CN108950369B - A kind of preparation method of case of transmission spheroidal graphite cast-iron - Google Patents

A kind of preparation method of case of transmission spheroidal graphite cast-iron Download PDF

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CN108950369B
CN108950369B CN201810778633.3A CN201810778633A CN108950369B CN 108950369 B CN108950369 B CN 108950369B CN 201810778633 A CN201810778633 A CN 201810778633A CN 108950369 B CN108950369 B CN 108950369B
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iron
inovulant
spheroidal graphite
graphite cast
nodulizer
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CN108950369A (en
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叶展亮
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Foshan City High Ball Mil Iron Co Ltd
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Foshan City High Ball Mil Iron Co Ltd
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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
    • C—CHEMISTRY; METALLURGY
    • C21—METALLURGY OF IRON
    • C21C—PROCESSING OF PIG-IRON, e.g. REFINING, MANUFACTURE OF WROUGHT-IRON OR STEEL; TREATMENT IN MOLTEN STATE OF FERROUS ALLOYS
    • C21C1/00—Refining of pig-iron; Cast iron
    • C21C1/10—Making spheroidal graphite cast-iron
    • C21C1/105—Nodularising additive agents
    • 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
    • C21D1/00—General methods or devices for heat treatment, e.g. annealing, hardening, quenching or tempering
    • C21D1/26—Methods of annealing
    • 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
    • C21D5/00—Heat treatments of cast-iron
    • 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
    • C22C33/10—Making cast-iron alloys including procedures for adding magnesium
    • 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
    • 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

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  • Engineering & Computer Science (AREA)
  • Materials Engineering (AREA)
  • Metallurgy (AREA)
  • Organic Chemistry (AREA)
  • Mechanical Engineering (AREA)
  • Physics & Mathematics (AREA)
  • Thermal Sciences (AREA)
  • Crystallography & Structural Chemistry (AREA)
  • Refinement Of Pig-Iron, Manufacture Of Cast Iron, And Steel Manufacture Other Than In Revolving Furnaces (AREA)

Abstract

The invention discloses a kind of preparation methods of case of transmission spheroidal graphite cast-iron, the spheroidal graphite cast-iron is made of the elemental composition of following mass percent: C:3.7-3.9%, Si:3.5-3.8%, Mn:0.1-0.3%, Sn:0.02-0.03%, Ge:0.005-0.015%, Ni:0.4-0.6%, Ti:0.3-0.4%, Mo:0.5-0.6%, Sb:0.004-0.012%, RE:0.02-0.04%, P≤0.04%, S≤0.02%, surplus are Fe and inevitable impurity.The tensile strength of spheroidal graphite cast-iron of the invention is 980-1050Mpa, yield strength 800-820Mpa, elongation percentage 15-16%, Oxygen potential is 95%, properties are excellent, overcome existing spheroidal graphite cast-iron case of transmission material while with very high intensity, cannot have high toughness；Or while with high toughness, intensity is not able to satisfy the defect of requirement but.

Description

A kind of preparation method of case of transmission spheroidal graphite cast-iron
Technical field
The present invention relates to cast iron metallurgical technology fields, more particularly to a kind of preparation of case of transmission spheroidal graphite cast-iron Method.
Background technique
Spheroidal graphite cast-iron is to obtain globular graphite by nodularization and inoculation, effectively improves the mechanical performance of cast iron, Plasticity and toughness are in particular improved, to obtain the intensity also higher than carbon steel.Spheroidal graphite cast-iron is sent out from 20th century the fifties A kind of high strength cast iron material that exhibition is got up, comprehensive performance are based on its excellent performance, successfully use close to steel Complicated, the more demanding part of intensity, toughness, wearability in some stress of casting.Spheroidal graphite cast-iron has rapidly developed to be only second to Gray cast iron, using very extensive cast iron materials.So-called " with iron Dai Gang ", refers mainly to spheroidal graphite cast-iron.
Speed changer is typically mounted between the clutch of vehicle and transmission shaft, expands vehicle drive force by changing transmission ratio With the variation range of speed, to adapt to the driving conditions often changed.In certain extreme cases, case of transmission is needed to have Higher intensity and good toughness.Existing transmission for vehicles is usually plain cast iron manufacture, cannot guarantee high intensity Have high toughness concurrently simultaneously.
Summary of the invention
In order to make up the defect of prior art, the present invention provides a kind of preparation method of case of transmission spheroidal graphite cast-iron.
The technical problems to be solved by the invention are achieved by the following technical programs:
A kind of preparation method of case of transmission spheroidal graphite cast-iron, the spheroidal graphite cast-iron by following mass percent element at Be grouped as: C:3.7-3.9%, Si:3.5-3.8%, Mn:0.1-0.3%, Sn:0.02-0.03%, Ge:0.005-0.015%, Ni:0.4-0.6%, Ti:0.3-0.4%, Mo:0.5-0.6%, Sb:0.004-0.012%, RE:0.02-0.04%, P≤ 0.04%, S≤0.02%, surplus are Fe and inevitable impurity.
For cast iron materials, wherein between different component specific component content difference, to the metallographic group actually generated It is great for knitting the influence of form, material application performance, difficulty of processing and final product quality.
Silicon is the element having a major impact in spheroidal graphite cast-iron, it can not only effectively reduce chilling tendency, but also have There is refining eutectic group, improves the effect of graphite nodule roundness；It forms silica oxidation film layer again simultaneously, hinders the intrusion of oxygen, Increase casting oxidation resistance.But the high casting brittleness of silicone content increases.Therefore, silicone content is unsuitable excessively high, and usual silicone content is not More than 3.3%.In the present invention, silicone content is increased, the mass percent of silicon reaches 3.5-3.8%, promotes graphitization, realizes Higher intensity promotes the refinement of solidified structure, increases the number of graphite, enhance matrix, solve by increasing nickel and titanium As brought by the increase of silicone content brittle influence, improves the toughness of casting.
Compared with common magnesium iron, due to the addition of molybdenum element, matrix is enhanced, and yield strength can be improved, improve material The dimensional stability of material.
Further, preparation method includes the following steps:
S1. using steel scrap, the pig iron, foundry returns, ferrosilicon, manganese iron, ferrotianium, nickel ingot, molybdenum-iron, carburant as raw material, raw material is melted Refining is iron liquid；
S2. it is put into nodulizer in the side at nodularization packet bottom, one layer of carborundum powder is covered on nodulizer, on carborundum powder The first inovulant is covered, iron filings are uniformly covered on the first inovulant, perlite is used in the casting of the upper surface of iron filings uniform fold And it consolidates；Iron liquid is injected along nodularization packet along the nodularization packet other side using the method that pours, bonded hard ferrite magnet is 1400-1430 DEG C, is carried out Spheroidising and Bao Nei inoculation；When the amount for pouring iron liquid in nodularization packet accounts for iron liquid gross mass 2/3, the second inovulant is added Mould cavity inoculation processing is carried out, and continues to pour remaining iron liquid；
S3. it is poured, third inovulant is added with stream while casting and carries out current-following inoculation；
S4. it is heat-treated: annealing heat-treatment will be carried out after the cast iron cooling after casting complete, annealing temperature is 900 DEG C, heat preservation Time is 3 hours, is cooled to 580 DEG C after annealing with the speed of 10-12 DEG C/min, is then air-cooled to room temperature, obtains spheroidal graphite Cast iron.
Further, the concrete operations of step S1 are as follows: (1) ingredient: as follows using raw material and proportion: steel scrap 20-30%, Pig iron 40-50%, foundry returns 15-25%, ferrosilicon 1.5-2.0%, manganese iron 0.8-1%, ferrotianium 0.8-1.2%, nickel ingot 0.5-1%, molybdenum-iron 1-1.2%, carburant 0.4-0.6%；(2) melting: being added steel scrap, the pig iron, foundry returns to intermediate frequency furnace and heat, in temperature liter Carburant is added to intermediate frequency furnace in three times before to 750 DEG C；After intermediate frequency in-furnace temperature is higher than 1400 DEG C, silicon is added Iron, manganese iron, ferrotianium, nickel ingot and molybdenum-iron；1510 DEG C -1530 DEG C are warming up to, melting obtains iron liquid to whole fusings.
In the present invention, when steel scrap, the pig iron, foundry returns being put into intermediate frequency furnace being heated, first temperature rise to 750 DEG C it Preceding that carburant is added, inventor is in practice, it has been found that if carburant is added when in-furnace temperature is higher than 750 DEG C is easy to happen group Poly- caking phenomenon, and combustion can not be promoted, and when being lower than 750 DEG C, carburant can play combustion-supporting effect, promote The raising of in-furnace temperature, so that the heating effect of intermediate frequency furnace is more preferable.
The method of pouring is the spheroidizing process being most widely used at present, does not have special requirement to iron liquid packet, and method is the simplest It is single, and the briquetting technique in pour-over process is mostly the side of one layer of nodulizer, two layers of inovulant, three layers of iron filings in the prior art Case.The present invention improves briquetting technique, one layer of nodulizer, two layers of carborundum powder, three layers of inovulant, four layers of iron filings, and five layers Perlite, on the one hand overcoming nodulizer, in advance on the other hand the low problem of thermal response and absorptivity excessively can increase graphite Forming core core promotes the refinement of graphite, makes that graphite nodule is more tiny, rounding, improves the nodularization for the spheroidal graphite cast-iron being prepared Rate.
Further, nodulizer accounts for the 1.2-1.5% of iron liquid gross mass；The carborundum powder, nodulizer, iron filings and pearl The mass ratio of rock is 0.3:1.5:1:0.5；First inovulant accounts for the 0.3-0.4% of iron liquid gross mass；It is total that second inovulant accounts for iron liquid The 0.4% of quality；Third inovulant accounts for the 0.2% of iron liquid gross mass；The granularity of the nodulizer is 5-25mm；Described first is pregnant The granularity for educating agent is 5-8mm；The granularity of second inovulant is 4-10mm；The granularity of third inovulant is 0.5-1mm.
Further, the mass percentage composition of the nodulizer is magnesium: 5.5-6.2%, silicon: 44-48%, calcium: 0.8- 1.2%, manganese: 0.05-0.08%, nickel: 1-1.2%, rare earth: 0.8-1.2%, remaining is iron.
Nodularization refers to that the graphite in cast iron becomes the process of graphite crystallization under the influence of the nodulizer of addition.Conventional ball During black iron casting, it is usually added into magnesium-rare earth FeSiMg8Re7 nodulizer.The present invention passes through to nodularization agent prescription It improves and optimizates, introduces a variety of elements with synergy, improve nodulizer to the Oxygen potential of graphite, minimum can guarantee 1-2 grades of nodularization effect, Oxygen potential >=95% have obtained great reinforcement in anti-decaying spheroidisation ability, and nodularization effect is good, obtains The spheroidal graphite cast-iron arrived has high tenacity.
Nodulizer of the invention is designed to distribution fong theory according to as follows: Mg is strongest nodulizer, can make hypoeutectic, Spheroidization of graphite in the iron liquid of eutectic and hypereutectic composition simultaneously has good desulfurization oxygen uptake ability.Rare earth element (RE) and iron liquid In oxygen, sulphur, hydrogen and it is other interference nodularization member be known as stronger affinity interaction, purify iron liquid, and can provide certain Heterogeneous nuclei, advantageously reduce be mingled with, the casting flaws such as subcutaneous blowhole；Fully play the spheroidizing of magnesium simultaneously, Play the role of nodularization or indirect nodularization；But excessive rare earth residual volume will lead to graphite form deterioration in magnesium iron, cause Graphite morphology.In the present invention, the adding proportion of Reasonable Regulation And Control rare earth element and Mg, while calcium, manganese, nickel element are added, collaboration is made With delaying the decomposition of magnesium, control the absorption and reaction speed of nodulizer, can prevent graphite morphology, increase graphite nuclei calculation, promote Into graphitization, extend the decaying spheroidisation time, promote forming core thinning microstructure, hence it is evident that increases number of graphite ball, make the mechanical property of casting It is improved.
Further, in the first inovulant each component mass percent be Si:72-74%, Ba:1.2-1.8%, Ca:1-2%, Mn:4-5%, RE:10-20%, Bi:3-5%, Al:1.0-2.0%, surplus Fe.
Further, each component mass percent is Si:30-45%, Ca:1.8-3%, Zr:2- in the second inovulant 3%, Mn:6-8%, RE:0.5-1%, surplus Fe.
Further, each component mass percent is Si:68-75%, Ca :≤2.0%, Al in the third inovulant: ≤ 1.5%, Bi:0.5- 2.5%, surplus are iron.
It is bred in the present invention including being bred in packet, mould cavity inoculation and current-following inoculation are bred three times.Inovulant is that one kind can promote Into graphitization, chilling tendency is reduced, improves graphite form and distribution situation, increases eutectic cell quantity, refines adding for matrix Work auxiliary agent.In the prior art, the inovulant bred in packet is frequently with FeSi75 inovulant, and the inovulant of mould cavity inoculation is frequently with silicon Barium inovulant, the inovulant of current-following inoculation is frequently with silicon strontium inoculant.Inventor is in practice, it has been found that using existing in the present invention The inovulant of technology, can not effectively improve the intensity of spheroidal graphite cast-iron, therefore be unable to satisfy the intensity requirement of casting.
Using inovulant of the invention, its pregnant effect is good, can reinforce nodularization effect, increases the quantity of spheroidal graphite and close Degree improves graphite nodule roundness, graphite nodule is made to be evenly distributed, and reduces decaying spheroidisation, and extension is bred effective time, can not only be subtracted Few chilling tendency, moreover it is possible to keep the homogeneity of ingredients for breeding rear cast iron good, dynamics, performance, which have, significantly to be promoted, and it is strong to improve finished product Degree.
Further, pouring temperature control is at 1370-1420 DEG C.
Each step is to test to determine many times by applicant in preparation method of the present invention, any one step It goes wrong and will lead to properties of product decline.
The invention has the following beneficial effects:
The tensile strength of spheroidal graphite cast-iron of the invention is 980-1050Mpa, yield strength 800-820Mpa, and elongation percentage is 15-16%, Oxygen potential 95%, properties are excellent, overcome existing spheroidal graphite cast-iron case of transmission material with very high Intensity while, cannot have high toughness；Or while with high toughness, intensity is not able to satisfy requirement but Defect.
Specific embodiment
The present invention will now be described in detail with reference to examples, and the examples are only preferred embodiments of the present invention, It is not limitation of the invention.
Embodiment 1
A kind of preparation method of case of transmission spheroidal graphite cast-iron, the spheroidal graphite cast-iron by following mass percent element at It is grouped as: C:3.8%, Si:3.6%, Mn:0.2%, Sn:0.02%, Ge:0.008%, Ni:0.5%, Ti:0.35%, Mo: 0.5%, Sb:0.008%, RE:0.03%, P≤0.04%, S≤0.02%, surplus are Fe and inevitable impurity.
Preparation method includes the following steps:
S1. (1) ingredient: it is as follows using raw material and proportion: steel scrap 25%, the pig iron 46%, foundry returns 23%, ferrosilicon 1.8%, Manganese iron 0.9%, ferrotianium 0.9%, nickel ingot 0.8%, molybdenum-iron 1.1%, carburant 0.5%；(2) melting: steel scrap, the pig iron, foundry returns are added It is heated to intermediate frequency furnace, carburant is added to intermediate frequency furnace in three times before temperature rises to 750 DEG C；It is warm in intermediate frequency furnace Degree is higher than after 1400 DEG C, and ferrosilicon, manganese iron, ferrotianium, nickel ingot and molybdenum-iron is added；1520 DEG C are warming up to, melting is obtained to whole fusings To iron liquid；
S2. it is put into nodulizer in the side at nodularization packet bottom, one layer of carborundum powder is covered on nodulizer, on carborundum powder The first inovulant is covered, iron filings are uniformly covered on the first inovulant, perlite is used in the casting of the upper surface of iron filings uniform fold And it consolidates；Iron liquid is injected along nodularization packet along the nodularization packet other side using the method that pours, bonded hard ferrite magnet is 1420 DEG C, is carried out at nodularization Inoculation in reason and packet；When the amount for pouring iron liquid in nodularization packet accounts for iron liquid gross mass 2/3, the second inovulant carry out type is added Interior inoculation, and continue to pour remaining iron liquid；Nodulizer accounts for the 1.3% of iron liquid gross mass；The carborundum powder, nodulizer, iron The mass ratio of bits and perlite is 0.3:1.5:1:0.5；First inovulant accounts for the 0.3% of iron liquid gross mass；Second inovulant accounts for iron The 0.4% of liquid gross mass；Third inovulant accounts for the 0.2% of iron liquid gross mass；The granularity of the nodulizer is 5-25mm；Described The granularity of one inovulant is 5-8mm；The granularity of second inovulant is 4-10mm；The granularity of third inovulant is 0.5-1mm； The mass percentage composition of the nodulizer is magnesium: 6%, silicon: 46%, calcium: 1%, manganese: 0.06%, nickel: 1.1%, rare earth: 1%, Remaining is iron；In first inovulant each component mass percent be Si:73%, Ba:1.5%, Ca:1.5%, Mn:4.5%, RE:12%, Bi:4%, Al:1.5%, surplus Fe；Each component mass percent is Si:38%, Ca:2.2%, Zr in second inovulant: 2.5%, Mn:7%, RE:0.8%, surplus Fe；Each component mass percent is Si:70%, Ca in the third inovulant: ≤ 2.0%, Al :≤1.5%, Bi:1.8%, surplus are iron；
S3. be poured, pouring temperature control 1400 DEG C casting while with stream be added third inovulant carry out with Stream is bred；
S4. it is heat-treated: annealing heat-treatment will be carried out after the cast iron cooling after casting complete, annealing temperature is 900 DEG C, heat preservation Time is 3 hours, is cooled to 580 DEG C after annealing with the speed of 10-12 DEG C/min, is then air-cooled to room temperature, obtains spheroidal graphite Cast iron.
Embodiment 2
A kind of preparation method of case of transmission spheroidal graphite cast-iron, the spheroidal graphite cast-iron by following mass percent element at It is grouped as: C:3.7%, Si:3.5%, Mn:0.1%, Sn:0.02%, Ge:0.005%, Ni:0.4%, Ti:0.3%, Mo: 0.56%, Sb:0.004%, RE:0.02%, P≤0.04%, S≤0.02%, surplus are Fe and inevitable impurity.
Preparation method includes the following steps:
S1. (1) ingredient: it is as follows using raw material and proportion: steel scrap 20%, the pig iron 50%, foundry returns 25%, ferrosilicon 1.5%, Manganese iron 0.8%, ferrotianium 0.8%, nickel ingot 0.5%, molybdenum-iron 1%, carburant 0.4%；(2) melting: by steel scrap, the pig iron, foundry returns be added to Intermediate frequency furnace is heated, and carburant is added to intermediate frequency furnace in three times before temperature rises to 750 DEG C；In intermediate frequency in-furnace temperature After 1400 DEG C, ferrosilicon, manganese iron, ferrotianium, nickel ingot and molybdenum-iron is added；1510 DEG C are warming up to, melting is obtained to whole fusings Iron liquid；
S2. it is put into nodulizer in the side at nodularization packet bottom, one layer of carborundum powder is covered on nodulizer, on carborundum powder The first inovulant is covered, iron filings are uniformly covered on the first inovulant, perlite is used in the casting of the upper surface of iron filings uniform fold And it consolidates；Iron liquid is injected along nodularization packet along the nodularization packet other side using the method that pours, bonded hard ferrite magnet is 1400 DEG C, is carried out at nodularization Inoculation in reason and packet；When the amount for pouring iron liquid in nodularization packet accounts for iron liquid gross mass 2/3, the second inovulant carry out type is added Interior inoculation, and continue to pour remaining iron liquid；Nodulizer accounts for the 1.2% of iron liquid gross mass；The carborundum powder, nodulizer, iron The mass ratio of bits and perlite is 0.3:1.5:1:0.5；First inovulant accounts for the 0.4% of iron liquid gross mass；Second inovulant accounts for iron The 0.4% of liquid gross mass；Third inovulant accounts for the 0.2% of iron liquid gross mass；The granularity of the nodulizer is 5-25mm；Described The granularity of one inovulant is 5-8mm；The granularity of second inovulant is 4-10mm；The granularity of third inovulant is 0.5-1mm； The mass percentage composition of the nodulizer is magnesium: 5.5%, silicon: 44%, calcium: 0.8%, manganese: 0.05%, nickel: 1%, rare earth: 0.8%, remaining is iron；Each component mass percent is Si:72%, Ba:1.2%, Ca:1%, Mn:4%, RE in first inovulant: 10%, Bi:3%, Al:1.0%, surplus Fe；Each component mass percent is Si:30%, Ca:1.8%, Zr in second inovulant: 2%, Mn:6%, RE:0.5%, surplus Fe；Each component mass percent is Si:68%, Ca in the third inovulant :≤ 2.0%, Al :≤1.5%, Bi:0.5%, surplus are iron；
S3. be poured, pouring temperature control 1370 DEG C casting while with stream be added third inovulant carry out with Stream is bred；
S4. it is heat-treated: annealing heat-treatment will be carried out after the cast iron cooling after casting complete, annealing temperature is 900 DEG C, heat preservation Time is 3 hours, is cooled to 580 DEG C after annealing with the speed of 10-12 DEG C/min, is then air-cooled to room temperature, obtains spheroidal graphite Cast iron.
Embodiment 3
A kind of preparation method of case of transmission spheroidal graphite cast-iron, the spheroidal graphite cast-iron by following mass percent element at It is grouped as: C:3.9%, Si:3.8%, Mn:0.3%, Sn:0.03%, Ge:0.015%, Ni:0.6%, Ti:0.4%, Mo: 0.6%, Sb:0.012%, RE:0.04%, P≤0.04%, S≤0.02%, surplus are Fe and inevitable impurity.
Preparation method includes the following steps:
S1. (1) ingredient: it is as follows using raw material and proportion: steel scrap 30%, the pig iron 40%, foundry returns 23%, ferrosilicon 2.0%, Manganese iron 1%, ferrotianium 1.2%, nickel ingot 1%, molybdenum-iron 1.2%, carburant 0.6%；(2) melting: steel scrap, the pig iron, foundry returns are added into Frequency furnace is heated, and carburant is added to intermediate frequency furnace in three times before temperature rises to 750 DEG C；It is high in intermediate frequency in-furnace temperature After 1400 DEG C, ferrosilicon, manganese iron, ferrotianium, nickel ingot and molybdenum-iron is added；1530 DEG C are warming up to, melting obtains iron to whole fusings Liquid；
S2. it is put into nodulizer in the side at nodularization packet bottom, one layer of carborundum powder is covered on nodulizer, on carborundum powder The first inovulant is covered, iron filings are uniformly covered on the first inovulant, perlite is used in the casting of the upper surface of iron filings uniform fold And it consolidates；Iron liquid is injected along nodularization packet along the nodularization packet other side using the method that pours, bonded hard ferrite magnet is 1400-1430 DEG C, is carried out Spheroidising and Bao Nei inoculation；When the amount for pouring iron liquid in nodularization packet accounts for iron liquid gross mass 2/3, the second inovulant is added Mould cavity inoculation processing is carried out, and continues to pour remaining iron liquid；Nodulizer accounts for the 1.5% of iron liquid gross mass；The carborundum powder, ball The mass ratio of agent, iron filings and perlite is 0.3:1.5:1:0.5；First inovulant accounts for the 0.35% of iron liquid gross mass；Second is pregnant Educate agent accounts for iron liquid gross mass 0.4%；Third inovulant accounts for the 0.2% of iron liquid gross mass；The granularity of the nodulizer is 5- 25mm；The granularity of first inovulant is 5-8mm；The granularity of second inovulant is 4-10mm；The grain of third inovulant Degree is 0.5-1mm；The mass percentage composition of the nodulizer is magnesium: 6.2%, silicon: 48%, calcium: 1.2%, manganese: 0.08%, nickel: 1.2%, rare earth: 1.2%, remaining is iron；In first inovulant each component mass percent be Si:74%, Ba:1.2%, Ca:2%, Mn:5%, RE:10%, Bi:5%, Al:2.0%, surplus Fe；Each component quality percentage in second inovulant Than for Si:45%, Ca:3%, Zr:3%, Mn:8%, RE:1%, surplus Fe；Each component quality hundred in the third inovulant Divide than being Si:68-75%, Ca :≤2.0%, Al :≤1.5%, Bi:2.5%, surplus is iron；
S3. be poured, pouring temperature control 1420 DEG C casting while with stream be added third inovulant carry out with Stream is bred；
S4. it is heat-treated: annealing heat-treatment will be carried out after the cast iron cooling after casting complete, annealing temperature is 900 DEG C, heat preservation Time is 3 hours, is cooled to 580 DEG C after annealing with the speed of 10-12 DEG C/min, is then air-cooled to room temperature, obtains spheroidal graphite Cast iron.
Comparative example 1
It based on embodiment 1, the difference is that only: in this comparative example: not covering silicon carbide on nodulizer in step S2 Powder.
Comparative example 2
Based on embodiment 1, the difference is that only: in this comparative example: nodulizer uses commercially available magnesium-rare earth FeSiMg8Re7 nodulizer.
Comparative example 3
Based on embodiment 1, the difference is that only: in this comparative example: the first inovulant is bred using commercially available FeSi75 Agent.
Comparative example 4
Based on embodiment 1, the difference is that only: in this comparative example: the second inovulant uses commercially available silicon titanate innoculant, Its ingredient and its percentage composition are as follows: Si:60-70%, Ba:2-6%, Ca:0.5-2.0%, Al:1-2%, surplus are iron.
Comparative example 5
Based on embodiment 1, the difference is that only: in this comparative example: third inovulant uses commercially available silicon strontium inoculant, Its ingredient and its percentage composition are as follows: Si:73-78%, Zr:1.0-1.5%, Sr:0.8-1.2%, Ca≤0.1%, Al≤ 0.5%, surplus Fe.
The spheroidal graphite cast-iron of embodiment 1-3 and comparative example 1-5 are tested for the property, the ball through detecting, in embodiment 1-3 The tensile strength of black cast iron is 980-1050Mpa, yield strength 800-820Mpa, elongation percentage 15-16%, and Oxygen potential is 95%；Tensile strength in comparative example 1-5 is respectively 620MPa, 780MPa, 680MPa, 720MPa, 750MPa, in comparative example 1-5 Yield strength be respectively 585Mpa, 480Mpa, 525Mpa, 465Mpa, 610Mpa, the elongation percentage in comparative example 1-5 is respectively 9%, the Oxygen potential in 8%, 9%, 7%, 7%, comparative example 1-5 is respectively 87%, 85%, 86%, 86%, 85%.
The main chemical elements symbol and Name Resolution that the present invention uses are as follows: C: carbon, Si: silicon, Mn: manganese, P: phosphorus, S: Sulphur, Ge: germanium, Mo: molybdenum, Ni: nickel, Ti: titanium, Sb: antimony, Al: aluminium, Fe: iron, Ba: barium, Ca: calcium, Bi: bismuth, Zr zirconium；RE: full name is RareEarth, refers to rare earth element, and rare earth element is lanthanide series and closely related with lanthanide series in the periodic table of elements Scandium (Sc) element and yttrium (Y) element.
Embodiments of the present invention above described embodiment only expresses, the description thereof is more specific and detailed, but can not Therefore limitations on the scope of the patent of the present invention are interpreted as, as long as skill obtained in the form of equivalent substitutions or equivalent transformations Art scheme should all be fallen within the scope and spirit of the invention.

Claims (7)

1. a kind of preparation method of case of transmission spheroidal graphite cast-iron, the spheroidal graphite cast-iron by following mass percent elemental composition Composition: C:3.7-3.9%, Si:3.5-3.8%, Mn:0.1-0.3%, Sn:0.02-0.03%, Ge:0.005-0.015%, Ni:0.4-0.6%, Ti:0.3-0.4%, Mo:0.5-0.6%, Sb:0.004-0.012%, RE:0.02-0.04%, P≤ 0.04%, S≤0.02%, surplus are Fe and inevitable impurity；Preparation method includes the following steps:
S1. using steel scrap, the pig iron, foundry returns, ferrosilicon, manganese iron, ferrotianium, nickel ingot, molybdenum-iron, carburant as raw material, it is by raw material melting Iron liquid；
S2. it is put into nodulizer in the side at nodularization packet bottom, one layer of carborundum powder is covered on nodulizer, is covered on carborundum powder Iron filings are uniformly covered on the first inovulant by the first inovulant, and the upper surface of iron filings uniform fold casting perlite is simultaneously smash It is real；Iron liquid is injected along nodularization packet along the nodularization packet other side using the method that pours, bonded hard ferrite magnet is 1400-1430 DEG C, carries out nodularization Inoculation in processing and packet；When the amount for pouring iron liquid in nodularization packet accounts for iron liquid gross mass 2/3, the second inovulant is added and carries out Mould cavity inoculation processing, and continue to pour remaining iron liquid；
S3. it is poured, third inovulant is added with stream while casting and carries out current-following inoculation；
S4. it is heat-treated: annealing heat-treatment will be carried out after the cast iron cooling after casting complete, annealing temperature is 900 DEG C, soaking time It is 3 hours, is cooled to 580 DEG C after annealing with the speed of 10-12 DEG C/min, is then air-cooled to room temperature, obtain spheroidal graphite cast-iron；
Wherein, nodulizer accounts for the 1.2-1.5% of iron liquid gross mass；The quality of the carborundum powder, nodulizer, iron filings and perlite Than for 0.3:1.5:1:0.5；First inovulant accounts for the 0.3-0.4% of iron liquid gross mass；Second inovulant accounts for iron liquid gross mass 0.4%；Third inovulant accounts for the 0.2% of iron liquid gross mass；The granularity of the nodulizer is 5-25mm；First inovulant Granularity is 5-8mm；The granularity of second inovulant is 4-10mm；The granularity of third inovulant is 0.5-1mm.
2. the preparation method of spheroidal graphite cast-iron as described in claim 1, which is characterized in that the concrete operations of step S1 are as follows: (1) match Material: as follows using raw material and proportion: steel scrap 20-30%, pig iron 40-50%, foundry returns 15-25%, ferrosilicon 1.5-2.0%, manganese iron 0.8-1%, ferrotianium 0.8-1.2%, nickel ingot 0.5-1%, molybdenum-iron 1-1.2%, carburant 0.4-0.6%；(2) melting: by steel scrap, the pig iron, Foundry returns is added to intermediate frequency furnace and is heated, and carburant is added to intermediate frequency furnace in three times before temperature rises to 750 DEG C；In Intermediate frequency in-furnace temperature is higher than after 1400 DEG C, and ferrosilicon, manganese iron, ferrotianium, nickel ingot and molybdenum-iron is added；1510 DEG C -1530 DEG C are warming up to, Melting obtains iron liquid to whole fusings.
3. the preparation method of spheroidal graphite cast-iron as described in claim 1, which is characterized in that the mass percent group of the nodulizer As magnesium: 5.5-6.2%, silicon: 44-48%, calcium: 0.8-1.2%, manganese: 0.05-0.08%, nickel: 1-1.2%, rare earth: 0.8- 1.2%, remaining is iron.
4. the preparation method of spheroidal graphite cast-iron as described in claim 1, which is characterized in that each component quality hundred in the first inovulant Divide than being Si:72-74%, Ba:1.2-1.8%, Ca:1-2%, Mn:4-5%, RE:10-20%, Bi:3-5%, Al: 1.0-2.0%, it is remaining Amount is Fe.
5. the preparation method of spheroidal graphite cast-iron as described in claim 1, which is characterized in that each component quality hundred in the second inovulant Divide than being Si:30-45%, Ca:1.8-3%, Zr:2-3%, Mn:6-8%, RE:0.5-1%, surplus Fe.
6. the preparation method of spheroidal graphite cast-iron as described in claim 1, which is characterized in that each group sub-prime in the third inovulant Amount percentage is Si:68-75%, Ca :≤2.0%, Al :≤1.5%, Bi:0.5- 2.5%, and surplus is iron.
7. the preparation method of spheroidal graphite cast-iron as described in claim 1, which is characterized in that pouring temperature is controlled in 1370-1420 ℃。
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