CN115141971B - Vermicular graphite cast iron high-strength hydraulic pump body and production process thereof - Google Patents
Vermicular graphite cast iron high-strength hydraulic pump body and production process thereof Download PDFInfo
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- CN115141971B CN115141971B CN202210885824.6A CN202210885824A CN115141971B CN 115141971 B CN115141971 B CN 115141971B CN 202210885824 A CN202210885824 A CN 202210885824A CN 115141971 B CN115141971 B CN 115141971B
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- OKTJSMMVPCPJKN-UHFFFAOYSA-N Carbon Chemical compound [C] OKTJSMMVPCPJKN-UHFFFAOYSA-N 0.000 title claims abstract description 88
- 229910002804 graphite Inorganic materials 0.000 title claims abstract description 72
- 239000010439 graphite Substances 0.000 title claims abstract description 72
- 229910001018 Cast iron Inorganic materials 0.000 title claims abstract description 53
- 238000004519 manufacturing process Methods 0.000 title claims abstract description 13
- XEEYBQQBJWHFJM-UHFFFAOYSA-N iron Substances [Fe] XEEYBQQBJWHFJM-UHFFFAOYSA-N 0.000 claims abstract description 111
- 229910052742 iron Inorganic materials 0.000 claims abstract description 54
- 239000003795 chemical substances by application Substances 0.000 claims abstract description 22
- 239000002994 raw material Substances 0.000 claims abstract description 20
- 239000012535 impurity Substances 0.000 claims abstract description 4
- 235000014347 soups Nutrition 0.000 claims description 25
- 238000007599 discharging Methods 0.000 claims description 20
- 239000000463 material Substances 0.000 claims description 20
- 230000004048 modification Effects 0.000 claims description 19
- 238000012986 modification Methods 0.000 claims description 19
- 229910052799 carbon Inorganic materials 0.000 claims description 14
- 238000005266 casting Methods 0.000 claims description 14
- 229910052804 chromium Inorganic materials 0.000 claims description 13
- 239000011777 magnesium Substances 0.000 claims description 13
- 238000011081 inoculation Methods 0.000 claims description 12
- 229910052747 lanthanoid Inorganic materials 0.000 claims description 11
- 150000002602 lanthanoids Chemical class 0.000 claims description 11
- 229910052698 phosphorus Inorganic materials 0.000 claims description 11
- 229910052761 rare earth metal Inorganic materials 0.000 claims description 11
- 229910052710 silicon Inorganic materials 0.000 claims description 11
- 229910052717 sulfur Inorganic materials 0.000 claims description 11
- 229910045601 alloy Inorganic materials 0.000 claims description 9
- 239000000956 alloy Substances 0.000 claims description 9
- 230000009471 action Effects 0.000 claims description 8
- 230000008018 melting Effects 0.000 claims description 8
- 238000002844 melting Methods 0.000 claims description 8
- 229910000640 Fe alloy Inorganic materials 0.000 claims description 7
- 239000011575 calcium Substances 0.000 claims description 7
- 239000004615 ingredient Substances 0.000 claims description 7
- 239000002054 inoculum Substances 0.000 claims description 7
- 238000000034 method Methods 0.000 claims description 7
- 239000000203 mixture Substances 0.000 claims description 7
- 229910052748 manganese Inorganic materials 0.000 claims description 6
- 230000006866 deterioration Effects 0.000 claims description 5
- 238000003723 Smelting Methods 0.000 claims description 4
- HMDDXIMCDZRSNE-UHFFFAOYSA-N [C].[Si] Chemical compound [C].[Si] HMDDXIMCDZRSNE-UHFFFAOYSA-N 0.000 claims description 4
- KARQLFDESQCUJT-UHFFFAOYSA-N [Mg].[Si].[Ca].[Fe] Chemical compound [Mg].[Si].[Ca].[Fe] KARQLFDESQCUJT-UHFFFAOYSA-N 0.000 claims description 4
- 238000012790 confirmation Methods 0.000 claims description 4
- 229910052802 copper Inorganic materials 0.000 claims description 4
- 238000010438 heat treatment Methods 0.000 claims description 4
- 150000002910 rare earth metals Chemical class 0.000 claims description 4
- 238000005070 sampling Methods 0.000 claims description 4
- 239000004576 sand Substances 0.000 claims description 4
- 229910052718 tin Inorganic materials 0.000 claims description 4
- 238000010079 rubber tapping Methods 0.000 claims description 3
- -1 silicon-barium-aluminum-calcium-iron Chemical group 0.000 claims description 3
- 238000012360 testing method Methods 0.000 abstract description 5
- 229910001060 Gray iron Inorganic materials 0.000 description 18
- 241001584785 Anavitrinella pampinaria Species 0.000 description 5
- 229910001562 pearlite Inorganic materials 0.000 description 5
- 239000000126 substance Substances 0.000 description 4
- 238000006243 chemical reaction Methods 0.000 description 3
- 230000000694 effects Effects 0.000 description 3
- 238000011056 performance test Methods 0.000 description 3
- 230000008569 process Effects 0.000 description 3
- 229910000859 α-Fe Inorganic materials 0.000 description 3
- IJGRMHOSHXDMSA-UHFFFAOYSA-N Atomic nitrogen Chemical compound N#N IJGRMHOSHXDMSA-UHFFFAOYSA-N 0.000 description 2
- 229910001141 Ductile iron Inorganic materials 0.000 description 2
- 229910001296 Malleable iron Inorganic materials 0.000 description 2
- 229910000831 Steel Inorganic materials 0.000 description 2
- 239000011159 matrix material Substances 0.000 description 2
- 230000003647 oxidation Effects 0.000 description 2
- 238000007254 oxidation reaction Methods 0.000 description 2
- 238000010587 phase diagram Methods 0.000 description 2
- 230000000087 stabilizing effect Effects 0.000 description 2
- 239000010959 steel Substances 0.000 description 2
- 229910052684 Cerium Inorganic materials 0.000 description 1
- UFHFLCQGNIYNRP-UHFFFAOYSA-N Hydrogen Chemical compound [H][H] UFHFLCQGNIYNRP-UHFFFAOYSA-N 0.000 description 1
- 230000002411 adverse Effects 0.000 description 1
- QVGXLLKOCUKJST-UHFFFAOYSA-N atomic oxygen Chemical compound [O] QVGXLLKOCUKJST-UHFFFAOYSA-N 0.000 description 1
- 230000009286 beneficial effect Effects 0.000 description 1
- 238000005336 cracking Methods 0.000 description 1
- 238000002425 crystallisation Methods 0.000 description 1
- 230000008025 crystallization Effects 0.000 description 1
- 238000007872 degassing Methods 0.000 description 1
- 238000006477 desulfuration reaction Methods 0.000 description 1
- 230000023556 desulfurization Effects 0.000 description 1
- 238000001514 detection method Methods 0.000 description 1
- 230000007613 environmental effect Effects 0.000 description 1
- 230000005496 eutectics Effects 0.000 description 1
- 238000004880 explosion Methods 0.000 description 1
- 239000004744 fabric Substances 0.000 description 1
- 229910052739 hydrogen Inorganic materials 0.000 description 1
- 239000001257 hydrogen Substances 0.000 description 1
- 230000006872 improvement Effects 0.000 description 1
- VAKIVKMUBMZANL-UHFFFAOYSA-N iron phosphide Chemical compound P.[Fe].[Fe].[Fe] VAKIVKMUBMZANL-UHFFFAOYSA-N 0.000 description 1
- 229910052749 magnesium Inorganic materials 0.000 description 1
- 229910052757 nitrogen Inorganic materials 0.000 description 1
- 229910052760 oxygen Inorganic materials 0.000 description 1
- 239000001301 oxygen Substances 0.000 description 1
- 238000001556 precipitation Methods 0.000 description 1
- 230000002028 premature Effects 0.000 description 1
- 230000001737 promoting effect Effects 0.000 description 1
- 238000007670 refining Methods 0.000 description 1
- 238000005204 segregation Methods 0.000 description 1
- 238000007711 solidification Methods 0.000 description 1
- 230000008023 solidification Effects 0.000 description 1
- 238000005728 strengthening Methods 0.000 description 1
- 238000009864 tensile test Methods 0.000 description 1
Classifications
-
- C—CHEMISTRY; METALLURGY
- C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
- C22C—ALLOYS
- C22C37/00—Cast-iron alloys
- C22C37/10—Cast-iron alloys containing aluminium or silicon
-
- C—CHEMISTRY; METALLURGY
- C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
- C22C—ALLOYS
- C22C33/00—Making ferrous alloys
- C22C33/08—Making cast-iron alloys
- C22C33/10—Making cast-iron alloys including procedures for adding magnesium
-
- C—CHEMISTRY; METALLURGY
- C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
- C22C—ALLOYS
- C22C37/00—Cast-iron alloys
- C22C37/06—Cast-iron alloys containing chromium
-
- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F04—POSITIVE - DISPLACEMENT MACHINES FOR LIQUIDS; PUMPS FOR LIQUIDS OR ELASTIC FLUIDS
- F04B—POSITIVE-DISPLACEMENT MACHINES FOR LIQUIDS; PUMPS
- F04B53/00—Component parts, details or accessories not provided for in, or of interest apart from, groups F04B1/00 - F04B23/00 or F04B39/00 - F04B47/00
- F04B53/16—Casings; Cylinders; Cylinder liners or heads; Fluid connections
-
- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02P—CLIMATE CHANGE MITIGATION TECHNOLOGIES IN THE PRODUCTION OR PROCESSING OF GOODS
- Y02P10/00—Technologies related to metal processing
- Y02P10/20—Recycling
Landscapes
- Chemical & Material Sciences (AREA)
- Engineering & Computer Science (AREA)
- Mechanical Engineering (AREA)
- Materials Engineering (AREA)
- Metallurgy (AREA)
- Organic Chemistry (AREA)
- General Engineering & Computer Science (AREA)
- Refinement Of Pig-Iron, Manufacture Of Cast Iron, And Steel Manufacture Other Than In Revolving Furnaces (AREA)
Abstract
The invention discloses a vermicular graphite cast iron high-strength hydraulic pump body and a production process thereof, wherein the pump body is cast by vermicular graphite cast iron, and the pump body comprises the following raw materials in percentage by mass: 3.2% -3.8% of C, 1.8% -2.4% of Si, 0.5% -1.0% of Mn, 0% -0.25% of P, 0.08% -0.03% of S, 0.10% -0.40% of Cu, 0.01% -0.03% of Sn, 0.004% -0.02% of Sb, 0.10% -0.3% of Cr and the balance of Fe and accompanying impurities, wherein a modifying agent accounting for 0.20% -0.40% of the total mass of molten iron is adopted in the raw material production process so as to control the vermicular rate of graphite form to be 25% -50%. The mechanical property of the hydraulic pump is greatly improved, and the tensile strength is more than or equal to 420N/mm 2 The hardness range is HB 153-HB 229, and the pressure resistance test at 60MPa exceeds 24.6 ten thousand times.
Description
Technical Field
The invention relates to a vermicular graphite cast iron high-strength hydraulic pump body and a production process thereof, and belongs to the technical field of graphite cast iron.
Background
The hydraulic control parts used on large industrial machinery in the market at present all use common gray cast iron as raw materials. When the gray cast iron pump body is applied to equipment in a high pressure difference condition, the problem of hydraulic pump fracture caused by insufficient mechanical strength can occur under the use condition of frequent high-low pressure conversion working conditions, and the mechanical strength of the gray cast iron pump body cannot meet the use requirement.
Gray cast iron can be classified into: ordinary gray cast iron, spheroidal graphite cast iron, malleable cast iron and vermicular graphite cast iron, graphite of ordinary gray cast iron is flake, graphite is scattered on basal body in the form of separate flake when metallographic observation, they are separated, not connected each other, as shown in figure 1; graphite in the spheroidal graphite cast iron is in a spheroidal shape, graphite in the malleable cast iron is in a spheroidal shape, and graphite in the vermicular cast iron is in a vermicular shape, which is also called vermicular graphite cast iron.
The mechanical properties of gray cast iron are closely related to the structure of a matrix and the morphology of graphite, the flaky graphite in the gray cast iron has serious cracking on the matrix, and stress concentration is easy to cause at the sharp angle of graphite, so that the tensile strength, plasticity and toughness of the gray cast iron are far lower than those of steel, but the compressive strength is equivalent to that of the steel, and the gray cast iron is widely applied to the fields of hydraulic systems and the like. Currently, gray cast iron is used as a preferred material for hydraulic system core parts of large-scale industrial machinery in the market. In recent years, under the requirements of national environmental protection policies, the exhaust emission of large industrial machinery is continuously required to be reduced in order to reduce the exhaust emission and improve the air quality. Under such a background, engineering hydraulic components with higher energy conversion efficiency and higher holding pressure start to develop vigorously. As described above, in the working environment of frequent high-low pressure conversion conditions, the hydraulic pump made of ordinary gray cast iron may have a risk of breakage due to insufficient mechanical strength.
In view of the above, a new hydraulic pump body with high mechanical strength must be developed to be suitable for new engineering machinery applications.
Disclosure of Invention
The invention provides a vermicular graphite cast iron high-strength hydraulic pump body and a production process thereof, which aim to solve the problems in the prior art.
The invention adopts the following technical scheme: the vermicular graphite cast iron high-strength hydraulic pump body is prepared by casting vermicular graphite cast iron, and comprises the following raw materials in percentage by mass: 3.2% -3.8% of C, 1.8% -2.4% of Si, 0.5% -1.0% of Mn, 0% -0.25% of P, 0.08% -0.03% of S, 0.10% -0.40% of Cu, 0.01% -0.03% of Sn, 0.004% -0.02% of Sb, 0.10% -0.3% of Cr and the balance of Fe and accompanying impurities, wherein a modifying agent accounting for 0.20% -0.40% of the total mass of molten iron is adopted in the raw material production process so as to control the vermicular rate of graphite form to be 25% -50%.
Further, the vermicular graphite cast iron high-strength hydraulic pump body has the tensile strength more than or equal to 420N/mm 2 The hardness ranges from HB153 to HB229.
Further, the deterioration agent comprises the following components in percentage by mass: 4.0-6.0% of Mg, 0-1.0% of Al, 40-50% of Si, 1.5-2.5% of Ca, 4.5-5.5% of RE and the balance of Fe, wherein RE represents the sum of lanthanide rare earth elements.
Further, the sum of the mass of Mg and the mass of Ce accounts for 0.01-0.03% of the mass of the whole vermicular graphite cast iron, wherein Ce is one element in RE.
The invention also adopts the following technical scheme: a production process of a vermicular graphite cast iron high-strength hydraulic pump body comprises the following steps:
s1, melting: heating the main raw materials, the scraps and the return materials to 1400-1450 ℃ in an intermediate frequency furnace for smelting, melting the materials into molten iron, detecting the carbon content of the molten iron by using a carbon-silicon meter, detecting the content of Si, mn, P, S, cu, sn, sb and Cr by using a spectroscope, powering off after analysis is finished, performing primary deslagging operation, adding alloy ingredients, and performing secondary deslagging operation after component analysis confirmation;
s2, soup discharging: transferring the ladle to the front of a furnace for soup discharging operation, controlling the soup discharging temperature to 1450-1600 ℃, and adding 0.2% inoculant into the ladle for molten iron inoculation before soup discharging so as to finish soup discharging action;
s3, vermiculizer treatment: adding modification silk thread accounting for 0.80-1% of the total mass of molten iron into a ladle by using a silk feeding method to carry out vermiculizer treatment on the molten iron, wherein the modification silk thread is lanthanide rare earth magnesium silicon calcium iron alloy, and the mass percentage of each element in the modification agent is 4.0-6.0% of Mg, 0-1.0% of Al, 40-50% of Si, 1.5-2.5% of Ca, 4.5-5.5% of RE and the balance of Fe, and RE represents the total sum of lanthanide rare earth elements;
and S4, sampling molten iron before casting, analyzing and confirming the components again, filling casting into a sand mold cavity when the components are qualified, and simultaneously adding stream inoculation of 5-10 g/S to perform molten iron inoculation action, wherein the temperature of the molten iron is maintained to be 1350-1450 ℃ in the casting process, so that the vermicular graphite cast iron high-strength hydraulic pump body is obtained.
Further, the mass ratio of the main raw material to the leftover material to the return furnace material is 5 percent: 65%:30% and one or more of Si, mn, P, S, cu, sn, sb and Cr are included in the alloy composition.
Further, the inoculant is silicon-barium-aluminum-calcium-iron alloy.
Further, the vermiculizer treatment time is 60-120 s.
Further, in the steps S1 and S4, the target contents of the components are: 3.2 to 3.8 percent of C, 1.8 to 2.4 percent of Si, 0.5 to 1.0 percent of Mn, 0 to 0.25 percent of P, 0.08 to 0.03 percent of S, 0.10 to 0.40 percent of Cu, 0.01 to 0.03 percent of Sn, 0.004 to 0.02 percent of Sb and 0.10 to 0.30 percent of Cr.
Further, when the S content is 0.008% -0.015%, the addition amount of the modifying agent is 0.8% of the weight of molten iron soup; when the S percentage content is 0.016% -0.030%, the addition amount of the modifying agent is 1% of the weight of the molten iron for tapping molten iron.
The invention has the following beneficial effects:
(1) The C.E. value of the carbon equivalent is controlled to be 3.8-4.6, so that the carbon equivalent of molten iron in the solidification process is ensured to be close to the eutectic composition, and the purposes of refining the graphite size (avoiding graphite explosion) and avoiding internal shrinkage porosity are achieved;
(2) According to the invention, the mass percentages of Mn, cu, sb and Cr are reasonably controlled, the pearlite content in the whole base structure of the hydraulic pump body is ensured to be more than 80%, and meanwhile, the problem of overhigh hardness caused by overhigh Mn, cu and Cr contents is avoided;
(3) The vermicular rate is controlled by controlling the contents of Mg and Ce, so that the vermicular rate of graphite form in the raw materials of the vermicular graphite cast iron hydraulic pump is 20% -50%, and compared with the common gray cast iron on the market, the mechanical property of the vermicular graphite cast iron hydraulic pump body is greatly improved, and the tensile strength is more than or equal to 420N/mm 2 The hardness range is HB 153-HB 229, and the pressure resistance test at 60MPa exceeds 24.6 ten thousand times.
Drawings
Fig. 1 is a golden phase diagram of a prior art common gray cast iron hydraulic pump body.
Fig. 2 is a golden phase diagram of the vermicular graphite cast iron hydraulic pump body of the present invention.
Fig. 3 is a schematic structural view of the vermicular graphite cast iron hydraulic pump body of the present invention.
Detailed Description
The invention is further described below with reference to the accompanying drawings.
The invention discloses a vermicular graphite cast iron high-strength hydraulic pump body, which is cast by vermicular graphite cast iron, and comprises the following raw materials in percentage by mass: 3.2% -3.8% of C, 1.8% -2.4% of Si, 0.5% -1.0% of Mn, 0% -0.25% of P, 0.08% -0.03% of S, 0.10% -0.40% of Cu, 0.01% -0.03% of Sn, 0.004% -0.02% of Sb, 0.10% -0.3% of Cr and the balance of Fe and accompanying impurities, wherein a deterioration treatment agent accounting for 0.20% -0.40% of the total mass of molten iron is adopted in the raw material production process to control the vermicular rate of graphite form to be 25% -50%.
C (carbon) is an element forming a graphite structure, the content of the C (carbon) has a critical influence on the elongation of the material, and ferrite is easy to generate due to the fact that the content of the C is too high, so that the content of the C is 3.2% -3.8%, and the C.E. value of the carbon equivalent is controlled to be 3.8% -4.6.
Si is an element for promoting graphite crystallization, if the Si content is insufficient, the morphology of the vermicular graphite cast iron is unfavorable to be stable, if the Si content is too much, the graphite shape becomes large, the ferrite content in a base structure is increased, and the improvement of the mechanical properties of the vermicular graphite cast iron is unfavorable, so that the Si content is 1.8% -2.4%.
Mn has the effect of stabilizing the structure of pearlite, and the preferable range is 0.5% -1.0%, so that the chilling trend is avoided.
The P content should not exceed 0.25% otherwise iron phosphide is precipitated in the base structure, which is a hard material leading to premature wear of the product used with cast iron products.
In the present invention, the vermicular graphite cast iron hydraulic pump body is obtained, the vermicular graphite rate of the raw material reaches 20% -50%, so that the addition of S is indispensable, and the graphite spheroidization can be prevented by S, but when the S content exceeds 0.03%, the graphite becomes flaky, and stable vermicular graphite cast iron cannot be obtained, and therefore, the preferable range is 0.008% -0.03%. Meanwhile, the content of S also influences the addition amount of alloy auxiliary materials serving as a modification agent, when the content of S is 0.008-0.015%, the added modification agent is 0.8% of the weight of molten iron soup, and when the content of S is 0.016-0.030%, the added modification agent is 1.0% of the weight of molten iron soup.
Cu is a stabilizing element of a pearlite structure, and has an influence on mechanical properties such as elongation and tensile strength, and the content thereof is 0.10% -0.40%.
The Sn content is 0.01% -0.03%, and can alleviate graphite segregation and prevent graphite oxidation and falling due to internal oxidation.
The content of Sb is 0.004% -0.02%, graphite can be thinned, the compactness of graphite in a structure is improved, and the mechanical properties of cast iron are optimized.
The Cr content is 0.10% -0.30%, carbide is precipitated by combining with carbon in the cast iron base material, and the mechanical properties of the cast iron are optimized through precipitation strengthening of the base material.
The base structure of the vermicular graphite cast iron is a mixed structure of pearlite and ferrite, wherein the mass percentage of the pearlite in the base structure is more than or equal to 80 percent.
The vermicular graphite cast iron hydraulic pump body has the tensile strength more than or equal to 420N/mm 2 The hardness range is HB 153-HB 229, and the pressure resistance test at 60MPA exceeds 24.6 ten thousand times, and is greatly superior to the common gray cast iron hydraulic pump body in the market.
The modifying agent comprises the following components in percentage by mass: 4.0-6.0% of Mg, 0-1.0% of Al, 40-50% of Si, 1.5-2.5% of Ca, 4.5-5.5% of RE and the balance of Fe, wherein RE represents the sum of lanthanide rare earth elements.
The sum of the mass of Mg and the mass of Ce accounts for 0.01-0.03 percent of the mass of the whole vermicular graphite cast iron, wherein Ce is one element in RE. Mg is an important element for vermicular graphite, and Ce has strong degassing capability (such as oxygen, nitrogen and hydrogen) and desulfurization in molten iron, so that the elements adverse to vermicular effect can be reduced, and the elements are converted into scum such as Ce2O2S and then effectively removed, thereby avoiding influencing the vermicular effect of Mg.
A production process of a vermicular graphite cast iron high-strength hydraulic pump body comprises the following steps:
s1, melting: heating the main raw materials, the scraps and the return materials to 1400-1450 ℃ in an intermediate frequency furnace for smelting, melting the materials into molten iron, detecting the carbon content of the molten iron by using a carbon-silicon meter, detecting the content of Si, mn, P, S, cu, sn, sb and Cr by using a spectroscope, powering off after analysis is finished, performing primary deslagging operation, adding alloy ingredients, and performing secondary deslagging operation after component analysis confirmation;
s2, soup discharging: transferring the ladle to the front of a furnace for soup discharging operation, controlling the soup discharging temperature to 1450-1600 ℃, and adding 0.2% inoculant into the ladle for molten iron inoculation before soup discharging so as to finish soup discharging action;
s3, vermiculizer treatment: adding modification silk thread accounting for 0.80-1% of the total mass of molten iron into a ladle by using a silk feeding method to carry out vermiculizer treatment on the molten iron, wherein the modification silk thread is lanthanide rare earth magnesium silicon calcium iron alloy, and the mass percentage of each element in the modification agent is 4.0-6.0% of Mg, 0-1.0% of Al, 40-50% of Si, 1.5-2.5% of Ca, 4.5-5.5% of RE and the balance of Fe, and RE represents the total sum of lanthanide rare earth elements;
and S4, sampling molten iron before casting, analyzing and confirming the components again, filling casting into a sand mold cavity when the components are qualified, and simultaneously adding stream inoculation of 5-10 g/S to perform molten iron inoculation action, wherein the temperature of the molten iron is maintained to be 1350-1450 ℃ in the casting process, so as to obtain the vermicular graphite cast iron hydraulic pump body.
The mass ratio of the main raw materials to the leftover materials to the return furnace materials is 5 percent: 65%:30, wherein one or more of Si, mn, P, S, cu, sn, sb and Cr are contained in the alloy ingredients, and the ingredients of the cast iron are adjusted to target values by adding the alloy ingredients.
The inoculant is silicon-barium-aluminum-calcium-iron alloy.
The vermiculizer treatment time is 60-120 s.
In the foregoing steps S1 and S4, the target contents of the components are: 3.2 to 3.8 percent of C, 1.8 to 2.4 percent of Si, 0.5 to 1.0 percent of Mn, 0 to 0.25 percent of P, 0.08 to 0.03 percent of S, 0.10 to 0.40 percent of Cu, 0.01 to 0.03 percent of Sn, 0.004 to 0.02 percent of Sb and 0.10 to 0.30 percent of Cr.
The addition amount of the modification agent is closely related to S percent, and particularly, when the content of S percent is 0.008-0.015 percent, the addition amount of the modification agent is 0.8 percent of the weight of molten iron soup; when the S percentage content is 0.016% -0.030%, the addition amount of the modifying agent is 1% of the weight of the molten iron for tapping molten iron.
The invention is described in detail below with reference to the drawings and the specific embodiments.
Examples 1 to 6 are raw material element components of the hydraulic pump body of each example of the present invention.
Table 1 examples 1 to 6 chemical composition
Table 2 chemical composition of the deterioration agent in examples 1 to 6
Graphite cast iron having the chemical composition (mass%) shown in table 1 was cast into a scroll plate according to the following process, and then performance was examined, and the specific production process included the following steps:
s1, melting: heating the main raw materials, the scraps and the return materials to 1400-1450 ℃ in an intermediate frequency furnace for smelting, melting the materials into molten iron, detecting the carbon content of the molten iron by using a carbon-silicon meter, detecting the content of Si, mn, P, S, cu, sn, sb and Cr by using a spectroscope, powering off after analysis is finished, performing primary deslagging operation, adding alloy ingredients, and performing secondary deslagging operation after component analysis confirmation;
s2, soup discharging: transferring the ladle to the front of a furnace for soup discharging operation, controlling the soup discharging temperature to 1450-1600 ℃, and adding 0.2% inoculant into the ladle for molten iron inoculation before soup discharging so as to finish soup discharging action;
s3, vermiculizer treatment: adding a modification silk thread accounting for 0.80-1.00% of the total mass of molten iron into a ladle by using a silk feeding method to carry out vermiculizer treatment on the molten iron, wherein the modification silk thread is lanthanide rare earth magnesium silicon calcium iron alloy, and the mass percentage of each element in the modification agent is 4.0-6.0% of Mg, 0-1.0% of Al, 40-50% of Si, 1.5-2.5% of Ca, 4.5-5.5% of RE and the balance of Fe, and RE represents the total sum of lanthanide rare earth elements;
s4, sampling molten iron before casting, analyzing and confirming the components again, filling casting into a sand mold cavity when the components are qualified, maintaining the temperature of the molten iron at 1350-1450 ℃ in the casting process, and simultaneously adding stream inoculation of 5-10 g/S for carrying out molten iron inoculation action to obtain the vermicular graphite cast iron hydraulic pump body; and if the product is not qualified, directly returning to the furnace for treatment.
In step S1, the components are strictly controlled and detected, and in step S4, the components are reconfirmed so as to avoid the influence of the creep and other processes on the components. The addition amount of the vermicular graphite wire accounts for small proportion (0.8-1.0%) of the total mass of the molten iron, so that the chemical composition is not obviously changed generally.
The following performance tests were performed on each test piece:
(1) Metallographic structure: adopting a metallographic microscope for detection, and branding: OLYMPUS, model: BX41M;
(2) Mechanical properties: adopt tensile testing machine to detect, brand: the Japanese Shimadzu, model: AG-X-PLUS;
(3) Hardness: adopt cloth formula hardness machine to detect, brand: jinjing refiner, model BRINELL-BO3.
The performance test results are shown in Table 3:
TABLE 3 Performance test results for examples 1-6
Compared with the metallographic structure of the gray cast iron in FIG. 1, the metallographic structure of the vermicular graphite cast iron is shown in FIG. 2, and compared with the metallographic structure of the gray cast iron in FIG. 1, the hydraulic pump body has the advantages that the graphite morphology of the raw material is changed remarkably, the vermicular graphite cast iron consists of vermicular graphite and spheroidal graphite, and the vermicular rate (namely the proportion of the vermicular graphite) is 20% -50%. Compared with a hydraulic pump body made of common gray cast iron in the market, the mechanical property of the hydraulic pump body is greatly improved, and the tensile strength is more than or equal to 420N/mm 2 Is 1.4 times of the hydraulic pump body on the market, has the hardness range of HB 153-HB 229 and is 60MP a Up to 24.6 ten thousand times (the hydraulic pump body pressure resistance test in the market is not more than 15 ten thousand times), the service performance is improved by 23.6%, and therefore, the vermicular graphite cast iron hydraulic pump body can be used as a hydraulic system core part with high mechanical strength requirement, and the structure is shown in figure 3.
The foregoing is merely a preferred embodiment of the invention, and it should be noted that modifications could be made by those skilled in the art without departing from the principles of the invention, which modifications would also be considered to be within the scope of the invention.
Claims (7)
1. The utility model provides a vermicular graphite cast iron high strength hydraulic pump body which characterized in that: the graphite cast iron is prepared by casting vermicular graphite cast iron, and comprises the following raw materials in percentage by mass: 3.2 to 3.8 percent of C, 1.8 to 2.4 percent of Si, 0.5 to 1.0 percent of Mn, 0 to 0.25 percent of P, 0.008 to 0.03 percent of S, 0.10 to 0.40 percent of Cu, 0.01 to 0.03 percent of Sn, 0.004 to 0.02 percent of Sb, 0.10 to 0.3 percent of Cr and the balance of Fe and accompanying impurities, wherein an deterioration treatment agent accounting for 0.20 to 0.40 percent of the total mass of molten iron is adopted in the raw material production process to control the vermicular rate of graphite form to be 25 to 50 percent;
the deterioration agent comprises the following components in percentage by mass: 4.0-6.0% of Mg, 0-1.0% of Al, 40-50% of Si, 1.5-2.5% of Ca, 4.5-5.5% of RE and the balance of Fe, wherein RE represents the sum of lanthanide rare earth elements;
the sum of the mass of Mg and the mass of Ce accounts for 0.01-0.03% of the mass of the whole vermicular graphite cast iron, wherein Ce is one element in RE;
the production process of the pump body comprises the following steps:
s1, melting: heating the main raw materials, the scraps and the return materials to 1400-1450 ℃ in an intermediate frequency furnace for smelting, melting the materials into molten iron, detecting the carbon content of the molten iron by using a carbon-silicon meter, detecting the content of Si, mn, P, S, cu, sn, sb and Cr by using a spectroscope, powering off after analysis is finished, performing primary deslagging operation, adding alloy ingredients, and performing secondary deslagging operation after component analysis confirmation;
s2, soup discharging: transferring the ladle to the front of a furnace for soup discharging operation, controlling the soup discharging temperature to 1450-1600 ℃, and adding 0.2% inoculant into the ladle for molten iron inoculation before soup discharging so as to finish soup discharging action;
s3, vermiculizer treatment: adding modification silk thread accounting for 0.80-1% of the total mass of molten iron into a ladle by using a silk feeding method to carry out vermiculizer treatment on the molten iron, wherein the modification silk thread is lanthanide rare earth magnesium silicon calcium iron alloy, and the mass percentage of each element in the modification agent is 4.0-6.0% of Mg, 0-1.0% of Al, 40-50% of Si, 1.5-2.5% of Ca, 4.5-5.5% of RE and the balance of Fe, and RE represents the total sum of lanthanide rare earth elements;
and S4, sampling molten iron before casting, analyzing and confirming the components again, filling casting into a sand mold cavity when the components are qualified, and simultaneously adding stream inoculation of 5-10 g/S to perform molten iron inoculation action, wherein the temperature of the molten iron is maintained to be 1350-1450 ℃ in the casting process, so that the vermicular graphite cast iron high-strength hydraulic pump body is obtained.
2. The vermicular graphite cast iron high strength hydraulic pump body of claim 1, wherein: the vermicular graphite cast iron high-strength hydraulic pump body has the tensile strength more than or equal to 420N/mm 2 The hardness ranges from HB153 to HB229.
3. The vermicular graphite cast iron high strength hydraulic pump body of claim 1, wherein: the mass ratio of the main raw materials to the leftover materials to the return furnace materials is 5 percent: 65%:30% and one or more of Si, mn, P, S, cu, sn, sb and Cr are included in the alloy composition.
4. The vermicular graphite cast iron high strength hydraulic pump body of claim 1, wherein: the inoculant is silicon-barium-aluminum-calcium-iron alloy.
5. The vermicular graphite cast iron high strength hydraulic pump body of claim 1, wherein: the vermiculizer treatment time is 60-120 s.
6. The vermicular graphite cast iron high strength hydraulic pump body of claim 1, wherein: in the steps S1 and S4, the target contents of the components are: 3.2 to 3.8 percent of C, 1.8 to 2.4 percent of Si, 0.5 to 1.0 percent of Mn, 0 to 0.25 percent of P, 0.008 to 0.03 percent of S, 0.10 to 0.40 percent of Cu, 0.01 to 0.03 percent of Sn, 0.004 to 0.02 percent of Sb and 0.10 to 0.30 percent of Cr.
7. The vermicular graphite cast iron high strength hydraulic pump body of claim 6, wherein: when the S percent content is 0.008-0.015 percent, the addition amount of the modifying agent is 0.8 percent of the weight of molten iron soup; when the S percentage content is 0.016% -0.030%, the addition amount of the modifying agent is 1% of the weight of the molten iron for tapping molten iron.
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