CN102888551B - Preparation method of high-temperature-resistant antioxidant exhaust manifold nodular cast iron - Google Patents
Preparation method of high-temperature-resistant antioxidant exhaust manifold nodular cast iron Download PDFInfo
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- 229910001141 Ductile iron Inorganic materials 0.000 title claims abstract description 59
- 238000002360 preparation method Methods 0.000 title claims abstract description 27
- 230000003078 antioxidant effect Effects 0.000 title abstract description 14
- 239000003963 antioxidant agent Substances 0.000 title abstract description 9
- XEEYBQQBJWHFJM-UHFFFAOYSA-N Iron Chemical compound [Fe] XEEYBQQBJWHFJM-UHFFFAOYSA-N 0.000 claims abstract description 38
- 229910052742 iron Inorganic materials 0.000 claims abstract description 17
- 238000003723 Smelting Methods 0.000 claims abstract description 5
- 238000011081 inoculation Methods 0.000 claims abstract description 5
- 230000003647 oxidation Effects 0.000 claims description 50
- 238000007254 oxidation reaction Methods 0.000 claims description 50
- 229910000831 Steel Inorganic materials 0.000 claims description 38
- 230000009970 fire resistant effect Effects 0.000 claims description 38
- 239000010959 steel Substances 0.000 claims description 38
- 229910000805 Pig iron Inorganic materials 0.000 claims description 36
- 229910000519 Ferrosilicon Inorganic materials 0.000 claims description 28
- 229910052710 silicon Inorganic materials 0.000 claims description 22
- 239000003795 chemical substances by application Substances 0.000 claims description 20
- XUIMIQQOPSSXEZ-UHFFFAOYSA-N Silicon Chemical compound [Si] XUIMIQQOPSSXEZ-UHFFFAOYSA-N 0.000 claims description 16
- RTAQQCXQSZGOHL-UHFFFAOYSA-N Titanium Chemical compound [Ti] RTAQQCXQSZGOHL-UHFFFAOYSA-N 0.000 claims description 16
- 239000007788 liquid Substances 0.000 claims description 16
- 239000010703 silicon Substances 0.000 claims description 16
- 238000003825 pressing Methods 0.000 claims description 15
- 229910001309 Ferromolybdenum Inorganic materials 0.000 claims description 14
- 229910000756 V alloy Inorganic materials 0.000 claims description 14
- 239000002667 nucleating agent Substances 0.000 claims description 14
- 229910052748 manganese Inorganic materials 0.000 claims description 6
- 239000000203 mixture Substances 0.000 claims description 6
- 229910052717 sulfur Inorganic materials 0.000 claims description 6
- 229910052698 phosphorus Inorganic materials 0.000 claims description 5
- 229910045601 alloy Inorganic materials 0.000 claims description 4
- 239000000956 alloy Substances 0.000 claims description 4
- 238000005266 casting Methods 0.000 claims description 4
- 238000009413 insulation Methods 0.000 claims description 4
- 229910052750 molybdenum Inorganic materials 0.000 claims description 4
- 229910052720 vanadium Inorganic materials 0.000 claims description 4
- 238000010792 warming Methods 0.000 claims description 4
- 229910052799 carbon Inorganic materials 0.000 claims description 3
- 229910052749 magnesium Inorganic materials 0.000 claims description 3
- 229910052761 rare earth metal Inorganic materials 0.000 claims description 2
- 229910000859 α-Fe Inorganic materials 0.000 abstract description 14
- 238000005382 thermal cycling Methods 0.000 abstract description 9
- 238000012360 testing method Methods 0.000 description 24
- 239000000463 material Substances 0.000 description 11
- 239000011159 matrix material Substances 0.000 description 10
- VYPSYNLAJGMNEJ-UHFFFAOYSA-N Silicium dioxide Chemical compound O=[Si]=O VYPSYNLAJGMNEJ-UHFFFAOYSA-N 0.000 description 8
- -1 oxonium ion Chemical class 0.000 description 7
- 238000000034 method Methods 0.000 description 5
- OKTJSMMVPCPJKN-UHFFFAOYSA-N Carbon Chemical compound [C] OKTJSMMVPCPJKN-UHFFFAOYSA-N 0.000 description 4
- 229910001018 Cast iron Inorganic materials 0.000 description 4
- 235000006708 antioxidants Nutrition 0.000 description 4
- 229910001567 cementite Inorganic materials 0.000 description 4
- 229910002804 graphite Inorganic materials 0.000 description 4
- 239000010439 graphite Substances 0.000 description 4
- 230000008595 infiltration Effects 0.000 description 4
- 238000001764 infiltration Methods 0.000 description 4
- KSOKAHYVTMZFBJ-UHFFFAOYSA-N iron;methane Chemical compound C.[Fe].[Fe].[Fe] KSOKAHYVTMZFBJ-UHFFFAOYSA-N 0.000 description 4
- 229960001866 silicon dioxide Drugs 0.000 description 4
- 235000012239 silicon dioxide Nutrition 0.000 description 4
- 239000000377 silicon dioxide Substances 0.000 description 4
- 238000007669 thermal treatment Methods 0.000 description 4
- 230000003245 working effect Effects 0.000 description 4
- QVGXLLKOCUKJST-UHFFFAOYSA-N atomic oxygen Chemical compound [O] QVGXLLKOCUKJST-UHFFFAOYSA-N 0.000 description 3
- 230000006378 damage Effects 0.000 description 3
- 238000006477 desulfuration reaction Methods 0.000 description 3
- 230000023556 desulfurization Effects 0.000 description 3
- 230000003292 diminished effect Effects 0.000 description 3
- 238000005516 engineering process Methods 0.000 description 3
- 229910052760 oxygen Inorganic materials 0.000 description 3
- 239000001301 oxygen Substances 0.000 description 3
- 230000007704 transition Effects 0.000 description 3
- 230000009286 beneficial effect Effects 0.000 description 2
- 238000009661 fatigue test Methods 0.000 description 2
- 238000011056 performance test Methods 0.000 description 2
- 238000012795 verification Methods 0.000 description 2
- 238000006555 catalytic reaction Methods 0.000 description 1
- 238000002485 combustion reaction Methods 0.000 description 1
- 230000006835 compression Effects 0.000 description 1
- 238000007906 compression Methods 0.000 description 1
- 239000013078 crystal Substances 0.000 description 1
- 239000000446 fuel Substances 0.000 description 1
- 238000010438 heat treatment Methods 0.000 description 1
- 239000000126 substance Substances 0.000 description 1
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- Exhaust Silencers (AREA)
Abstract
The invention discloses a preparation method of a high-temperature-resistant antioxidant exhaust manifold nodular cast iron, relates to the preparation method of the exhaust manifold nodular cast iron and aims to the solve the technical problems of poor heat resistance and less failure circulation time at high thermal cycling temperature of the traditional exhaust manifold nodular cast iron. The preparation method of the high-temperature-resistant antioxidant exhaust manifold nodular cast iron comprises the following steps of:1, molten iron smelting; and 2, spheroidization and inoculation treatment. According to the high-temperature-resistant antioxidant exhaust manifold nodular cast iron obtained through the preparation method, the volume fraction of ferrite reaches 95-99 percent, the tensile strength is 160N/mm<2> at high temperature of 650 DEG C, the heat resistance is good, the failure circulation time is 410-440 times at thermal cycling temperature of 500-700 DEG C, the high-temperature creep resistance and the creep-resistance breaking ability are good, and the high-temperature-resistant antioxidant exhaust manifold nodular cast iron can be applied to exhaust manifolds of automobile engines.
Description
Technical field
The present invention relates to a kind of preparation method of exhaust manifold spheroidal graphite cast iron.
Background technology
In recent years, for the consideration of protection of the environment and the aspect that economizes on resources, improving compression ratio, improve fuel combustion efficiency and reduce the aspects such as discharge, constantly motor car engine is proposed to new requirement, after adapting to catalysis technique and turbocharging technology application, the requirement that engine exhaust temperature constantly raises, mechanical behavior under high temperature to vehicle engine exhaust divided manifold and the requirement of antioxidant property are more and more higher, abroad to vehicle engine exhaust divided manifold, high temperature resistant requirement has reached 900 ℃ of left and right, and domestic existing exhaust manifold material generally can only meet the service requirements when temperature is 750 ℃ of left and right, along with the further raising of motor performance, particularly turbocharging technology improves constantly, the working temperature of exhaust manifold also will improve, and in addition, exhaust manifold is worked for a long time under high temperature circulation alternation state, heating temperature is inhomogeneous, top layer and inner chamber differ hundreds of degree, and working conditions is severe, and exhaust manifold material antioxidant property at high temperature has directly affected the work-ing life of discharge manifold, common ductile iron material is that under the condition of 650 ℃, its tensile strength is still 50N/mm in temperature
2left and right, heat resistance is poor, and under the thermal cycling temperature of 500-700 ℃, the cycle index of inefficacy is 100 left and right, and high temperature and creep resistance and creep resistance fracture energy are poor, cannot meet exhaust manifold material at high temperature mechanical property and oxidation resistant requirement.
Summary of the invention
The present invention is for solving under the poor and high thermal cycling temperature of existing exhaust manifold spheroidal graphite cast iron heat resistance, the low technical problem of cycle index of inefficacy, and a kind of preparation method of fire-resistant oxidation resistant exhaust manifold spheroidal graphite cast iron is provided.
A kind of fire-resistant oxidation resistant discharge manifold spheroidal graphite cast iron of the present invention is respectively 3.15%～3.25%, 4.15%～4.35%, 1.20%～1.30%, 0.20%～0.24%, 0.15%～0.18%, 0.012%～0.014%, 0.027%～0.031%, 0.048%～0.055% C, Si, Mo, V, Mn, S, P, Mg and surplus Fe by massfraction forms; Wherein also comprise that massfraction is 0.019%～0.024% residual Re element Re.
The preparation method of a kind of fire-resistant oxidation resistant discharge manifold spheroidal graphite cast iron of the present invention carries out according to the following steps:
One, smelting iron liquid: be first 70～75 and 25～30 by the mass fraction of the Q12 pig iron and steel scrap, take the Q12 pig iron and steel scrap, the ratio of pressing again the quality of ferro-molybdenum and the total mass of the Q12 pig iron and steel scrap is (2～2.5): 100, the ratio of pressing the quality of vanadium alloy and the total mass of the Q12 pig iron and steel scrap is (0.4～0.5): 100, the ratio of pressing the quality of ferro-silicon and the total mass of the Q12 pig iron and steel scrap is (2.0～2.3): 100, take ferro-molybdenum, vanadium alloy and ferro-silicon, then by the Q12 pig iron taking, steel scrap, ferro-molybdenum, vanadium alloy and ferro-silicon join in intermediate frequency furnace, being warming up to temperature is 1500～1550 ℃, standing 2～4min, come out of the stove, obtain iron liquid,
Two, nodularization and inoculation: the ratio of first pressing the quality of nodulizing agent and the total mass of the Q12 pig iron and steel scrap is (1.5～1.7): 100, the ratio of pressing again the quality of ferrosilicon nucleating agent and the total mass of the Q12 pig iron and steel scrap is (2.0～2.4): 100, the quality of silicon titanate innoculant is (0.10～0.15) with the ratio of the total mass of the Q12 pig iron and steel scrap: 100, take nodulizing agent, ferrosilicon nucleating agent and silicon titanate innoculant, then the nodulizing agent taking is put in to dykes and dams one side of pouring ladle, by the ferrosilicon nucleating agent uniform fold taking on nodulizing agent, by the iron liquid of step 1, in teeming temperature, be under the condition of 1380～1420 ℃ again, be poured in bag, in casting process, with stream, add the silicon titanate innoculant taking, in temperature, be under the condition of 1430～1450 ℃, insulation 0.4～0.6min completes nodularization and breeds, obtain the fire-resistant oxidation resistant discharge manifold spheroidal graphite cast iron before thermal treatment,
Beneficial effect of the present invention
Preparation method of the present invention is first by controlling the content of Si element in iron liquid, make foundry goods obtain ferrite matrix, ferrite volume fraction reaches 95%～99%, ferrite matrix is owing to not containing cementite, is difficult for decomposing under high temperature, can not cause volumetric expansion and makes foundry goods destruction, and at high temperature promote cast iron to form fine and close silicon-dioxide oxidation film layer, effectively stop oxonium ion to be invaded to the infiltration of foundry goods inside, prevent further oxidation, the anti-oxidant growth performance of foundry goods is improved greatly, secondly by controlling the content of Mo element, the mechanical behavior under high temperature of foundry goods is significantly improved, and V element improves foundry goods heat resistance by forming tiny equally distributed carbide in ferritic spheroidal graphite cast iron foundry goods, common ductile iron material is under the thermal cycling temperature condition of 500～700 ℃ in temperature, the cycle index losing efficacy is 100 left and right, and fire-resistant oxidation resistant discharge manifold spheroidal graphite cast iron of the present invention is under the thermal cycling temperature of 500～700 ℃ in temperature, the cycle index losing efficacy is 410～440 times, significantly improve high temperature and creep resistance and the creep resistance fracture energy of foundry goods, in temperature, be under the condition of 650 ℃, its Testing Tensile Strength at Elevated Temperature is still 150～160N/mm
2, heat resistance is good, and foundry goods is difficult for producing distortion, and common ductile iron material yield tensile ratio is at room temperature only 0.6-0.7, and fire-resistant oxidation resistant discharge manifold spheroidal graphite cast iron of the present invention, at ambient temperature, tensile strength is 620～650N/mm
2, yield strength is 500～530N/mm
2, unit elongation is 4.5%～5.5%, hardness is 246～255HBW, yield tensile ratio reaches 0.8～0.9, yield tensile ratio is high, in addition in preparation method of the present invention, adopt and breed for twice, mainly breed for the first time desulfurization, deoxidation, improve the nodularization situation in section centre, sphere diameter is diminished, breed for the second time, make can reach>=200/mm of S. G. count
2due to mutually discontinuous between globular graphite, isolated existence, oxygen can not be deep into internal oxidation, therefore the oxidation-resistance of material further strengthens, formed stable metallographic microstructure, make foundry goods in operating temperature range, not occur as far as possible or undergo phase transition less, and make foundry goods volume be difficult for deform, extended the work-ing life of foundry goods, met the requirement of vehicle engine exhaust divided manifold to spheroidal graphite cast iron mechanical behavior under high temperature and antioxidant property, can be applicable in vehicle engine exhaust divided manifold.
Accompanying drawing explanation
Fig. 1 is the spheroidization of graphite rank metaloscope photo of the fire-resistant oxidation resistant exhaust manifold spheroidal graphite cast iron prepared of embodiment 1;
Fig. 2 is the matrix metaloscope photo of the fire-resistant oxidation resistant exhaust manifold spheroidal graphite cast iron prepared of embodiment 1.
Embodiment
Technical solution of the present invention is not limited to following cited embodiment, also comprises the arbitrary combination between each embodiment.
Embodiment one: a kind of fire-resistant oxidation resistant discharge manifold spheroidal graphite cast iron of present embodiment is respectively 3.15%～3.25%, 4.15%～4.35%, 1.20%～1.30%, 0.20%～0.24%, 0.15%～0.18%, 0.012%～0.014%, 0.027%～0.031%, 0.048%～0.055% C, Si, Mo, V, Mn, S, P, Mg and surplus Fe by massfraction forms; Wherein also comprise that massfraction is 0.019%～0.024% residual Re element Re.
Embodiment two: the preparation method of a kind of fire-resistant oxidation resistant exhaust manifold spheroidal graphite cast iron of present embodiment carries out according to the following steps:
One, smelting iron liquid: be first 70～75 and 25～30 by the mass fraction of the Q12 pig iron and steel scrap, take the Q12 pig iron and steel scrap, the ratio of pressing again the quality of ferro-molybdenum and the total mass of the Q12 pig iron and steel scrap is (2～2.5): 100, the ratio of pressing the quality of vanadium alloy and the total mass of the Q12 pig iron and steel scrap is (0.4～0.5): 100, the ratio of pressing the quality of ferro-silicon and the total mass of the Q12 pig iron and steel scrap is (2.0～2.3): 100, take ferro-molybdenum, vanadium alloy and ferro-silicon, then by the Q12 pig iron taking, steel scrap, ferro-molybdenum, vanadium alloy and ferro-silicon join in intermediate frequency furnace, being warming up to temperature is 1500～1550 ℃, standing 2～4min, come out of the stove, obtain iron liquid,
Two, nodularization and inoculation: the ratio of first pressing the quality of nodulizing agent and the total mass of the Q12 pig iron and steel scrap is (1.5～1.7): 100, the ratio of pressing again the quality of ferrosilicon nucleating agent and the total mass of the Q12 pig iron and steel scrap is (2.0～2.4): 100, the quality of silicon titanate innoculant is (0.10～0.15) with the ratio of the total mass of the Q12 pig iron and steel scrap: 100, take nodulizing agent, ferrosilicon nucleating agent and silicon titanate innoculant, then the nodulizing agent taking is put in to dykes and dams one side of pouring ladle, by the ferrosilicon nucleating agent uniform fold taking on nodulizing agent, by the iron liquid of step 1, in teeming temperature, be under the condition of 1380～1420 ℃ again, be poured in bag, in casting process, with stream, add the silicon titanate innoculant taking, in temperature, be under the condition of 1430～1450 ℃, insulation 0.4～0.6min completes nodularization and breeds, obtain the fire-resistant oxidation resistant discharge manifold spheroidal graphite cast iron before thermal treatment.
The preparation method of present embodiment is first by controlling the content of Si element in iron liquid, make foundry goods obtain ferrite matrix, ferrite volume fraction reaches 95%～99%, ferrite matrix is owing to not containing cementite, is difficult for decomposing under high temperature, can not cause volumetric expansion and makes foundry goods destruction, and at high temperature promote cast iron to form fine and close silicon-dioxide oxidation film layer, effectively stop oxonium ion to be invaded to the infiltration of foundry goods inside, prevent further oxidation, the anti-oxidant growth performance of foundry goods is improved greatly, secondly by controlling the content of Mo element, the mechanical behavior under high temperature of foundry goods is significantly improved, and V element improves foundry goods heat resistance by forming tiny equally distributed carbide in ferritic spheroidal graphite cast iron foundry goods, common ductile iron material is under the thermal cycling temperature condition of 500～700 ℃ in temperature, the cycle index losing efficacy is 100 left and right, and the fire-resistant oxidation resistant discharge manifold spheroidal graphite cast iron of present embodiment is under the thermal cycling temperature of 500～700 ℃ in temperature, the cycle index losing efficacy is 410～440 times, significantly improve high temperature and creep resistance and the creep resistance fracture energy of foundry goods, in temperature, be under the condition of 650 ℃, its Testing Tensile Strength at Elevated Temperature is still 150～160N/mm
2, heat resistance is good, and foundry goods is difficult for producing distortion, and common ductile iron material yield tensile ratio is at room temperature only 0.6-0.7, and the fire-resistant oxidation resistant discharge manifold spheroidal graphite cast iron of present embodiment, at ambient temperature, tensile strength is 620～650N/mm
2, yield strength is 500～530N/mm
2, unit elongation is 4.5%～5.5%, hardness is 246～255HBW, yield tensile ratio reaches 0.8～0.9, yield tensile ratio is high, in addition in the preparation method of present embodiment, adopt and breed for twice, mainly breed for the first time desulfurization, deoxidation, improve the nodularization situation in section centre, sphere diameter is diminished, breed for the second time, make can reach>=200/mm of S. G. count
2due to mutually discontinuous between globular graphite, isolated existence, oxygen can not be deep into internal oxidation, therefore the oxidation-resistance of material further strengthens, formed stable metallographic microstructure, make foundry goods in operating temperature range, not occur as far as possible or undergo phase transition less, and make foundry goods volume be difficult for deform, extended the work-ing life of foundry goods, met the requirement of vehicle engine exhaust divided manifold to spheroidal graphite cast iron mechanical behavior under high temperature and antioxidant property, can be applicable in vehicle engine exhaust divided manifold.
Embodiment three: present embodiment is different from embodiment two: in step 1, in steel scrap, composition and each composition quality mark are: C:0.17%～0.21%, S:0.012%～0.016%, P:0.020%～0.025%, Mn:0.24%～0.28%, Si:0.30%～0.40%, other steps and parameter are identical with embodiment one or two.
Embodiment four: present embodiment is different from embodiment two or three: in step 1, ferro-silicon is FeSi75 alloy, wherein the massfraction of Si is 65%-75%, other steps and parameter are identical with embodiment two or three.
Embodiment five: present embodiment is different from one of embodiment two to four: in step 1, in ferro-molybdenum, the massfraction of Mo is 56%～56%, other steps and parameter are identical with one of embodiment two to four.
Embodiment six: present embodiment is different from one of embodiment two to five: in step 1, in vanadium alloy, the massfraction of V is 45%～55%, other steps and parameter are identical with one of embodiment two to five.
Embodiment seven: present embodiment is different from one of embodiment two to six: in step 2, nodulizing agent is magnesium-rare earth FeSiMg8Re7 nodulizing agent, and other steps and parameter are identical with one of embodiment two to six.
Embodiment eight: present embodiment is different from one of embodiment two to seven: in step 2, ferrosilicon nucleating agent is FeSi75 alloy, wherein the massfraction of Si is 65%-75%, and other steps and parameter are identical with one of embodiment two to seven.
Embodiment nine: present embodiment is different from one of embodiment two to eight: in step 2, in silicon titanate innoculant, the massfraction of Si is 45%-48%, the granularity of silicon titanate innoculant is 0.2～0.7mm, and other steps and parameter are identical with one of embodiment two to eight.
With following verification experimental verification beneficial effect of the present invention
The preparation method of embodiment 1, a kind of fire-resistant oxidation resistant exhaust manifold spheroidal graphite cast iron carries out according to the following steps:
One, smelting iron liquid: be first 75 and 25 by the mass fraction of the Q12 pig iron and steel scrap, take the Q12 pig iron and steel scrap, by the quality of ferro-molybdenum, be 2.5:100 with the ratio of the total mass of the Q12 pig iron and steel scrap again, by the quality of vanadium alloy, be 0.45:100 with the ratio of the total mass of the Q12 pig iron and steel scrap, by the quality of ferro-silicon with the ratio of the total mass of the Q12 pig iron and steel scrap be 2.2:100, take ferro-molybdenum, vanadium alloy and ferro-silicon, then by the Q12 pig iron taking, steel scrap, ferro-molybdenum, vanadium alloy and ferro-silicon join in intermediate frequency furnace, being warming up to temperature is 1530 ℃, standing 3min, come out of the stove, obtain iron liquid,
Two, nodularization and inoculation: by the quality of nodulizing agent, be first 1.6:100 with the ratio of the total mass of the Q12 pig iron and steel scrap, by the quality of ferrosilicon nucleating agent, be 2.3:100 with the ratio of the total mass of the Q12 pig iron and steel scrap again, the quality of silicon titanate innoculant is 0.13:100 with the ratio of the total mass of the Q12 pig iron and steel scrap, take nodulizing agent, ferrosilicon nucleating agent and silicon titanate innoculant, then the nodulizing agent taking is put in to dykes and dams one side of pouring ladle, by the ferrosilicon nucleating agent uniform fold taking on nodulizing agent, by the iron liquid of step 1, in teeming temperature, be under the condition of 1400 ℃ again, be poured in bag, in casting process, with stream, add the silicon titanate innoculant taking, in temperature, be under the condition of 1440 ℃, insulation 0.5min completes nodularization and breeds, obtain the fire-resistant oxidation resistant discharge manifold spheroidal graphite cast iron before thermal treatment.
The preparation method of the present embodiment is first by controlling the content of Si element in iron liquid, make foundry goods obtain ferrite matrix, ferrite matrix is owing to not containing cementite, under high temperature, be difficult for decomposing, can not cause volumetric expansion and foundry goods is destroyed, and at high temperature promote cast iron to form fine and close silicon-dioxide oxidation film layer, effectively stop oxonium ion to be invaded to the infiltration of foundry goods inside, prevent further oxidation, the anti-oxidant growth performance of foundry goods is improved greatly; Secondly by controlling the content of Mo element, the mechanical behavior under high temperature of foundry goods is significantly improved, and V element improves foundry goods heat resistance by forming tiny equally distributed carbide in ferritic spheroidal graphite cast iron foundry goods, in addition in the preparation method of the present embodiment, adopt and breed for twice, mainly breed for the first time desulfurization, deoxidation, improve the nodularization situation in section centre, sphere diameter is diminished, breed for the second time, make can reach>=200/mm of S. G. count
2due to mutually discontinuous between globular graphite, isolated existence, oxygen can not be deep into internal oxidation, therefore the oxidation-resistance of material further strengthens, formed stable metallographic microstructure, make foundry goods in operating temperature range, not occur as far as possible or undergo phase transition less, and make foundry goods volume be difficult for deform, extended the work-ing life of foundry goods, met the requirement of vehicle engine exhaust divided manifold to spheroidal graphite cast iron mechanical behavior under high temperature and antioxidant property, can be applicable in vehicle engine exhaust divided manifold.
Test one, a kind of fire-resistant oxidation resistant exhaust manifold spheroidal graphite cast iron prepared by embodiment 1 carry out physics and chemistry test, and result is as follows:
Chemical composition and each composition quality mark of a kind of fire-resistant oxidation resistant exhaust manifold spheroidal graphite cast iron prepared by embodiment 1 are: the Fe of C:3.22%, Si:4.31%, Mn:0.15%, Mo:1.21%, V:0.23%, S:0.013, P:0.029, Mg:0.048% and surplus; In it, be 0.021% with the residual volume of Re.
Test two, a kind of fire-resistant oxidation resistant exhaust manifold spheroidal graphite cast iron prepared by embodiment 1 carry out metallographic structure analysis test, and process of the test is as follows:
At ambient temperature, adopt 4XB type metaloscope, a kind of fire-resistant oxidation resistant exhaust manifold spheroidal graphite cast iron sample prepared by embodiment 1 carries out metallographic structure analysis, obtain metaloscope photo as depicted in figs. 1 and 2, as can be seen from Figure 1, nodularization rate is 96%, and sphere diameter is little, nodule number is many, as can be seen from Figure 2, after thermal treatment, matrix ferrite content is 97%, and ferrite crystal grain is tiny, be evenly distributed, plasticity is high.
Test three, a kind of fire-resistant oxidation resistant exhaust manifold spheroidal graphite cast iron prepared by embodiment 1 carry out conventional mechanical performance test, and process of the test is as follows:
Now, according to GB/T228-2002 testing standard, with CSS-88300 type electronic tension tester, under 25 ℃ of conditions of room temperature, a kind of fire-resistant oxidation resistant exhaust manifold spheroidal graphite cast iron prepared by embodiment 1 carries out conventional mechanical performance test, tests three times, and result is as follows
Test four, a kind of fire-resistant oxidation resistant exhaust manifold spheroidal graphite cast iron prepared by embodiment 1 carry out Testing Tensile Strength at Elevated Temperature test, and process of the test is as follows:
Now according to GB/T228-2002 testing standard, with the high cryotronics tension testing machine of QJ211B type, under 650 ℃ of conditions of high temperature, a kind of fire-resistant oxidation resistant exhaust manifold spheroidal graphite cast iron prepared by embodiment 1 carries out test for tensile strength under hot conditions, and recording its tensile strength is 160N/mm
2, heat resistance is good.
Test five, a kind of fire-resistant oxidation resistant exhaust manifold spheroidal graphite cast iron prepared by embodiment 1 carry out fatique testing at elevated temperature, and process of the test is as follows:
Now according to GB3075 testing standard, adopt SEN high temperature fatigue testing machine, under the condition of high temperature 400-500 ℃, 450～550 ℃ and 500～650 ℃, a kind of fire-resistant oxidation resistant exhaust manifold spheroidal graphite cast iron prepared by embodiment 1 carries out Fatigue Test, obtains test result as follows respectively:
The preparation method of embodiment 1 is first by controlling the content of Si element in iron liquid in sum, make foundry goods obtain ferrite matrix, ferrite volume fraction reaches 97%, ferrite matrix is owing to not containing cementite, is difficult for decomposing under high temperature, can not cause volumetric expansion and makes foundry goods destruction, and at high temperature promote cast iron to form fine and close silicon-dioxide oxidation film layer, effectively stop oxonium ion to be invaded to the infiltration of foundry goods inside, prevent further oxidation, the anti-oxidant growth performance of foundry goods is improved greatly; Secondly by controlling the content of Mo element, the mechanical behavior under high temperature of foundry goods is significantly improved, and V element improves foundry goods heat resistance by forming tiny equally distributed carbide in ferritic spheroidal graphite cast iron foundry goods, the fire-resistant oxidation resistant discharge manifold spheroidal graphite cast iron of embodiment 1 is under the thermal cycling temperature of 500～650 ℃ in temperature, the cycle index losing efficacy is still 410 times, significantly improve high temperature and creep resistance and the creep resistance fracture energy of foundry goods, in temperature, be that under the condition of 650 ℃, its Testing Tensile Strength at Elevated Temperature is still 160N/mm
2, heat resistance is good, and foundry goods is difficult for producing distortion, and the fire-resistant oxidation resistant discharge manifold spheroidal graphite cast iron of embodiment 1, and at ambient temperature, tensile strength is 640N/mm
2, yield strength is 520N/mm
2, unit elongation is 4.5%, hardness is 252HBW, yield tensile ratio reaches 0.81, yield tensile ratio is high, can be applicable in vehicle engine exhaust divided manifold.
Claims (8)
1. a preparation method for fire-resistant oxidation resistant discharge manifold spheroidal graphite cast iron, is characterized in that this preparation method carries out according to the following steps:
One, smelting iron liquid: be first 70～75 and 25～30 by the mass fraction of the Q12 pig iron and steel scrap, take the Q12 pig iron and steel scrap, the ratio of pressing again the quality of ferro-molybdenum and the total mass of the Q12 pig iron and steel scrap is (2～2.5): 100, the ratio of pressing the quality of vanadium alloy and the total mass of the Q12 pig iron and steel scrap is (0.4～0.5): 100, the ratio of pressing the quality of ferro-silicon and the total mass of the Q12 pig iron and steel scrap is (2.0～2.3): 100, take ferro-molybdenum, vanadium alloy and ferro-silicon, then by the Q12 pig iron taking, steel scrap, ferro-molybdenum, vanadium alloy and ferro-silicon join in intermediate frequency furnace, being warming up to temperature is 1500～1550 ℃, standing 2～4min, come out of the stove, obtain iron liquid,
Two, nodularization and inoculation: the ratio of first pressing the quality of nodulizing agent and the total mass of the Q12 pig iron and steel scrap is (1.5～1.7): 100, the ratio of pressing again the quality of ferrosilicon nucleating agent and the total mass of the Q12 pig iron and steel scrap is (2.0～2.4): 100, the quality of silicon titanate innoculant is (0.10～0.15) with the ratio of the total mass of the Q12 pig iron and steel scrap: 100, take nodulizing agent, ferrosilicon nucleating agent and silicon titanate innoculant, then the nodulizing agent taking is put in to dykes and dams one side of pouring ladle, by the ferrosilicon nucleating agent uniform fold taking on nodulizing agent, by the iron liquid of step 1, in teeming temperature, be under the condition of 1380～1420 ℃ again, be poured in bag, in casting process, with stream, add the silicon titanate innoculant taking, in temperature, be under the condition of 1430～1450 ℃, insulation 0.4～0.6min completes nodularization and breeds, obtain fire-resistant oxidation resistant discharge manifold spheroidal graphite cast iron,
Described fire-resistant oxidation resistant discharge manifold spheroidal graphite cast iron is respectively 3.15%～3.25%, 4.15%～4.35%, 1.20%～1.30%, 0.20%～0.24%, 0.15%～0.18%, 0.012%～0.014%, 0.027%～0.031%, 0.048%～0.055% C, Si, Mo, V, Mn, S, P, Mg and surplus Fe by massfraction forms; Wherein also comprise that massfraction is 0.019%～0.024% residual Re element Re.
2. the preparation method of a kind of fire-resistant oxidation resistant exhaust manifold spheroidal graphite cast iron according to claim 1, is characterized in that in step 1 in steel scrap that composition and each composition quality mark are: C:0.17%～0.21%, S:0.012%～0.016%, P:0.020%～0.025%, Mn:0.24%～0.28%, Si:0.30%～0.40%.
3. the preparation method of a kind of fire-resistant oxidation resistant exhaust manifold spheroidal graphite cast iron according to claim 1 and 2, is characterized in that in step 1, ferro-silicon is FeSi75 alloy, and wherein the massfraction of Si is 65%-75%.
4. the preparation method of a kind of fire-resistant oxidation resistant exhaust manifold spheroidal graphite cast iron according to claim 3, is characterized in that in step 1 in ferro-molybdenum that the massfraction of Mo is 56%～56%.
5. the preparation method of a kind of fire-resistant oxidation resistant exhaust manifold spheroidal graphite cast iron according to claim 3, is characterized in that in step 1 in vanadium alloy that the massfraction of V is 45%～55%.
6. the preparation method of a kind of fire-resistant oxidation resistant exhaust manifold spheroidal graphite cast iron according to claim 3, is characterized in that in step 2, nodulizing agent is magnesium-rare earth FeSiMg8Re7 nodulizing agent.
7. the preparation method of a kind of fire-resistant oxidation resistant exhaust manifold spheroidal graphite cast iron according to claim 3, is characterized in that in step 2, ferrosilicon nucleating agent is FeSi75 alloy, and wherein the massfraction of Si is 65%-75%.
8. the preparation method of a kind of fire-resistant oxidation resistant exhaust manifold spheroidal graphite cast iron according to claim 3, is characterized in that in step 2 in silicon titanate innoculant that the massfraction of Si is 45%-48%, and the granularity of silicon titanate innoculant is 0.2～0.7mm.
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| CN106077508B (en) * | 2016-07-19 | 2018-11-02 | 东北大学 | The manufacturing method of enmgine exhaust material and enmgine exhaust |
| CN106011609B (en) * | 2016-07-29 | 2018-03-02 | 西峡县内燃机进排气管有限责任公司 | A kind of middle silicon molybdenum niobium ductile cast iron material and preparation method thereof |
| CN106148811A (en) * | 2016-08-18 | 2016-11-23 | 江阴联华铸造有限公司 | A kind of automobile gas exhausting manifold branch high temperature resistant nodular cast iron part and preparation method thereof |
| CN108642370A (en) * | 2018-06-06 | 2018-10-12 | 含山县东山德雨球墨铸造厂 | A kind of antioxidant wear-resistant spheroidal graphite cast-iron and preparation method thereof |
| CN110000339A (en) * | 2019-05-09 | 2019-07-12 | 上海圣德曼铸造海安有限公司 | A kind of sand mould structure of automobile engine exhaust pipe |
| CN111004968A (en) * | 2020-02-15 | 2020-04-14 | 溧阳市联华机械制造有限公司 | High-silicon heat-resistant vermicular graphite cast iron with thermal fatigue resistance and high performance and preparation method thereof |
| CN113322417B (en) * | 2021-06-04 | 2022-06-28 | 西安建筑科技大学 | A kind of Laves phase strengthened stainless steel and preparation method thereof |
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