CN115141971A - High-strength hydraulic pump body made of vermicular graphite cast iron and production process thereof - Google Patents
High-strength hydraulic pump body made of vermicular graphite cast iron and production process thereof Download PDFInfo
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- CN115141971A CN115141971A CN202210885824.6A CN202210885824A CN115141971A CN 115141971 A CN115141971 A CN 115141971A CN 202210885824 A CN202210885824 A CN 202210885824A CN 115141971 A CN115141971 A CN 115141971A
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- OKTJSMMVPCPJKN-UHFFFAOYSA-N Carbon Chemical compound [C] OKTJSMMVPCPJKN-UHFFFAOYSA-N 0.000 title claims abstract description 80
- 229910002804 graphite Inorganic materials 0.000 title claims abstract description 65
- 239000010439 graphite Substances 0.000 title claims abstract description 65
- 229910001018 Cast iron Inorganic materials 0.000 title claims abstract description 51
- 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 51
- 230000004048 modification Effects 0.000 claims abstract description 31
- 238000012986 modification Methods 0.000 claims abstract description 31
- 239000003795 chemical substances by application Substances 0.000 claims abstract description 22
- 239000002994 raw material Substances 0.000 claims abstract description 18
- 239000012535 impurity Substances 0.000 claims abstract description 4
- 235000014347 soups Nutrition 0.000 claims description 26
- 238000007599 discharging Methods 0.000 claims description 20
- 239000000463 material Substances 0.000 claims description 18
- 238000000034 method Methods 0.000 claims description 17
- 238000005266 casting Methods 0.000 claims description 14
- 239000011777 magnesium Substances 0.000 claims description 13
- 229910052799 carbon Inorganic materials 0.000 claims description 12
- 229910052804 chromium Inorganic materials 0.000 claims description 12
- 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
- 229910052761 rare earth metal Inorganic materials 0.000 claims description 11
- 229910052698 phosphorus Inorganic materials 0.000 claims description 10
- 229910052717 sulfur Inorganic materials 0.000 claims description 10
- 229910045601 alloy Inorganic materials 0.000 claims description 9
- 239000000956 alloy Substances 0.000 claims description 9
- 239000004615 ingredient Substances 0.000 claims description 8
- 239000000203 mixture Substances 0.000 claims description 8
- 230000008569 process Effects 0.000 claims description 8
- 229910000640 Fe alloy Inorganic materials 0.000 claims description 7
- 239000011575 calcium Substances 0.000 claims description 7
- 239000002054 inoculum Substances 0.000 claims description 7
- 229910052710 silicon Inorganic materials 0.000 claims description 6
- 238000005520 cutting process Methods 0.000 claims description 5
- 229910052748 manganese Inorganic materials 0.000 claims description 5
- 229910052684 Cerium Inorganic materials 0.000 claims description 4
- 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
- 238000010438 heat treatment Methods 0.000 claims description 4
- 229910052749 magnesium Inorganic materials 0.000 claims description 4
- 230000008018 melting Effects 0.000 claims description 4
- 238000002844 melting 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
- 229910052802 copper Inorganic materials 0.000 claims description 3
- -1 silicon-barium-aluminum-calcium-iron Chemical group 0.000 claims description 3
- 229910052718 tin Inorganic materials 0.000 claims description 3
- 229910001060 Gray iron Inorganic materials 0.000 description 16
- 229910001562 pearlite Inorganic materials 0.000 description 5
- 239000000126 substance Substances 0.000 description 5
- 239000011159 matrix material Substances 0.000 description 4
- 239000000047 product Substances 0.000 description 4
- 230000000694 effects Effects 0.000 description 3
- 238000011056 performance test Methods 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
- 230000009286 beneficial effect Effects 0.000 description 2
- 239000007789 gas Substances 0.000 description 2
- 230000003647 oxidation Effects 0.000 description 2
- 238000007254 oxidation reaction Methods 0.000 description 2
- 230000000087 stabilizing effect Effects 0.000 description 2
- 239000010959 steel Substances 0.000 description 2
- 241001584785 Anavitrinella pampinaria Species 0.000 description 1
- 208000010392 Bone Fractures Diseases 0.000 description 1
- 206010017076 Fracture Diseases 0.000 description 1
- UFHFLCQGNIYNRP-UHFFFAOYSA-N Hydrogen Chemical compound [H][H] UFHFLCQGNIYNRP-UHFFFAOYSA-N 0.000 description 1
- 230000009471 action Effects 0.000 description 1
- QVGXLLKOCUKJST-UHFFFAOYSA-N atomic oxygen Chemical compound [O] QVGXLLKOCUKJST-UHFFFAOYSA-N 0.000 description 1
- 238000006243 chemical reaction Methods 0.000 description 1
- 238000010276 construction 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
- 238000004299 exfoliation Methods 0.000 description 1
- 238000004880 explosion Methods 0.000 description 1
- PCHJSUWPFVWCPO-UHFFFAOYSA-N gold Chemical compound [Au] PCHJSUWPFVWCPO-UHFFFAOYSA-N 0.000 description 1
- 229910052737 gold Inorganic materials 0.000 description 1
- 239000010931 gold 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
- 229910052757 nitrogen Inorganic materials 0.000 description 1
- 229910052760 oxygen Inorganic materials 0.000 description 1
- 239000001301 oxygen Substances 0.000 description 1
- 238000010587 phase diagram Methods 0.000 description 1
- 239000002244 precipitate 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
- 230000009467 reduction 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
Images
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
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- 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 high-strength hydraulic pump body made of vermicular graphite cast iron and a production process thereof, wherein the high-strength hydraulic pump body is made of 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 incidental impurities, wherein a modification agent accounting for 0.20-0.40% of the total mass of the molten iron is adopted in the production process of the raw materials to control the creep rate of the 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 withstand voltage test at 60MPa exceeds 24.6 ten thousand times.
Description
Technical Field
The invention relates to a high-strength hydraulic pump body made of vermicular graphite cast iron and a production process thereof, and belongs to the technical field of graphite cast iron.
Background
At present, common grey cast iron is used as a raw material for hydraulic control parts on large engineering machinery in the market. A grey cast iron pump body for hydraulic system is last, when being applied to the equipment of high pressure differential condition, can take place to lead to the cracked problem of hydraulic pump because of mechanical strength is not enough under frequent high-low pressure transform operating mode service condition, and its mechanical strength can't satisfy the user demand.
According to the morphology of graphite, gray cast iron can be divided into: ordinary gray cast iron, nodular cast iron, malleable cast iron and vermicular cast iron, wherein the graphite of the ordinary gray cast iron is flaky, and when the graphite is observed in a metallographic phase, the graphite is scattered on a matrix in single flaky shapes and is separated and not connected with each other, as shown in figure 1; the graphite in the nodular cast iron is spherical, the graphite in the malleable cast iron is flocculent, and the graphite in the vermicular cast iron is vermicular, also called vermicular cast iron.
The mechanical property of the gray cast iron is closely related to the structure of a matrix and the form of graphite, and the flaky graphite in the gray cast iron has serious cutting cracks on the matrix and easily causes stress concentration at the sharp corners of the graphite, so that the tensile strength, the plasticity and the 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 in the fields of hydraulic systems and the like. At present, the hydraulic pump which is used as a core part of a hydraulic system of large engineering machinery on the market uses gray cast iron as a preferred material. In recent years, under the requirements of national environmental protection policies, in order to reduce exhaust gas emissions and improve air quality, reductions in exhaust gas emissions of large construction machines have been required. Under such circumstances, engineering hydraulic components having higher energy conversion efficiency and higher holding pressure have been developed vigorously. As mentioned above, in the working environment with frequent high-low pressure changing working conditions, the hydraulic pump made of ordinary gray cast iron has a risk of fracture due to insufficient mechanical strength.
In view of the above problems, new hydraulic pump bodies with high mechanical strength must be developed to be suitable for new engineering machinery applications.
Disclosure of Invention
The invention provides a high-strength vermicular graphite cast iron hydraulic pump body and a production process thereof, aiming at solving the problems in the prior art.
The invention adopts the following technical scheme: a high-strength hydraulic pump body made of vermicular graphite cast iron is cast by the 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 incidental impurities, wherein a modification agent accounting for 0.20-0.40% of the total mass of molten iron is adopted in the production process of raw materials to control the creep rate of the graphite form to be 25-50%.
Furthermore, the tensile strength of the vermicular graphite cast iron high-strength hydraulic pump body is more than or equal to 420N/mm 2 The hardness range is HB 153-HB 229.
Further, the modification treatment agent comprises, 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 total amount of lanthanide rare earth elements.
Further, the mass sum of Mg and Ce accounts for 0.01-0.03% of the whole vermicular graphite cast iron, wherein Ce is one element of 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: putting main raw materials, leftover materials and a scrap into an intermediate frequency furnace, heating to 1400-1450 ℃, smelting to melt the materials into molten iron, detecting the carbon content of the molten iron by using a carbon-silicon instrument, detecting the contents of Si%, mn%, P%, S%, cu%, sn%, sb% and Cr% by using a spectroscopic spectrometer, cutting off the power after the analysis is finished, carrying out first deslagging operation, adding alloy ingredients, and carrying out second deslagging operation after the composition analysis is confirmed;
s2, soup discharging: transferring the ladle to the front of a furnace to carry out soup discharging operation, controlling the soup discharging temperature to be 1450-1600 ℃, and adding 0.2% of an inoculant into the ladle before discharging soup to carry out molten iron inoculation so as to finish the soup discharging operation;
s3, vermicular treatment: the method comprises the following steps of adding a modification treatment thread accounting for 0.80-1% of the total mass of molten iron into a ladle by using a wire feeding method to perform vermicular treatment on the molten iron, wherein the modification treatment thread is lanthanide rare earth magnesium silicon calcium iron alloy, the mass percentage of each element in a modification treatment agent is respectively 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, namely filling and casting the components into a sand mold cavity when the components are qualified, adding 5-10g/S of stream inoculation to perform molten iron inoculation, and keeping the temperature of the molten iron at 1350-1450 ℃ in the casting process to obtain the high-strength hydraulic pump body of the vermicular graphite cast iron.
Further, the mass ratio of the main raw materials, the leftover materials and the scrap returns is 5%:65%:30 percent, wherein the alloy ingredients comprise one or more of Si, mn, P, S, cu, sn, sb and Cr.
Further, the inoculant is a silicon-barium-aluminum-calcium-iron alloy.
Further, the vermicularizing treatment time is 60 to 120s.
Further, in the steps S1 and S4, the target contents of the components are both: 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, which are all mass percentages.
Further, when the content of S% is 0.008% -0.015%, the addition amount of the modification treatment agent is 0.8% of the weight of the molten iron soup; when the content of S% is 0.016% -0.030%, the addition amount of the modification treatment agent is 1% of the weight of the molten iron in the molten iron soup.
The invention has the following beneficial effects:
(1) The carbon equivalent C.E. value is controlled to be between 3.8 and 4.6, so that the carbon equivalent of the molten iron in the solidification process can be ensured to be close to an eutectic component, 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 the problem of overhigh hardness caused by overhigh contents of Mn, cu and Cr 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 cast iron hydraulic pump is 20-50%, compared with common grey cast iron in the market, the mechanical property of the vermicular 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 withstand voltage test at 60MPa exceeds 24.6 ten thousand times.
Drawings
FIG. 1 is a metallographic picture of a conventional gray cast iron hydraulic pump body of the prior art.
FIG. 2 is a gold phase diagram of the vermicular cast iron hydraulic pump body of the present invention.
Fig. 3 is a schematic structural view of the hydraulic pump body of vermicular graphite cast iron according to the present invention.
Detailed Description
The invention is further described below with reference to the accompanying drawings.
The invention discloses a high-strength hydraulic pump body made of vermicular graphite cast iron through casting, which 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 incidental impurities, wherein the creep rate of the graphite form is controlled to be 25-50% by adopting a modification agent accounting for 0.20-0.40% of the total mass of molten iron in the production process of raw materials.
C (carbon) is an element which becomes a graphite structure, the content of the C has a crucial influence on the elongation of the material, and ferrite is easily generated when the content of the C is too high, so that the content of the C is 3.2-3.8%, and the carbon equivalent C.E. value is controlled to be 3.8-4.6.
Si is an element for promoting graphite crystallization, if the content of Si is not enough, the shape stability of the vermicular graphite cast iron is not facilitated, if the content of Si is too much, the graphite shape becomes large, the ferrite content in a base structure is increased, and the improvement of the mechanical property of the vermicular graphite cast iron is not facilitated, so that the content of Si is 1.8% -2.4%.
The Mn has the function of stabilizing the structure of pearlite, the preferable range is 0.5-1.0%, and the chilling trend is avoided.
The content of P should not exceed 0.25% otherwise it would precipitate iron phosphide, a hard substance, in the matrix structure, leading to premature wear of the product used in conjunction with the cast iron product.
The invention aims to obtain the vermicular graphite cast iron hydraulic pump body, the vermicular rate of the raw materials reaches 20-50%, so the addition of S is indispensable, the S can prevent graphite spheroidization, but if the content of S exceeds 0.03%, the graphite is flaky, and stable vermicular graphite cast iron cannot be obtained, so the preferable range is 0.008-0.03%. Meanwhile, the content of S also influences the adding amount of alloy auxiliary materials serving as the modification treatment agent, when the content of S is 0.008% -0.015%, the adding amount of the modification treatment agent is 0.8% of the weight of the molten iron discharged soup, and when the content of S is 0.016% -0.030%, the adding amount of the modification treatment agent is 1.0% of the weight of the molten iron discharged soup.
Cu is a stabilizing element of a pearlite structure, has influence on mechanical properties such as elongation and tensile strength, and is 0.10-0.40%.
The content of Sn is 0.01-0.03%, which can alleviate graphite segregation and prevent graphite oxidation and exfoliation due to internal oxidation.
The content of Sb is 0.004-0.02%, the graphite can be refined, the graphite in the structure is reduced, the compactness is increased, and the mechanical property of the cast iron is optimized.
The content of Cr is 0.10% -0.30%, and the Cr is combined with carbon in a cast iron base material to precipitate carbide, so that the mechanical property of the cast iron is 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 content of the pearlite in the base structure is more than or equal to 80%.
The tensile strength of the vermicular graphite cast iron hydraulic pump body is more than or equal to 420N/mm 2 The hardness range is HB 153-HB 229, the pressure resistance test of 60MPA exceeds 24.6 ten thousand times, and the pump body is greatly superior to the common gray cast iron hydraulic pump body on 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 total amount of lanthanide rare earth elements.
The mass sum of Mg and Ce accounts for 0.01-0.03 percent of the total mass of the vermicular graphite cast iron, wherein Ce is one element in RE. Mg is an important element for graphite creeping, and Ce has strong degassing capacity (such as oxygen, nitrogen and hydrogen) and desulfurization effect in molten iron, so that the elements which are not beneficial to the creeping effect can be reduced, and the elements are effectively removed after being converted into dross such as Ce2O2S, and the creeping effect of Mg is prevented from being influenced.
A production process of a vermicular graphite cast iron high-strength hydraulic pump body comprises the following steps:
s1, melting: putting main raw materials, leftover materials and a scrap into an intermediate frequency furnace, heating to 1400-1450 ℃, smelting to melt the materials into molten iron, detecting the carbon content of the molten iron by using a carbon-silicon instrument, detecting the contents of Si%, mn%, P%, S%, cu%, sn%, sb% and Cr% by using a spectroscopic spectrometer, cutting off the power after the analysis is finished, carrying out first deslagging operation, adding alloy ingredients, and carrying out second deslagging operation after the composition analysis is confirmed;
s2, soup discharging: transferring the ladle to the front of a furnace to carry out soup discharging operation, controlling the soup discharging temperature to be 1450-1600 ℃, and adding 0.2% of inoculant into the ladle to carry out molten iron inoculation before discharging so as to finish the soup discharging operation;
s3, vermicular treatment: the method comprises the steps of adding modification treatment wires accounting for 0.80-1% of the total mass of molten iron into a ladle by using a wire feeding method to conduct vermicularizing treatment on the molten iron, wherein the modification treatment wires are lanthanide rare earth magnesium silicon calcium iron alloy, the mass percentage of each element in a modification treatment agent is respectively 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 the RE represents the sum of lanthanide rare earth elements;
and S4, sampling molten iron before casting, analyzing and confirming the components again, namely filling and casting the sand mould cavity when the components are qualified, adding 5-10g/S stream inoculation to perform molten iron inoculation, and keeping the temperature of the molten iron at 1350-1450 ℃ in the casting process to obtain the vermicular graphite cast iron hydraulic pump body.
The mass ratio of the main raw materials, the leftover materials and the scrap returns is 5%:65%:30 percent, wherein the alloy ingredients comprise one or more of Si, mn, P, S, cu, sn, sb and Cr, and the components of the cast iron are adjusted to target values by adding the alloy ingredients.
The inoculant is a silicon-barium-aluminum-calcium-iron alloy.
The creep treatment time is 60 to 120s.
In the foregoing steps S1 and S4, the target contents of the components are both: 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, wherein the percentages are mass percent.
The addition amount of the modification treatment agent is closely related to the S%, and specifically, when the S content is 0.008% -0.015%, the addition amount of the modification treatment agent is 0.8% of the weight of the molten iron soup; when the content of S% is 0.016% -0.030%, the addition amount of the modification treatment agent is 1% of the weight of the molten iron in the molten iron soup.
The invention is described in detail below with reference to the figures and the embodiments.
Example 1~6 is a hydraulic pump block elemental composition according to various examples of the present invention.
TABLE 1 example 1~6 chemical composition
TABLE 2 chemical composition of the modification agent in example 1~6
Graphite cast iron having a chemical composition (mass%) shown in table 1 was cast into a scroll by the following process, and then the performance was examined, and the specific production process included the following steps:
s1, melting: putting main raw materials, leftover materials and a scrap into an intermediate frequency furnace, heating to 1400-1450 ℃, smelting to melt the materials into molten iron, detecting the carbon content of the molten iron by using a carbon-silicon instrument, detecting the contents of Si%, mn%, P%, S%, cu%, sn%, sb% and Cr% by using a spectroscopic spectrometer, cutting off the power after the analysis is finished, carrying out first deslagging operation, adding alloy ingredients, and carrying out second deslagging operation after the composition analysis is confirmed;
s2, soup discharging: transferring the ladle to the front of a furnace to carry out soup discharging operation, controlling the soup discharging temperature to be 1450-1600 ℃, and adding 0.2% of an inoculant into the ladle before discharging soup to carry out molten iron inoculation so as to finish the soup discharging operation;
s3, vermicular treatment: the method comprises the steps of adding a modification treatment thread accounting for 0.80-1.00% of the total mass of molten iron into a ladle by using a wire feeding method to perform vermicular treatment on the molten iron, wherein the modification treatment thread is lanthanide rare earth magnesium silicon calcium iron alloy, the mass percentage of each element in a modification treatment agent is respectively 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 the RE represents the total sum of lanthanide rare earth elements;
s4, sampling molten iron before casting, analyzing and confirming the components again, namely filling and casting the sand mold cavity when the components are qualified, wherein the temperature of the molten iron is kept at 1350-1450 ℃ in the casting process, and simultaneously adding 5-10g/S stream-following inoculation to perform molten iron inoculation action, so as to obtain the hydraulic pump body of the vermicular graphite cast iron; if the product is not qualified, the product is directly returned to the furnace.
In step S1, the components are strictly controlled and detected, and in step S4, the components are reconfirmed in order to avoid the influence of processes such as creep on the components. Because the proportion (0.8 to 1.0 percent) of the addition amount of the vermicular wires to the total mass of the molten iron is very small, the chemical components are not obviously changed generally.
The following performance tests were performed on each test material:
(1) Metallographic structure: adopting metallographic microscope to detect, the brand: OLYMPUS, model: BX41M;
(2) Mechanical properties: adopt tensile test machine to detect, the brand: japanese shimadzu, model: AG-X-PLUS;
(3) Hardness: adopt the detection of distributing type hardness machine, the brand: jinjing Jingji, model BRINELL-BO3.
The performance test results are shown in table 3:
table 3 results of performance tests of examples 1 to 6
The metallographic structure of the vermicular graphite cast iron of the present invention is shown in FIG. 2. The graphite morphology of the material of the hydraulic pump body of the present invention is significantly observed in comparison with the metallographic structure of the gray cast iron of FIG. 1The vermicular graphite and the spherical graphite are jointly used, and the vermicular rate (namely the proportion of the vermicular graphite) is 20-50%. Compared with the hydraulic pump body made of common grey cast iron on 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 1.4 times of the hydraulic pump body on the market, the hardness range is HB 153-HB 229, and the working pressure is 60MP a The pressure resistance test of the pump body is as high as 24.6 ten thousand times (the pressure resistance test of the hydraulic pump body on the market is not more than 15 ten thousand times), the service performance is improved by 23.6 percent, and therefore, the vermicular graphite cast iron hydraulic pump body can be used as a core part of a hydraulic system with high mechanical strength requirements, and the structure of the vermicular graphite cast iron hydraulic pump body is shown in figure 3.
The foregoing is only a preferred embodiment of this invention and it should be noted that modifications can be made by those skilled in the art without departing from the principle of the invention and these modifications should also be considered as the protection scope of the invention.
Claims (10)
1. A vermicular graphite cast iron high-strength hydraulic pump body is characterized in that: the vermicular graphite cast iron 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 incidental impurities, wherein a modification agent accounting for 0.20-0.40% of the total mass of molten iron is adopted in the production process of raw materials to control the creep rate of the graphite form to be 25-50%.
2. The high strength hydraulic pump body of claim 1, wherein: the tensile strength of the vermicular graphite cast iron high-strength hydraulic pump body is more than or equal to 420N/mm 2 The hardness range is HB 153-HB 229.
3. The high strength hydraulic pump body of claim 2, wherein: the modification treatment 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 total of lanthanide rare earth elements.
4. The high strength hydraulic pump body of claim 3, wherein: the mass sum of Mg and Ce accounts for 0.01-0.03 percent of the total mass of the vermicular graphite cast iron, wherein Ce is one element in RE.
5. A production process of a vermicular graphite cast iron high-strength hydraulic pump body is characterized by comprising the following steps: the method comprises the following steps:
s1, melting: putting main raw materials, leftover materials and a scrap into an intermediate frequency furnace, heating to 1400-1450 ℃, smelting to melt the materials into molten iron, detecting the carbon content of the molten iron by using a carbon-silicon instrument, detecting the contents of Si%, mn%, P%, S%, cu%, sn%, sb% and Cr% by using a spectroscopic spectrometer, cutting off the power after the analysis is finished, carrying out first deslagging operation, adding alloy ingredients, and carrying out second deslagging operation after the composition analysis is confirmed;
s2, soup discharging: transferring the ladle to the front of a furnace to carry out soup discharging operation, controlling the soup discharging temperature to be 1450-1600 ℃, and adding 0.2% of inoculant into the ladle to carry out molten iron inoculation before discharging so as to finish the soup discharging operation;
s3, vermicularizing treatment: the method comprises the steps of adding modification treatment wires accounting for 0.80-1% of the total mass of molten iron into a ladle by using a wire feeding method to conduct vermicularizing treatment on the molten iron, wherein the modification treatment wires are lanthanide rare earth magnesium silicon calcium iron alloy, the mass percentage of each element in a modification treatment agent is respectively 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 the RE represents the sum of lanthanide rare earth elements;
and S4, sampling molten iron before casting, analyzing and confirming the components again, namely filling and casting the sand mould cavity when the components are qualified, adding 5-10g/S stream inoculation to perform molten iron inoculation, and keeping the temperature of the molten iron at 1350-1450 ℃ in the casting process to obtain the high-strength hydraulic pump body of the vermicular graphite cast iron.
6. The process for producing a high-strength hydraulic pump body of graphite cast iron according to claim 5, wherein: the mass ratio of the main raw material to the leftover material to the scrap returns is 5%:65%:30 percent, wherein the alloy ingredients comprise one or more of Si, mn, P, S, cu, sn, sb and Cr.
7. The process for producing a high-strength hydraulic pump body of graphite cast iron according to claim 6, wherein: the inoculant is a silicon-barium-aluminum-calcium-iron alloy.
8. The process for producing a high-strength hydraulic pump body of graphite cast iron according to claim 7, wherein: the vermicularizing treatment time is 60 to 120s.
9. The process for producing a high-strength hydraulic pump body of graphite cast iron according to claim 8, wherein: in the steps S1 and S4, the target contents of the components are as follows: 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, which are all mass percentages.
10. The process for producing a high-strength hydraulic pump body of vermicular graphite cast iron according to claim 9, wherein: when the content of S% is 0.008% -0.015%, the addition amount of the modification treatment agent is 0.8% of the weight of the molten iron soup; when the content of S% is 0.016% -0.030%, the addition amount of the modification treatment agent is 1% of the weight of the molten iron in the molten iron soup.
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