CN104004959A - Method for treating ductile cast iron foundry returns by applying non-silicone nodulizing agent in ductile cast iron smelting - Google Patents
Method for treating ductile cast iron foundry returns by applying non-silicone nodulizing agent in ductile cast iron smelting Download PDFInfo
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- CN104004959A CN104004959A CN201410219500.4A CN201410219500A CN104004959A CN 104004959 A CN104004959 A CN 104004959A CN 201410219500 A CN201410219500 A CN 201410219500A CN 104004959 A CN104004959 A CN 104004959A
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Abstract
The invention discloses a method for treating ductile cast iron foundry returns by applying a non-silicone nodulizing agent in ductile cast iron smelting. The method comprises the following steps: base iron preparation, nodulizing treatment, inoculation treatment, cast pouring and time control. The method disclosed by the invention plays a nodulizing role without adding Si to molten iron by controlling the temperature and time of the molten iron and adding the non-silicone nodulizing agent with specified granularity, thereby saving the raw materials, namely a large amount of pig iron and the like, solving the problem of the waste of a large quantity of waste materials and maintaining the ecological equilibrium; the method disclosed by the invention can outstandingly reduce the product cost of a cast, obtains great economic benefit and achieves the national standards in terms of a chemical component, a metallurgical structure and mechanical property.
Description
Technical field
The present invention relates to a kind of smelting technique, be specifically related to application in a kind of magnesium iron melting and without Si nodularizer, process the method for magnesium iron foundry returns.
Background technology
At present, Chinese most engineering works G. Iron Castings is used sand casting, evaporative pattern and " V " method casting technique to produce.Because sand casting process yield is low, evaporative pattern starts advanced development, and waste product is more, and molten iron utilization ratio is very poor, and dead head and useless part account for the more than 60% of molten iron total mass.The bulk deposition of magnesium iron foundry returns, not only takies company's production cost, and causes the wasting of resources also to cause certain destruction to environment, and magnesium iron melting will be carried out nodularization and inoculation, and these two kinds of processing are all to increase Si process.
Qualified in order to guarantee the final chemical composition of molten iron, when batching, must make base iron Si amount very low, to adding 30% left and right containing the high magnesium iron foundry returns of Si, so just there is more than 30% foundry returns residue.Therefore, a large amount of residues of magnesium iron foundry returns are the difficult problems during domestic and international sand cast ball ironware is produced.For guaranteeing that G. Iron Castings chemical composition, metallographic structure, mechanical property are qualified, and improve foundry returns proportioning, only have following two approach.A. use the siliceous very low pig iron.B. use low silicon (5%～10%) during spheroidizing or without the nodulizing agent of silicon (<5%).At present, be subject to the restriction of smelting technology containing the very low pig iron of Si, price is high, should not use in a large number.
Density (4.5～5.5 g ,/cm) without Si nodularizer is little, thereby nodulizing agent agglomerate easily floats during spheroidizing reacion, on molten iron surface, contacts and oxidizing fire with air, does not play spheroidization.Easily outburst of reaction during spheroidizing, level of response is violent, very easily causes a large amount of scaling loss of nodularization element, and molten iron severe oxidation even makes whole stove molten iron scrap.
Summary of the invention
Object of the present invention is exactly the defect existing for prior art, a kind of spheroidization that both risen is provided, molten iron is not increased to Si again, a large amount of starting material such as the pig iron have been saved, solve the waste of a large amount of waste materials, safeguarded the eubiosis, can significantly reduce castings production cost, obtained great economic benefit, in the magnesium iron melting that chemical composition, metallographic structure, mechanical property are all up to state standards, the method for magnesium iron foundry returns is processed in application without Si nodularizer.
Its technical scheme is: in magnesium iron melting, the method for magnesium iron foundry returns is processed in application without Si nodularizer, comprises the following steps:
A, base iron preparation: melting unit is medium-frequency induction furnace, and molten iron material comprises the pig iron, steel scrap, magnesium iron foundry returns;
B, spheroidizing: with 1000kg dykes and dams pit type liquid iron balling bag, the method that pours is processed, and molten iron tapping temperature is 1500～1550 degree, casing cast temperature 1420～1430 degree, magnesium-rare earth granularity 5～30mm, is 5mm～30mm without Si nodularizer granularity;
C, inoculation: nucleating agent adopts 75SiBa nucleating agent, comprises and breeding for twice, and once breed in nodularization bag, nucleating agent granularity is 3～8mm; When late inoculation is ladle-to-ladle after nodularization, with stream, carry out, nucleating agent granularity is 0.3～0.5mm;
D, pouring cast part: control casting quality;
E, time control: be less than 10min from spheroidizing to the time pouring.
The height and the diameter ratio H/D that in described step b, control nodularization bag, H/D is 1.8.
In described step b, without Si nodularizer, in molten iron, can successively react, the half-cylindrical pit radius that the bag end is built into refractory brick is 26mm, is highly 20mm.
In described step b, by strengthening the covering without Si nodularizer, control the spheroidizing reacion time opening.
In described step b, the strict molten iron temperature of controlling, determines that molten iron tapping temperature is 1520～1550 ℃.
Being added on before molten iron discharging without Si nodularizer in described step b.
In described steps d, pouring cast part pours peace and quiet molten iron surface slag while hot.
The present invention compared with prior art, has the following advantages: use without Si nodularizer and process magnesium iron, the height of nodularization bag and diameter ratio are 1.8, and pit is radius 26mm, height 20mm, and effect is fine; Magnesium iron foundry returns proportioning is up to 80%, and under any produce rate of technology condition, all can keep furnace charge balance; When late inoculation is ladle-to-ladle after nodularization, with stream, carry out, nucleating agent material granularity 0.3～0.5mm, further increases nodule number and the rounding property of graphite pebbles, improves nodularization rate; Solve the waste of a large amount of waste materials, safeguarded the eubiosis, can significantly reduce castings production cost, obtained great economic benefit; By control molten iron temperature, time and add designated size without Si nodularizer, its chemical composition, metallographic structure, mechanical property are not only all up to state standards, some index is better than national standard.
Embodiment
In magnesium iron melting, the method for magnesium iron foundry returns is processed in application without Si nodularizer, comprises the following steps:
A, base iron preparation: melting unit is medium-frequency induction furnace, and molten iron material comprises the pig iron, steel scrap, magnesium iron foundry returns;
B, spheroidizing: with 1000kg dykes and dams pit type liquid iron balling bag, the method that pours is processed, and molten iron tapping temperature is 1500～1550 degree, casing cast temperature 1420～1430 degree, magnesium-rare earth granularity 5～30mm, is 5mm～30mm without Si nodularizer granularity;
C, inoculation: nucleating agent adopts 75SiBa nucleating agent, comprises and breeding for twice, and once breed in nodularization bag, nucleating agent granularity is 3～8mm; When late inoculation is ladle-to-ladle after nodularization, with stream, carry out, nucleating agent granularity is 0.3～0.5mm;
D, pouring cast part: control casting quality;
E, time control: be less than 10min from spheroidizing to the time pouring.
The height and the diameter ratio H/D that in described step b, control nodularization bag, H/D is 1.8.
In described step b, without Si nodularizer, in molten iron, can successively react, the half-cylindrical pit radius that the bag end is built into refractory brick is 26mm, is highly 20mm.
In described step b, by strengthening the covering without Si nodularizer, control the spheroidizing reacion time opening.
In described step b, the strict molten iron temperature of controlling, determines that molten iron tapping temperature is 1520～1550 ℃.
Being added on before molten iron discharging without Si nodularizer in described step b.
In described steps d, pouring cast part pours peace and quiet molten iron surface slag while hot.
Concrete operation method is: a., according to the spheroidizing reacion feature without Si nodularizer, should guarantee that molten iron rushes after people's nodularization bag, and there is enough molten iron pressure nodulizing agent top, to reduce molten iron, seethes, and fully absorbs Mg steam, and the vaporescence of Mg is reached steadily evenly.For this reason, the height of nodularization bag and diameter ratio H/D should be suitable, are 1.8-2.0 as calculated.The H/D of nodularization bag changes 1.8 into.
B. for guaranteeing, without Si nodularizer, in molten iron, can successively react, the half-cylindrical pit that the bag end is built into refractory brick is accurately calculated, make it just in time can fill nodulizing agent, nucleating agent and topped material consolidation.Pit is crossed conference and is postponed the spheroidizing reacion time opening, reduces molten iron temperature, even makes nodulizing agent " freeze " not react at the bag end; The too small molten iron of pit is firm raises covering material once rushing people, causes the exposed a large amount of scaling loss of nodularization element that make of nodulizing agent.Nodularization bag pit changes radius 26mm as calculated into, height 20 mm, and effect is fine.
C. strengthen the covering without Si nodularizer, control the spheroidizing reacion time opening.Nodulizing agent adds bag at the end, pave, tamping, covers the silicon shellfish abrasive grit for once breeding above, then covers the special-purpose insulating covering agent of thick layer 15 mm, granularity 1～3 mm, and last tamping presses the magnesium iron cover plate of thick 10 mm.Like this, guaranteed that, after 2/3 molten iron, spheroidizing reacion just carries out, made whole reaction very steady.
D. strictly control molten iron temperature.Very sensitive to treatment temp without Si nodularizer, temperature is slightly high, and spheroidizing reacion is violent, and nodularization melting loss of elements is serious; Temperature is on the low side, and spheroidizing reacion obviously slows down again, even occurs that nodulizing agent paste is extremely in the nonreactive situation in the bag end.Our factory, according to particular cases such as watered foundry goods sizes, determines that molten iron tapping temperature is l520～1550 ℃.Once find that molten iron temperature is too high, can, after spheroidizing reacion finishes, while going out remaining 1/3 molten iron, add 0.1%～0.2% magnesium-rare earth with stream, the scaling loss of complementary element.When molten iron temperature is lower, available drill rod stirred at the bag end, forced molten iron and nodulizing agent to react.
E. because existing with pure magnesium powdery state without Mg in Si nodularizer, fusing point is very low, adds at once without Si nodularizer and can cause Mg burning in the situation that of nodularization bag fresh out of, and nodularization was lost efficacy.Therefore, the heat bag of high temperature must add nodulizing agent before facing molten iron discharging, adds molten iron discharging immediately, and the middle residence time can not surpass 30S.
F. many without the reacted slag of Si nodularizer, easily stick with paste dead bag hole, pour peace and quiet slag while hot, in order to using again.
Adopt above-mentioned technique, make to have reached completely without the application of Si nodularizer the effect of independent use magnesium-rare earth.
During melting, increase foundry returns proportioning
Because of without Si nodularizer substantially without silicon, therefore its proportion is larger, it is just fewer that it brings Si in molten iron into, more can increase the proportioning containing the high magnesium iron foundry returns of Si.According to the difference without Si nodularizer proportion, determine different foundry returns add-ons, test-results is in Table 1.
Table 1 is according to the ratio-dependent foundry returns proportioning without Si nodularizer and magnesium-rare earth
The castings material of the different foundry returns mix proportion schemes of table 2
Above scheme is through test of many times and batch production, and the RE in foundry goods chemical composition and Mg residual quantity, as-cast metallographic structure, mechanical property are as shown in table 2.As can be seen from the above data, along with in nodulizing agent without the increase of Si nodularizer ratio, the proportioning of foundry returns can bring up to 80% by 30%, and the whole silicon amount of foundry goods meets chemical composition requirement, and metallographic structure and mechanical property have reached foundry goods technical qualification and GB1348-88 standard.
By statistical effect after site operation and enforcement, apply the magnesium iron sand foundry goods that this technological achievement is produced, material is completely qualified.Chemical composition, metallographic structure, mechanical property are not only all up to state standards, and some index is also better than national standard.Foundry goods metallographic structure qualification rate is brought up to more than 95% by 80%, and mechanical property qualification rate is stabilized in 100% always, can it is evident that it has played good effect.
Without its silicon content of Si nodularizer, can freely control, even can reduce to zero, effectively control the silicon content of foundry goods, reduce casting cost.Our company is used always and thisly without Si nodularizer, processes ductile iron process and succeed in process of production.Foundry returns proportioning is brought up to 80% by 30%, saved a large amount of starting material such as the pig iron, significantly reduce castings production cost, obtained great economic benefit.According to magnesium iron batching, reach furnace charge balance, foundry returns add-on is brought up to 80% by 30% and is carried out Economic Benefit Accounting, and it is 89257680 yuan that every hundred tons of application are created benefit without Si nodularizer year, remarkable in economical benefits; And this economic benefit is by energy-saving and cost-reducing, reduce costs accounting out, the waste that has solved a large amount of waste materials, has safeguarded the eubiosis, has good social benefit.
Claims (7)
1. in magnesium iron melting, the method for magnesium iron foundry returns is processed in application without Si nodularizer, it is characterized in that: comprise the following steps:
A, base iron preparation: melting unit is medium-frequency induction furnace, and molten iron material comprises the pig iron, steel scrap, magnesium iron foundry returns;
B, spheroidizing: with 1000kg dykes and dams pit type liquid iron balling bag, the method that pours is processed, and molten iron tapping temperature is 1500～1550 degree, casing cast temperature 1420～1430 degree, magnesium-rare earth granularity 5～30mm, is 5mm～30mm without Si nodularizer granularity;
C, inoculation: nucleating agent adopts 75SiBa nucleating agent, comprises and breeding for twice, and once breed in nodularization bag, nucleating agent granularity is 3～8mm; When late inoculation is ladle-to-ladle after nodularization, with stream, carry out, nucleating agent granularity is 0.3～0.5mm;
D, pouring cast part: control casting quality;
E, time control: be less than 10min from spheroidizing to the time pouring.
2. in magnesium iron melting according to claim 1, the method for magnesium iron foundry returns is processed in application without Si nodularizer, it is characterized in that: in described step b, control height and the diameter ratio H/D of nodularization bag, H/D is 1.8.
3. in magnesium iron melting according to claim 1, the method for magnesium iron foundry returns is processed in application without Si nodularizer, it is characterized in that: in described step b, without Si nodularizer, in molten iron, can successively react, the half-cylindrical pit radius that the bag end is built into refractory brick is 26mm, is highly 20mm.
4. in magnesium iron melting according to claim 1, the method for magnesium iron foundry returns is processed in application without Si nodularizer, it is characterized in that: in described step b, by strengthening the covering without Si nodularizer, control the spheroidizing reacion time opening.
5. in magnesium iron melting according to claim 1, the method for magnesium iron foundry returns is processed in application without Si nodularizer, it is characterized in that: the strict molten iron temperature of controlling in described step b, determine that molten iron tapping temperature is 1520～1550 ℃.
6. in magnesium iron melting according to claim 1, the method for magnesium iron foundry returns is processed in application without Si nodularizer, it is characterized in that: being added on before molten iron discharging without Si nodularizer in described step b.
7. in magnesium iron melting according to claim 1, the method for magnesium iron foundry returns is processed in application without Si nodularizer, it is characterized in that: in described steps d, pouring cast part pours peace and quiet molten iron surface slag while hot.
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Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN110438281A (en) * | 2019-08-16 | 2019-11-12 | 哈尔滨理工大学 | A kind of magnesium-rare earth nodulizer and the preparation method and application thereof without Si |
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| CN101209491A (en) * | 2006-12-25 | 2008-07-02 | 上海华新合金有限公司 | Method for casting printing machine as-cast nodular iron roller body |
| CN101255524A (en) * | 2007-12-22 | 2008-09-03 | 繁昌县金贸铸造有限责任公司 | Method for producing nodular graphite cast iron |
| CN103433471A (en) * | 2013-09-06 | 2013-12-11 | 天津市万路科技有限公司 | Spheroidizing method of nodular cast iron |
| CN103589940A (en) * | 2013-10-30 | 2014-02-19 | 吴江市液铸液压件铸造有限公司 | Casting method of thin-wall nodular cast iron |
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2014
- 2014-05-23 CN CN201410219500.4A patent/CN104004959A/en active Pending
Patent Citations (5)
| Publication number | Priority date | Publication date | Assignee | Title |
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| JPS60184659A (en) * | 1984-03-02 | 1985-09-20 | Toyota Motor Corp | Spheroidal graphite cast iron having high strength and toughness |
| CN101209491A (en) * | 2006-12-25 | 2008-07-02 | 上海华新合金有限公司 | Method for casting printing machine as-cast nodular iron roller body |
| CN101255524A (en) * | 2007-12-22 | 2008-09-03 | 繁昌县金贸铸造有限责任公司 | Method for producing nodular graphite cast iron |
| CN103433471A (en) * | 2013-09-06 | 2013-12-11 | 天津市万路科技有限公司 | Spheroidizing method of nodular cast iron |
| CN103589940A (en) * | 2013-10-30 | 2014-02-19 | 吴江市液铸液压件铸造有限公司 | Casting method of thin-wall nodular cast iron |
Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN110438281A (en) * | 2019-08-16 | 2019-11-12 | 哈尔滨理工大学 | A kind of magnesium-rare earth nodulizer and the preparation method and application thereof without Si |
| CN110438281B (en) * | 2019-08-16 | 2021-04-16 | 哈尔滨理工大学 | Si-free rare earth magnesium alloy nodulizer and preparation method and application thereof |
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