CN111961954A - Preparation method of as-cast mixed matrix QT500-14 nodular cast iron - Google Patents

Preparation method of as-cast mixed matrix QT500-14 nodular cast iron Download PDF

Info

Publication number
CN111961954A
CN111961954A CN202010871267.3A CN202010871267A CN111961954A CN 111961954 A CN111961954 A CN 111961954A CN 202010871267 A CN202010871267 A CN 202010871267A CN 111961954 A CN111961954 A CN 111961954A
Authority
CN
China
Prior art keywords
iron
cast
spheroidization
grade
less
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Pending
Application number
CN202010871267.3A
Other languages
Chinese (zh)
Inventor
李艳磊
张辉
赵龙
耿鹏鹏
褚玮
李�瑞
吴国
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Shanghai Tobacco Machinery Xinchang Foundry Co ltd
Shanghai Tobacco Machinery Co Ltd
Original Assignee
Shanghai Tobacco Machinery Xinchang Foundry Co ltd
Shanghai Tobacco Machinery Co Ltd
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Shanghai Tobacco Machinery Xinchang Foundry Co ltd, Shanghai Tobacco Machinery Co Ltd filed Critical Shanghai Tobacco Machinery Xinchang Foundry Co ltd
Priority to CN202010871267.3A priority Critical patent/CN111961954A/en
Publication of CN111961954A publication Critical patent/CN111961954A/en
Pending legal-status Critical Current

Links

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
    • C22C37/04—Cast-iron alloys containing spheroidal graphite
    • 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
    • C22C37/10—Cast-iron alloys containing aluminium or silicon

Landscapes

  • Chemical & Material Sciences (AREA)
  • Engineering & Computer Science (AREA)
  • Materials Engineering (AREA)
  • Mechanical 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 preparation method of as-cast mixed matrix QT500-14 nodular cast iron, which comprises the following steps: the method comprises the steps of raw material selection, furnace burden proportioning, alloy component design, smelting process control, melt treatment and purification of inoculant, nodulizer, stream-following inoculant, foamed ceramic filter and the like, and is assisted by corresponding melt inoculation and spheroidization treatment processes, so as to obtain the cast mixed matrix nodular cast iron material with excellent performance. The cast mixed matrix QT500-14 nodular cast iron material has the pearlite content in the matrix tissue ranging from 5% to 20%, the ferrite content ranging from 75% to 90%, the spheroidization grade being grade 2, the graphite nodule size being grade 6 to grade 7, and the graphite nodule spheroidization rate being more than or equal to 90%. The mechanical properties of the single cast test block can reach Rm more than or equal to 500MPa, Rp0.2 more than or equal to 380MPa and A more than or equal to 14 percent. The method combines the furan self-hardening resin sand casting process, can meet the production and technical development requirements of large nodular iron castings, produces the nodular iron castings with high strength and high elongation, and meets the requirements of high-grade parts on prolonging the fatigue service life and realizing the lightweight design.

Description

Preparation method of as-cast mixed matrix QT500-14 nodular cast iron
Technical Field
The invention relates to the field of high-performance metal materials, in particular to a preparation method of as-cast mixed matrix QT500-14 nodular cast iron.
Background
In recent years, as is known from development trends of industries such as energy chemical industry, automobile lightweight, high-end machine tools, rail transit and the like, equipment technologies and device structures are gradually developed towards the direction of complexity and high precision, which undoubtedly puts higher requirements on the comprehensive mechanical properties of materials, and especially the requirements on performance indexes such as strength, elongation and the like of nodular cast iron materials applied to large-scale and high-end equipment are higher and higher, so that the comprehensive properties such as toughness and the like of the nodular cast iron materials are required to be continuously improved, and market requirements are met. The matrix structure of the castings made of the QT500-7 and QT600-3 nodular cast iron produced by the traditional process contains 30-60% of pearlite structure, although the castings have higher tensile strength, the elongation and yield strength of the castings are relatively lower, and in addition, the processing performance of the castings is relatively higher than that of the nodular cast iron castings made of full-ferrite matrix materials because the matrix contains a certain amount of pearlite and the castings have relatively higher abrasion to processing tools.
At present, two new material grades of EN-GJS-500-14 and EN-GJS-600-10 are proposed in the EN1563:2012 standard, and the materials of the grades all adopt a high-silicon solid solution strengthening process to ensure the comprehensive performance indexes of the grades. In the method disclosed in the chinese patent application CN107022712A, "a method for manufacturing shaft products with thick and large cross-section QT 500-14", the contents of carbon and silicon in molten iron after spheroidizing treatment need to be controlled to be C: 3.1-3.30%, Si: 3.30-3.60% of the alloy material can ensure the internal structure balance of the thick and large section casting, and the mechanical property of the alloy material can not stably reach the EN1563:2012 standard requirement. In the chinese patent application CN108611551A "high-silicon solid solution strengthened ferritic nodular iron casting and manufacturing method thereof", the contents of carbon and silicon elements after spheroidizing are respectively controlled at C: 3.25-3.35%, Si: 3.70-3.80 percent, trace element Sb is added into the alloy components, a cupola furnace is adopted for smelting, the melt treatment process is long, the operation is complicated, and the matrix graphite structure is unstable. In the Chinese patent application CN103757517A 'production method of as-cast ferrite-based nodular cast iron QT 500-14', the elongation of the attached casting test block can not be stabilized to be more than or equal to 14% in the mechanical properties detected by the method. Although the high-silicon solid solution strengthening process ensures that the full-ferrite matrix structure is obtained from the aspects of component design, smelting process and the like, the comprehensive mechanical property of the nodular cast iron material with the matrix metallographic structure is still required to be further improved.
Disclosure of Invention
Aiming at the defects, the technical problem to be solved by the invention is to provide a preparation method of as-cast mixed matrix QT500-14 nodular cast iron, so that the nodular cast iron with higher comprehensive mechanical property and machining property is obtained.
The invention provides a preparation method of as-cast mixed matrix QT500-14 nodular cast iron, which comprises the following steps:
s1, the raw materials are added in percentage by mass as follows: pig iron: 60-80%, scrap steel: 5-20%, foundry returns: 5-20%, electrolytic copper plate: 0.1-0.2%, pure nickel plate: 0.3-0.4%;
s2, smelting molten iron: firstly, adding scrap steel, pig iron and foundry returns, adding an electrolytic copper plate after the scrap steel, the pig iron and the foundry returns are completely melted, controlling the temperature in the melting process to be 1350-1390 ℃, and controlling the tapping temperature of a melt to be 1470-1500 ℃;
s3, melt treatment in the spheroidizing bag: putting ZFCR-7 type rare earth-containing nodulizing agent on one side of the bottommost part of a nodulizing ladle, putting CBSALLOY type barium-silicon-calcium inoculant on the upper parts of ZFCR-7 type rare earth-containing metal particles, discharging molten iron from a furnace, flushing the molten iron into the nodulizing ladle, and performing nodulizing and ladle inoculation, wherein the nodulizing treatment temperature is 1470-1500 ℃;
s4, pouring: and transferring the molten iron in the spheroidizing ladle to a pouring site for pouring, wherein the pouring temperature of the molten iron is 1400-1430 ℃, and a strontium-silicon random inoculant is added above a pouring cup along with the molten iron during pouring.
Preferably, in step S1, the pig iron comprises the following components in percentage by mass: c: 4.3-4.5%, Si: 0.8-0.9%, Mn less than 0.1%, P less than 0.04%, S less than 0.02%; the scrap steel comprises the following components in percentage by mass: c: 0.1-0.15%, Si: 0.2-0.4%, Mn: 1-1.3%, P less than 0.03%, S less than 0.02%.
Preferably, in step S3, the spheroidizing bag is a dam-type bag, and the intra-bag spheroidizing method is a punch-in method.
Preferably, the particle size of the ZFCR-7 type rare earth-containing nodulizer is 10-30 mm, and the ZFCR-7 type rare earth-containing nodulizer comprises the following components in percentage by mass: re: 0.8-1.2%, Mg: 6.7-7.3%, Si: 38-42%, Al: < 1%, Ca: proper amount.
Preferably, in step S3, the CBSALLOY-type calcium barium silicate inoculant has a particle size of 3-10 mm, and comprises the following components in percentage by mass: ca: 0.5-2.5%, Si: 65-72%, Al: less than 1.5 percent and 4 to 6 percent of Ba.
Preferably, in step S3, after the spheroidization reaction is finished, sampling and detecting to control that the spheroidized molten iron includes the following components by mass percent: 3.5-3.8% of C, 2.5-2.8% of Si, less than 0.3% of Mn, 0.05-0.2% of Cu, and Ni: 0.3-0.4%, P < 0.02%, S < 0.02%, Mg: 0.04-0.07% of Fe, 0.01-0.02% of Re, and the balance of Fe and impurities.
Preferably, in step S4, the grain size of the strontium silicon stream inoculant is 0.2-0.8 mm.
Preferably, the method further comprises the following steps:
s5, filtering: filtering the molten iron by adopting a foamed ceramic filter;
s6, sand mold heat preservation: and (5) after heat preservation for 12 hours, shakeout and unpacking.
Preferably, in step S5, the material of the ceramic foam filter is ZrO2、SiC、Al2O3Or from ZrO2SiC and Al2O3The foamed ceramic filter is formed by mixing, wherein the pore size of the foamed ceramic filter is 5-10 ppi, and the size of the foamed ceramic filter is 80mm multiplied by 30 mm.
Preferably, in the step S5, the ceramic foam filter is placed on both sides of the runner.
Compared with the prior art, the invention has the following beneficial effects:
1. controlling the content of main alloy elements: the invention fully utilizes the solid solution strengthening effect of the Si element and ensures the ferrite content. Compared with other high-silicon solid solution strengthening methods, the control range of the Si content is 2.5-2.8%, and meanwhile, a pearlite matrix is reserved, so that a matrix structure mainly comprising the ferrite matrix has certain ductility and toughness. In addition, in order to ensure good spheroidizing effect, promote the improvement of magnesium absorption rate and improve the fluidity, the content of C is controlled to be 3.5-3.8%.
2. Selection and component control of trace alloy elements: cu has a solid solution strengthening effect on ferrite, pearlite can be stabilized and refined, Cu is completely dissolved in a matrix in a solid solution mode, but the effect of promoting the formation of the pearlite is too strong, and the elongation after fracture is influenced, so that the Cu content is controlled within the range of 0.1-0.2%. Ni has obvious effect on improving the strength of a matrix and has weak influence on the elongation, and the content range of the Ni element is controlled to be 0.3-0.4 percent. Meanwhile, the content of Mn in the invention is limited to be not more than 0.3 percent and is generally controlled to be less than or equal to 0.2 percent. The content range of pearlite in the matrix structure is controlled to be 5-20% by adding the trace elements, so that the strength requirement of the nodular cast iron material can be met without losing ductility and toughness.
3. Selection of inoculant and nodulizer: the ZFCR-7 type rare earth-containing nodulizer belongs to a medium-magnesium low-rare earth nodulizer, and has the prominent effects of changing flake graphite into spherical graphite, refining as-cast structure and improving the form and distribution of nonmetallic inclusions; the rare earth element has stronger deoxidizing and desulfurizing capacity than magnesium, the generated compounds such as rare earth sulfide and rare earth oxide have high melting point and good stability, and meanwhile, the rare earth element and the spheroidization interference element in molten iron can also form stable compounds, thereby being beneficial to improving the material performance. The magnesium alloy nodulizer of high and medium rare earth is used, so that excessive carbides are easily generated in the casting, the graphite nodule shape is not round, and the plasticity and toughness of the casting are reduced to some extent. The CBSALLOY type silicon barium calcium inoculant belongs to a high-silicon barium calcium long-acting inoculant, and Ba and Ca elements are important inoculation elements and have the advantages of deoxidation and desulfurization and stronger graphite core forming capability. The vapor pressure of Ba is small at high temperature, Ba in the molten iron is not easy to lose, and Ca is also protected from being easy to lose, so that the recession of the inoculant is slowed down; the Ba and Ca are compounded, so that the number of graphite spheres per unit area in the structure is increased, and the fluctuating strength of the concentrations of C and Si in molten iron is increased, thereby being more beneficial to the formation and growth of ferrite in the structure and improving the elongation. In the melt processing method used by the invention, the spheroidization grade of the graphite nodules in the matrix tissue stably reaches 1-2 grades, the size of the graphite nodules is 6-7 grades, and the spheroidization rate of the graphite nodules is more than or equal to 90 percent.
Drawings
FIG. 1 is a metallographic photograph (100 times) of a matrix structure in a corroded state in example 1 of the present invention;
FIG. 2 is a metallographic photograph (100 times) of a matrix structure in a corroded state in example 2 of the present invention;
FIG. 3 is a metallographic photograph (100 times) of a matrix structure in a corroded state of comparative example 1 of the present invention;
FIG. 4 is a metallographic photograph (100 times) of a matrix structure in a corroded state of comparative example 2 of the present invention;
FIG. 5 is a metallographic photograph (100 times) of a matrix structure in a corroded state in comparative example 3 of the present invention;
FIG. 6 is a metallographic photograph (100 times) of a matrix structure in a corroded state of comparative example 4 of the present invention;
FIG. 7 is a metallographic photograph (100 times) of a matrix structure in a corroded state of comparative example 5 of the present invention;
FIG. 8 is a metallographic photograph (100 times) of a matrix structure in a corroded state of comparative example 6 of the present invention;
FIG. 9 is a metallographic photograph (100 times) of a matrix structure in a corroded state of comparative example 7 according to the invention;
Detailed Description
The embodiments of the present invention are described below with reference to specific embodiments, and other advantages and effects of the present invention will be easily understood by those skilled in the art from the disclosure of the present specification. The invention is capable of other and different embodiments and of being practiced or of being carried out in various ways, and its several details are capable of modification in various respects, all without departing from the spirit and scope of the present invention. It is to be understood that the processing equipment or apparatus not specifically identified in the following examples is conventional in the art. Furthermore, it is to be understood that one or more method steps mentioned in the present invention does not exclude that other method steps may also be present before or after the combined steps or that other method steps may also be inserted between these explicitly mentioned steps, unless otherwise indicated; it is also to be understood that a combined connection between one or more devices/apparatus as referred to in the present application does not exclude that further devices/apparatus may be present before or after the combined device/apparatus or that further devices/apparatus may be interposed between two devices/apparatus explicitly referred to, unless otherwise indicated. Moreover, unless otherwise indicated, the numbering of the various method steps is merely a convenient tool for identifying the various method steps, and is not intended to limit the order in which the method steps are arranged or the scope of the invention in which the invention may be practiced, and changes or modifications in the relative relationship may be made without substantially changing the technical content.
Example 1
The invention provides a preparation method of as-cast mixed matrix QT500-14 nodular cast iron, which comprises the following steps:
s1, the raw materials are added in percentage by mass as follows: pig iron: 60-80%, scrap steel: 5-20%, foundry returns: 5-20%, electrolytic copper plate: 0.1-0.2%, pure nickel plate: 0.3 to 0.4 percent. Specifically, the pig iron used is Q10 nodular iron pig iron, and comprises the following components in percentage by mass: c: 4.3-4.5%, Si: 0.8-0.9%, Mn less than 0.1%, P less than 0.04%, S less than 0.02%; the waste steel is high-quality carbon waste steel and comprises the following components in percentage by mass: c: 0.1-0.15%, Si: 0.2-0.4%, Mn: 1-1.3%, P less than 0.03%, S less than 0.02%. Both pig iron and scrap steel need to be subjected to shot blasting treatment to treat surface rust and other impurities before use.
S2, smelting molten iron: firstly, adding scrap steel, pig iron and foundry returns into a melting bag, adding an electrolytic copper plate after the scrap steel, the pig iron and the foundry returns are completely melted, controlling the temperature in the melting process to be 1350-1390 ℃, and controlling the tapping temperature of a melt to be 1470-1500 ℃.
S3, melt treatment in the spheroidizing bag: and (3) cleaning the slag on the surface of the molten iron, then flushing all the discharged molten iron into a spheroidizing ladle, and carrying out spheroidizing and ladle inoculation. 0.8-1.5% of ZFCR-7 type rare earth-containing nodulizer by mass percent is placed at one side of the bottommost part of the nodulizing ladle, and the rare earth nodulizer comprises the following components by mass percent: re: 0.8-1.2%, Mg: 6.7-7.3%, Si: 38-42%, Al: < 1%, Ca: proper amount, and the granularity is 10-30 mm. Uniformly covering the upper parts of ZFCR-7 type metal particles containing a rare earth nodulizer with 0.4-0.7% of CBSALLOY type silicon barium calcium inoculant in percentage by mass, wherein the granularity of the CBSALLOY type silicon barium calcium inoculant is 3-10 mm, and the CBSALLOY type silicon barium calcium inoculant comprises the following components in percentage by mass: ca: 0.5-2.5%, Si: 65-72%, Al: less than 1.5 percent and 4 to 6 percent of Ba. The spheroidised granules in the ladle were pounded and then covered with a thin sheet of ductile iron. Wherein, the mass percentages of the ZFCR-7 type rare earth-containing nodulizer and the CBSALLOY type silicon barium calcium inoculant are percentages relative to the total mass of molten iron in the nodulizing ladle.
The spheroidizing bag is specifically processed by adopting a dam type bag, the spheroidizing reaction time is controlled to be 20-30 seconds, and the spheroidizing temperature is 1470-1500 ℃. After the spheroidization reaction is finished, sampling and detecting, and controlling the spheroidized molten iron to comprise the following components in percentage by mass: 3.5-3.8% of C, 2.5-2.8% of Si, less than 0.3% of Mn, 0.1-0.2% of Cu, and Ni: 0.3-0.4%, P < 0.02%, S < 0.02%, Mg: 0.04-0.07% of Fe, 0.01-0.02% of Re, and the balance of Fe and inevitable impurities. And after the reaction is finished, spreading a slag removing agent on the molten iron in the spheroidizing bag to remove slag quickly, and completely removing the molten slag on the surface of the molten iron.
S4, pouring: and transferring the molten iron in the spheroidizing ladle to a pouring site for pouring, wherein the pouring temperature of the molten iron is 1400-1430 ℃, and a strontium-silicon stream inoculant with the mass percent of 0.05-0.15 percent is added above a pouring cup along with the molten iron during pouring, and the granularity of the strontium-silicon stream inoculant is 0.2-0.8 mm. And controlling the time within 8min from the end of spheroidization to the end of casting.
S5, filtering: filtering molten iron by adopting a foamed ceramic filter, wherein the foamed ceramic filter is made of ZrO2、SiC、Al2O3Or is formed by mixing ZrO2, SiC and Al2O3, wherein ZrO in the mixed composition2SiC and Al2O3The mass percentage content of the organic silicon compound is 80-65%, 10-25% and 10-25% in sequence. The pore diameter of the foamed ceramic filter is 5-10 ppi, and the specific size is 80mm multiplied by 30 mm. The ceramic foam filter is placed on both sides of the runner.
S6, sand mold heat preservation: and (5) after heat preservation for 12 hours, shakeout and unpacking.
Between the steps S5 and S6, the method further comprises the step of single casting a Y-shaped test block, wherein the size of the Y-shaped test block is performed according to the GB/T1348-2009 nodular iron casting. And (3) dissecting the single-cast Y-shaped test block, processing the core part of the single-cast Y-shaped test block into a tensile test bar, a metallographic sample and a component analysis sample, and inspecting chemical components, metallographic structures and mechanical properties.
The chemical analysis results of the prepared single-cast test block are shown in table 1, the as-cast metallographic structure examination results are shown in table 2, and as can be seen from fig. 1, the spheroidization grade of the nodular cast iron prepared in this example is grade 2, the graphite nodule size is grade 6 (observed at 100 × and the graphite length is greater than 3-6 mm), the spheroidization rate is greater than or equal to 90%, the matrix structure is pearlite 5-20%, and ferrite 75-85%. The performance test of the as-cast mixed matrix QT500-14 nodular cast iron prepared in the embodiment is shown in Table 3, and the test result shows that the mechanical property of the single-cast test block in the embodiment reaches Rm≥500MPa、Rp0.2380MPa or more and 14 percent or more of A, and various performances meet the design requirements.
Example 2
Example 2 relates to a method for preparing an as-cast mixed matrix QT500-14 nodular cast iron, which differs from example 1 in that: in example 2, the mass percentage of the Cu element is controlled to be 0.05-0.1%. This embodiment is after the spheroidization reaction, and the sample detection controls the molten iron composition after the balling: c: 3.5-3.8%, Si 2.5-2.8%, Mn less than 0.3%, Cu 0.05-0.1%, Ni: 0.3-0.4%, P < 0.02%, S < 0.02%, Mg: 0.04-0.07% of Fe, 0.01-0.02% of Re, and the balance of Fe and inevitable impurities.
The chemical analysis results of the prepared single cast test block are shown in table 1, the as-cast metallographic structure is shown in table 2, and as can be seen from the combination of fig. 2, the spheroidization grade is grade 2, the graphite nodule size is grade 7 (observed at 100 x, the graphite length is more than 1.5-3 mm), the spheroidization rate is not less than 90%, the matrix structure is pearlite 5-15%, and ferrite 75-90%. The performance test of the as-cast mixed matrix QT500-14 nodular cast iron prepared in the embodiment is shown in Table 3, and the test results show that when the mass percent control ranges of Cu and Ni elements are respectively controlled to be 0.05-0.1%, the mechanical property of the single cast test block of the embodiment can also stably reach that Rm is more than or equal to 500MPa, Rp0.2 is more than or equal to 380MPa, A is more than or equal to 14%, and all properties meet the design requirements.
Comparative example 1
Comparative example 1 relates to a process for the preparation of an as-cast mixed matrix QT500-14 nodular cast iron, which differs from example 1 in that: in comparative example 1, no Ni alloying element was added. After the spheroidization reaction is finished, sampling and detecting are carried out, and the components of molten iron after spheroidization are controlled: c: 3.5-3.8%, Si 2.5-2.8%, Mn less than 0.3%, Cu 0.1-0.2%, P less than 0.02%, S less than 0.02%, Mg: 0.04-0.07% of Fe, 0.01-0.02% of Re, and the balance of Fe and inevitable impurities.
The chemical analysis results of the prepared single cast test block are shown in table 1, the as-cast metallographic structure is shown in table 2, and as can be seen from the combination of fig. 3, the spheroidization grade is grade 2, the graphite nodule size is grade 6 (observed at 100 x, the graphite length is more than 3-6 mm), the spheroidization rate is not less than 90%, the matrix structure is pearlite 10-25%, and ferrite 70-85%. The performance test of the as-cast mixed matrix QT500-14 nodular cast iron prepared by the comparative example is shown in Table 3, and the test result shows that compared with the embodiment, the tensile strength and the yield strength of the nodular cast iron material prepared by the comparative example are remarkably reduced, only the tensile strength and the elongation rate meet the design requirement, and the yield strength is lower than the design requirement.
Comparative example 2
Comparative example 2 relates to a method for preparing as-cast mixed matrix QT500-14 nodular cast iron, which differs from example 1 in that: comparative example 2 the mass percent of the Ni element was controlled to 0.1 to 0.2%. After the spheroidization reaction is finished, sampling and detecting are carried out, and the components of molten iron after spheroidization are controlled: c: 3.5-3.8%, Si 2.5-2.8%, Mn less than 0.3%, Cu 0.1-0.2%, Ni: 0.1-0.2%, P < 0.02%, S < 0.02%, Mg: 0.04-0.07% of Fe, 0.01-0.02% of Re, and the balance of Fe and inevitable impurities.
The chemical analysis results of the single cast test block prepared by the comparative example are shown in table 1, the as-cast metallographic structure test is shown in table 2, and as can be seen from fig. 4, the spheroidization grade is grade 2, the graphite nodule size is grade 7 (observed at 100 x, the graphite length is more than 1.5-3 mm), the spheroidization rate is more than or equal to 90%, the matrix structure is 20-35% of pearlite, and the ferrite is 60-75%. The performance test of the as-cast mixed matrix QT500-14 nodular cast iron prepared by the comparative example is shown in Table 3, and the test result shows that compared with the example 1, the yield strength of the nodular cast iron material prepared by the comparative example is lower than that of the example 1 and the comparative example 1, only the tensile strength and the elongation rate meet the design requirement, and the comprehensive mechanical property is far lower than the design requirement.
Comparative example 3
Comparative example 3 relates to a method for preparing as-cast mixed matrix QT500-14 nodular cast iron, which differs from example 2 in that: in comparative example 3, the mass percent of the Ni element is controlled to be 0.05-0.1%. After the spheroidization reaction is finished, sampling and detecting are carried out, and the components of molten iron after spheroidization are controlled: c: 3.5-3.8%, Si 2.5-2.8%, Mn less than 0.3%, Cu 0.05-0.1%, Ni: 0.05-0.1%, P less than 0.02%, S less than 0.02%, Mg: 0.04-0.07% of Fe, 0.01-0.02% of Re, and the balance of Fe and inevitable impurities.
The chemical analysis results of the single cast test block prepared by the comparative example are shown in table 1, the as-cast metallographic structure test is shown in table 2, and as can be seen from fig. 5, the spheroidization grade is grade 2, the graphite nodule size is grade 6 (observed at 100 x, the graphite length is more than 3-6 mm), the spheroidization rate is not less than 90%, the matrix structure is 25-35% of pearlite, and the ferrite is 60-70%. The performance test of the as-cast mixed matrix QT500-14 nodular cast iron prepared by the comparative example is shown in Table 3, and the test result shows that compared with the example 2, the tensile strength and the yield strength of the nodular cast iron material prepared by the comparative example are lower than those of the example 2, only the tensile strength and the elongation rate meet the design requirements, but the comprehensive mechanical property of the nodular cast iron material is far lower than the design requirements.
Comparative example 4
Comparative example 4 relates to a method for preparing as-cast mixed matrix QT500-14 nodular cast iron, which differs from examples 1 and 2 in that: in comparative example 4, in order to reduce the production cost, the matrix structure was adjusted by increasing the contents of Mn element and Cu element without adding Ni element, and the mechanical properties were improved. The mass percentage range of Mn element is 0.5-0.6%, and the mass percentage range of Cu element is 0.2-0.3%. After the spheroidization reaction is finished, sampling and detecting are carried out, and the components of molten iron after spheroidization are controlled: c: 3.5-3.8%, Si 2.5-2.8%, Mn 0.5-0.6%, Cu 0.2-0.3%, P < 0.02%, S < 0.02%, Mg: 0.04-0.07% of Fe, 0.01-0.02% of Re, and the balance of Fe and inevitable impurities.
The chemical analysis results of the single cast test block prepared by the comparative example are shown in table 1, the as-cast metallographic structure test is shown in table 2, and as can be seen from fig. 6, the spheroidization grade is grade 2, the graphite nodule size is grade 6 (observed at 100 x, the graphite length is more than 3-6 mm), the spheroidization rate is not less than 90%, the matrix structure is pearlite 35-45%, and ferrite 50-60%. The performance test of the as-cast mixed matrix QT500-14 nodular cast iron prepared by the comparative example is shown in Table 3, and the test result shows that compared with the examples 1 and 2, the tensile strength and the yield strength of the nodular cast iron material prepared by the comparative example are far higher than those of the example 2, namely Rm is more than or equal to 700MPa, Rp0.2 is more than or equal to 450MPa, but the elongation is sharply reduced, and the comprehensive mechanical property is far lower than the design requirement.
Comparative example 5
Comparative example 5 relates to a method for preparing as-cast mixed matrix QT500-14 nodular cast iron, which differs from examples 1 and 2 in that no Cu alloying element is added in comparative example 5. After the spheroidization reaction is finished, sampling and detecting are carried out, and the components of molten iron after spheroidization are controlled: c: 3.5-3.8%, Si 2.5-2.8%, Mn less than 0.3%, Ni: 0.3-0.4%, P < 0.02%, S < 0.02%, Mg: 0.04-0.07% of Fe, 0.01-0.02% of Re, and the balance of Fe and inevitable impurities.
The chemical analysis results of the single cast test block prepared by the comparative example are shown in table 1, the as-cast metallographic structure test is shown in table 2, and as can be seen from fig. 7, the spheroidization grade is grade 2, the graphite nodule size is grade 6 (observed at 100 x, the graphite length is more than 3-6 mm), the spheroidization rate is not less than 90%, the matrix structure is 25-35% of pearlite, and the ferrite is 60-70%. The performance test of the as-cast mixed matrix QT500-14 nodular cast iron prepared by the comparative example is shown in Table 3, and the test results show that compared with the examples 1 and 2, the tensile strength and the yield strength of the nodular cast iron material prepared by the comparative example are lower than those of the examples 1 and 2, only the tensile strength and the elongation rate meet the design requirements, but the comprehensive mechanical property is lower than the design requirements.
Comparative example 6
Comparative example 6 relates to a method for preparing as-cast mixed matrix QT500-14 nodular cast iron, which differs from example 1 in that: in comparative example 6, a conventional rare earth-containing spheroidizing agent (magnesium alloy spheroidizing agent of high, medium rare earth) was used. After the spheroidization reaction is finished, sampling and detecting are carried out, and the components of molten iron after spheroidization are controlled: c: 3.5-3.8%, Si 2.5-2.8%, Mn less than 0.3%, Cu 0.1-0.2%, Ni: 0.3-0.4%, P < 0.02%, S < 0.02%, Mg: 0.04-0.07% of Fe, 0.01-0.02% of Re, and the balance of Fe and inevitable impurities.
The chemical analysis results of the prepared single cast test block are shown in table 1, the as-cast metallographic structure test is shown in table 2, and as can be seen from the combination of fig. 8, the spheroidization grade is grade 3, the graphite nodule size is grade 5-6 (observed at 100 x, the graphite length is more than 3-4 mm), the spheroidization rate is not less than 85%, the matrix structure is pearlite 5-15%, and ferrite 75-90%. The performance test of the as-cast mixed matrix QT500-14 nodular cast iron prepared by the comparative example is shown in Table 3, and the test results show that after the high-magnesium high-rare earth nodulizer and the medium-magnesium high-rare earth nodulizer are used, the size grade, the nodulizing grade and the morphology of graphite nodules in a metallographic structure are obviously changed, the structure morphology is deteriorated, and the metallographic structure cannot meet the design requirements.
Comparative example 7
Comparative example 7 relates to a process for the preparation of an as-cast mixed matrix QT500-14 nodular cast iron, which differs from example 1 in that: in the comparative example 7, a common conventional silicon-barium-calcium inoculant containing 0.7-2.0% of Ca is used. After the spheroidization reaction is finished, sampling and detecting are carried out, and the components of molten iron after spheroidization are controlled: c: 3.5-3.8%, Si 2.5-2.8%, Mn less than 0.3%, Cu 0.1-0.2%, Ni: 0.3-0.4%, P < 0.02%, S < 0.02%, Mg: 0.04-0.07% of Fe, 0.01-0.02% of Re, and the balance of Fe and inevitable impurities.
The chemical analysis results of the prepared single cast test block are shown in table 1, the as-cast metallographic structure test is shown in table 2, and as can be seen from the combination of fig. 8, the spheroidization grade is grade 3, the graphite nodule size is grade 5-6 (observed at 100 x, the graphite length is more than 3-4 mm), the spheroidization rate is not less than 85%, the matrix structure is pearlite 5-15%, and ferrite 75-90%. The performance test of the as-cast mixed matrix QT500-14 nodular cast iron prepared by the comparative example is shown in Table 3, and the test result shows that after the common conventional silicon-barium-calcium inoculant is used, the number and the appearance of graphite nodules in a metallographic structure in a unit area are obviously changed, the structure appearance is deteriorated, and the metallographic structure cannot meet the design requirements.
TABLE 1
Figure BDA0002651194220000091
Figure BDA0002651194220000101
TABLE 2
Figure BDA0002651194220000102
TABLE 3
Item numbering Tensile strength MPa Yield strength MPa Elongation percentage% Hardness HBW
Example 1 545/525 390/375 17/17 180
Example 2 545/575 380/405 18.5/14.5 181
Comparative example 1 515/520 360/365 16.5/16.5 185
Comparative example 2 530/540 355/360 17.5/18 188
Comparative example 3 540/530 365/365 16/15.5 190
Comparative example 4 755/735 470/460 7/7 195
Comparative example 5 520/525 360/355 14.5/14 185
Comparative example 6 525/515 370/375 16/15 182
Comparative example 7 535/520 370/374 15.5/15.5 183
The above description is only a preferred embodiment of the present invention, and it should be noted that, for those skilled in the art, various modifications and substitutions can be made without departing from the technical principle of the present invention, and these modifications and substitutions should also be regarded as the protection scope of the present invention.

Claims (10)

1. A preparation method of as-cast mixed matrix QT500-14 nodular cast iron is characterized by comprising the following steps:
s1, the raw materials are added in percentage by mass as follows: pig iron: 60-80%, scrap steel: 5-20%, foundry returns: 5-20%, electrolytic copper plate: 0.1-0.2%, pure nickel plate: 0.3-0.4%;
s2, smelting molten iron: firstly, adding scrap steel, pig iron and foundry returns, adding an electrolytic copper plate after the scrap steel, the pig iron and the foundry returns are completely melted, controlling the temperature in the melting process to be 1350-1390 ℃, and controlling the tapping temperature of a melt to be 1470-1500 ℃;
s3, melt treatment in the spheroidizing bag: putting ZFCR-7 type rare earth-containing nodulizing agent on one side of the bottommost part of a nodulizing ladle, putting CBSALLOY type barium-silicon-calcium inoculant on the upper parts of ZFCR-7 type rare earth-containing metal particles, discharging molten iron from a furnace, flushing the molten iron into the nodulizing ladle, and performing nodulizing and ladle inoculation, wherein the nodulizing treatment temperature is 1470-1500 ℃;
s4, pouring: and transferring the molten iron in the spheroidizing ladle to a pouring site for pouring, wherein the pouring temperature of the molten iron is 1400-1430 ℃, and a strontium-silicon random inoculant is added above a pouring cup along with the molten iron during pouring.
2. The method according to claim 1, wherein in step S1, the pig iron comprises the following components in mass percent: c: 4.3-4.5%, Si: 0.8-0.9%, Mn less than 0.1%, P less than 0.04%, S less than 0.02%; the scrap steel comprises the following components in percentage by mass: c: 0.1-0.15%, Si: 0.2-0.4%, Mn: 1-1.3%, P less than 0.03%, S less than 0.02%.
3. The method of manufacturing spheroidal graphite cast iron according to claim 1, wherein in step S3, the spheroidization ladle is a dam-type ladle, and the intra-ladle spheroidization method employs a punch-in method.
4. The preparation method of ductile iron according to claim 1, wherein the particle size of the ZFCR-7 type rare earth-containing nodulizer is 10-30 mm, and comprises the following components in percentage by mass: re: 0.8-1.2%, Mg: 6.7-7.3%, Si: 38-42%, Al: < 1%, Ca: proper amount.
5. The preparation method of nodular cast iron according to claim 1, wherein in step S3, the CBSALLOY type calcium-silicon inoculant has a particle size of 3-10 mm, and comprises the following components in percentage by mass: ca: 0.5-2.5%, Si: 65-72%, Al: less than 1.5 percent and 4 to 6 percent of Ba.
6. The method according to claim 1, wherein in step S3, after the spheroidization reaction is completed, sampling and detecting are performed to control that the molten iron after spheroidization comprises the following components in percentage by mass: 3.5-3.8% of C, 2.5-2.8% of Si, less than 0.3% of Mn, 0.05-0.2% of Cu, and Ni: 0.3-0.4%, P < 0.02%, S < 0.02%, Mg: 0.04-0.07% of Fe, 0.01-0.02% of Re, and the balance of Fe and impurities.
7. The method for preparing spheroidal graphite cast iron according to claim 1, wherein in step S4, the grain size of the strontium silicon stream inoculant is 0.2-0.8 mm.
8. The method of preparing ductile iron according to claim 1, further comprising the steps of:
s5, filtering: filtering the molten iron by adopting a foamed ceramic filter;
s6, sand mold heat preservation: and (5) after heat preservation for 12 hours, shakeout and unpacking.
9. The method according to claim 8, wherein in step S5, the ceramic foam filter is made of a material such asZrO2、SiC、Al2O3Or from ZrO2SiC and Al2O3And mixing, wherein the pore diameter of the foamed ceramic filter is 5-10 ppi, and the size is 80mm multiplied by 30 mm.
10. The method of manufacturing spheroidal graphite cast iron according to claim 8, wherein in the step S5, the ceramic foam filters are placed on both sides of a runner.
CN202010871267.3A 2020-08-26 2020-08-26 Preparation method of as-cast mixed matrix QT500-14 nodular cast iron Pending CN111961954A (en)

Priority Applications (1)

Application Number Priority Date Filing Date Title
CN202010871267.3A CN111961954A (en) 2020-08-26 2020-08-26 Preparation method of as-cast mixed matrix QT500-14 nodular cast iron

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
CN202010871267.3A CN111961954A (en) 2020-08-26 2020-08-26 Preparation method of as-cast mixed matrix QT500-14 nodular cast iron

Publications (1)

Publication Number Publication Date
CN111961954A true CN111961954A (en) 2020-11-20

Family

ID=73391300

Family Applications (1)

Application Number Title Priority Date Filing Date
CN202010871267.3A Pending CN111961954A (en) 2020-08-26 2020-08-26 Preparation method of as-cast mixed matrix QT500-14 nodular cast iron

Country Status (1)

Country Link
CN (1) CN111961954A (en)

Cited By (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN112853196A (en) * 2020-12-09 2021-05-28 宁波日星铸业有限公司 Solid solution strengthening ferrite casting and preparation method thereof
CN115255294A (en) * 2022-06-13 2022-11-01 天润工业技术股份有限公司 Treatment process for producing high-strength and high-toughness nodular cast iron through green sand molding
CN115852236A (en) * 2022-12-07 2023-03-28 陕西柴油机重工有限公司 Preparation method of large-tonnage thick-large-section wind power main frame
CN116200646A (en) * 2022-12-30 2023-06-02 四川天奇永大机械制造有限公司 Casting material and casting method for large-scale wind power casting product

Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN101363097A (en) * 2008-10-07 2009-02-11 辽宁隆达集团百星达铸造有限责任公司 Low-temperature impact resistant as-cast ductile iron with big section and production method thereof
EP2267174A2 (en) * 2009-06-23 2010-12-29 General Electric Company Simo ductile iron castings for gas turbine applications
CN106498267A (en) * 2016-12-30 2017-03-15 山东省源通机械股份有限公司 Spheroidal graphite cast-iron metal material and preparation method thereof
CN111074034A (en) * 2019-12-27 2020-04-28 上海烟草机械有限责任公司 Preparation method of as-cast mixed matrix QT600-10 nodular cast iron

Patent Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN101363097A (en) * 2008-10-07 2009-02-11 辽宁隆达集团百星达铸造有限责任公司 Low-temperature impact resistant as-cast ductile iron with big section and production method thereof
EP2267174A2 (en) * 2009-06-23 2010-12-29 General Electric Company Simo ductile iron castings for gas turbine applications
CN106498267A (en) * 2016-12-30 2017-03-15 山东省源通机械股份有限公司 Spheroidal graphite cast-iron metal material and preparation method thereof
CN111074034A (en) * 2019-12-27 2020-04-28 上海烟草机械有限责任公司 Preparation method of as-cast mixed matrix QT600-10 nodular cast iron

Non-Patent Citations (2)

* Cited by examiner, † Cited by third party
Title
国家机械工业委员会: "《高级化铁工工艺学》", 30 September 1988, 机械工业出版社 *
朱光亚: "《中国科学技术文库》", 31 January 1998, 科学技术文献出版社 *

Cited By (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN112853196A (en) * 2020-12-09 2021-05-28 宁波日星铸业有限公司 Solid solution strengthening ferrite casting and preparation method thereof
CN115255294A (en) * 2022-06-13 2022-11-01 天润工业技术股份有限公司 Treatment process for producing high-strength and high-toughness nodular cast iron through green sand molding
CN115255294B (en) * 2022-06-13 2023-08-15 天润工业技术股份有限公司 Treatment process for producing high-strength high-toughness spheroidal graphite cast iron by using damp mould sand molding
CN115852236A (en) * 2022-12-07 2023-03-28 陕西柴油机重工有限公司 Preparation method of large-tonnage thick-large-section wind power main frame
CN116200646A (en) * 2022-12-30 2023-06-02 四川天奇永大机械制造有限公司 Casting material and casting method for large-scale wind power casting product

Similar Documents

Publication Publication Date Title
CN111961954A (en) Preparation method of as-cast mixed matrix QT500-14 nodular cast iron
CN106011610B (en) A kind of high-strength ductile cast iron QT900 6 and preparation method thereof
CN102367537B (en) High strength and toughness as-cast nodular cast iron and its production method
CN100453674C (en) Low cost, high-wearability hypereutectic high chromium cast iron and its production method
CN102703817B (en) Free-machining pinion steel and production technique thereof
CN109957631B (en) Treatment method of high-nickel austenite nodular cast iron melt
CN111074034A (en) Preparation method of as-cast mixed matrix QT600-10 nodular cast iron
CN104060157B (en) A kind of hypereutectic high-chromium white cast iron and preparation method thereof
WO2006068487A1 (en) Modifying agents for cast iron
WO2002095081A1 (en) High temperature oxidation resistant ductile iron
CN104313457B (en) Vanadium carbide reinforced composite cast iron material, preparation method thereof and sand making machine impact block
CN108707813B (en) As-cast high-strength ductile iron and its manufacturing process
CN106591689A (en) Hypereutectic high-chromium alloy white cast iron chute lining plate and preparation method thereof
CN109023034A (en) A kind of preparation method of high-strength thin-walled gray iron casting
CN102400032B (en) Large-cross-section nodular cast iron
CN109930059B (en) Low-temperature high-strength high-toughness nodular cast iron, preparation method thereof and railway locomotive part
CN112553521A (en) Ductile iron bearing seat and preparation method thereof
CN110760738B (en) Method for manufacturing low-temperature impact-resistant ductile cast iron
CN110066959B (en) High-strength low-sulfur high-manganese inoculated gray cast iron material and smelting and pouring process thereof
CN115896634B (en) High-temperature-resistant nonferrous metal die-casting forming die steel material and preparation method thereof
CN111455263A (en) Environment-friendly low-temperature nodular cast iron produced by using low-rare earth alloy and production process thereof
CN115537642B (en) Refining method of hypereutectic high-chromium cast iron primary carbide
CN114369756B (en) As-cast QT700-8 material and casting method and application thereof
CN114657451A (en) Hypereutectic high-chromium cast iron and suspension and modification composite treatment method thereof
CN104651721B (en) Alloy steel for bucket teeth and preparation method of bucket teeth

Legal Events

Date Code Title Description
PB01 Publication
PB01 Publication
SE01 Entry into force of request for substantive examination
SE01 Entry into force of request for substantive examination