CN1088619A

CN1088619A - Cast condition ductile iron compound additive

Info

Publication number: CN1088619A
Application number: CN 92115264
Authority: CN
Inventors: 张发; 李少雄
Original assignee: Individual
Current assignee: Individual
Priority date: 1992-12-24
Filing date: 1992-12-24
Publication date: 1994-06-29

Abstract

The granular composite additive of as-cast high-tenacity cast iron, comprise and place the contain composition such as Mg and the composite nodulizer of solvent and the composite inoculant that contains Ca, Na placed on it of pit bottom at the bottom of the hot metal ladle to form, water once pours, not tight to base iron composition and temperature requirement, spheroidizing reacion is steady, anti-nodularization, inoculation fade are effective, easy and simple to handle, fundamentally stop because of nodularization and breed the quality accident of losing efficacy and to cause, foundry goods does not have free cementite more than 5mm, ferrite is more than 80%, the nodulizing grade one-level.Improved quality and the high-toughness ductile iron spare quality of magnesium iron, reduced the production cost of the two significantly with additive.

Description

Cast condition ductile iron compound additive

Cast condition ductile iron compound additive belongs to produces nodulizing agent and the nucleating agent that as-cast high-tenacity cast spheroidal graphite cast iron and other thin-walled spheroidal graphite cast iron are used.

The used processing method of high tenacity (unit elongation＞10%) spheroidal graphite cast iron of domestic production at present mainly contains three kinds: the one, adopts block rare earth magnesium nodularizer (Mg, Re, Si, the surplus Fe of being) to add secondary or breed (nucleating agent is 75%SiFe) for three times base iron is carried out spheroidizing and inoculation, will water then foundry goods carry out a stage or two-stage anneal.The shortcoming of this method is that (1) employed nodulizing agent contains Mg, Re is higher, and spheroidizing reacion is more violent, and the cast iron chilling tendency is big, is difficult to avoid free cementite under the as cast condition, also is difficult to obtain the ferrite matrix more than 80%; (2) nodularization and inoculation are generally separately carried out in the early stage of pouring molten iron and later stage, and nodulizing agent and nucleating agent absorption region are little, and specific absorption is low; (3) block nodulizing agent all melts through smelting furnace and joins, and adding needs more Mg and Re, and the cost of nodulizing agent is increased; (4) molten iron temperature, nodulizing agent lumpiness, consolidation and topped, foundary weight piece etc. are required tighter, otherwise easily produce quality accidents such as a large amount of too early come-ups of nodulizing agent or nodulizing agent do not react.The 2nd, adopt block composite nodulizer (Mg, Re, Ca, Ba, Si, surplus is Fe) to add late inoculation (nucleating agent 75%SiFe), base iron is carried out spheroidizing and inoculation, thereby obtain as-cast high-tenacity cast spheroidal graphite cast iron.This method has overcome the previous shortcoming of above-mentioned common rare earth magnesium nodularizer, but still can't fundamentally solve back three shortcomings.The 3rd, adopt powdered composite nodulizer (Mg powder, ferrosilicon powder, mechanical mixturies such as delayer) to add that late inoculation (nucleating agent 75%SiFe) carries out nodularization to base iron and reason when breeding, thus acquisition as-cast high-tenacity cast spheroidal graphite cast iron.This method gram has been answered the previous shortcoming of above-mentioned common rare earth magnesium nodularizer, and all nodulizing agent need not be joined through smelting furnace is molten, and delayer itself can play retarding action, improves the Mg specific absorption, and its reaction product can play the nodularization inoculation(effect) again.But the shortcoming of this method is: (1) pure Mg powder costs an arm and a leg; (2) however pure Mg powder easily before pouring molten iron under the high temperature action of hot metal ladle from scaling loss; (3) molten iron temperature, the nodulizing agent degree of packing etc. are required tighter, quality accident such as easily produce too early big quantitative response or do not react.

In order to overcome the above-mentioned shortcoming of existing cast condition ductile iron additive, it is low to the invention provides a kind of production cost, the new additive agent that quality is high, handle operation to simplify spheroidization and inoculation, fundamentally stop the spheroidization and inoculation quality accident, the cancellation heat treatment step reduces production costs under the prerequisite that guarantees the high-toughness ductile iron quality, improves working conditions.

Concrete technical scheme of the present invention is: the cast condition ductile iron compound additive of being made up of composite nodulizer and composite inoculant, its special character is that composite nodulizer is made up of Mg, Re, Ca, Ba, Si, Fe and composite fluxing agent, its content is: Mg4-7%, ReO-3%, Ca0.5-2%, Ba3-5%, Si40-45%, composite fluxing agent 5-30%, all the other are iron; The main component of composite fluxing agent: a) Zr ₂O ₃20-40%, CaF ₂20-40%, Na ₂O10-20%, all the other are the C powder; B) MgF ₂40-50%, BaO20-40%, all the other are K ₂O; C) CaF ₂30-50%, BaO10-30%, Zr ₂O ₃10-20%, all the other are K ₂O and Na ₂O; The main component of composite inoculant, 75%SiFe and K, Na, Ca base desulfurizer, its proportioning is 1: 1-1.5.

Above-mentioned composite nodulizer and composite inoculant are granular, and granularity is 1-5mm, and wherein the part starting material can be pulverized through the molten back of joining of smelting furnace, and a part of starting material are directly pulverized, and press the mixed of above-mentioned requirements then.

Use additive provided by the invention to carry out nodularization and inoculation is very simple, concrete operations are being placed on bag pit bottom, the end before the nodularization, be nucleating agent it on, and molten iron once pours, and it is promptly pourable after skimming to react end.

Nodulizing agent provided by the invention and nucleating agent have the specific absorption height, and scaling loss is few, reacting balance, can fundamentally stop spheroidization and inoculation and handle quality accident, this additive is not tight to base iron chemical ingredients and temperature requirement, is suitable for electric furnace, and cupola furnace and spoon stove are produced magnesium iron; The above no free cementite of 5mm under the foundry goods as cast condition, ferrite accounts for more than 80%, σ _b〉=500N/mm ², δ 〉=10%, composite additive and casting cost all can obviously reduce.

Description of drawings:

Fig. 1 is the spheroidal graphite cast iron metallographic structure (amplifying 100 times) with the water treatment of electric furnace smelting iron;

Fig. 2 is the spheroidal graphite cast iron metallographic structure (amplifying 400 times) with the water treatment of electric furnace smelting iron;

Fig. 3 is the spheroidal graphite cast iron metallographic structure (amplifying 100 times) with the water treatment of spoon stove smelting iron;

Fig. 4 is the spheroidal graphite cast iron metallographic structure (side is big 400 times) with the water treatment of spoon stove smelting iron.

Illustrate the specific implementation process of this programme below:

Embodiment one

The composite nodulizer composition is: Mg4%, and Re3%, Ba4%, Ca0.5%, Si40%, composite fluxing agent 30%, surplus is Fe.The manner of formulation of composite nodulizer is: with magnesium ingot, rare earth ferrosilicon and Si-Ba alloy composition according to supplied materials laboratory test report and requirement, and the scaling loss in the consideration melting, batching by a certain percentage.Pour into swage after the fusing, be ground into the particle of 1-5mm behind the naturally cooling, again with give the composite fluxing agent that is ground into 1-5mm earlier and 75 ferrosilicon and carry out proportioning and reach the composition requirement.

The proportioning of the composite fluxing agent in composite nodulizer is: Zn ₂O ₃20%, CaF ₂30%, Na ₂O15%, surplus is the C powder.

The compound method of composite inoculant is: will give the 75SiFe that is ground into the 1-5mm granularity earlier and calcium-based desulfurizing agent by 1: 1 mixed.

The composite additive of above preparation is used for electric furnace production as-cast high-tenacity cast iron.Used electric furnace is the 500Kg medium-frequency induction furnace, and spheroidizing bag (pouring ladle) capacity is 200Kg, base iron composition C=3.64%, Si=1.57%, Mn=0.31%, S=0.05%, P=0.06%, 1420 ℃ of molten iron tapping temperatures, the composite additive add-on is: nodulizing agent 1.6%, nucleating agent 1.0%.The stokehold wedge test piece does not have spoken parts in traditional operas, and by intercepting on the standard wedge-shaped samples and being processed into standard tension coupon, the mechanical property measurement result is three sample mean: σ _b=524.84N/mm ², δ=14.6%.Chemical analysis results is behind the stove: C=3.61%, Si=3.15%, Mn=0.30%, S=0.025%, P=0.06%, Mg _Residual=0.053%, Re _Residual=0.041%.Microstructure (tension rod end face) (seeing accompanying drawing 1,2) is: nodulizing grade one-level, ferrite 90%, no free cementite.Co-processing 5 bags, about 1 ton of foundry goods (auto parts machinery) is all qualified.

Embodiment two:

The composition of composite nodulizer is: Mg6.5%, and Re1.5%, Ba5%, Ca1.5%, Si40%, composite fluxing agent 10%, surplus is Fe.

The compound method of composite nodulizer is with embodiment one, but wherein the proportioning of composite fluxing agent is: CaF ₂40%, BaO20%, Zr ₂O ₃20%, surplus is K ₂O and Na ₂O.

The compound method of composite inoculant is: will give the 75SiFe that is ground into the 1-5mm granularity earlier and sodium calcium-based desulfurizing agent by 1: 1.5 mixed.

The composite additive of above preparation is used for a spoonful stove production as-cast high-tenacity cast iron.Used spoon stove melting rate is 1 ton/hour, and nodularization (cast) bag is 100Kg, base iron composition C=3.87%, Si=1.62%, Mn=0.56%, S=0.078%, P=0.04%, about 1350 ℃ of molten iron tapping temperatures, the composite additive add-on is: nodulizing agent 1.9%, and nucleating agent 1.0%, the stokehold wedge test piece does not have spoken parts in traditional operas, by intercepting on the standard wedge-shaped samples and being processed into standard tension coupon, the mechanical property measurement result is (three coupon mean value) σ _b=S38N/mm ², δ=12.5%, chemical analysis results is behind the stove: C=3.85%, Si=2.9%, Mn=0.54%, S=0.03%, P=0.04%, Mg _Residual=0.042%, Re _Residual=0.039%, microstructure (tension coupon end face) analytical results (seeing accompanying drawing 3-4) is: the nodulizing grade one-level, co-processing 25 bag about 2 tons of foundry goods (boiler fitting) are all qualified.

Claims

1, a kind of as-cast ball iron composite additive of forming by composite nodulizer and composite inoculant, it is characterized in that composite nodulizer is made up of Mg, Re, Ca, Ba, Si, Fe and composite fluxing agent, its content: Mg4-7%, Re0-3%, Ca0.5-2%, Ba3-5%, Si40-45%, composite fluxing agent 5-30%, all the other are iron; The main component of composite fluxing agent: a) Zr ₂O ₃20-30%, CaF ₂20-40%, Na ₂O10-20%, all the other are the C powder; B) MgF ₂40-50%, BaO20-40%, all the other are K ₂O; C) CaF ₂30-50%, BaO10-30%, Zr ₂O ₃10-20%, all the other are K ₂O and Na ₂O; The main component of composite inoculant: 75%SiFe and K, Na, Ca base desulfurizer, its proportioning is 1: 1-1.5.

2, a kind of cast condition ductile iron compound additive of forming by composite nodulizer and composite inoculant according to claim 1, the granularity that it is characterized in that composite nodulizer and composite inoculant is 1-5mm, the part starting material are joined the back pulverizing through smelting furnace is molten, the part starting material are directly pulverized, and are mixed in proportion then.