CN114000042A - Nodular cast iron axle housing and preparation method thereof - Google Patents
Nodular cast iron axle housing and preparation method thereof Download PDFInfo
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- CN114000042A CN114000042A CN202111252041.6A CN202111252041A CN114000042A CN 114000042 A CN114000042 A CN 114000042A CN 202111252041 A CN202111252041 A CN 202111252041A CN 114000042 A CN114000042 A CN 114000042A
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- 229910001141 Ductile iron Inorganic materials 0.000 title claims abstract description 103
- 238000002360 preparation method Methods 0.000 title claims abstract description 7
- XEEYBQQBJWHFJM-UHFFFAOYSA-N iron Substances [Fe] XEEYBQQBJWHFJM-UHFFFAOYSA-N 0.000 claims abstract description 30
- 229910052796 boron Inorganic materials 0.000 claims abstract description 17
- 229910052710 silicon Inorganic materials 0.000 claims abstract description 13
- 239000000126 substance Substances 0.000 claims abstract description 9
- 239000012535 impurity Substances 0.000 claims abstract description 8
- 229910052748 manganese Inorganic materials 0.000 claims abstract description 6
- 229910052802 copper Inorganic materials 0.000 claims abstract description 5
- 238000012360 testing method Methods 0.000 claims description 13
- 238000000034 method Methods 0.000 claims description 7
- 238000003723 Smelting Methods 0.000 claims description 5
- 239000000203 mixture Substances 0.000 claims description 4
- 229910052720 vanadium Inorganic materials 0.000 claims description 3
- 238000004519 manufacturing process Methods 0.000 claims description 2
- 229910052749 magnesium Inorganic materials 0.000 abstract description 3
- OKTJSMMVPCPJKN-UHFFFAOYSA-N Carbon Chemical compound [C] OKTJSMMVPCPJKN-UHFFFAOYSA-N 0.000 description 56
- 230000000052 comparative effect Effects 0.000 description 44
- 229910002804 graphite Inorganic materials 0.000 description 40
- 239000010439 graphite Substances 0.000 description 40
- 238000005266 casting Methods 0.000 description 24
- 230000000694 effects Effects 0.000 description 24
- 229910052799 carbon Inorganic materials 0.000 description 21
- 229910052580 B4C Inorganic materials 0.000 description 19
- INAHAJYZKVIDIZ-UHFFFAOYSA-N boron carbide Chemical compound B12B3B4C32B41 INAHAJYZKVIDIZ-UHFFFAOYSA-N 0.000 description 19
- 229910052742 iron Inorganic materials 0.000 description 13
- 239000011572 manganese Substances 0.000 description 10
- 230000007547 defect Effects 0.000 description 9
- 238000005087 graphitization Methods 0.000 description 9
- 238000005728 strengthening Methods 0.000 description 8
- 239000010949 copper Substances 0.000 description 7
- 239000011777 magnesium Substances 0.000 description 7
- 229910052717 sulfur Inorganic materials 0.000 description 7
- ZOXJGFHDIHLPTG-UHFFFAOYSA-N Boron Chemical compound [B] ZOXJGFHDIHLPTG-UHFFFAOYSA-N 0.000 description 6
- 238000013461 design Methods 0.000 description 6
- 230000006872 improvement Effects 0.000 description 6
- 230000001737 promoting effect Effects 0.000 description 6
- 230000009286 beneficial effect Effects 0.000 description 5
- 238000007670 refining Methods 0.000 description 5
- 230000008901 benefit Effects 0.000 description 4
- 229910052761 rare earth metal Inorganic materials 0.000 description 4
- 150000002910 rare earth metals Chemical class 0.000 description 4
- NINIDFKCEFEMDL-UHFFFAOYSA-N Sulfur Chemical compound [S] NINIDFKCEFEMDL-UHFFFAOYSA-N 0.000 description 3
- 230000015572 biosynthetic process Effects 0.000 description 3
- -1 boron carbides Chemical class 0.000 description 3
- 238000002425 crystallisation Methods 0.000 description 3
- 230000008025 crystallization Effects 0.000 description 3
- 150000001247 metal acetylides Chemical class 0.000 description 3
- 230000004048 modification Effects 0.000 description 3
- 238000012986 modification Methods 0.000 description 3
- 229910052760 oxygen Inorganic materials 0.000 description 3
- 230000008569 process Effects 0.000 description 3
- 239000002994 raw material Substances 0.000 description 3
- 230000009467 reduction Effects 0.000 description 3
- FYYHWMGAXLPEAU-UHFFFAOYSA-N Magnesium Chemical compound [Mg] FYYHWMGAXLPEAU-UHFFFAOYSA-N 0.000 description 2
- PWHULOQIROXLJO-UHFFFAOYSA-N Manganese Chemical compound [Mn] PWHULOQIROXLJO-UHFFFAOYSA-N 0.000 description 2
- XUIMIQQOPSSXEZ-UHFFFAOYSA-N Silicon Chemical compound [Si] XUIMIQQOPSSXEZ-UHFFFAOYSA-N 0.000 description 2
- 229910000831 Steel Inorganic materials 0.000 description 2
- 239000005864 Sulphur Substances 0.000 description 2
- 239000000654 additive Substances 0.000 description 2
- 230000000996 additive effect Effects 0.000 description 2
- 238000011081 inoculation Methods 0.000 description 2
- 239000000463 material Substances 0.000 description 2
- 229910052751 metal Inorganic materials 0.000 description 2
- 239000002184 metal Substances 0.000 description 2
- 229910052750 molybdenum Inorganic materials 0.000 description 2
- 229910052698 phosphorus Inorganic materials 0.000 description 2
- 239000010703 silicon Substances 0.000 description 2
- 239000010959 steel Substances 0.000 description 2
- RYGMFSIKBFXOCR-UHFFFAOYSA-N Copper Chemical compound [Cu] RYGMFSIKBFXOCR-UHFFFAOYSA-N 0.000 description 1
- 229910000519 Ferrosilicon Inorganic materials 0.000 description 1
- OAICVXFJPJFONN-UHFFFAOYSA-N Phosphorus Chemical compound [P] OAICVXFJPJFONN-UHFFFAOYSA-N 0.000 description 1
- 229910000805 Pig iron Inorganic materials 0.000 description 1
- MKPXGEVFQSIKGE-UHFFFAOYSA-N [Mg].[Si] Chemical compound [Mg].[Si] MKPXGEVFQSIKGE-UHFFFAOYSA-N 0.000 description 1
- 238000005275 alloying Methods 0.000 description 1
- 230000002929 anti-fatigue Effects 0.000 description 1
- 230000000903 blocking effect Effects 0.000 description 1
- 239000013078 crystal Substances 0.000 description 1
- 238000005520 cutting process Methods 0.000 description 1
- 238000006477 desulfuration reaction Methods 0.000 description 1
- 230000023556 desulfurization Effects 0.000 description 1
- 230000002708 enhancing effect Effects 0.000 description 1
- 238000011010 flushing procedure Methods 0.000 description 1
- 230000006698 induction Effects 0.000 description 1
- 230000005764 inhibitory process Effects 0.000 description 1
- 239000002054 inoculum Substances 0.000 description 1
- 239000007788 liquid Substances 0.000 description 1
- 239000011159 matrix material Substances 0.000 description 1
- 238000005457 optimization Methods 0.000 description 1
- 230000003647 oxidation Effects 0.000 description 1
- 238000007254 oxidation reaction Methods 0.000 description 1
- 229910001562 pearlite Inorganic materials 0.000 description 1
- 239000011574 phosphorus Substances 0.000 description 1
- 238000011160 research Methods 0.000 description 1
- 238000005204 segregation Methods 0.000 description 1
- 239000006104 solid solution Substances 0.000 description 1
- 239000011593 sulfur Substances 0.000 description 1
- 229910000859 α-Fe Inorganic materials 0.000 description 1
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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
-
- 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
-
- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02T—CLIMATE CHANGE MITIGATION TECHNOLOGIES RELATED TO TRANSPORTATION
- Y02T10/00—Road transport of goods or passengers
- Y02T10/80—Technologies aiming to reduce greenhouse gasses emissions common to all road transportation technologies
- Y02T10/86—Optimisation of rolling resistance, e.g. weight reduction
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- 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 relates to a nodular cast iron axle housing and a preparation method thereof, wherein the nodular cast iron axle housing comprises the following chemical components: c: 3.5-3.9%, Si: 1.8-2.5%, Mn: 0.2-0.4%, Cu: 0.4-0.8%, B: 10-50ppm, less than or equal to 0.08 percent of Mg, less than or equal to 0.05 percent of RE, and the balance of Fe and inevitable impurities, wherein C/10B is 80-360, Si/10B is 44-200, CE is C +1/3Si is 4.3-4.6.
Description
Technical Field
The invention relates to a nodular cast iron axle housing and a preparation method thereof, wherein the nodular cast iron axle housing has excellent strength, fatigue property, plasticity and toughness, has high long-period working reliability and low cost advantage, and can be suitable for vehicle application under various working conditions and loads.
Background
Ductile iron, which has properties close to steel and significant cost advantages, is often used as a material for vehicle axle housings. The axle housing supports the mass load of the vehicle and bears the torque transmitted by the wheels, and the working conditions are severe, so that the strength, the fatigue resistance, the plasticity and the toughness of the nodular cast iron for preparing the axle housing are properties which need to be considered simultaneously.
The prior art can often improve the intensity of nodular cast iron axle housing through adding the alloying of multiple element, but the improvement of intensity often leads to plasticity and toughness to descend, needs just further control the tissue or add other elements and improve plasticity, toughness, and the antifatigue characteristic also can not obtain guaranteeing, leads to the cost of nodular cast iron axle housing to go high on the one hand, and the operational reliability of on the other hand nodular cast iron axle housing can not obtain guaranteeing.
Based on the above knowledge, the invention provides a nodular cast iron axle housing which has simple element design, obvious cost advantage and excellent strength, plasticity, toughness and fatigue property.
Disclosure of Invention
The invention provides a nodular cast iron axle housing with strength, plasticity, toughness and fatigue characteristics, which has simple component design, can ensure excellent strength, plasticity, toughness and fatigue characteristics at low cost and improves the reliability of the axle housing.
The technical object of the present invention is achieved by the following means.
The invention provides a nodular cast iron axle housing which comprises the following chemical components: c: 3.5-3.9%, Si: 1.8-2.5%, Mn: 0.2-0.4%, Cu: 0.4-0.8%, B: 10-50ppm, Mg is less than or equal to 0.08%, RE is less than or equal to 0.05%, and the balance is Fe and inevitable impurities, wherein C/10B is 80-360, Si/10B is 44-200, and CE is C +1/3Si is 4.3-4.6.
The design principle of the composition, content and proportion relationship of the invention is described below.
C: carbon is an element constituting the graphite structure, and contributes to improvement of the molten iron fluidity of spheroidal graphite cast iron. The carbon is beneficial to improving the strength, the performances such as strength, toughness and elongation and the like are simultaneously reduced due to graphite segregation when the carbon is too high, the strength of the nodular cast iron axle housing cannot be guaranteed when the carbon is too low, the fluidity of molten iron is poor, casting defects are increased, and various mechanical properties are reduced. The nodular cast iron axle housing is a thin-wall structural part, and the condition that the carbon content is too high or too low is crucial to obtaining various mechanical properties of the thin-wall axle housing. Suitable C contents of the present invention are 3.5-3.9%, preferably 3.55-3.85%, more preferably 3.6-3.8%.
Si: silicon is a graphitization promoting element and a solid solution strengthening element, the influence of the content of Si on the fluidity of molten iron is large, and the high-temperature oxidation resistance of Si can be improved. If the Si content is too low, the graphitization effect and the strengthening effect of the nodular cast iron axle housing are insufficient, if the Si content is too high, the plasticity and the elongation of the nodular cast iron axle housing are remarkably reduced, and the toughness is obviously deteriorated, and the Si content in the invention is limited to 1.8-2.5%, preferably 1.9-2.4%, and more preferably 2.0-2.3%.
Mn: manganese can combine with sulphur to generate MnS thereby reduce impurity sulphur to the worsening of nodular cast iron axle housing performance to right amount of Mn is profitable to the intensity of guaranteeing the nodular cast iron axle housing, and too high Mn can lead to the plasticity and the toughness of nodular cast iron axle housing to descend, and Mn crosses low then desulfurization effect and intensive effect not enough. The Mn content in the present invention is set to 0.2 to 0.4%, preferably 0.25 to 0.35%.
Cu: copper is a strengthening element of spheroidal graphite cast iron axle housings, but causes the elongation property to be reduced. If Cu is too low, the strengthening effect is not significant, and if Cu is too high, the elongation property is seriously deteriorated. The Cu content in the present invention is limited to 0.4 to 0.8%, preferably 0.45 to 0.75%, more preferably 0.55 to 0.65%.
Mg: magnesium is an optional additive element of the nodular cast iron axle housing, magnesium is an element for promoting spheroidization, O and S are impurities for preventing graphite spheroidization, and Mg can react with the O and S to promote nodular crystallization. The Mg content is too high, and the inclusions are easy to form or are separated out during crystallization, so that the nodular cast iron axle housing becomes brittle, and the plasticity and the toughness are reduced. The content of Mg in the present invention is set to 0.08% or less, preferably 0.02 to 0.07%, more preferably 0.03 to 0.06%.
RE: the rare earth is an optional additive element of the nodular cast iron axle housing, and the rare earth is an element for promoting spheroidization, can react with O, S, ensures the spheroidization effect of graphite, and is beneficial to the refinement of the spheroidal graphite. The cost is excessively high and the cost of the manufacturing process is increased. The rare earth content is set to 0.05% or less, preferably 0.01 to 0.04%, more preferably 0.02 to 0.03% in the present invention.
B. C/10B and Si/10B: the trace amount of boron promotes the presence of free carbon to reduce the amount of carbide generated, thereby promoting graphitization and refining graphite. Although trace boron is beneficial to improving the toughness, strength, fatigue strength and the like of the nodular cast iron axle housing, and can form boron carbide which can effectively hinder the expansion of fatigue cracks so as to greatly improve the fatigue performance of the material, the boron carbide usually presents a continuous net-shaped structure, and the net-shaped structure can cause the mechanical properties of the nodular cast iron axle housing, such as the strength, the toughness, the plasticity, the fatigue strength and the like, to be deteriorated. The inventor of the invention researches and discovers that by controlling the proportion range of C and B within a certain range, not only can enough free carbon be ensured to be existed for graphitization and graphite thinning, but also a certain amount of boron carbide can be formed, and by controlling the reasonable proportion range of Si and B, the boron carbide can be existed in a discontinuous net form, and the negative effects on strength, toughness, fatigue strength and plasticity are avoided. Thus, on the basis of adding trace boron and controlling the proportion of carbon, silicon and boron, the strength, toughness, plasticity and fatigue performance of the nodular cast iron axle housing are considered, the graphite size grade reaches 6-7 grades, and the spheroidization grade reaches 1-2 grades. In order to obtain the above effects, the content of B in the present invention is set to 10 to 50ppm, preferably 25 to 45ppm, more preferably 30 to 40 ppm; C/10B is defined as 80-360, preferably 85-150, and Si/10B is defined as 44-200, preferably 50-90.
CE: the proper carbon equivalent is important for ensuring the graphitization effect and the molten iron fluidity, and the excellent molten iron fluidity has good inhibition effect on casting defects, so that various mechanical properties of the nodular cast iron axle housing can be effectively improved. The nodular cast iron axle housing is a thin-wall structural part, has high requirements on casting performance and graphite form, and has a particularly remarkable influence on various performances of the thin-wall axle housing due to carbon equivalent. If the carbon equivalent is too low, the spheroidization of graphite is poor, the fluidity of molten iron is insufficient, casting defects are increased, and if the carbon equivalent is too high, the graphite floating phenomenon is easy to occur, and the casting quality is reduced. The carbon equivalent CE is limited to 4.3-4.6 by the invention.
In the present invention, a non-exhaustive list of the inevitable impurity elements is P, S, and the contents of the inevitable impurity elements are defined as P: 0.05% or less, S: below 0.03%, the lower the content of impurities, the better, but the higher the requirements for raw materials and smelting, the higher the cost, and the preferred P: 0.03% or less, S: less than 0.02%.
The nodular cast iron axle housing of the invention can further comprise 0.01 to 1 percent of V and/or Mo on the basis of the elements.
V and/or Mo: v and Mo are elements capable of enhancing tensile strength, yield strength and fatigue characteristics of the nodular cast iron axle housing by forming carbides, but too high content of V or Mo causes too much carbides to be generated to affect the spheroidizing effect of graphite, and the increase of carbides sharply deteriorates toughness and plasticity of the nodular cast iron axle housing. Thus, the amount of V and/or Mo to be added is controlled to be 0.01 to 1%, preferably 0.05 to 0.95%, more preferably 0.1 to 0.9%, still more preferably 0.2 to 0.8%, most preferably 0.3 to 0.7%.
The microstructure matrix of the nodular cast iron axle housing is pearlite and ferrite, the spheroidization grade of the nodular cast iron axle housing is 1-2 grades, and the size grade of graphite is 6-7 grades.
Through the optimization of the components, the content and the proportion relation, the tensile strength of the nodular cast iron axle housing is more than 700MPa, the elongation is more than 10 percent, the yield strength is more than 480MPa, and the room-temperature impact toughness is 45J/cm2The fatigue life of the bench test is more than 150 ten thousand times.
In addition, as another aspect of the invention, the invention also provides a preparation method of the nodular cast iron axle housing, which comprises the steps of smelting, spheroidizing, inoculating and pouring.
Preferably, the sand-lined metal mold process is selected in the pouring step, sand-lined metal mold casting has a chilling effect in the crystallization process of the nodular cast iron liquid, crystal grains can be further refined, the strength and the hardness are effectively improved, self-feeding can be carried out on the axle housing through graphitization expansion of the nodular cast iron, the casting defects are further reduced, and the axle housing casting quality is improved.
The beneficial effects of the invention are as follows.
The nodular cast iron axle housing disclosed by the invention is simple in component design, is strengthened by cheap common elements of Si, Mn and Cu, and is added with trace B to further improve the mechanical property of the nodular cast iron axle housing. By controlling the content proportion relation of the elements C and B, a certain amount of boron carbide is generated while the effects of promoting graphitization and refining graphite by B are fully exerted, and by limiting the relation of Si and B, the boron carbide is prevented from being generated in a continuous net form, and the boron carbide in the discontinuous net form does not have negative influence on various mechanical properties of the nodular cast iron axle housing, so that the improvement effect of trace boron on the strength and toughness of the nodular cast iron axle housing is ensured, the boron carbide in the discontinuous net form has a blocking effect on the expansion of fatigue cracks, and the effect of the boron carbide on the improvement of the fatigue property of the nodular cast iron axle housing is effectively exerted; the control of CE is important for obtaining excellent graphite form, particularly for a thin-wall structural member such as an axle housing, the graphite floating is difficult to control in the casting process of too high CE, the fluidity of too low CE molten iron is reduced, the casting defects are increased, and the proper CE is very important for ensuring the mechanical property of the axle housing. The nodular cast iron axle housing provided by the invention has the advantages that the cost is effectively controlled, and meanwhile, the excellent strength, toughness, plasticity and fatigue property are obtained.
Drawings
FIG. 1 is a pictorial view of an axle housing made of nodular cast iron cast by pouring in the invention example 1.
Detailed Description
In order to make those skilled in the art fully understand the technical scheme and the beneficial effects of the present invention, the following further description is made in combination with specific test examples.
And (3) preparing the nodular cast iron axle housing according to the design components, wherein all P elements are qualified if controlled to be 0.025% +/-0.002%, and all S elements are qualified if controlled to be 0.02% +/-0.002%. The specific preparation method is as follows.
The first step, chemical composition design: selecting pig iron, scrap steel, foundry returns and the like with low sulfur, phosphorus and manganese contents as raw materials according to target chemical components, and calculating the consumption of each raw material.
Step two, smelting in an intermediate frequency furnace: and smelting each component into molten iron by adopting a medium-frequency induction furnace.
Step three, spheroidizing: the nodulizer is a rare earth magnesium silicon nodulizer, and the nodulizing method is to perform nodulizing treatment by adopting a flushing method.
Step four, inoculation treatment and pouring: adopting a ferrosilicon inoculant to perform inoculation treatment in a ladle; and casting by adopting an iron mold sand-lined process, and respectively pouring each group of components to obtain two nodular cast iron axle housings.
And cutting one nodular cast iron axle housing obtained by pouring, then carrying out chemical component analysis, and simultaneously carrying out observation and analysis on the microstructure by detecting the strength, the elongation (plasticity) and the toughness. The analysis of chemical components, the test of strength, elongation (plasticity), toughness performance and the observation and analysis of microstructure are carried out according to the national standard GB/T1348-2009 and the cited standard requirements. Performing a fatigue performance bench test on the other nodular cast iron axle housing obtained by casting, wherein a fatigue life of more than 180 ten thousand times is marked as 'delta', a fatigue life of more than 150 ten thousand times but less than 180 ten thousand times is marked as 'good', and a fatigue fracture before less than 150 ten thousand times is marked as 'x'; the bench test of the fatigue property of the nodular cast iron axle housing is carried out according to the QC/T533-1999 standard. The analysis results of the chemical components of the nodular cast iron axle housings of test numbers 1 to 25 are recorded in table 1, and the results of various mechanical property tests and structure observation are shown in table 2.
Table 1 (the components are in percentage by mass, and the balance is Fe)
| Numbering | C | Si | Mn | Cu | Mg | RE | B | C/10B | Si/10B | CE | Type (B) |
| 1 | 3.52 | 2.44 | 0.38 | 0.58 | 0.064 | 0.016 | 0.0018 | 195.6 | 135.6 | 4.33 | Examples of the invention |
| 2 | 3.55 | 2.35 | 0.22 | 0.49 | 0.036 | 0.025 | 0.0014 | 253.6 | 167.9 | 4.33 | Examples of the invention |
| 3 | 3.59 | 2.17 | 0.27 | 0.41 | 0.019 | 0.045 | 0.0034 | 105.6 | 63.8 | 4.31 | Examples of the invention |
| 4 | 3.64 | 2.04 | 0.35 | 0.43 | 0.045 | 0.013 | 0.0025 | 145.6 | 81.6 | 4.32 | Examples of the invention |
| 5 | 3.67 | 2.24 | 0.24 | 0.64 | 0.024 | 0.022 | 0.0039 | 94.1 | 57.4 | 4.42 | Examples of the invention |
| 6 | 3.71 | 1.84 | 0.31 | 0.52 | 0.013 | 0.042 | 0.0028 | 132.5 | 65.7 | 4.32 | Examples of the invention |
| 7 | 3.76 | 2.08 | 0.34 | 0.71 | 0.057 | 0.031 | 0.004 | 94.0 | 52.0 | 4.45 | Examples of the invention |
| 8 | 3.78 | 1.89 | 0.22 | 0.45 | 0.072 | 0.039 | 0.0036 | 105.0 | 52.5 | 4.41 | Examples of the invention |
| 9 | 3.83 | 1.95 | 0.28 | 0.61 | 0.028 | 0.047 | 0.0021 | 182.4 | 92.9 | 4.48 | Examples of the invention |
| 10 | 3.85 | 2.11 | 0.29 | 0.78 | 0.018 | 0.028 | 0.0046 | 83.7 | 45.9 | 4.55 | Examples of the invention |
| 11 | 3.88 | 1.87 | 0.36 | 0.55 | 0.015 | 0.045 | 0.0041 | 94.6 | 45.6 | 4.50 | Examples of the invention |
| 12 | 3.88 | 1.87 | 0.36 | 0.55 | 0.015 | 0.045 | 0.001 | 388.0 | 187.0 | 4.50 | Comparative example |
| 13 | 3.88 | 1.87 | 0.36 | 0.55 | 0.015 | 0.045 | 0.0045 | 86.2 | 41.6 | 4.50 | Comparative example |
| 14 | 3.52 | 2.44 | 0.38 | 0.58 | 0.064 | 0.017 | 0.0011 | 320.0 | 221.8 | 4.33 | Comparative example |
| 15 | 3.52 | 2.44 | 0.38 | 0.58 | 0.064 | 0.017 | 0.0046 | 76.5 | 53.0 | 4.33 | Comparative example |
| 16 | 3.95 | 2.11 | 0.29 | 0.78 | 0.018 | 0.028 | 0.0046 | 85.9 | 45.9 | 4.65 | Comparative example |
| 17 | 3.37 | 2.11 | 0.29 | 0.78 | 0.018 | 0.028 | 0.0046 | 73.3 | 45.9 | 4.07 | Comparative example |
| 18 | 3.55 | 1.68 | 0.22 | 0.49 | 0.036 | 0.025 | 0.0014 | 253.6 | 120.0 | 4.11 | Comparative example |
| 19 | 3.78 | 2.64 | 0.22 | 0.45 | 0.072 | 0.039 | 0.0036 | 105.0 | 73.3 | 4.66 | Comparative example |
| 20 | 3.85 | 2.42 | 0.29 | 0.78 | 0.018 | 0.028 | 0.0046 | 83.7 | 52.6 | 4.66 | Comparative example |
| 21 | 3.83 | 2.44 | 0.38 | 0.58 | 0.064 | 0.016 | 0.0018 | 212.8 | 135.6 | 4.64 | Comparative example |
| 22 | 3.55 | 2.04 | 0.35 | 0.43 | 0.045 | 0.013 | 0.0025 | 142.0 | 81.6 | 4.23 | Comparative example |
| 23 | 3.59 | 1.85 | 0.27 | 0.41 | 0.019 | 0.045 | 0.0034 | 105.6 | 54.4 | 4.21 | Comparative example |
| 24 | 3.67 | 2.24 | 0.24 | 0.64 | 0.024 | 0.022 | 0.0062 | 59.2 | 36.1 | 4.42 | Comparative example |
| 25 | 3.67 | 2.24 | 0.24 | 0.64 | 0.024 | 0.022 | 0.0007 | 524.3 | 320.0 | 4.42 | Comparative example |
In the above test examples, the components numbered 1 to 11 and the element ratio elements all meet the requirements of the present invention, and are the invention examples of the present invention. 12-25 parts of spheroidal graphite cast iron axle housing, at least one of the components or the element ratios thereof does not meet the requirements of the present invention, and therefore, test example nos. 12-25 are comparative examples of the present invention.
Table 2 shows the mechanical properties and microstructure of test Nos. 1 to 25.
TABLE 2
Further analysis is described below with reference to the chemical composition of table 1 and the mechanical properties and microstructure of table 2.
The numbers 1 to 11 in the table 1 are all inventive examples of the present invention, which satisfy the requirements of the present invention for the content and the ratio of each element. The mechanical properties of the invention examples in Table 2 can satisfy the requirements of tensile strength of more than 700MPa, elongation of more than 10%, yield strength of more than 480MPa and room-temperature impact toughness of 45J/cm2The fatigue life of the bench test is more than 150 ten thousand times. In terms of microstructure, the spheroidization grades of the invention examples in Table 2 are 1-2 grades, and the graphite size grades are 6-7 grades. In particular, in the invention examples 3 to 8 satisfying 85 to 150 of C/10B and 50 to 90 of Si/10B, the fatigue life in the bench test was 180 ten thousand or more (i.e., ". DELTA."), and it was found that C/10B, Si/10B, which is controlled reasonably, is in the preferable range, and the significance of obtaining excellent fatigue performance was particularly outstanding.
Comparative examples of the present invention are analyzed one by one in conjunction with tables 1 and 2 below.
Comparative example 12 is a comparative example of invention example 11, which reduces the B content in invention example 11, resulting in C/10B being higher than the requirements of the present invention, however, since C/10B is too high, the amount of boron carbide generated is too small, the effect of improving mechanical properties is insufficient, and the effect of boron on promoting graphitization and thinning graphite is weakened, resulting in that the yield strength, toughness, elongation, and fatigue properties of the nodular cast iron axle housing fail to meet the requirements of the present invention, neither the spheroidization grade nor the graphite size grade meet the requirements of the present invention, and the tensile strength is also greatly reduced relative to invention example 11. The specification of proper C/10B is important for ensuring the tensile strength, yield strength, elongation, toughness, fatigue property, spheroidization rate and graphite size grade of the nodular cast iron axle housing.
Comparative example 13 is a comparative example of invention example 11, which increases the B content in invention example 11, resulting in Si/10B being lower than the requirements of the invention, however, while an increase in B content is advantageous for refining graphite to increase the graphite size grade, an increase in B content means more network-structured boron carbides exist, Si has limited ability to hinder continuous network-structured boron carbides, the presence of continuous network-structured boron carbides counteracts the strengthening effect brought by B and further deteriorates the mechanical properties, resulting in that the yield strength, toughness, elongation, fatigue properties of the nodular cast iron axle housing do not meet the requirements of the invention, and the tensile strength is also greatly reduced relative to invention example 11. The specification of proper Si/10B is important for ensuring the tensile strength, yield strength, elongation, toughness and fatigue performance of the nodular cast iron axle housing.
Comparative example 14 is a comparative example of invention example 1, which reduces the content of B in invention example 1, resulting in Si/10B being higher than the requirements of the present invention, however, since Si/10B is too high, the hindering effect of Si on the formation capability of continuous network boron carbide is limited, resulting in that the yield strength, toughness, elongation, fatigue property of the nodular cast iron axle housing cannot meet the requirements of the present invention, and the tensile strength is also greatly reduced compared to invention example 1. The specification of proper Si/10B is important for ensuring the tensile strength, yield strength, elongation, toughness and fatigue performance of the nodular cast iron axle housing.
Comparative example 15 is a comparative example of invention example 1, which increases the B content in invention example 1, resulting in C/10B being lower than the requirements of the invention, however, while an increase in B content is advantageous for refining graphite to increase the graphite size grade, an increase in B content means more network-structured boron carbide exists, Si has a limited ability to hinder continuous network-structured boron carbide, the presence of continuous network-structured boron carbide counteracts the strengthening effect brought by B and further deteriorates the mechanical properties, resulting in that the toughness, elongation, fatigue properties of the nodular cast iron axle housing do not meet the requirements of the invention, and the tensile strength and yield strength are also greatly reduced relative to invention example 1. The specification of proper C/10B is important for ensuring the tensile strength, yield strength, elongation, toughness and fatigue performance of the nodular cast iron axle housing.
The comparative example 16 is the comparative example of invention example 10, which increases the content of C in invention example 10, and although C/10B is still within the scope of the present invention, since the content of C is higher than the requirement of the present invention, CE is higher than the requirement of the present invention, too high CE causes the floating graphite to increase during the casting process of the thin-wall axle housing, so that the casting quality is obviously reduced, and each mechanical property of the nodular cast iron axle housing is seriously affected, so that the tensile strength, yield strength, elongation, toughness, fatigue property, and graphite size grade of the nodular cast iron axle housing cannot meet the invention requirement, which shows that controlling the appropriate content of C and CE is important for ensuring the tensile strength, yield strength, elongation, toughness, fatigue property, and graphite size grade of the nodular cast iron axle housing.
The comparative example 17 is the comparative example of invention example 10, which reduces the content of C in invention example 10, and although the C/10B thereof is still within the scope of the present invention, CE is lower than the requirement of the present invention due to the content of C being lower than the requirement of the present invention, CE is too low to cause the reduction of the fluidity of molten iron, the insufficiency of the spheroidizing ability of graphite, casting defects are increased, various mechanical properties of the nodular cast iron axle housing are seriously affected, and the tensile strength, yield strength, elongation, toughness, fatigue property and spheroidization grade of the nodular cast iron axle housing cannot meet the requirements of the present invention, which shows that the control of the appropriate content of C and CE is important for ensuring the tensile strength, yield strength, elongation, toughness, fatigue property and spheroidization grade of the nodular cast iron axle housing.
The comparative example 18 is the comparative example of invention example 2, which reduces the Si content in invention example 2, and although the Si/10B thereof is still within the scope of the present invention, CE is lower than the requirement of the present invention due to the Si content being higher than the requirement of the present invention, CE is too low to cause the reduction of the fluidity of molten iron, the insufficiency of the spheroidizing ability of graphite, casting defects are increased, various mechanical properties of the nodular cast iron axle housing are seriously affected, and the tensile strength, yield strength, elongation, toughness, fatigue property, and spheroidization grade of the nodular cast iron axle housing cannot meet the requirements of the present invention, which shows that controlling the appropriate Si content and CE is important for ensuring the tensile strength, yield strength, elongation, toughness, fatigue property, and spheroidization grade of the nodular cast iron axle housing.
The comparative example 19 is the comparative example of invention example 8, which increases the Si content in invention example 8, although the Si/10B is still within the scope of the present invention, since the Si content is higher than the requirement of the present invention, CE is higher than the requirement of the present invention, too high CE causes the floating graphite to increase during the casting process of the thin-wall axle housing, the casting quality is obviously reduced, various mechanical properties of the nodular cast iron axle housing are seriously affected, and the tensile strength, yield strength, elongation, toughness, fatigue property and graphite size grade of the nodular cast iron axle housing cannot meet the invention requirements, which shows that controlling the appropriate Si content and CE is important for ensuring the tensile strength, yield strength, elongation, toughness, fatigue property and graphite size grade of the nodular cast iron axle housing.
The comparative example 20 is the comparative example of the invention example 10, the content of Si in the invention example 10 is increased, although Si and Si/10B are still within the scope of the invention, CE is higher than the requirement of the invention, too high CE causes the floating graphite to increase in the casting process of the thin-wall axle housing, the casting quality is obviously reduced, various mechanical properties of the nodular cast iron axle housing are seriously affected, the yield strength, elongation, toughness, fatigue property and graphite size level of the nodular cast iron axle housing cannot meet the invention requirement, and the tensile strength is greatly reduced, which shows that controlling proper CE is important for ensuring the tensile strength, yield strength, elongation, toughness, fatigue property and graphite size level of the nodular cast iron axle housing.
The comparative example 21 is the comparative example of the invention example 1, the content of C in the invention example 1 is increased, although C and C/10B are still within the scope of the invention, CE is higher than the requirement of the invention, too high CE causes the floating graphite to increase in the casting process of the thin-wall axle housing, the casting quality is obviously reduced, various mechanical properties of the nodular cast iron axle housing are seriously affected, the yield strength, elongation, toughness, fatigue property and graphite size grade of the nodular cast iron axle housing cannot meet the invention requirement, and the tensile strength is greatly reduced, which shows that controlling proper CE is important for ensuring the tensile strength, yield strength, elongation, toughness, fatigue property and graphite size grade of the nodular cast iron axle housing.
Comparative example 22 is a comparative example of invention example 4, which reduces the content of C in invention example 4, and although C and C/10B are still within the scope of the present invention, CE is lower than the requirements of the present invention, too low CE leads to reduced molten iron fluidity, insufficient graphite spheroidization capacity, increased casting defects, and severe influence on various mechanical properties of the nodular cast iron axle housing, resulting in that the tensile strength, yield strength, elongation, toughness, fatigue property, and spheroidization grade of the nodular cast iron axle housing cannot meet the requirements of the present invention, indicating that controlling appropriate CE is important for ensuring the tensile strength, yield strength, elongation, toughness, fatigue property, and spheroidization grade of the nodular cast iron axle housing.
The comparative example 23 is the comparative example of invention example 3, which reduces the content of Si in invention example 3, and although Si and Si/10B are still within the scope of the present invention, CE is lower than the requirement of the present invention, too low CE causes the reduction of the fluidity of molten iron, the insufficient spheroidization ability of graphite, the increase of casting defects, and seriously affects various mechanical properties of the nodular cast iron axle housing, so that the tensile strength, yield strength, elongation, toughness, fatigue property, and spheroidization grade of the nodular cast iron axle housing cannot meet the requirements of the present invention, which indicates that controlling proper CE is important for ensuring the tensile strength, yield strength, elongation, toughness, fatigue property, and spheroidization grade of the nodular cast iron axle housing.
Comparative example 24 is a comparative example of inventive example 5, which increased the amount of B in inventive example 5, resulting in B being higher than the requirements of the invention and C/10B, Si/10B being both lower than the requirements of the invention; the C/10B and Si/10B are too low due to the fact that the content of B is too high, the increase of the content of B means the existence of more boron carbide with a net structure, Si has limited capacity of hindering the boron carbide with the continuous net structure, the strengthening effect brought by B is offset by the existence of the continuous net boron carbide, mechanical properties are further deteriorated, the yield strength, toughness, elongation and fatigue strength of the nodular cast iron axle housing cannot meet the requirements of the invention, and the tensile strength is greatly reduced. The specification of proper B, C/10B, Si/10B is important for ensuring the tensile strength, yield strength, elongation, toughness and fatigue performance of the nodular cast iron axle housing.
Comparative example 25 is a comparative example of invention example 5, which reduces the B content in invention example 5, resulting in B being lower than the requirements of the present invention and C/10B, Si/10B being higher than the requirements of the present invention, too low B resulting in too high C/10B, reduced formation of boron carbide by B resulting in reduced strengthening effect and reduced graphitization promotion and graphite refining effects, too low B resulting in too high Si/10B resulting in limited hindering effect of Si on the formation of continuous network boron carbide, resulting in spheroidal graphite cast iron axle housings whose tensile strength, yield strength, toughness, elongation, fatigue strength do not meet the requirements of the present invention, and neither spheroidization grade nor graphite size grade meet the requirements of the present invention. The specification of an appropriate B, Si/10B, C/10B is important to ensure the tensile strength, yield strength, elongation, toughness, fatigue characteristics, spheroidization rate and graphite size grade of the nodular cast iron axle housing.
The above description of the embodiments is only intended to facilitate the understanding of the method of the invention and its core idea. It should be noted that, for those skilled in the art, it is possible to make various improvements and modifications to the present invention without departing from the principle of the present invention, and those improvements and modifications also fall within the scope of the claims of the present invention.
The previous description of the disclosed embodiments is provided to enable any person skilled in the art to make or use the present invention. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the generic principles defined herein may be applied to other embodiments without departing from the spirit or scope of the invention. Thus, the present invention is not intended to be limited to the embodiments shown herein but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.
Claims (10)
1. The utility model provides a nodular cast iron axle housing, its characterized in that, the chemical composition of nodular cast iron axle housing is: c: 3.5-3.9%, Si: 1.8-2.5%, Mn: 0.2-0.4%, Cu: 0.4-0.8%, B: 10-50ppm, Mg is less than or equal to 0.08%, RE is less than or equal to 0.05%, and the balance is Fe and inevitable impurities, wherein C/10B is 80-360, Si/10B is 44-200, and CE is C +1/3Si is 4.3-4.6.
2. The spheroidal graphite cast iron axle housing according to claim 1, further containing 0.45-0.75% of Cu.
3. A nodular cast iron axle housing according to any one of claims 1 to 2, characterised in that it further contains 0.01-1% V and/or Mo.
4. A ductile iron axle housing according to any one of claims 1 to 3, wherein said C content is 3.55 to 3.85%.
5. A ductile iron axle housing according to any one of claims 1 to 4, wherein said Si content is 1.9 to 2.4%.
6. A ductile iron axle housing according to any one of claims 1 to 5, wherein said B content is 25 to 65 ppm.
7. A ductile iron axle housing according to any one of claims 1 to 6, wherein said RE content is 0.01 to 0.04% and said Mg content is 0.02 to 0.07%.
8. A ductile iron axle housing according to any one of claims 1 to 7, wherein said C/10B-85-150 and Si/10B-50-90.
9. The nodular cast iron axle housing of any one of claims 1 to 8, wherein the tensile strength of the nodular cast iron axle housing is 700MPa or more, the elongation is 10% or more, the yield strength is 480MPa or more, and the room temperature impact toughness is 45J/cm2The fatigue life of the bench test is more than 150 ten thousand times.
10. A method for manufacturing a spheroidal graphite cast iron axle housing according to any one of claims 1 to 9, characterized in that: the preparation method of the nodular cast iron axle housing comprises the steps of smelting, spheroidizing, inoculating and pouring.
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| CN114700461A (en) * | 2022-03-09 | 2022-07-05 | 山西康腾威机械制造有限公司 | Casting method of thin-wall nodular iron casting capable of eliminating free cementite |
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| CN103834854A (en) * | 2014-03-20 | 2014-06-04 | 上海宝华威热处理设备有限公司 | Isothermal quenching nodular cast iron roller for push-pull vehicle on heat treatment production line and production method thereof |
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| CN114700461A (en) * | 2022-03-09 | 2022-07-05 | 山西康腾威机械制造有限公司 | Casting method of thin-wall nodular iron casting capable of eliminating free cementite |
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