CN117684083A - Centrifugal pump impeller suitable for alkaline environment and casting method thereof - Google Patents
Centrifugal pump impeller suitable for alkaline environment and casting method thereof Download PDFInfo
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- CN117684083A CN117684083A CN202311511324.7A CN202311511324A CN117684083A CN 117684083 A CN117684083 A CN 117684083A CN 202311511324 A CN202311511324 A CN 202311511324A CN 117684083 A CN117684083 A CN 117684083A
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- 238000000034 method Methods 0.000 title claims abstract description 35
- 238000005266 casting Methods 0.000 title claims abstract description 33
- XEEYBQQBJWHFJM-UHFFFAOYSA-N iron Substances [Fe] XEEYBQQBJWHFJM-UHFFFAOYSA-N 0.000 claims abstract description 117
- 239000002054 inoculum Substances 0.000 claims abstract description 75
- 229910001141 Ductile iron Inorganic materials 0.000 claims abstract description 67
- 238000011081 inoculation Methods 0.000 claims abstract description 28
- 229910052799 carbon Inorganic materials 0.000 claims abstract description 18
- 229910052802 copper Inorganic materials 0.000 claims abstract description 15
- 229910052710 silicon Inorganic materials 0.000 claims abstract description 15
- 229910052684 Cerium Inorganic materials 0.000 claims abstract description 7
- 239000012535 impurity Substances 0.000 claims abstract description 4
- 229910052748 manganese Inorganic materials 0.000 claims abstract description 4
- 229910052742 iron Inorganic materials 0.000 claims description 55
- OKTJSMMVPCPJKN-UHFFFAOYSA-N Carbon Chemical compound [C] OKTJSMMVPCPJKN-UHFFFAOYSA-N 0.000 claims description 30
- 229910000805 Pig iron Inorganic materials 0.000 claims description 19
- 238000003723 Smelting Methods 0.000 claims description 18
- OOJQNBIDYDPHHE-UHFFFAOYSA-N barium silicon Chemical compound [Si].[Ba] OOJQNBIDYDPHHE-UHFFFAOYSA-N 0.000 claims description 18
- 229910052797 bismuth Inorganic materials 0.000 claims description 18
- JCXGWMGPZLAOME-UHFFFAOYSA-N bismuth atom Chemical compound [Bi] JCXGWMGPZLAOME-UHFFFAOYSA-N 0.000 claims description 18
- 239000003795 chemical substances by application Substances 0.000 claims description 14
- 239000010949 copper Substances 0.000 claims description 14
- RYGMFSIKBFXOCR-UHFFFAOYSA-N Copper Chemical compound [Cu] RYGMFSIKBFXOCR-UHFFFAOYSA-N 0.000 claims description 11
- XUIMIQQOPSSXEZ-UHFFFAOYSA-N Silicon Chemical compound [Si] XUIMIQQOPSSXEZ-UHFFFAOYSA-N 0.000 claims description 11
- 239000010703 silicon Substances 0.000 claims description 11
- 238000007599 discharging Methods 0.000 claims description 10
- 229910001562 pearlite Inorganic materials 0.000 claims description 10
- 239000004576 sand Substances 0.000 claims description 10
- 229910000831 Steel Inorganic materials 0.000 claims description 9
- 230000006698 induction Effects 0.000 claims description 9
- 239000010959 steel Substances 0.000 claims description 9
- 239000004115 Sodium Silicate Substances 0.000 claims description 8
- 238000010079 rubber tapping Methods 0.000 claims description 8
- 229910052911 sodium silicate Inorganic materials 0.000 claims description 8
- 238000006243 chemical reaction Methods 0.000 claims description 6
- 239000003973 paint Substances 0.000 claims description 6
- NTHWMYGWWRZVTN-UHFFFAOYSA-N sodium silicate Chemical compound [Na+].[Na+].[O-][Si]([O-])=O NTHWMYGWWRZVTN-UHFFFAOYSA-N 0.000 claims description 6
- 238000003892 spreading Methods 0.000 claims description 6
- 230000007480 spreading Effects 0.000 claims description 6
- 241001062472 Stokellia anisodon Species 0.000 claims description 3
- 238000011010 flushing procedure Methods 0.000 claims description 3
- 230000003628 erosive effect Effects 0.000 abstract description 44
- 229910001060 Gray iron Inorganic materials 0.000 abstract description 20
- 238000004519 manufacturing process Methods 0.000 abstract description 5
- 239000007769 metal material Substances 0.000 abstract description 3
- 238000012360 testing method Methods 0.000 description 20
- 239000000463 material Substances 0.000 description 17
- 239000010439 graphite Substances 0.000 description 15
- 229910002804 graphite Inorganic materials 0.000 description 15
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 description 15
- 238000005299 abrasion Methods 0.000 description 13
- 239000003245 coal Substances 0.000 description 9
- 239000011159 matrix material Substances 0.000 description 9
- 230000007797 corrosion Effects 0.000 description 8
- 238000005260 corrosion Methods 0.000 description 8
- 239000002002 slurry Substances 0.000 description 8
- 230000001502 supplementing effect Effects 0.000 description 7
- 229910000859 α-Fe Inorganic materials 0.000 description 6
- 230000005496 eutectics Effects 0.000 description 5
- 239000000243 solution Substances 0.000 description 5
- 239000000126 substance Substances 0.000 description 5
- 230000000694 effects Effects 0.000 description 4
- 238000002474 experimental method Methods 0.000 description 4
- 238000005498 polishing Methods 0.000 description 4
- 239000002994 raw material Substances 0.000 description 4
- 238000005070 sampling Methods 0.000 description 4
- 238000005303 weighing Methods 0.000 description 4
- 229910018072 Al 2 O 3 Inorganic materials 0.000 description 3
- HEMHJVSKTPXQMS-UHFFFAOYSA-M Sodium hydroxide Chemical compound [OH-].[Na+] HEMHJVSKTPXQMS-UHFFFAOYSA-M 0.000 description 3
- 230000015572 biosynthetic process Effects 0.000 description 3
- 239000000919 ceramic Substances 0.000 description 3
- 238000004140 cleaning Methods 0.000 description 3
- 238000005087 graphitization Methods 0.000 description 3
- 239000003112 inhibitor Substances 0.000 description 3
- 238000005065 mining Methods 0.000 description 3
- 238000000465 moulding Methods 0.000 description 3
- 238000002360 preparation method Methods 0.000 description 3
- 230000008569 process Effects 0.000 description 3
- 239000010935 stainless steel Substances 0.000 description 3
- 229910001220 stainless steel Inorganic materials 0.000 description 3
- 239000002699 waste material Substances 0.000 description 3
- 229910001018 Cast iron Inorganic materials 0.000 description 2
- LFQSCWFLJHTTHZ-UHFFFAOYSA-N Ethanol Chemical compound CCO LFQSCWFLJHTTHZ-UHFFFAOYSA-N 0.000 description 2
- 230000009471 action Effects 0.000 description 2
- 239000003513 alkali Substances 0.000 description 2
- 238000005275 alloying Methods 0.000 description 2
- 239000002585 base Substances 0.000 description 2
- 229910001567 cementite Inorganic materials 0.000 description 2
- 229910052804 chromium Inorganic materials 0.000 description 2
- 239000011651 chromium Substances 0.000 description 2
- 238000005520 cutting process Methods 0.000 description 2
- 238000009826 distribution Methods 0.000 description 2
- 238000005562 fading Methods 0.000 description 2
- 238000000227 grinding Methods 0.000 description 2
- 239000003673 groundwater Substances 0.000 description 2
- KSOKAHYVTMZFBJ-UHFFFAOYSA-N iron;methane Chemical compound C.[Fe].[Fe].[Fe] KSOKAHYVTMZFBJ-UHFFFAOYSA-N 0.000 description 2
- 230000004048 modification Effects 0.000 description 2
- 238000012986 modification Methods 0.000 description 2
- 238000011160 research Methods 0.000 description 2
- 238000001878 scanning electron micrograph Methods 0.000 description 2
- 238000005728 strengthening Methods 0.000 description 2
- 230000009466 transformation Effects 0.000 description 2
- 239000002351 wastewater Substances 0.000 description 2
- 230000004580 weight loss Effects 0.000 description 2
- BVKZGUZCCUSVTD-UHFFFAOYSA-L Carbonate Chemical compound [O-]C([O-])=O BVKZGUZCCUSVTD-UHFFFAOYSA-L 0.000 description 1
- VYZAMTAEIAYCRO-UHFFFAOYSA-N Chromium Chemical compound [Cr] VYZAMTAEIAYCRO-UHFFFAOYSA-N 0.000 description 1
- GRYLNZFGIOXLOG-UHFFFAOYSA-N Nitric acid Chemical compound O[N+]([O-])=O GRYLNZFGIOXLOG-UHFFFAOYSA-N 0.000 description 1
- 244000137852 Petrea volubilis Species 0.000 description 1
- 241001417490 Sillaginidae Species 0.000 description 1
- QAOWNCQODCNURD-UHFFFAOYSA-L Sulfate Chemical compound [O-]S([O-])(=O)=O QAOWNCQODCNURD-UHFFFAOYSA-L 0.000 description 1
- 229910001037 White iron Inorganic materials 0.000 description 1
- 230000002378 acidificating effect Effects 0.000 description 1
- 239000000654 additive Substances 0.000 description 1
- 230000002411 adverse Effects 0.000 description 1
- 229910045601 alloy Inorganic materials 0.000 description 1
- 239000000956 alloy Substances 0.000 description 1
- 230000009286 beneficial effect Effects 0.000 description 1
- 239000003518 caustics Substances 0.000 description 1
- 238000005524 ceramic coating Methods 0.000 description 1
- 239000011248 coating agent Substances 0.000 description 1
- 238000000576 coating method Methods 0.000 description 1
- 230000000052 comparative effect Effects 0.000 description 1
- 229910052593 corundum Inorganic materials 0.000 description 1
- 239000010431 corundum Substances 0.000 description 1
- 238000005336 cracking Methods 0.000 description 1
- 230000007812 deficiency Effects 0.000 description 1
- 238000013461 design Methods 0.000 description 1
- 238000001514 detection method Methods 0.000 description 1
- 238000001035 drying Methods 0.000 description 1
- 230000009977 dual effect Effects 0.000 description 1
- 238000005530 etching Methods 0.000 description 1
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- 238000011049 filling Methods 0.000 description 1
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- 229910052500 inorganic mineral Inorganic materials 0.000 description 1
- 150000002500 ions Chemical class 0.000 description 1
- 239000011707 mineral Substances 0.000 description 1
- 238000002156 mixing Methods 0.000 description 1
- 239000000203 mixture Substances 0.000 description 1
- 229910017604 nitric acid Inorganic materials 0.000 description 1
- 238000005457 optimization Methods 0.000 description 1
- 238000004881 precipitation hardening Methods 0.000 description 1
- 230000001681 protective effect Effects 0.000 description 1
- 229910052761 rare earth metal Inorganic materials 0.000 description 1
- 238000009991 scouring Methods 0.000 description 1
- 238000005204 segregation Methods 0.000 description 1
- 239000006104 solid solution Substances 0.000 description 1
- 238000004781 supercooling Methods 0.000 description 1
- 230000002195 synergetic effect Effects 0.000 description 1
- 239000003643 water by type Substances 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
- C22C37/04—Cast-iron alloys containing spheroidal graphite
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B22—CASTING; POWDER METALLURGY
- B22C—FOUNDRY MOULDING
- B22C23/00—Tools; Devices not mentioned before for moulding
- B22C23/02—Devices for coating moulds or cores
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B22—CASTING; POWDER METALLURGY
- B22D—CASTING OF METALS; CASTING OF OTHER SUBSTANCES BY THE SAME PROCESSES OR DEVICES
- B22D43/00—Mechanical cleaning, e.g. skimming of molten metals
-
- C—CHEMISTRY; METALLURGY
- C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
- C22C—ALLOYS
- C22C1/00—Making non-ferrous alloys
- C22C1/02—Making non-ferrous alloys by melting
- C22C1/03—Making non-ferrous alloys by melting using master alloys
-
- 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
Landscapes
- Chemical & Material Sciences (AREA)
- Engineering & Computer Science (AREA)
- Mechanical Engineering (AREA)
- Materials Engineering (AREA)
- Metallurgy (AREA)
- Organic Chemistry (AREA)
- Refinement Of Pig-Iron, Manufacture Of Cast Iron, And Steel Manufacture Other Than In Revolving Furnaces (AREA)
Abstract
The invention provides a centrifugal pump impeller suitable for an alkaline environment and a casting method thereof, and belongs to the technical field of metal materials, wherein the centrifugal pump impeller is made of spheroidal graphite cast iron which comprises the following components in percentage by mass: 3.6 to 3.9 percent of C, 2.2 to 2.6 percent of Si, 0.4 to 0.8 percent of Mn, 0.4 to 0.8 percent of Cu and S<0.03％，P<0.06％，Mg Residue (C) 0.03％～0.06％，Ce Residue (C) 0.01% -0.03%, and the balance of Fe and unavoidable impurities. The casting method provided by the invention uses different inoculants to perform three inoculation and other operations through spheroidizationThe prepared ductile cast iron impeller has good erosion and wear resistance in alkaline environment, is superior to the existing gray cast iron, has low production cost and is suitable for popularization and application.
Description
Technical Field
The invention belongs to the technical field of metal materials, and particularly relates to a centrifugal pump impeller suitable for an alkaline environment and a casting method thereof.
Background
Coal mine drainage equipment is an integral part of coal mining operations. According to statistics, each time 1 ton of coal is mined, 2-7 tons of mine water is generally required to be discharged, and some coal mines can even reach 30-40 tons. Under the condition that the drainage requirement is high, the efficiency of the drainage equipment determines the working efficiency of coal mining. The water pump impeller and other over-current components are easily damaged under the synergistic effect of scouring abrasion and corrosion, and the working efficiency of the drainage equipment is reduced. Therefore, the erosion resistance and wear resistance of the flow-through member such as an impeller are required to be high.
For mine drainage centrifugal pump impellers, the existing coal mine enterprises adopt materials such as stainless steel except for the first-stage impellers, the secondary-stage impellers, the last-stage impellers and the like are mostly made of gray cast iron materials, the blades are easy to crack/crack, and the blades are rapid in erosion and abrasion, so that the normal operation of the impellers and the centrifugal water pump is influenced.
Mine water can be divided into 5 general categories: clean mine water, suspended matter-containing mine water, hypersalinity mine water, acidic mine water and special pollution type mine water. Typically, cl in groundwater systems － The high content is hypersalinited water. When groundwater contacts with the carbonate and sulfate thin layers in the coal stratum, a great deal of mineral is dissolved, so that Ca in mine water 2+ 、Mg 2+ 、Cl － 、HCO 3 － 、CO 3 2－ 、SO 4 2－ The plasma is increased. The pH value of the hypersalinated water is generally between 7 and 10, and the abrasion to the impeller is shown by the combined action of corrosion and erosion.
The influence of different ions and concentrations, suspended matter types and concentrations and pH values in the mine water on the erosion and corrosion of the impeller is greatly different, and the design selection and optimization of the materials of the overcurrent components such as the impeller are required to be carried out according to the characteristics of different mine waters, so that the erosion and corrosion resistance of the overcurrent components is ensured, and the manufacturing cost is also considered.
Huang ChaohuiEt Al Al 2 O 3 Evaluation of erosion and wear properties of ceramics shows that 90% of Al 2 O 3 The ceramic has better erosion and abrasion resistance effect, but does not combine the combined action of corrosion factors to analyze Al 2 O 3 The erosion resistance of the ceramic, and the impeller is made of metal material, al is formed on the surface of the impeller 2 O 3 When the ceramic coating is coated, the binding force problem among different materials and the peeling problem of the coating under the erosion effect also need to be solved.
In the prior art, the related research on the service life of the centrifugal pump impeller in a corrosive environment is less, and the related research on how to prolong the service life of the centrifugal pump impeller in an alkaline environment is less. At present, part of mining enterprises use a method for filling corrosion inhibitors to prolong the service lives of impellers and centrifugal pumps, but due to complex mine water components, large fluctuation, large discharge amount, unstable protective effect of the filled corrosion inhibitors and higher cost. In addition, the erosion of the impeller is caused by the dual effects of chemical substances and mechanical impact, and the corrosion inhibitor only can protect the chemical substances and cannot solve the abrasion caused by the mechanical impact.
Accordingly, there is a need to provide an improved solution to the above-mentioned deficiencies of the prior art.
Disclosure of Invention
The invention aims to provide a centrifugal pump impeller suitable for an alkaline environment, which replaces the existing gray cast iron impeller to solve the problems that the impeller is not resistant to erosion, serious in abrasion and the like when the mine drainage equipment is used for conveying alkaline wastewater.
The present invention also provides a method for casting the centrifugal pump impeller suitable for the alkaline environment.
In order to achieve the above object, the present invention provides the following technical solutions:
a centrifugal pump impeller suitable for alkaline environments, which is made of spheroidal graphite cast iron comprising the following components in mass ratio: 3.6 to 3.9 percent of C, 2.2 to 2.6 percent of Si, 0.4 to 0.8 percent of Mn, 0.4 to 0.8 percent of Cu and S<0.03％，P<0.06％，Mg Residue (C) 0.03％～0.06％，Ce Residue (C) 0.01% -0.03%, and the balance of Fe and unavoidable impurities.
Preferably, the pearlite content in the spheroidal graphite cast iron is not less than 70%.
The invention also provides a casting method of the centrifugal pump impeller suitable for the alkaline environment, which comprises the following steps:
s1, core making and modeling: core making and modeling are carried out by adopting a sodium silicate sand method, fireproof paint is coated on the surface of the prepared sand core, and then core setting and box closing treatment are carried out, and smelting is waited;
s2, smelting: adding pig iron, carbon scrap steel, ductile iron returns and carburant into an induction furnace to smelt molten iron, and discharging at 1500-1550 ℃;
s3, spheroidizing: adding 75SiFe inoculant into the tapping trough, and pouring the inoculant into a spheroidizing ladle along with molten iron flow for primary inoculation; spheroidizing by adopting a flushing method, wherein the spheroidizing agent is FeSiRE3Mg8;
s4, inoculation: after the spheroidizing reaction is stable, adding a copper plate into a spheroidizing ladle before adding residual molten iron, and simultaneously adding a barium-silicon inoculant, a bismuth-containing inoculant and a 75SiFe inoculant into the spheroidizing ladle for secondary inoculation;
s5, pouring: after the scum in the treated molten iron is removed, spreading a covering agent on the surface of the molten iron; and adding 75SiFe inoculant for stream inoculation during casting, wherein the casting temperature is controlled to be 1380-1400 ℃.
Preferably, in the step S2, the pig iron is Q10 or Q12 pig iron, and the pig iron, the carbon scrap steel and the ductile iron returns, wherein the pig iron accounts for 30-40% by weight, the carbon scrap steel accounts for 30-50% by weight, and the balance is the ductile iron returns.
Preferably, in step S2, the electric furnace is a power frequency or medium frequency induction electric furnace.
Preferably, in the step S3, the adding amount of the 75SiFe inoculant is 0.1-0.15%, and the adding amount of the nodulizer is 1.1-1.4%.
Preferably, in the step S4, the addition amount of the barium-silicon inoculant is 0.2-0.25% and the addition amount of the bismuth-containing inoculant is 0.1-0.15%, and the silicon content gap in the molten iron is complemented by using a 75SiFe inoculant.
Preferably, in the step S5, 0.6 kg-1.0 kg of covering agent is added to 100kg of molten iron, and the addition amount of 75SiFe inoculant is 0.08% -0.1% during pouring.
Preferably, the content of Ba in the barium-silicon inoculant is 5.0%, and the content of Bi in the bismuth-containing inoculant is 1.0%.
Preferably, in step S5, the pouring is performed while pouring the kirt block.
The beneficial effects are that:
(1) The invention adopts the measures of sodium silicate sand core making molding, copper alloying, strengthening inoculation treatment and the like, and the pearlite content in the produced spheroidal graphite cast iron matrix tissue is more than 70 percent, compared with gray iron and alloy white cast iron, the strength is high, the plasticity and the toughness are better, the crack/cracking phenomenon at the blade can be reduced, and the invention has better erosion and abrasion performance under alkaline conditions, thereby being applicable to parts such as slurry pump impellers and the like used under alkaline working conditions such as coal mines and the like.
(2) The invention adopts sodium silicate sand core molding, adopts Q10 or Q12 pig iron, carbon scrap steel and a furnace return, smelts molten iron in an intermediate frequency furnace or a power frequency furnace, adopts copper alloying, adopts 75SiFe tapping chute inoculation, barium silicon inoculant and bismuth inoculant package secondary inoculation treatment and 75SiFe inoculant stream inoculation, and produces the ductile cast iron for impeller with high strength, good plasticity and toughness, and has low production cost compared with impeller materials such as stainless steel, austempered ductile iron, high chromium cast iron and the like.
Drawings
The accompanying drawings, which are included to provide a further understanding of the invention and are incorporated in and constitute a part of this specification, illustrate embodiments of the invention and together with the description serve to explain the invention. Wherein:
FIG. 1 is a metallographic photograph of spheroidal graphite cast iron prepared in example 1 of the present invention.
Fig. 2 is a metallographic photograph of gray cast iron.
Fig. 3 is a scanning electron micrograph of spheroidal graphite cast iron prepared in example 1 of the present invention after an erosive wear test using a test slurry having a ph=10.
Fig. 4 is a scanning electron micrograph of gray cast iron after erosive wear test with a test slurry having ph=10.
Detailed Description
The following description of the technical solutions in the embodiments of the present invention will be clear and complete, and it is obvious that the described embodiments are only some embodiments of the present invention, but not all embodiments. All other embodiments, which are derived by a person skilled in the art based on the embodiments of the invention, fall within the scope of protection of the invention.
The present invention will be described in detail with reference to examples. It should be noted that, without conflict, the embodiments of the present invention and features of the embodiments may be combined with each other.
Aiming at the problem that the existing coal mine drainage equipment is not resistant to alkali wastewater erosion, the invention provides a centrifugal pump impeller suitable for an alkaline environment, wherein the centrifugal pump impeller is made of spheroidal graphite cast iron, and the spheroidal graphite cast iron comprises the following components in percentage by mass: 3.6 to 3.9 percent of C, 2.2 to 2.6 percent of Si, 0.4 to 0.8 percent of Mn, 0.4 to 0.8 percent of Cu and S<0.03％，P<0.06％，Mg Residue (C) 0.03％～0.06％，Ce Residue (C) 0.01% -0.03%, and the balance of Fe and unavoidable impurities.
In a preferred embodiment of the present invention, the pearlite content in the spheroidal graphite cast iron is not less than 70%.
The invention also provides a casting method of the centrifugal pump impeller suitable for the alkaline environment, which comprises the following steps:
s1, core making and modeling: core making and modeling are carried out by adopting a sodium silicate sand method, fireproof paint is coated on the surface of the prepared sand core, and then core setting and box closing treatment are carried out, and smelting is waited;
s2, smelting: adding pig iron, carbon scrap steel, ductile iron returns and carburant into an induction furnace to smelt molten iron, discharging the molten iron at 1500-1550 ℃, sampling the molten iron before discharging, and analyzing element content;
s3, spheroidizing: adding 75SiFe inoculant into the tapping trough, and pouring the inoculant into a spheroidizing ladle along with molten iron flow for primary inoculation; spheroidizing by adopting a flushing method, wherein the spheroidizing agent is FeSiRE3Mg8;
s4, inoculation: after the spheroidizing reaction is stable, adding a copper plate into a spheroidizing ladle before adding residual molten iron, and simultaneously adding a barium-silicon inoculant, a bismuth-containing inoculant and a 75SiFe inoculant into the spheroidizing ladle for secondary inoculation;
s5, pouring: after the scum in the treated molten iron is removed, spreading a covering agent on the surface of the molten iron; and adding 75SiFe inoculant for stream inoculation during casting, wherein the casting temperature is controlled to be 1380-1400 ℃.
In the preferred embodiment of the invention, in the step S2, pig iron is Q10 or Q12 pig iron, and the pig iron, carbon scrap and ductile iron returns, wherein the pig iron accounts for 30-40% by weight, the carbon scrap accounts for 30-50% by weight, and the balance is the ductile iron returns.
In the preferred embodiment of the present invention, in step S2, the electric furnace is a power frequency or intermediate frequency induction electric furnace.
In the preferred embodiment of the invention, in the step S3, the adding amount of the 75SiFe inoculant is 0.1-0.15%, and the adding amount of the nodulizer is 1.1-1.4%.
In the preferred embodiment of the invention, in the step S4, the addition amount of the barium-silicon inoculant is 0.2-0.25 percent and the addition amount of the bismuth-containing inoculant is 0.1-0.15 percent, the silicon content notch of the molten iron is calculated according to the elemental composition of the molten iron before tapping and the use amount of other silicon-containing additives, and 75SiFe inoculant is used for supplementing the silicon content notch.
In the preferred embodiment of the invention, in the step S5, 0.6 kg-1.0 kg of covering agent is added to 100kg of molten iron, and the addition amount of 75SiFe inoculant is 0.08-0.1% during pouring.
In the preferred embodiment of the invention, the Ba content in the barium-silicon inoculant is 5.0 percent, and the Bi content in the bismuth-containing inoculant is 1.0 percent.
In a preferred embodiment of the present invention, in step S5, the pouring is performed while pouring the kirt block.
The following describes a centrifugal pump impeller and a casting method thereof suitable for an alkaline environment in detail by way of specific examples.
In the following examples:
according to the mass ratio, the Ba content in the barium-silicon inoculant is 5.0%, the Bi content in the bismuth-containing inoculant is 1.0%, the nodulizer FeSiRE3Mg8 contains Ca2.5% -3.5%, mgO is less than or equal to 0.7%, si is 35% -44%, and the FeSiRE3Mg8 is a low-rare-earth nodulizer.
Copper promotes graphitization during eutectic transformation, and can reduce or eliminate the formation of free cementite; during eutectoid transformation, the formation of pearlite is promoted, and the formation of ferrite can be suppressed; copper has solid solution strengthening and precipitation hardening effects on the matrix, and as the copper content increases, the tensile strength of the spheroidal graphite cast iron also increases.
The 75SiFe inoculant can promote graphitization, reduce the tendency of white mouth, improve the morphology and distribution of graphite, increase the number of eutectic cells and refine the matrix structure; in the production of spheroidal graphite cast iron, inoculation is an indispensable procedure because of the relatively large supercooling tendency; the main functions of the inoculation treatment by using the 75SiFe inoculant are to increase the number of graphite nodules in the ductile iron, improve the roundness of the ductile iron, refine the graphite nodules, prevent spheroidization recession, reduce the tendency of white mouths, and prevent free cementite from forming among eutectic cells and segregation; and the number of graphite cores in the process of solidifying the ductile iron can be increased, so that the number of eutectic cells is increased to improve the mechanical property of the ductile iron.
The barium-silicon inoculant promotes graphitization, reduces the tendency of white mouth, improves the morphology and distribution of graphite, has tiny and round graphite nodules, increases the quantity of eutectic cells, refines matrix tissues, is a long-acting inoculant, has strong anti-fading capability, and can prevent the concomitant spheroidization fading.
The bismuth-containing inoculant can improve the roundness of graphite nodules, inhibit the adverse effect of Ce on the state of graphite nodules, refine the graphite nodules, increase the number of graphite nodules and ensure that the graphite nodules are distributed more uniformly.
The carburant is graphite carburant, and the fixed carbon content is more than 95%.
Example 1
The embodiment provides a centrifugal pump impeller made of spheroidal graphite cast iron, which is made of spheroidal graphite cast iron, and specifically, the chemical components of the spheroidal graphite cast iron are designed as follows: the weight percentage of the components is calculated according to the mass percentage,C3.69％，Si2.45％，Mn0.52％，Cu0.51％，S<0.03％，P<0.06％，Mg residue (C) 0.047％，Ce Residue (C) 0.018%, the remainder being Fe.
The preparation method of the centrifugal pump impeller comprises the following steps:
s1, core making and modeling: core making and modeling are carried out by adopting a sodium silicate sand method, fireproof paint is coated on the surface of the prepared sand core, and then core setting and box closing treatment are carried out, and smelting is waited;
s2, smelting: weighing Q10 pig iron, carbon waste steel and ductile iron returns according to the mass ratio of 30-40-30%, smelting the materials and a proper amount of carburant in an intermediate frequency induction furnace, discharging the materials at 1500-1550 ℃, sampling the molten iron before discharging, and analyzing the element content;
s3, spheroidizing: adopting a pouring method to spheroidize, adding 0.1% of 75SiFe inoculant into an iron tapping groove, adding FeSiRE3Mg8 spheroidizer into a spheroidizing ladle, wherein the mass of the spheroidizer is 1.2% of that of the raw material, and pouring molten iron melted in the step S2 into the spheroidizing ladle for spheroidizing;
s4, inoculation: after the spheroidizing reaction is stable, adding a copper plate into a spheroidizing ladle before supplementing residual molten iron, and simultaneously adding a barium silicon inoculant, a bismuth-containing inoculant and a 75SiFe inoculant into the spheroidizing ladle for secondary inoculation, wherein the addition amount of the barium silicon inoculant is 0.25%, the addition amount of the bismuth-containing inoculant is 0.15%, and the 75SiFe inoculant is used for supplementing a notch of silicon content in the molten iron, so that the silicon content of the molten iron after adding the 75SiFe inoculant meets the requirement of 2.45%;
s5, pouring: after the scum in the treated molten iron is removed, spreading a covering agent on the surface of the molten iron, adding 0.6kg of the covering agent to each 100kg of molten iron, pouring the molten iron inoculated in the step S4 into an impeller sand mold for casting and forming at the casting temperature of 1380-1400 ℃, and simultaneously pouring a base test block, and adding 0.1% of 75SiFe inoculant for stream inoculation during casting.
The spheroidal graphite cast iron obtained by smelting is detected, the graphite spheroidization grade is 2, the matrix structure is 85% pearlite+15% ferrite, the tensile strength is 671.5MPa, the elongation is 6.1%, and the hardness is 235HBS.
Example 2
The embodiment provides a centrifugal pump impeller made of spheroidal graphite cast iron, which is made of spheroidal graphite cast iron, and specifically, the chemical components of the spheroidal graphite cast iron are designed as follows: according to the mass percentage, C3.73%, si2.31%, mn0.74%, cu0.63%, S<0.03％，P<0.06％，Mg Residue (C) 0.037％，Ce Residue (C) 0.016 percent and the balance of Fe.
S1, core making and modeling: core making and modeling are carried out by adopting a sodium silicate sand method, fireproof paint is coated on the surface of the prepared sand core, and then core setting and box closing treatment are carried out, and smelting is waited;
s2: smelting: weighing Q10 pig iron, carbon waste steel and ductile iron returns according to the mass ratio of 40-30% to 30%, smelting the materials and a proper amount of carburant in an intermediate frequency induction furnace, discharging the materials at 1500-1550 ℃, sampling the molten iron before discharging, and analyzing the element content;
s3: spheroidizing: adopting a pouring method to spheroidize, adding 0.15% of 75SiFe inoculant into an iron tapping groove, adding FeSiRE3Mg8 spheroidizer into a spheroidizing ladle, wherein the mass of the spheroidizer is 1.2% of that of the raw material, and pouring molten iron melted in the step S2 into the spheroidizing ladle for spheroidizing;
s4: inoculation: after the spheroidizing reaction is stable, adding a copper plate into a spheroidizing ladle before supplementing residual molten iron, and simultaneously adding a barium silicon inoculant, a bismuth-containing inoculant and a 75SiFe inoculant into the spheroidizing ladle for secondary inoculation, wherein the addition of the barium silicon inoculant is 0.2 percent and the addition of the bismuth-containing inoculant is 0.1 percent, and the 75SiFe inoculant is used for supplementing a notch of the silicon content in the molten iron, so that the silicon content of the molten iron added with the 75SiFe inoculant meets the requirement of 2.31 percent.
S5: after the scum in the treated molten iron is removed, spreading a covering agent on the surface of the molten iron, adding 0.6kg of the covering agent to each 100kg of molten iron, pouring the molten iron inoculated in the step S4 into an impeller sand mold for casting and forming at the casting temperature of 1380-1400 ℃, and simultaneously pouring a base test block, and adding 0.1% of 75SiFe for stream inoculation during casting.
The spheroidal graphite cast iron obtained by smelting is detected, the graphite spheroidization grade is 1-2, the matrix structure is 90% pearlite+10% ferrite, the tensile strength is 728MPa, the elongation is 5.7%, and the hardness is 276HBS.
Example 3
The embodiment provides a centrifugal pump impeller made of spheroidal graphite cast iron, which is made of spheroidal graphite cast iron, and specifically, the chemical components of the spheroidal graphite cast iron are designed as follows: according to the mass percentage, C3.65%, si2.44%, mn0.61%, cu0.75%, S<0.03％，P<0.06％，Mg Residue (C) 0.039％，Ce Residue (C) 0.023% and the balance of Fe.
S1, core making and modeling: core making and modeling are carried out by adopting a sodium silicate sand method, fireproof paint is coated on the surface of the prepared sand core, and then core setting and box closing treatment are carried out, and smelting is waited;
s2: smelting: weighing Q10 pig iron, carbon waste steel and ductile iron returns according to the mass ratio of 30-50-20%, smelting the materials and a proper amount of carburant in an intermediate frequency induction furnace, discharging the materials at 1500-1550 ℃, sampling the molten iron before discharging, and analyzing the element content;
s3: spheroidizing: adopting a pouring method to spheroidize, adding 0.1% of 75SiFe inoculant into an iron tapping groove, adding FeSiRE3Mg8 spheroidizer into a spheroidizing ladle, wherein the mass of the spheroidizer is 1.2% of that of the raw material, and pouring molten iron melted in the step S2 into the spheroidizing ladle for spheroidizing;
s4: inoculation: after the spheroidizing reaction is stable, adding a copper plate into a spheroidizing ladle before supplementing residual molten iron, and simultaneously adding a barium silicon inoculant, a bismuth-containing inoculant and a 75SiFe inoculant into the spheroidizing ladle for secondary inoculation, wherein the addition of the barium silicon inoculant is 0.25% of the weight of the molten iron raw material, the addition of the bismuth-containing inoculant is 0.1%, and the 75SiFe inoculant is used for supplementing a notch of the silicon content in the molten iron, so that the silicon content of the molten iron after adding the 75SiFe inoculant meets the requirement of 2.44%.
S5: after the scum in the treated molten iron is removed, spreading a covering agent on the surface of the molten iron, pouring the molten iron inoculated in the step S4 into an impeller sand mold for casting molding at the casting temperature of 1380-1400 ℃, and simultaneously pouring a Kerr test block, and adding 0.1% of 75SiFe for stream inoculation during casting.
The spheroidal graphite cast iron obtained by smelting is detected, the graphite spheroidization grade is 2, the matrix structure is 90% pearlite+10% ferrite, the tensile strength is 734MPa, the elongation is 5.5%, and the hardness is 283HBS.
Metallographic detection:
selecting a Kerr test block of the nodular cast iron material prepared in the embodiment 1, using 4% nitric acid alcohol solution as a corrosive agent, and observing a microstructure by using a metallographic microscope, wherein as shown in figure 1, a matrix is pearlite, and a small amount of ferrite is mixed; as a comparison, a conventional gray cast iron material was selected, and as shown in fig. 2, graphite was in the form of flakes, and a matrix was pearlite plus a small amount of ferrite.
Erosion resistance test:
the erosion resistance of the Kerr test block of the ductile cast iron material prepared in example 1 was tested as follows:
(1) sample preparation:
cutting the cast ductile iron into 10mm multiplied by 20mm test pieces by adopting wire cutting, and polishing the surface of the test piece to be smooth by using 120# sand paper;
selecting a 10mm multiplied by 10mm surface as an erosion wear surface, sequentially polishing with abrasive paper with 200# to 1200# granularity, and finally polishing on a polishing machine;
immersing the sample in alcohol, placing the sample into an ultrasonic cleaner for cleaning, taking out the sample after cleaning, drying the sample by a blower, measuring the weight of the sample on an analytical balance with the precision of 0.1mg, and recording the weight of the sample.
(2) Preparing test slurry:
NaOH with the purity of more than or equal to 96% is used for preparing alkali solutions with the pH values of 8, 9 and 10 respectively, corundum sand with the mass fraction of 5% is added, and the test slurry is obtained after uniform mixing.
(3) Erosion wear test:
experimental conditions: 8L of test slurry is filled in the slurry tank, and the temperature of the slurry is controlled to be 25+/-3 ℃ in the test process; the motor speed is 1200r/min, and the erosion time is 2h.
And repeating the experiment for three times on each sample, taking out the sample after each experiment is finished, weighing again after cleaning according to the same mode of the preparation stage, taking the weight difference of the front and back times as the weight loss of the sample, and taking the average value of the weight loss of the sample in the three experiments as the weight of the sample after the experiment.
The test results of erosion abrasion test on spheroidal graphite cast iron with the rotary erosion abrasion test equipment and the comparative material of gray iron and the erosion abrasion loss weight are shown in table 1.
TABLE 1 erosion mill loss weight of spheroidal graphite cast iron and gray iron under alkaline conditions
As can be seen from the data in Table 1, at pH 8, the weight of the ductile cast iron lost in the erosion mill was 1.4mg, and the weight of the gray iron lost in the erosion mill was 1.5mg; when the pH value is 9, the erosion grinding loss weight of the spheroidal graphite cast iron is 1.2mg, and the erosion grinding loss weight of the gray iron is 1.3mg; at pH 10, the weight of the erosion mill loss of the spheroidal graphite cast iron is 0.6mg, and the weight of the erosion mill loss of the gray iron is 0.9mg.
The method has the advantages that when the pH value is 8 and 9, the erosion loss weight of the spheroidal graphite cast iron and the gray iron is not greatly different, and the erosion loss weight of the spheroidal graphite cast iron is slightly smaller, namely, the anti-erosion abrasion performance of the spheroidal graphite cast iron is slightly better than that of the gray iron; when the pH value is 10, the erosion loss weight of the spheroidal graphite cast iron is 0.6mg, and the erosion loss weight of the gray iron is 0.9mg, so that the erosion wear resistance of the spheroidal graphite cast iron is obviously improved in a strong alkaline environment, and the erosion wear resistance of the spheroidal graphite cast iron impeller is better than that of the gray iron in an alkaline environment.
And respectively observing and scanning the erosive wear morphology of the spheroidal graphite cast iron and the gray iron under the alkaline condition by using a scanning electron microscope, as shown in figures 3 and 4.
As can be seen from fig. 3, the surface of the spheroidal graphite cast iron has more round etching pits and scratches under the condition of the pH value of 8; at a pH of 9, the number and size of the erosion pits on the surface are reduced compared with those at a pH of 8; when the pH value is 10, larger erosion pits are not seen on the surface, the surface is complete, and the erosion and abrasion resistance of the nodular cast iron can be improved in the process of increasing the pH value; FIG. 3 is a graph showing that the gray iron of FIG. 4 has a surface having a greater degree of surface damage than the ductile iron of FIG. 3 under the same pH conditions as shown in FIG. 4; in addition, compared with gray cast iron, the ductile cast iron has better erosion and abrasion resistance under the same pH value.
In summary, the invention provides the spheroidal graphite cast iron material with good erosion resistance in alkaline environment, and the centrifugal pump impeller cast by using the spheroidal graphite cast iron can effectively resist the erosion of alkaline mine water, has longer service life compared with the existing gray iron centrifugal pump impeller, and has high tensile strength and good plasticity, and the production cost is lower than that of impeller materials such as stainless steel, austempered ductile iron, high-chromium cast iron and the like.
The above description is only of the preferred embodiments of the present invention and is not intended to limit the present invention, but various modifications and variations can be made to the present invention by those skilled in the art. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention should be included in the protection scope of the present invention.
Claims (10)
1. The centrifugal pump impeller suitable for the alkaline environment is characterized by being made of spheroidal graphite cast iron, and the spheroidal graphite cast iron comprises the following components in percentage by mass: 3.6 to 3.9 percent of C, 2.2 to 2.6 percent of Si, 0.4 to 0.8 percent of Mn, 0.4 to 0.8 percent of Cu and S<0.03％，P<0.06％，Mg Residue (C) 0.03％～0.06％，Ce Residue (C) 0.01% -0.03%, and the balance of Fe and unavoidable impurities.
2. A centrifugal pump impeller according to claim 1, wherein the pearlite content in said spheroidal graphite cast iron is not less than 70%.
3. A method of casting a centrifugal pump impeller suitable for use in an alkaline environment as claimed in claim 1 or 2, comprising the steps of:
s1, core making and modeling: core making and modeling are carried out by adopting a sodium silicate sand method, fireproof paint is coated on the surface of the prepared sand core, and then core setting and box closing treatment are carried out, and smelting is waited;
s2, smelting: adding pig iron, carbon scrap steel, ductile iron returns and carburant into an induction furnace to smelt molten iron, and discharging at 1500-1550 ℃;
s3, spheroidizing: adding 75SiFe inoculant into the tapping trough, and pouring the inoculant into a spheroidizing ladle along with molten iron flow for primary inoculation; spheroidizing by adopting a flushing method, wherein the spheroidizing agent is FeSiRE3Mg8;
s4, inoculation: after the spheroidizing reaction is stable, adding a copper plate into a spheroidizing ladle before adding residual molten iron, and simultaneously adding a barium-silicon inoculant, a bismuth-containing inoculant and a 75SiFe inoculant into the spheroidizing ladle for secondary inoculation;
s5, pouring: after the scum in the treated molten iron is removed, spreading a covering agent on the surface of the molten iron; and adding 75SiFe inoculant for stream inoculation during casting, wherein the casting temperature is controlled to be 1380-1400 ℃.
4. The casting method of centrifugal pump impeller suitable for alkaline environment as claimed in claim 3, wherein in the step S2, the pig iron is Q10 or Q12 pig iron, and the pig iron, carbon scrap and ductile iron returns, in weight percent, 30% -40% of pig iron, 30% -50% of carbon scrap and the balance of ductile iron returns.
5. A method of casting a centrifugal pump impeller suitable for use in an alkaline environment as claimed in claim 3, wherein in step S2, the electric furnace is a power frequency or medium frequency induction furnace.
6. A method of casting a centrifugal pump impeller suitable for use in alkaline environments as claimed in claim 3, wherein in step S3, 75SiFe inoculant is added in an amount of 0.1% to 0.15% and nodulizer is added in an amount of 1.1% to 1.4%.
7. The casting method of a centrifugal pump impeller suitable for alkaline environment as claimed in claim 3, wherein in the step S4, the adding amount of the barium-silicon inoculant is 0.2% -0.25% and the adding amount of the bismuth-containing inoculant is 0.1% -0.15%, and the silicon content gap in the molten iron is complemented by using 75SiFe inoculant.
8. A casting method of a centrifugal pump impeller suitable for alkaline environment as claimed in claim 3, wherein in step S5, 0.6 kg-1.0 kg of covering agent is added per 100kg of molten iron, and the addition amount of 75SiFe inoculant is 0.08% -0.1% during casting.
9. The casting method of centrifugal pump impeller suitable for alkaline environment as claimed in claim 7, wherein the Ba content in said barium silicon inoculant is 5.0%, and the Bi content in said bismuth inoculant is 1.0%.
10. A method of casting a centrifugal pump impeller suitable for use in an alkaline environment as claimed in any one of claims 3 to 9, wherein in step S5, pouring is performed while pouring the kirk block.
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