CN102796940B - Preparation method of high-silicon heat-resistant ductile iron - Google Patents
Preparation method of high-silicon heat-resistant ductile iron Download PDFInfo
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- CN102796940B CN102796940B CN201210317635.5A CN201210317635A CN102796940B CN 102796940 B CN102796940 B CN 102796940B CN 201210317635 A CN201210317635 A CN 201210317635A CN 102796940 B CN102796940 B CN 102796940B
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Abstract
The invention discloses a preparation method of high-silicon heat-resistant ductile iron. The preparation method comprises the following steps of: (1) proportioning; (2) allocating a spheroidizing agent; (3) performing spheroidization; (4) performing inoculation; (5) performing rapid metallographic inspection on an on-the-spot sample; (6) slagging and covering; and (7) casting. According to the preparation method, rare earth magnesium and calcium and a low-silicon magnesium block mass mixed spheroidizing agent are adopted to perform spheroidization; and after primary inoculation of 75 iron silicon alloy and secondary inoculation treatment of silicon barium alloy, the spheroidizing rate of the prepared high-silicon heat-resistant ductile iron is greater than or equal to 95 percent, the spheroidizing level is level 1 to 2, the ferrite content in a matrix is greater than or equal to 90 percent, the cast iron tensile strength sigma b is greater than or equal to 520-580 Mpa, the hardness HB is 185-230, the extensibility delta is greater than or equal to 10-14 percent, and the heat resistance temperature is greater than or equal to 850 DEG C.
Description
Technical field
The present invention relates to cast iron process field, be specifically related to rare-earth, Mg, Ca and mix with low silicon magnesium agglomerate nodulizing agent, molten iron is carried out spheroidizing and adopts compound inoculated high silicon heat-resisting ductile iron preparation method.
Background technology
Spheroidal graphite cast iron not only has high intensity, good toughness properties index, has also had both good resistance toheat simultaneously.Therefore, this material is widely used in manufacturing the heat-resisting parts such as automobile exhaust pipe, supercharging blower housing.At present, the high silicon heat-resisting ductile iron of known preparation is because ferrite content and nodulizing grade in tissue are low, and the heat resisting temperature of material, lower than 850 ℃, has affected the work-ing life of foundry goods.
Summary of the invention
For the problems referred to above, the object of the present invention is to provide a kind of preparation method of high silicon heat-resisting ductile iron, to adopt rare-earth, Mg, Ca to mix by a certain percentage with low silicon magnesium agglomerate nodulizing agent, base iron is carried out to spheroidizing, and it is compound inoculated to adopt 75 ferro-silicons and Si-Ba alloy nucleating agent to carry out secondary to molten iron, the high silicon heat-resisting ductile iron material of stably manufactured heat resisting temperature >=850 ℃.
Technical scheme of the present invention is achieved in the following ways: a kind of preparation method of high silicon heat-resisting ductile iron, by weight percentage, comprise the following steps: 1) batching, 2) nodulizing agent configuration, 3) spheroidizing, 4) inoculation, 5) stokehold sample and metallographic examination, 6 fast) covering, 7 of skimming) cast; It is characterized in that:
1) batching: molten iron chemical composition: C:2.5～3.1%, Si:4.7～5.2%, Mn:0.3～0.5%, Cr:0.1～0.3%, phosphorus P :≤0.07%, sulphur S :≤0.02%, Mg:0.025～0.035%, Re:0.012～0.02%, all the other are iron;
2) configuration mixed nodulizer: 50% rare-earth, Mg, Ca and 50% low silicon magnesium agglomerate nodulizing agent are mixedly configured into mixed nodulizer;
Wherein: rare-earth, Mg, Ca composition is: Re:1.5～2.5%, Ca:3～5%, Mg:6～8%, Si:43～47%, all the other are iron;
Low silicon magnesium agglomerate nodulizing agent composition is: Mg:6～8%, Si :≤10%, all the other are iron.
3) spheroidizing: when molten iron treatment temp is controlled to 1430 ~ 1440 ℃, add mixed nodulizer, add-on is weight of molten iron 1.2～1.4%, and the spheroidizing reacion time is 1.5～2 minutes;
4) inoculation: adopt iron notch to pour once to breed method with stream late inoculation method, iron notch once breeds method and adopts 75 ferro-silicon nucleating agents, add-on is the 1.0-1.2% of weight of molten iron, with stream late inoculation, adopts Si-Ba alloy nucleating agent, the 0.15-0.3% that add-on is weight of molten iron;
The composition of described Si-Ba alloy nucleating agent is: Ba 4-6%, and Ca 1-2%, Si 65-70%, Al 1-2%, all the other are iron; The composition of 75 ferro-silicon nucleating agents is: Si72-80%, Cr≤0.5%, P≤0.5%, S≤0.04%, C≤0.02%, and all the other are iron; Weight of molten iron fluctuation ± 5%.
5) stokehold sample and metallographic examination fast: adopt stokehold sample and quick metallographic examination liquid iron balling effect, stokehold specimen size is φ 20mm;
6) covering of skimming: adopt the perlite deslagging agent of weight of molten iron 0.2% to skim 1～2 time, with the perlite insulation insulating covering agent of weight of molten iron 0.2～0.3%, at the thick insulation tectum in formation 35 ~ 40mm left and right, molten iron surface, prevent from wrapping naturally overflowing of interior molten iron fast cooling and nodularization element;
7) cast: after spheroidizing, in 15～17 minutes, molten iron is poured.
Beneficial effect of the present invention: adopt the spheroidizing of rare-earth, Mg, Ca+low silicon magnesium agglomerate mixed nodulizer, after 75 iron silicon alloys once breed and process with Si-Ba alloy late inoculation, nodularization rate>=95%, the nodulizing grade 1-2 level of the high silicon heat-resisting ductile iron of preparation, ferrite body burden>=90%, cast iron tensile strength sigma in matrix
b>=520～580 Mpa, hardness HB185～230, unit elongation δ>=10～14%, heat resisting temperature>=850 ℃.
Embodiment
Example 1:
A preparation method for high silicon heat-resisting ductile iron, by weight percentage, industrial furnace fire grate accessory, 850～900 ℃ of working temperatures, comprise the following steps:
1, batching: molten iron chemical composition: C:2.5～3.1%, Si:4.7～5.2%, Mn:0.3～0.5%, Cr:0.1～0.3%, phosphorus P :≤0.07%, sulphur S :≤0.02%, Mg:0.025～0.035%, Re:0.012～0.02%, all the other are iron;
2, nodulizing agent configuration: 50% rare-earth, Mg, Ca and 50% low silicon magnesium agglomerate nodulizing agent are mixedly configured into mixed nodulizer; Wherein: rare-earth, Mg, Ca composition is: Re:1.5～2.5%, Ca:3～5%, Mg:6～8%, Si:43～47%, all the other are iron; Low silicon magnesium agglomerate nodulizing agent composition is: Mg:6～8%, Si :≤10%, and all the other are iron.
3, spheroidizing: molten iron treatment temp is controlled to 1430 ~ 1440 ℃, adds the nodulizing agent of step 2, add-on is weight of molten iron 1.2～1.4%, 1.5～2 minutes spheroidizing reacion time.
4, inoculation: adopt iron notch to pour once to breed method with stream late inoculation method, iron notch once breeds method and adopts 75 ferro-silicon nucleating agents, add-on is the 1.0-1.2% of weight of molten iron, with stream late inoculation, adopts Si-Ba alloy nucleating agent, the 0.15-0.3% that add-on is weight of molten iron.The composition of Si-Ba alloy nucleating agent is: Ba 4-6%, and Ca 1-2%, Si 65-70%, Al 1-2%, all the other are iron; The composition of ferro-silicon nucleating agent is: Si72-80%, Cr≤0.5%, P≤0.5%, S≤0.04%, C≤0.02%, all the other are iron, weight of molten iron fluctuation ± 5%.
5, stokehold sample and metallographic examination fast: adopt stokehold sample and quick metallographic examination liquid iron balling effect, stokehold specimen size is φ 20mm;
6, the covering of skimming: adopt the perlite deslagging agent of weight of molten iron 0.2% to skim 1～2 time, with the perlite insulation insulating covering agent of weight of molten iron 0.2～0.3%, at the thick insulation tectum in formation 35 ~ 40mm left and right, molten iron surface, prevent from wrapping naturally overflowing of interior molten iron fast cooling and nodularization element;
7, cast: after spheroidizing, in 15～17 minutes, molten iron is poured.
The present embodiment, former employing RTcr heat resisting iron is manufactured, and be about 12 months work-ing life, uses instead after high silicon heat resisting iron manufacture of the present invention, and accessory reaches about 24 months work-ing life.
Example 2: step is with embodiment 1, chain furnace fire grate accessory, normal working temperature scope is 820～900 ℃, former employing RTcr heat resisting iron is manufactured, be 12～14 months work-ing life, uses instead after high silicon heat resisting iron manufacture of the present invention, and accessory reaches 24～26 months work-ing life.
Claims (1)
1. a preparation method for high silicon heat-resisting ductile iron, comprises the following steps: 1) batching, 2) nodulizing agent configuration, 3) spheroidizing, 4) inoculation, 5) stokehold sample and metallographic examination, 6 fast) covering, 7 of skimming) cast; It is characterized in that:
1) batching: molten iron chemical composition, by weight percentage: C:2.5～3.1%, Si:4.7～5.2%, Mn:0.3～0.5%, Cr:0.1～0.3%, phosphorus P :≤0.07%, sulphur S :≤0.02%, Mg:0.025～0.035%, RE:0.012～0.02%, all the other are iron;
2) nodulizing agent configuration: 50% rare-earth, Mg, Ca and 50% low silicon magnesium agglomerate nodulizing agent are mixedly configured into mixed nodulizer; Rare-earth, Mg, Ca composition is: RE:1.5～2.5%, Ca:3～5%, Mg:6～8%, Si:43～47%, and all the other are iron; Low silicon magnesium agglomerate nodulizing agent composition is: Mg:6～8%, Si :≤10%, all the other are iron;
3) spheroidizing: molten iron treatment temp is controlled to 1430 ~ 1440 ℃, adds nodulizing agent, add-on is weight of molten iron 1.2～1.4%, 1.5～2 minutes spheroidizing reacion time;
4) inoculation: adopt iron notch to pour once to breed method with stream late inoculation method, iron notch once breeds method and adopts composition to be: Si72-80%, Cr≤0.5%, P≤0.5%, S≤0.04%, C≤0.02%, all the other are 75 ferro-silicon nucleating agents of iron, add-on is the 1.0-1.2% of weight of molten iron, with stream late inoculation, adopt composition to be: Ba 4-6%, Ca 1-2%, Si 65-70%, Al 1-2%, all the other are the Si-Ba alloy nucleating agent of iron, the 0.15-0.3% that add-on is weight of molten iron;
5) stokehold sample and metallographic examination fast: adopt stokehold sample and quick metallographic examination liquid iron balling effect, stokehold specimen size is φ 20mm;
6) covering of skimming: adopt the perlite deslagging agent of weight of molten iron 0.2% to skim 1～2 time, with the perlite insulation insulating covering agent of weight of molten iron 0.2～0.3%, at the thick insulation tectum of molten iron surface formation 35 ~ 40mm, prevent from wrapping naturally overflowing of interior molten iron fast cooling and nodularization element;
7) cast: after spheroidizing, in 15～17 minutes, molten iron is poured.
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| CN106521309A (en) * | 2016-12-16 | 2017-03-22 | 广西大学 | Heat resisting cast iron boiler furnace bar and preparation method thereof |
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| Publication number | Priority date | Publication date | Assignee | Title |
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| CN102220540A (en) * | 2011-06-13 | 2011-10-19 | 江铃汽车股份有限公司 | Spheroidizing treatment technology by rush-in method |
| CN102634723A (en) * | 2012-05-11 | 2012-08-15 | 郑州机械研究所 | Ferrite ductile iron used at low temperature and manufacturing method thereof |
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| JPS6053736B2 (en) * | 1981-10-05 | 1985-11-27 | 日産自動車株式会社 | Heat-resistant spheroidal graphite cast iron |
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| Publication number | Priority date | Publication date | Assignee | Title |
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| CN102220540A (en) * | 2011-06-13 | 2011-10-19 | 江铃汽车股份有限公司 | Spheroidizing treatment technology by rush-in method |
| CN102634723A (en) * | 2012-05-11 | 2012-08-15 | 郑州机械研究所 | Ferrite ductile iron used at low temperature and manufacturing method thereof |
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| JP昭58-58248A 1983.04.06 |
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