CN1022421C - Process for casting nodular graphite cast iron with as-cast ferrite by metal mould - Google Patents
Process for casting nodular graphite cast iron with as-cast ferrite by metal mould Download PDFInfo
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- CN1022421C CN1022421C CN 89105277 CN89105277A CN1022421C CN 1022421 C CN1022421 C CN 1022421C CN 89105277 CN89105277 CN 89105277 CN 89105277 A CN89105277 A CN 89105277A CN 1022421 C CN1022421 C CN 1022421C
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- Refinement Of Pig-Iron, Manufacture Of Cast Iron, And Steel Manufacture Other Than In Revolving Furnaces (AREA)
Abstract
The present invention relates to a process for casting nodular cast iron by using as-cast ferrite in a metal mould. Ingredients of molten iron comprise low-content carbon, high-content silicon, low-content manganese, phosphorus and sulfur, and a composite inoculant is a mixture of barium salt, strontium salt, bismuth salt and silicon salt. When the molten iron is poured, heat insulating paint and exothermic paint are sprayed on the working surface of the metal mould. The process can omit the heat treatment of castings, can save energy, can shorten a production period and can improve labor conditions. Produced as-cast ferrite nodular cast iron is characterized in that tensile strength ranges from 50 Kg/mm<2> to 64.5 Kg/mm<2>, an elongation rate (delta) ranges from 10% to 18%, the content of ferrite in a metallographic structure is 90%, and a spheroidizing level ranges from the first level to the second level.
Description
The invention belongs to casting technology field, particularly use process for casting nodular graphite cast iron with as-cast ferrite by metal mould technology.
Spheroidal graphite cast iron has obtained to use widely on producing since being born.The ferrite ductile cast iron material that wherein is used to make component such as automobile, tractor chassis and agricultural machinery and implement is also developed rapidly.At present, produce ferrite ductile cast iron and mainly adopt ordinary sand casting, and foundry goods also to be handled through the low temperature and the graphitizing annealing in two stages of high temperature.Because graphitization expansion can not get compensation during with sand mold casting, foundry goods is easy to occur defectives such as shrinkage porosite, so the rising head of employing is bigger during casting, the molten iron of consumption is more.Though high pressure moulding can be avoided the problems such as shrinkage porosite of ordinary sand casting nodular iron casting, high pressure moulding needs bigger facility investment, is difficult for popularizing in general factory.In order to address this problem, many factories all utilize permanent mold casting to produce ferrite ductile cast iron.But use the permanent mold casting ferrite ductile cast iron, because the metal mold thermal conductivity is good, foundry goods is easy to produce spoken parts in traditional operas and perlite too soon because of cooling.Seek out the nodular iron casting of ferrite matrix, nearly all will carry out graphitizing annealing and handle.Use this heat treatment step, not only will increase the consumption of thermal source, but also cause the oxidation and the distortion of foundry goods easily, the surface of foundry goods also needs cleaning, has so both consumed great amount of manpower and material resources and financial resources, has prolonged the production cycle again, strengthen labour intensity, increased production cost.
In order to make full use of the strong point of permanent mold casting, the anneal operation reaches foundry goods oxidation and the distortion that brings thus when avoiding permanent mold casting, June nineteen eighty-two, the tangerine hall loyalty etc. of Japan proposed with permanent mold casting high tenacity as-cast ferrite ductile iron, adopt high-purity pig iron in silicon carbide rod furnace, to carry out melting, in metal mold, pour into a mould then, but it is very harsh that the research requires starting material, and be to test in silicon carbide rod furnace, so can't be used for industrial production.
The objective of the invention is to after the medium-frequency induction furnace melting, directly use process for casting nodular graphite cast iron with as-cast ferrite by metal mould with starting material such as the conventional cast pig iron.
Produce casting ferrite with nodular cast iron with metal mold, key of the present invention is that the composition of molten iron is low-carbon (LC), high silicon, low manganese, phosphorus, sulphur.Its content is C3.5-3.9%, Si2.8-3.8%, and Mn≤0.4%, P≤0.07%, S≤0.03%, all the other are Fe: and adopt the composite inoculant of forming by barium salt, strontium salt, bismuth salt and ferrosilicon; During pouring molten iron, the metal mold working-surface sprays two coatings, and skin is an adiabatic coating, and internal layer is an exothermic paint.
Carbon is the element that forms graphite.Improve carbon content, can increase the graphite grains number, improve the nodularization rate and reduce carbide effectively and perlite quantity, help the raising of ferrite content in the matrix.But carbon content is too high, and the cast condition ductile iron unit elongation is sharply descended.
Silicon is the strong graphited element that promotes.The silicone content height can increase the eutectic cell number, crystal grain thinning, obtain the roundness height easily, sphere diameter is little, quantity is many and the spheroidal graphite that is evenly distributed, and can eliminate primary cementite, and high content of pearlite in matrix is reduced, ferrite content increases, and helps the raising of as-cast ball iron unit elongation.But then, silicon again with the substitute mode solid solution in ferrite, ferrite is strengthened, hardness improves and unit elongation descends.Therefore, silicone content is also unsuitable too high.
Manganese is typical amphoteric element.On the one hand its solid solution is in cementite, strengthens once the stability with secondary cementite consumingly, stops the ferriteization of matrix; On the other hand, it generates compound with chemical combination such as the element-sulphur of stable cementite, nitrogen, oxygen again, makes the stabilization of these elements forfeitures to cementite, has promoted the ferriteization of matrix indirectly.In addition, the segregation of manganese in magnesium iron is comparatively serious.So take all factors into consideration in as cast condition rare earth ductile iron production, manganese content is low more good more.
Phosphorus is little to graphited influence, but very easily segregation.When phosphorus content surpassed solubility limit, phosphorus was just separated out along crystal boundary with hard and crisp iron phosphide eutectic form, seriously worsens the plasticity and the toughness of magnesium iron.
Sulphur is the strong greying that hinders in magnesium iron, strengthens chilling tendency, worsens graphite shape, and sulphur content height in the molten iron also easily causes heavy-gravity sulfuration slag, forms pore and slag inclusion in foundry goods.So the sulphur content in the molten iron should be low as far as possible.
The composite inoculant that the present invention adopts is the mixture of Ba salt, Sr salt, Bi salt and ferrosilicon.Its main component and proportioning following (% by weight): BaCO
31.5-15%, SrCO
31.5-15%, Bi(NO
3)
25H
2O1.5-15%, surplus is 75 ferrosilicon.
The ferrosilicon that contains Ba can prevent that spoken parts in traditional operas from appearring in foundry goods thin-walled place, and significantly the hardness at casting strength and heavy wall place improves in refining eutectic group.Contain Sr in the ferrosilicon, the effect that subtracts spoken parts in traditional operas is very strong, and the tendency of shrinkage cavity shrinkage porosity is also little, is used for magnesium iron and breeds and can increase number of graphite ball, delays inoculation fade.Bismuth is a surfactant, has refining eutectic group, increases the effect of number of graphite ball.When adding the bismuth amount within the specific limits the time, be favourable for eliminating abnormal graphite, forming globular graphite.
In permanent mold casting, use suitable coating, but not only protective money genotype prolongs the work-ing life of metal mold, and can avoid foundry goods to form a large amount of cementites and perlite.The present invention adopts two kinds of coating: adiabatic coating and exothermic paint.Working-surface in metal mold is coated with one deck adiabatic coating earlier, treats to be coated with one deck exothermic paint again after its drying.
Adiabatic coating makes the adiabatic barrier of one deck between metal mold and the foundry goods, thereby reduces cooling velocity of casting.The composition of adiabatic coating of the present invention and proportioning are (weight %): asbestos powder 40-60%, and silica powder 40-60%, wilkinite 10-20%, binding agent account for the 1-3% of first three items sum, and it is an amount of that other adds water.
The effect of exothermic paint is that thereby issuing biochemical reaction at molten steel pouring temperature emits the process of setting that heat delays spheroidal graphite cast iron, avoids crystallization to go out cementite.The composition of exothermic paint of the present invention and proportioning are (weight %): aluminium powder 20-40%, and brown iron oxide 60-80%, binding agent account for the 1-3% of preceding two sums, and it is an amount of that other adds water.
Adopt gravity die casting process of the present invention, can produce casting ferrite with nodular cast iron.Its tensile strength sigma
b50-64.5kg/mm
2, unit elongation δ 10-18%.This casting technique is not only saved the heat treatment step of foundry goods, has saved the energy, has shortened the production cycle, and has saved surface-conditioning after the heat treating castings and distortion correcting process, has improved labor condition, has remarkable economic efficiency and social benefit.
Embodiment:
The molten iron that melts in medium-frequency induction furnace, its composition are C3.70%, Si3.30%, and Mn0.35%, P0.05%, S0.02%, all the other are Fe.Spheroidizing and inoculation are with pouring method in the bag.Nodulizing agent GXtMg7-10; The composition of composite inoculant and proportioning are: BaCO
33.5%, SrCO
32%, Bi(NO
3)
25H
2O2%, 75 ferrosilicon 92.5%.At the working-surface elder generation spray-on insulation of metal mold, spray one deck exothermic paint again after waiting to dry in the shade before the blow-on.The proportioning of adiabatic coating is (weight %): asbestos powder 42%, and silica powder 42%, wilkinite 16%, Sudan Gum-arabic account for 1.5% of first three items sum, and it is an amount of that other adds water.The proportioning of exothermic paint is (weight %): aluminium powder 25%, and brown iron oxide 75%, Sudan Gum-arabic account for 1.5% of preceding two sums, and it is an amount of that other adds water.
Measure sample performance, tensile strength sigma according to nodular iron casting standard GB 1348-78 regulation
b〉=50Kg/mm
2, unit elongation δ 〉=10%.Ferritic content is 90% in its metallographic structure, and nodulizing grade is the 1-2 level.
Claims (3)
1, the gravity die casting process of casting ferrite with nodular cast iron, the composition that it is characterized in that this technology controlling and process molten iron is C3.5-3.9%, Si2.8-3.8%, Mn≤0.4%, P≤0.07%, S≤0.03%, all the other are iron; The composite inoculant that adopts is the mixture of barium salt, strontium salt, bismuth salt and ferrosilicon; During pouring molten iron, the metal mold working-surface sprays two coatings, and skin is an adiabatic coating, and internal layer is an exothermic paint.
2, gravity die casting process according to claim 1 is characterized in that the proportioning of described composite inoculant is (weight %): BaCO
31.5-15%, SrCO
31.5-15%, Bi(NO
3)
25H
2O1.5-15%, surplus is 75 ferrosilicon.
3, gravity die casting process according to claim 1 is characterized in that the composition of described exothermic paint and adiabatic coating and proportioning are (weight %):
Exothermic paint: aluminium powder 20-40%, brown iron oxide 60-80%, the 1-3% of sum in twos before binding agent accounts for, it is an amount of that other adds water.
Adiabatic coating: asbestos powder 40-60%, silica powder 40-60%, wilkinite 10-20%, binding agent account for the 1-3% of first three items sum, and it is an amount of that other adds water.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN 89105277 CN1022421C (en) | 1989-04-26 | 1989-04-26 | Process for casting nodular graphite cast iron with as-cast ferrite by metal mould |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN 89105277 CN1022421C (en) | 1989-04-26 | 1989-04-26 | Process for casting nodular graphite cast iron with as-cast ferrite by metal mould |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| CN1046760A CN1046760A (en) | 1990-11-07 |
| CN1022421C true CN1022421C (en) | 1993-10-13 |
Family
ID=4856044
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CN 89105277 Expired - Fee Related CN1022421C (en) | 1989-04-26 | 1989-04-26 | Process for casting nodular graphite cast iron with as-cast ferrite by metal mould |
Country Status (1)
| Country | Link |
|---|---|
| CN (1) | CN1022421C (en) |
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|---|---|---|---|---|
| US7494676B2 (en) * | 2002-05-30 | 2009-02-24 | Council Of Scientific And Industrial Research | Process for the pre-treatment of vegetable oils for physical refining |
| CN101228287B (en) * | 2005-05-18 | 2010-06-16 | 株式会社丰和 | High silicon stainless steel and material thereof and method for manufacturing high silicon stainless steel |
| CN100337770C (en) * | 2005-12-29 | 2007-09-19 | 江阴市吉鑫机械有限公司 | Casting method of large-toughness piece by ball-iron cast without Ni at low temperature |
| CN102962401A (en) * | 2012-11-30 | 2013-03-13 | 上海大学 | SrZrO3 shell for titanium and titanium alloy precise casting and preparation method thereof |
| CN103008536A (en) * | 2013-01-08 | 2013-04-03 | 辽宁科技学院 | Novel insulated multi-layer coating for permanent mold casting type ferritic nodular cast iron castings |
| CN103775290A (en) * | 2013-12-24 | 2014-05-07 | 广东明阳风电产业集团有限公司 | Yawing supporting structure of wind generating set |
| CN105861915B (en) * | 2016-06-27 | 2018-04-24 | 含山县兴达球墨铸铁厂 | The preparation method of ferrite ductile cast iron |
| CN106756466A (en) * | 2016-12-28 | 2017-05-31 | 重庆力劲机械有限公司 | A kind of big thick stick nut cast iron quality formula |
| CN107354274B (en) * | 2017-07-21 | 2019-03-29 | 沈阳工业大学 | A kind of short route austempering ductile iron subsoiling shovel tip preparation method |
| CN108284202B (en) * | 2018-04-04 | 2020-01-17 | 江苏吉鑫风能科技股份有限公司 | Casting method for improving structure and performance of nodular cast iron material and cast part cast by casting method |
| CN112921230A (en) * | 2021-01-15 | 2021-06-08 | 西安合力汽车配件有限公司 | Improved method of screw carburized part |
-
1989
- 1989-04-26 CN CN 89105277 patent/CN1022421C/en not_active Expired - Fee Related
Also Published As
| Publication number | Publication date |
|---|---|
| CN1046760A (en) | 1990-11-07 |
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