CN103540701B - Smelting process suitable for ultra-high strength gray cast iron - Google Patents
Smelting process suitable for ultra-high strength gray cast iron Download PDFInfo
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- CN103540701B CN103540701B CN201310100239.1A CN201310100239A CN103540701B CN 103540701 B CN103540701 B CN 103540701B CN 201310100239 A CN201310100239 A CN 201310100239A CN 103540701 B CN103540701 B CN 103540701B
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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
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Abstract
The invention aims at providing a smelting process suitable for ultra-high strength gray cast iron, which can improve the tensile strength of the gray cast iron. The smelting process comprises the following steps: step 1), adding foundry returns at the bottom of a furnace to start melting, then adding scrap steel, a carburant with high melting point and a silicon-increasing material, alternately adding the carburant, the silicon-increasing material and the scrap steel into the furnace to facilitate the dispersion of carbon (C) element, and further adding materials which are easy to cause burning loss and used to increase alloy elements of manganese, chromium, copper and sulfur after all the charging is completely molten; step 2), controlling the smelting temperature within the range of 1550-1580 DEG C, enabling the smelting temperature to exceed the overheating temperature of molten iron, and performing heat preservation for 3-5min to enable the molten iron to eliminate the heredity of the charging, refine grains, refine graphite and improve the purity of the molten iron at a high temperature; step 3), controlling the tapping temperature within the range of 1460-1480 DEG C, and adding an inoculant along with tapping; and step 4), controlling the pouring temperature within the range of 1360-1380 DEG C.
Description
Technical field
The present invention relates to gray cast iron smelting technique, particularly relate to ultra-high strength gray cast iron melting technology.
Background technology
Constantly bringing forth new ideas and developing along with automobile industry, also improving constantly the performance requriements of the gray cast iron material that automobile uses, such as gray iron material is from HT250 to HT300, even HT350, forward requirement perhaps can be higher, and this brings greatly difficulty to existing casting smelting technology.Traditional smelting technique (pig iron+steel scrap+foundry returns+alloy) can only produce HT300 material, cannot stably produce HT350 material at all.The quality of smelting technique to molten iron is most important, adopts different smelting techniques, same chemical composition, and the metallurgical quality of the iron liquid obtained is completely different, thus the casting material performance obtained is also completely different.
Summary of the invention
The object of the present invention is to provide a kind of melting technology being applicable to ultra-high strength gray cast iron, make raising graphitic cast iron tensile strength.
For realizing the melting technology being applicable to ultra-high strength gray cast iron of described object, it is characterized in that comprising
Step 1, foundry returns is added molten as opening at furnace bottom, and then add steel scrap and the high carburelant of fusing point, increase silicon materials, carburelant, increasing silicon materials and steel scrap will alternately add in stove, be convenient to the diffusion of carbon C element, after all furnace charges are melting down, then add the material for increasing alloying element manganese, chromium, copper, sulphur of easy scaling loss;
Step 2, smelting temperature controls within the scope of 1550-1580 DEG C, makes its smelting temperature exceed the temperature of superheat of iron liquid, and is incubated 3-5 minute, to make iron liquid at high temperature to eliminate the heredity of furnace charge, crystal grain thinning, refinement graphite and to improve the purity of iron liquid;
Step 3, tapping temperature controls within the scope of 1460-1480 DEG C, should add nucleating agent with tapping a blast furnace; And
Step 4, teeming temperature controls within the scope of 1360-1380 DEG C.
Described melting technology, wherein the span of control of the chemical composition of graphitic cast iron is (mass percent): C2.95-3.10, Si1.40-1.60, Mn1.10-1.20, P≤0.100, S0.060-0.085, Cr0.35-0.45, Cu0.50-0.60, CE3.42-3.63.
Described melting technology, wherein in step 1, main furnace charge all adopts steel scrap, or adopts steel scrap and foundry returns.
Described melting technology, wherein in step 1, steel scrap is the carbon steel of high-quality.
Described melting technology, wherein in step 1, carburelant adopts low nitrogen graphite carburelant, and increasing silicon materials are silicon carbide, and ferromanganese uses 65 ferromanganese, and ferrochrome uses 70 ferrochrome, and copper uses electrolytic copper.
Described melting technology, wherein in step 3, nucleating agent is silicon titanate innoculant.
Described melting technology, wherein graphitic cast iron comprises chemical composition (mass percent) C3.00, Si1.50, Mn1.15, P≤0.100, S0.075, Cr0.40, Cu0.55, CE3.5.
In an embodiment of the present invention, the graphitic cast iron tensile strength according to melting technology of the present invention reaches more than 380MPa, even more than 410MPa, improves the tensile strength of graphitic cast iron largely, improves reliability of material.Hardness of cast form can reach more than 270HB, drastically increases the wear resistance of graphitic cast iron and the stability of materials'use.
Embodiment
Step 1, super-strength gray cast iron material chemical composition design, selects rational C, Si and CE value, and designs the content of suitable Mn, Cr, Cu alloying element.The span of control of chemical composition is (following numerical value is mass percent): C2.95-3.10, Si1.40-1.60, Mn1.10-1.20, P≤0.100, S0.060-0.085, Cr0.35-0.45, Cu0.50-0.60, CE3.42-3.63.In the preferred embodiment, chemical composition is C3.00, Si1.50, Mn1.15, P≤0.100, S0.075, Cr0.40, Cu0.55, CE3.5.
Step 2, super-strength gray cast iron material melting ingredient calculates.Main furnace charge adopts whole steel scrap or steel scrap+foundry returns, and steel scrap will select the carbon steel of high-quality, does not use foundry iron; Carburelant adopts low nitrogen graphite carburelant (through high temperature graphitization process), and in full smelting scrap steel technology, carburelant is the most important link of iron liquid carburetting, so the quality of carburelant quality determines the quality of iron liquid quality; Do not use ferrosilicon to carry out increasing silicon, replace with silicon carbide; Ferromanganese uses 65 ferromanganese; Ferrochrome uses 70 ferrochrome; Copper uses electrolytic copper.Aforementioned steel scrap mainly refers to " eliminate or damage as recycle wastes of iron and steel; Its carbon content is generally less than 0.3%, and sulphur, phosphorus content are all not more than 0.05% ".In one embodiment of this invention, the batching of ultra-high strength gray cast iron as shown in Table 1.The carbon steel of high-quality comprises the highquality carbon steel (carbon content is low between 0.25%-0.5%) on common meaning, or or the lower carbon steel of carbon content, such as high-duty cast steel (phosphorous, sulphur is lower) or superfine high-quality steel.
Step 3, carries out furnace charge according to charger sheet, interpolation alloy is weighed, get out all furnace charges and add alloy.Open medium-frequency induction furnace, prepare reinforced.Furnace charge addition means: first add foundry returns at furnace bottom molten as opening, and then add steel scrap and the high carburelant of fusing point, (carburelant, silicon carbide and steel scrap will alternately add in stove silicon carbide, be convenient to the diffusion of carbon C element like this), after all furnace charges are melting down, add alloy ferromanganese, ferrochrome, electrolytic copper, the Iron sulfuret of easy scaling loss.
Step 4, the smelting temperature of iron liquid is controlled within the scope of 1550 DEG C-1580 DEG C, its smelting temperature is made to exceed the temperature of superheat of iron liquid, and be incubated 3-5 minute, iron liquid by being at high temperature incubated, calm after, impurity in iron liquid floats, and takes off impurity and the slag on iron liquid surface clearly, and gets stokehold spectrum samples.
Step 5, after spectrum samples analysis in stokehold is qualified, preparation is tapped a blast furnace liquid, tapping temperature controls at 1460 DEG C-1480 DEG C, start turndown switch turns body of heater and pour iron liquid in iron liquid bag, when pouring iron liquid about 1/3 in bag, long-acting silicon titanate innoculant can be added in bag, add nucleating agent unsuitable too fast, should with tapping a blast furnace and slowly adding, account for about 1/2 of tapping duration, tap a blast furnace complete, stir iron liquid, be sprinkled into slag-cleaning agent to skim, to make in bag iron liquid level just like " minute surface ", can pour into a mould, and get the finished product spectrum samples after breeding, analyze, record its chemical composition good.
Step 7, teeming temperature controls, at 1360 DEG C-1380 DEG C, can not interrupt flowing molten iron during cast, and bag mouth distance sprue cup does not exceed 300mm, should sprue cup be made all the time to remain full of;
Step 8, processes three tensile strength coupons and three hardness specimens, tests its mechanical property, hardness and metallographic structure.
Claims (6)
1. be applicable to the melting technology of ultra-high strength gray cast iron, it is characterized in that, the span of control of the chemical composition of graphitic cast iron is (mass percent): C2.95-3.10, Si1.40-1.60, Mn1.10-1.20, P≤0.100, S0.060-0.085, Cr0.35-0.45, Cu0.50-0.60, CE3.42-3.63, this melting technology comprises
Step 1, foundry returns is added molten as opening at furnace bottom, and then add steel scrap and the high carburelant of fusing point, increase silicon materials, carburelant, increasing silicon materials and steel scrap will alternately add in stove, be convenient to the diffusion of carbon C element, after all furnace charges are melting down, then add the material for increasing alloying element manganese, chromium, copper, sulphur of easy scaling loss;
Step 2, smelting temperature controls within the scope of 1550-1580 DEG C, makes its smelting temperature exceed the temperature of superheat of iron liquid, and is incubated 3-5 minute, to make iron liquid at high temperature to eliminate the heredity of furnace charge, crystal grain thinning, refinement graphite and to improve the purity of iron liquid;
Step 3, tapping temperature controls within the scope of 1460-1480 DEG C, should add nucleating agent with tapping a blast furnace; And
Step 4, teeming temperature controls within the scope of 1360-1380 DEG C.
2. melting technology as claimed in claim 1, it is characterized in that, in step 1, main furnace charge all adopts steel scrap, or adopts steel scrap and foundry returns.
3. melting technology as claimed in claim 1, it is characterized in that, in step 1, steel scrap is the carbon steel of high-quality.
4. melting technology as claimed in claim 1, it is characterized in that, in step 1, material for increasing alloying element manganese, chromium, copper, sulphur is alloy ferromanganese, ferrochrome, electrolytic copper, Iron sulfuret, carburelant adopts low nitrogen graphite carburelant, increasing silicon materials are silicon carbide, and ferromanganese uses 65 ferromanganese, and ferrochrome uses 70 ferrochrome.
5. melting technology as claimed in claim 1, it is characterized in that, in step 3, nucleating agent is silicon titanate innoculant.
6. melting technology as claimed in claim 1, it is characterized in that, graphitic cast iron comprises chemical composition (mass percent) C3.00, Si1.50, Mn1.15, P≤0.100, S0.075, Cr0.40, Cu0.55, CE3.5.
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Families Citing this family (10)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN103882278A (en) * | 2014-03-07 | 2014-06-25 | 天润曲轴股份有限公司 | Special composite alterant for silicon carbide-based nodular cast iron |
| CN103882279B (en) * | 2014-03-31 | 2015-11-18 | 江苏力源金河铸造有限公司 | A kind of melting method of high-strength gray cast iron part |
| CN104498659A (en) * | 2014-12-10 | 2015-04-08 | 中山市恒成球墨铸铁铸造有限公司 | Process for smelting synthetic nodular cast iron |
| CN104975223A (en) * | 2015-06-30 | 2015-10-14 | 柳州金特新型耐磨材料股份有限公司 | Production method of cast iron HT150 |
| CN106011360A (en) * | 2016-07-01 | 2016-10-12 | 宁国市开源电力耐磨材料有限公司 | Smelting technology of high-strength low-stress gray pig iron |
| CZ2017139A3 (en) * | 2017-03-10 | 2018-01-03 | První Brněnská Strojírna Velká Bíteš, A. S. | A method of casting using the method of investment pattern |
| CN107130165A (en) * | 2017-06-30 | 2017-09-05 | 马鞍山市兴隆铸造有限公司 | A kind of production method of microalloying bearing cap gray cast iron |
| CN109306430A (en) * | 2018-10-22 | 2019-02-05 | 安徽大天铸业有限责任公司 | A kind of casting technique of thermal crack resistant vermicular cast iron brake disc |
| CN113667884A (en) * | 2021-08-14 | 2021-11-19 | 昆明云内动力股份有限公司 | Gray cast iron casting smelting material and casting method thereof |
| CN114990419B (en) * | 2022-06-22 | 2023-10-27 | 吉林省诚鼎精密铸造有限公司 | Method for smelting cast iron by using scrap steel |
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| CN101649369A (en) * | 2009-08-28 | 2010-02-17 | 河南省四达仙龙实业有限公司 | Melting process for producing synthetic cast iron by utilizing SiC carburizing siliconizing |
| CN101778959A (en) * | 2007-06-26 | 2010-07-14 | 国立大学法人岩手大学 | Flake graphite cast iron and manufacture method thereof |
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| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN101778959A (en) * | 2007-06-26 | 2010-07-14 | 国立大学法人岩手大学 | Flake graphite cast iron and manufacture method thereof |
| CN101649369A (en) * | 2009-08-28 | 2010-02-17 | 河南省四达仙龙实业有限公司 | Melting process for producing synthetic cast iron by utilizing SiC carburizing siliconizing |
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