furnace
SiC, be conducive to improve Si and C content, while SiC add can as heterogeneous forming core core, graphite can also be improved
The core amounts of forming core, it is thus possible to improve the quantity of graphite nodule.Simultaneously as the raising of the number of graphite, is conducive to avoiding
Kish ball overgrowth and there is major diameter kish ball.The difference of the inside and outside tissue of section bar is so advantageously reduced, is carried
The hardness of high section bar center portion, reduces the hardness on top layer, and improve the machining property of section bar.Further, since SiC fusing point
For 2800 DEG C, density is much smaller than iron, thus its Adding Way is very crucial, can not be melted if directly being added in molten iron,
And SiC absorptivity is extremely low, it is impossible to as the core of heterogeneous forming core, and removed when being likely to become field trash or skimming.Cause
This, present invention employs distinctive preparation method.
The low rare-earth nodularizer of low magnesium containing 1%Sb is used in nodularization, the content for ensureing Sb in casting after nodularization is about
0.01~0.015%, MgIt is residual>=0.05%, REIt is residualFor 0.015~0.018%, the roundness of graphite nodule can be improved, is conducive to carrying
High-performance.
The amount of the long-acting silicon iron inoculator containing Sr and Ba is increased in preparation process, and uses late inoculation method, can be improved
Pregnant effect and extension incubation time, it is to avoid major diameter spheroidal graphite cast-iron section bar breeds caused by setting time length in process of production
Fail and carbide occur.
The noble metals such as Cu, Ni, Mo or Cr are not added in process of production, therefore the more common Ductile iron bar of production cost does not have
There is significant change.Further, since do not use these precious metal alloys elements, the quenching degree of Ductile iron bar of the invention and common
Ductile iron bar is basically identical, the carbide and needle austenite for not having complexity in tissue, therefore the hardness of material is far below at ADI
The hardness of reason, and the machinability of material is excellent.
Embodiment 1
Φ 35mm spheroidal graphite cast-iron section bar materials and its preparation.
By weight percentage consisting of C：3.3%, Si：3.0%, Mn：0.1%, P：0.10%, S：0.06%, Sb：
0.01%, MgIt is residual：0.05%, REIt is residual：0.015%, remaining is Fe.
Molten iron is melted using 2T intermediate frequency furnaces, according to above-mentioned percentage by weight composition, long-acting silicon iron inoculator band is deducted
The silicon amount entered, the amount of foundry iron, steel scrap, foundry returns and 75% ferrosilicon needed for calculating base iron, fusing charging sequence is followed successively by
A part of low manganese casting magnesium iron pig iron is first put into, is advisable with covering furnace bottom, is after the disposable granularity that adds after this batch of pig iron fusing
3mm SiC, its weight presses 0.8% calculating per stove weight of molten iron, then adds the remaining pig iron, steel scrap and foundry returns, and
It is pressed in above SiC, treats that all furnace charges are completely melt in stove；The ferroalloy added in intermediate frequency furnace according to 10% scaling loss
Amount is calculated；After all ferroalloys melt terminate after take base iron carry out stokehold fast analyzing constituent, it is determined that and supplement 75% silicon
Iron or carburant, and produce C, Si, Mn, P in the diameter of Ductile iron bar, adjustment base iron as needed, S composition with
Requirement is reached, prepares to come out of the stove.Fusion temperature is 1550 DEG C, and tapping temperature is 1520 DEG C.A stokehold is carried out before coming out of the stove every time fast
Speed analysis and composition adjustment, require supplementation with carburant when appropriate.
Iron will be gone out before tapping a blast furnace for 300kg, height/diameter is pre- more roasted than the dam-type molten ductile iron bag progress for 1.6, then enters
The boiling hot bag processing of row；Nodulizer containing Sb is selected in nodularization, and consumption is the 1.1% of molten iron gross weight, and granularity is 15mm.Nodulizer is added into dike
In dam, and it is covered in inovulant used is once bred on nodulizer, consumption is the 0.3% of molten iron gross weight, then using low-sulfur
Iron filings are covered on nodulizer, and the thickness of iron filings coating is not less than 2cm after tamping.Wherein, the granularity of an inovulant is
3mm.Covered after tapping a blast furnace with special molten iron clad rapidly, Mg and RE absorptivity are ensured with this, with this indirect control MgIt is residualFor
0.05~0.06%, REIt is residualFor 0.016~0.018%.Treat that spheroidizing reacion is finished, remove special molten iron clad, skim, in case
Cast.
According to the weight of every iron clad water, the long-acting silicon iron inoculator containing Sr and Ba, one are weighed according to the Si amounts of required supplement
The total amount of secondary and post inoculant is 0.7% of molten iron total amount in ladle, and the granularity of post inoculant is 1mm.Spheroidising
Molten iron after skimming, deduct the amount of an inovulant, remaining 0.4% inovulant is placed in the upper surface of molten iron in ladle.
Holding furnace is toasted into 30min with atomized diesel fuel nozzle, inserted in a crystallizer after dummy bar head, by the warm stove of the molten iron handled well
Cast gate pour into holding furnace, pouring temperature is 1420 DEG C.
Molten iron casting is entered after holding furnace and stopped 1 minute, the molten iron into crystallizer is wrapped dummy bar head, it is to be crystallized
Start dummy ingot traction after solidification, with " drawing~stopping~to draw " technological level continuous casting.Drawn wherein during horizontal continuous-casting
The rotating speed of motor is 800rpm, and the drawing time is 0.2s, and the residence time is 1s, and length of mould is 200mm, and inflow temperature is room
Temperature, leaving water temperature is 50~70 DEG C, and section bar crystallizer outlet temperature is controlled at 900 DEG C, that is, obtains nodular cast iron type material material.
Drawing speed and section bar outlet temperature are controlled, runout is prevented, control molten iron casting interval is no more than 10 minutes, to prevent
Only liquid iron balling and inoculation fade and occur graphite form variation and carbide.
Φ 35mm spheroidal graphite cast-iron section bar materials prepared by embodiment 1, in center sampling, tensile strength is 620MPa, is stretched
Long rate is 3.5%, and hardness is HB225~245, and tensile property index has exceeded LZQT600-3 standards (JB/T 10854-2008
Horizontal continuous-casting cast iron profile material, Chinese machinery industry standard) require.
Embodiment 2
Φ 145mm spheroidal graphite cast-iron section bar materials and its preparation.
By weight percentage consisting of：C：3.2%, Si：2.6%, Mn：0.2%, P：0.13%, S：0.04%, Sb：
0.012%, MgIt is residual：0.06%, REIt is residual：0.016%, remaining is Fe.
Molten iron is melted using 3T intermediate frequency furnaces, according to above-mentioned percentage by weight composition, long-acting silicon iron inoculator band is deducted
The silicon amount entered, the amount of foundry iron, steel scrap, foundry returns and 75% ferrosilicon needed for calculating base iron, fusing charging sequence is followed successively by
A part of low manganese casting magnesium iron pig iron is first put into, is advisable with covering furnace bottom, is after the disposable granularity that adds after this batch of pig iron fusing
10mm SiC, its weight presses 0.9% calculating per stove weight of molten iron, then adds the remaining pig iron, steel scrap and foundry returns,
And be pressed in above SiC, treat that all furnace charges are completely melt in stove；The ferroalloy added in intermediate frequency furnace according to 10% burning
Damage amount is calculated；After all ferroalloys melt terminate after take base iron carry out stokehold fast analyzing constituent, it is determined that and supplement 75%
Ferrosilicon or carburant, and the diameter of the Ductile iron bar produced as needed, adjustment base iron in C, Si, Mn, P, S into
Divide to reach requirement, prepare to come out of the stove.Fusion temperature is 1550 DEG C~1580 DEG C, and tapping temperature is 1500~1530 DEG C.Go out every time
Stokehold carries out a stokehold fast analyzing constituent and composition adjustment, and carburant is required supplementation with when appropriate.
Iron will be gone out before tapping a blast furnace for 600kg, height/diameter is pre- more roasted than the dam-type molten ductile iron bag progress for 1.6, then enters
The boiling hot bag processing of row；Nodulizer containing Sb is selected in nodularization, and consumption is the 1.6% of molten iron gross weight, and granularity is 20mm.Nodulizer is added into dike
In dam, and it will once breed inovulant used and be covered on nodulizer, consumption is the 0.4% of molten iron gross weight, then using low-sulfur iron
Bits are covered on nodulizer, and the thickness of iron filings coating is not less than 2cm after tamping.Wherein, the granularity of an inovulant is 5mm.
Covered after being tapped a blast furnace during nodularization with special molten iron clad rapidly, Mg and RE absorptivity are ensured with this, with this indirect control MgIt is residualFor
0.05~0.06%, REIt is residualFor 0.016~0.018%.Treat that spheroidizing reacion is finished, remove special molten iron clad, skim, in case
Cast.
According to the weight of every iron clad water, the long-acting silicon iron inoculator containing Sr and Ba, one are weighed according to the Si amounts of required supplement
The total amount of secondary and post inoculant is 0.9% of iron water amount in ladle, and the granularity of inovulant is 5mm.The molten iron of spheroidising
After skimming, the amount of an inovulant is deducted, remaining 0.5% inovulant is placed in the upper surface of molten iron in ladle.Will insulation
Stove toasts 40min with atomized diesel fuel nozzle, inserts in a crystallizer after dummy bar head, by the cast gate of the warm stove of the molten iron handled well
Holding furnace is poured into, pouring temperature is 1400 DEG C.
4min is stopped after molten iron casting is entered into holding furnace, the molten iron into crystallizer is wrapped dummy bar head, it is to be crystallized
Start dummy ingot traction after solidification, with " drawing~stopping~to draw " technological level continuous casting.Drawn wherein during horizontal continuous-casting
The rotating speed of motor is 900rpm, and the drawing time is 2.0s, and the residence time is 35s, and length of mould is 350mm, and inflow temperature is
Room temperature, leaving water temperature is 70 DEG C, and section bar crystallizer outlet temperature is controlled at 1050 DEG C, that is, obtains nodular cast iron type material material.
Drawing speed and section bar outlet temperature are controlled, runout is prevented, control molten iron casting interval is no more than 10min, to prevent
Only liquid iron balling and inoculation fade and occur graphite form variation and carbide.
Φ 145mm spheroidal graphite cast-iron section bar materials prepared by embodiment 2, are sampled at 1/2 radius, and tensile strength is
600MPa, elongation is 4%, and hardness is HB225~250, and tensile property index has exceeded LZQT600-3 standards (JB/T
10854-2008 horizontal continuous-casting cast iron profile materials, Chinese machinery industry standard) require.
Embodiment 3
Φ 320mm spheroidal graphite cast-iron section bar materials and its preparation.
By weight percentage consisting of：C：3.0%, Si：2.3%, Mn：0.3%, P：0.10%, S：0.03%, Sb：
0.015%, MgIt is residual：0.07%, REIt is residual：0.018%, remaining is Fe.
Molten iron is melted using 5T intermediate frequency furnaces, according to above-mentioned percentage by weight composition, long-acting silicon iron inoculator band is deducted
The silicon amount entered, the amount of foundry iron, steel scrap, foundry returns and 75% ferrosilicon needed for calculating base iron, fusing charging sequence is followed successively by
A part of low manganese casting magnesium iron pig iron is first put into, is advisable with covering furnace bottom, is after the disposable granularity that adds after this batch of pig iron fusing
7mm SiC, its weight presses 0.9% calculating per stove weight of molten iron, then adds the remaining pig iron, steel scrap and foundry returns, and
It is pressed in above SiC, treats that all furnace charges are completely melt in stove；The ferroalloy added in intermediate frequency furnace according to 10% scaling loss
Amount is calculated；After all ferroalloys melt terminate after take base iron carry out stokehold fast analyzing constituent, it is determined that and supplement 75% silicon
C, Si, Mn, P, S composition in iron or carburant, and the diameter of the Ductile iron bar produced as needed, adjustment base iron
To reach requirement, prepare to come out of the stove.Fusion temperature is 1565 DEG C, and tapping temperature is 1515 DEG C.A stokehold is carried out before coming out of the stove every time
Fast analyzing constituent and composition adjustment, require supplementation with carburant when appropriate.
Iron will be gone out before tapping a blast furnace for 1000kg, height/diameter is pre- more roasted than the dam-type molten ductile iron bag progress for 1.6, then
Carry out scalding bag processing；Nodulizer containing Sb is selected in nodularization, and consumption is the 1.3% of molten iron gross weight, and granularity is 23mm.Nodulizer is added
In dykes and dams, and it will once breed inovulant and be covered on nodulizer, consumption is the 0.35% of molten iron gross weight, then using low-sulfur iron filings
It is covered on nodulizer, the thickness of iron filings coating is not less than 2.5cm after tamping.Wherein, the granularity of an inovulant is 4mm.
Covered after being tapped a blast furnace during nodularization with special molten iron clad rapidly, Mg and RE absorptivity are ensured with this, with this indirect control MgIt is residualFor
0.05~0.06%, REIt is residualFor 0.016~0.018%.Treat that spheroidizing reacion is finished, remove special molten iron clad, skim, in case
Cast.
According to the weight of every iron clad water, the long-acting silicon iron inoculator containing Sr and Ba, one are weighed according to the Si amounts of required supplement
The total amount of secondary and post inoculant is 0.8% of iron water amount in ladle, and the granularity of post inoculant is 2mm.Spheroidising
Molten iron deducts the amount of an inovulant after skimming, and remaining 0.45% inovulant is placed in the upper surface of molten iron in ladle.Will
Holding furnace toasts 35min with atomized diesel fuel nozzle, inserts in a crystallizer after dummy bar head, by the warm stove of the molten iron handled well
Cast gate pours into holding furnace, and pouring temperature is 1380 DEG C.
Molten iron casting is entered after holding furnace and stopped 2 minutes, the molten iron into crystallizer is wrapped dummy bar head, it is to be crystallized
Start dummy ingot traction after solidification, with " drawing~stopping~to draw " technological level continuous casting.Drawn wherein during horizontal continuous-casting
The rotating speed of motor is 1200rpm, and the drawing time is 1.6s, and the residence time is 18s, and length of mould is 600mm, and inflow temperature is
Room temperature, leaving water temperature is 60 DEG C, and section bar crystallizer outlet temperature is controlled at 975 DEG C, that is, obtains nodular cast iron type material material.
Drawing speed and section bar outlet temperature are controlled, runout is prevented, control molten iron casting interval is no more than 10min, to prevent
Only liquid iron balling and inoculation fade and occur graphite form variation and carbide.
Φ 320mm spheroidal graphite cast-iron section bar materials prepared by embodiment 3, are sampled at 1/2 radius, and tensile strength is
600MPa, elongation is 3.5%, and hardness is HB215~260, and tensile property index has exceeded LZQT600-3 standards (JB/T
10854-2008 horizontal continuous-casting cast iron profile materials, Chinese machinery industry standard) require.
Claims (10)
1. a kind of hi-strength nodular iron section bar, it is characterised in that by weight percentage consisting of：C：3.0~3.3%, Si：2.2
~3.0%, Mn：0.1~0.3%, P≤0.15%, S≤0.06%, Sb：0.01~0.015%, MgIt is residual>=0.05%, REIt is residual：
0.015~0.018%, remaining is Fe, and composition described above percentage by weight sum is 100%.
2. a kind of preparation method of hi-strength nodular iron section bar, it is characterised in that specifically implement according to the following steps：
Step 1, cast iron melting：
According to the percentage by weight of setting, deduct the silicon amount that inovulant is brought into, weigh the casting magnesium iron pig iron needed for base iron,
Steel scrap, foundry returns, 75% ferrosilicon and SiC, are molten into molten iron in induction furnace, take base iron to carry out stokehold fast analyzing constituent,
Adjust the content of each element in base iron, wherein C：3.0~3.3%, Si：1.1~1.8%, Mn：0.1%~0.3%, P≤
0.15%, S≤0.06%, remaining is Fe, and composition described above percentage by weight sum is 100%, is tapped a blast furnace；
Step 2, molten iron step 1 obtained carries out spheroidising using dam-type molten ductile iron bag and bred；
Step 3, the molten iron casting that step 2 is obtained is entered into holding furnace, and carries out horizontal continuous-casting, that is, obtain hi-strength nodular iron type
Material.
3. the preparation method of a kind of hi-strength nodular iron section bar according to claim 2, it is characterised in that in the step 1
Fusing charging sequence is followed successively by：The part casting magnesium iron pig iron is first put into, is advisable with covering furnace bottom, is added after after this batch of pig iron fusing
Enter SiC, then add the remaining pig iron, steel scrap and foundry returns, and be pressed in above SiC.
4. the preparation method of a kind of hi-strength nodular iron section bar according to claim 2, it is characterised in that in the step 1
SiC consumption is the 0.8~1.1% of weight of molten iron, and granularity is 3~10mm.
5. a kind of preparation method of hi-strength nodular iron section bar according to claim 2, it is characterised in that the fusion temperature
For 1550~1580 DEG C, tapping temperature is 1500~1550 DEG C, and pouring temperature is 1360~1420 DEG C.
6. the preparation method of a kind of hi-strength nodular iron section bar according to claim 2, it is characterised in that in the step 2
Breed to breed twice, breed carried out simultaneously with spheroidising for the first time, breed completed in spheroidising for the second time, skim laggard
OK, inovulant is placed in the upper surface of molten iron in ladle, treats to pour into holding furnace with stream.
7. the preparation method of a kind of hi-strength nodular iron section bar according to claim 6, it is characterised in that in the step 2
Spheroidising is specially：In the ladle that molten iron is poured into pre- roasted mistake, Sb nodulizers will be contained and added in dykes and dams, and will be once pregnant
Educate inovulant used to be covered on nodulizer, then be covered in using low-sulfur iron filings on nodulizer, iron filings coating after tamping
Thickness is not less than 2~3cm, covers ladle lid rapidly after tapping a blast furnace, treats that spheroidizing reacion is finished, and removes ladle lid, skims.
8. the preparation method of a kind of hi-strength nodular iron section bar according to claim 6, it is characterised in that described once to breed
The granularity of agent is 3~5mm, and the consumption of an inovulant is the 0.3~0.4% of molten iron gross weight；The granularity of post inoculant is 1
~3mm, the consumption of post inoculant is the 0.4~0.5% of molten iron gross weight.
9. the preparation method of a kind of hi-strength nodular iron section bar according to claim 2, it is characterised in that in the step 2
Nodulizer consumption is 1.1~1.6%, and granularity is 15~30mm；The consumption of inovulant is the 0.7~0.9% of weight of molten iron.
10. the preparation method of a kind of hi-strength nodular iron section bar according to claim 2, it is characterised in that in the step 3
Horizontal continuous-casting uses the rotating speed of traction electric machine in " drawing~stopping~to draw " processing mode, casting process to be 800~1200rpm,
The drawing time is 0.2~2.0s, and the residence time is 1~35s, and length of mould is 200~600mm, and inflow temperature is room temperature, is gone out
Coolant-temperature gage is 50~70 DEG C, and section bar crystallizer outlet temperature is controlled at 900~1050 DEG C.
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| CN108611551A (en) * | 2018-06-28 | 2018-10-02 | 宁波日星铸业有限公司 | High silicon solution strengthening Ferrite nodular iron casting and its manufacturing method |
| CN109604533A (en) * | 2019-02-15 | 2019-04-12 | 莱州鸿源台钳制造有限公司 | A kind of preparation method of austempered ductile iron bench vice |
| CN110284050A (en) * | 2019-07-29 | 2019-09-27 | 河北恒工机械装备科技有限公司 | A kind of Large-cross-section nodular cast iron profile and technique preventing chunky graphite formation |
| CN113416886A (en) * | 2021-05-14 | 2021-09-21 | 西安理工大学 | Thermal shock fatigue-resistant glass mold iron section and preparation method thereof |
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