CN110952031A - Isothermal quenching nodular cast iron and preparation method and application thereof - Google Patents
Isothermal quenching nodular cast iron and preparation method and application thereof Download PDFInfo
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- 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
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B22—CASTING; POWDER METALLURGY
- B22C—FOUNDRY MOULDING
- B22C9/00—Moulds or cores; Moulding processes
- B22C9/02—Sand moulds or like moulds for shaped castings
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B60—VEHICLES IN GENERAL
- B60B—VEHICLE WHEELS; CASTORS; AXLES FOR WHEELS OR CASTORS; INCREASING WHEEL ADHESION
- B60B35/00—Axle units; Parts thereof ; Arrangements for lubrication of axles
- B60B35/12—Torque-transmitting axles
- B60B35/16—Axle housings
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- C—CHEMISTRY; METALLURGY
- C21—METALLURGY OF IRON
- C21D—MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUS METALS OR ALLOYS; MAKING METAL MALLEABLE, e.g. BY DECARBURISATION OR TEMPERING
- C21D1/00—General methods or devices for heat treatment, e.g. annealing, hardening, quenching or tempering
- C21D1/18—Hardening; Quenching with or without subsequent tempering
- C21D1/19—Hardening; Quenching with or without subsequent tempering by interrupted quenching
- C21D1/20—Isothermal quenching, e.g. bainitic hardening
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- 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
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- 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
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Abstract
The invention relates to austempered ductile iron and a preparation method and application thereof, wherein the austempered ductile iron comprises the following components in percentage by weight: 3.60 to 3.75 weight percent of C, 2.30 to 2.50 weight percent of Si, 0.20 to 0.40 weight percent of Mn, less than or equal to 0.06 weight percent of P, less than or equal to 0.03 weight percent of S, 0.70 to 0.80 weight percent of Cu, 0.10 to 0.20 weight percent of Mo, 0.03 to 0.06 weight percent of Mg, and the balance of Fe. The preparation method of the austempered ductile iron comprises the following steps: (1) carrying out spheroidizing inoculation on molten iron by adopting a flushing spheroidizing method, pouring after inoculation is finished, and cooling after pouring is finished to obtain nodular cast iron; (2) and (2) sequentially carrying out preheating, austenitizing and salt bath quenching on the nodular cast iron obtained in the step (1), and obtaining the austempered nodular cast iron after the salt bath quenching is finished. The invention solves the problem that the performance of the axle housing does not reach the standard when the isothermal quenching nodular cast iron material is used for integrated manufacturing, and realizes the efficient utilization of the isothermal quenching nodular cast iron in the integrated axle housing.
Description
Technical Field
The invention relates to the field of nodular cast iron, and particularly relates to austempered nodular cast iron and a preparation method and application thereof.
Background
At present, the axle housing used by domestic commercial vehicles mainly comprises a welding axle housing, an internal expansion axle housing, a nodular cast iron axle housing, a cast steel axle housing and the like, wherein the cast steel axle housing is generally used on a heavy engineering vehicle. The cast steel axle housing has the advantages of heavy weight, wall thickness of 36-40mm, complex manufacturing process due to welding of the axle head part of the axle housing and the steel plate bracket, more oil leakage phenomenon in the using process of customers, deformation after welding of the axle head part and the like. The prior art indirectly overcomes the problems, for example, the axle housing formed in one step is provided in CN102407429A, but the axle housing and the spindle head still need to be welded, and further, in CN105711338A, a reinforcing ring is provided to the welding part to enhance the service life of the axle housing, but the problems existing in the welded axle housing are not fundamentally solved.
The austempered ductile iron is a cast iron material obtained by carrying out austempering treatment on ductile cast iron with a certain component, and has the advantages of light weight, high tensile strength, high yield strength, high fatigue strength, good wear resistance and good antifriction property and the like compared with a common cast steel material. At present, the austempering ductile cast iron material is mainly applied to small parts, such as a hammer head in CN105463300A, so as to solve the problems of cracking, abrasion and the like of the hammer head in the using process. In CN205273051U, austempered ductile iron is applied to a plate spring mechanism in an axle housing to solve the problem that the plate spring mechanism is easy to break when being welded on the axle housing, and although the austempered ductile iron is utilized in the invention, the austempered ductile iron is not applied to an upper body of the axle housing. This is mainly because, when the integrated design is carried out and the austempered ductile iron is used as a material, the limitation of the self weight and structure of the axle housing, the insufficiency of the self performance of the material in the manufacturing process and the deformation of the casting cause less successful application of the austempered ductile iron on the integrated axle housing of the commercial vehicle in China at present.
Disclosure of Invention
In view of the problems in the prior art, the invention aims to provide the austempered ductile iron and the preparation method and application thereof.
In order to achieve the purpose, the invention adopts the following technical scheme:
in a first aspect, the invention provides austempered ductile iron which comprises the following components in percentage by weight: 3.60 to 3.75 weight percent of C, 2.30 to 2.50 weight percent of Si, 0.20 to 0.40 weight percent of Mn, less than or equal to 0.06 weight percent of P, less than or equal to 0.03 weight percent of S, 0.70 to 0.80 weight percent of Cu, 0.10 to 0.20 weight percent of Mo, 0.03 to 0.06 weight percent of Mg, and the balance of Fe.
In the present invention, the austempered ductile iron may have a C content of 3.60 to 3.75 wt%, for example, 3.60 wt%, 3.62 wt%, 3.64 wt%, 3.66 wt%, 3.68 wt%, 3.70 wt%, 3.72 wt%, or 3.75 wt%, and the like, and is not limited to the values listed above, and other values not listed above in the present range are also applicable.
In the present invention, the content of Si in the austempered ductile iron is 2.30 to 2.50 wt%, and may be, for example, 2.30 wt%, 2.32 wt%, 2.34 wt%, 2.36 wt%, 2.38 wt%, 2.40 wt%, 2.42 wt%, 2.44 wt%, 2.46 wt%, 2.48 wt%, or 2.50 wt%, and the like, and is not limited to the above-mentioned values, and other values not mentioned in the present range are also applicable.
In the present invention, the austempered ductile iron may have an Mn content of 0.20 to 0.40 wt%, for example, 0.20 wt%, 0.22 wt%, 0.24 wt%, 0.26 wt%, 0.28 wt%, 0.30 wt%, 0.32 wt%, 0.34 wt% 0, 0.36 wt%, 0.38 wt%, or 0.40 wt%, and the content is not limited to the above-mentioned values, and other values not listed in the present range are also applicable.
In the present invention, the content of P in the austempered ductile iron is not more than 0.06 wt%, and may be, for example, 0.06 wt%, 0.055 wt%, 0.05 wt%, 0.045 wt%, 0.04 wt%, 0.035 wt%, 0.03 wt%, 0.025 wt%, 0.02 wt%, 0.015 wt%, or 0.01 wt%, and the like, and is not limited to the above-mentioned numerical values, and other numerical values not mentioned in the present range are also applicable.
In the present invention, the austempered ductile iron may have an S content of 0.03 wt% or less, for example, 0.03 wt%, 0.028 wt%, 0.026 wt%, 0.024 wt%, 0.022 wt%, 0.02 wt%, 0.018 wt%, 0.016 wt%, 0.014 wt%, 0.012 wt%, or 0.01 wt%, and the like, and is not limited to the above-mentioned numerical values, and other numerical values not listed in the present range are also applicable.
In the present invention, the content of Cu in the austempered ductile iron is 0.70 to 0.80 wt%, and may be, for example, 0.70 wt%, 0.71 wt%, 0.72 wt%, 0.73 wt%, 0.74 wt%, 0.75 wt%, 0.76 wt%, 0.77 wt%, 0.78 wt%, 0.79 wt%, or 0.80 wt%, and the like, and is not limited to the above-mentioned values, and other values not listed in the present range are also applicable.
In the present invention, the content of Mo in the austempered ductile iron is 0.10 to 0.20 wt%, and may be, for example, 0.10 wt%, 0.11 wt%, 0.12 wt%, 0.13 wt%, 0.14 wt%, 0.15 wt%, 0.16 wt%, 0.17 wt%, 0.18 wt%, 0.19 wt%, or 0.20 wt%, and the like, and is not limited to the above-mentioned values, and other values not listed in the present range are also applicable.
In the present invention, the content of Mg in the austempered ductile iron is 0.03 to 0.06 wt%, and may be, for example, 0.03 wt%, 0.035 wt%, 0.04 wt%, 0.045 wt%, 0.05 wt%, 0.055 wt%, or 0.06 wt%, and the like, and is not limited to the above-mentioned values, and other values not mentioned in the present range are also applicable.
The isothermal quenching nodular cast iron provided by the invention is applied to a single axle housing through reasonable design of the components and the preparation method of the isothermal quenching nodular cast iron. The problems that the axle housing is easy to deform and the performance does not reach the standard when the axle housing is integrally manufactured by using an isothermal quenching nodular cast iron material are solved.
As a preferred technical scheme of the invention, the austempered ductile cast iron comprises the following components in percentage by weight: 3.65 to 3.70 weight percent of C, 2.35 to 2.45 weight percent of Si, 0.25 to 0.35 weight percent of Mn, less than or equal to 0.06 weight percent of P, less than or equal to 0.03 weight percent of S, 0.72 to 0.78 weight percent of Cu, 0.12 to 0.16 weight percent of Mo, 0.04 to 0.05 weight percent of Mg, and the balance of Fe.
Preferably, the austempered ductile cast iron comprises the following components in percentage by weight: 3.67 percent of C, 2.41wt percent of Si, 0.32 percent of Mn, less than or equal to 0.06 percent of P, less than or equal to 0.03 percent of S, 0.75 percent of Cu, 0.15 percent of Mo, 0.047 percent of Mg0, and the balance of iron.
In the invention, by regulating and controlling the element composition in the isothermal quenching nodular cast iron material, a better grain structure can be obtained to ensure that a casting can obtain a qualified matrix structure after heat treatment, thereby achieving the designed mechanical property. And the problem that the overall performance of the axle housing prepared by the method does not reach the standard is solved.
In a second aspect, the present invention provides a method for preparing austempered ductile iron according to the first aspect, the method comprising the steps of:
(1) carrying out spheroidizing inoculation on molten iron by adopting a flushing spheroidizing method, pouring after inoculation is finished, and cooling after pouring is finished to obtain nodular cast iron;
(2) and (2) sequentially carrying out preheating, austenitizing and salt bath quenching on the nodular cast iron obtained in the step (1), and obtaining the austempered nodular cast iron after the salt bath quenching is finished.
As a preferable technical scheme of the invention, the molten iron in the step (1) is prepared by melting raw materials comprising scrap steel, a carburant, ferrosilicon, ferromanganese, copper and ferromolybdenum in proportion by using an intermediate frequency furnace.
In a preferred embodiment of the present invention, the amount of the nodulizer added in the spheroidizing inoculation in step (1) is 1.2 to 1.4% by mass of the molten iron, and may be, for example, 1.2%, 1.23%, 1.26%, 1.3%, 1.33%, 1.36%, or 1.4%, and is not limited to the above-mentioned values, and other values not mentioned in the present range are also applicable.
Preferably, the nodulizer is a rare earth magnesium nodulizer.
The rare earth magnesium nodulizer used in the invention can be Mg6RE2Rare earth magnesium nodularizer, Mg8RE2Rare earth magnesium nodulariser or Mg8RE1.5Examples of the rare earth magnesium nodulizer include, but are not limited to, those listed above, and other rare earth magnesium nodulizers capable of achieving the effects of the present invention are also suitable.
Preferably, the particle size of the rare earth magnesium nodularizer is 10-30mm, for example, 10mm, 12mm, 14mm, 16mm, 18mm, 20mm, 22mm, 24mm, 26mm, 28mm or 30mm, etc., but not limited to the recited values, and other values not recited in this range are also applicable.
Preferably, the amount of the ferrosilicon inoculant added in the spheroidizing inoculation of the step (1) is 0.6 to 0.8% by mass of the molten iron, and may be, for example, 0.6%, 0.63%, 0.66%, 0.7%, 0.73%, 0.76%, 0.8% or the like, and is not limited to the enumerated values, and other values not enumerated in the present range are also applicable.
Preferably, the ferrosilicon inoculant has a particle size of 8-20mm, such as 8mm, 10mm, 12mm, 14mm, 16mm, 18mm or 20mm, but not limited to the values listed, and other values not listed in this range are equally applicable.
The ferrosilicon inoculant in the invention can be FeSi75Al1.5The ferrosilicon inoculant and the like are not limited to the exemplified ferrosilicon inoculants, and other ferrosilicon inoculants capable of achieving the effects of the present invention are also applicable.
As a preferable technical scheme of the invention, bismuth-containing inoculant is adopted for stream inoculation in the pouring in the step (1).
Preferably, the bismuth-containing inoculant is added in an amount of 0.01 to 0.10% by mass of the molten iron, for example, 0.01%, 0.02%, 0.03%, 0.04%, 0.05%, 0.06%, 0.07%, 0.08%, 0.09%, or 0.10%, and the like, and is not limited to the values listed, and other values not listed in the present range are also applicable.
Preferably, the bismuth-containing inoculant may be a bismuth-containing FOSECO INOCULIN 400 inoculant, a bismuth-containing koliyuan inoculant, or the like, and not limited to the bismuth-containing inoculant listed above, but other bismuth-containing inoculants capable of achieving the effects of the present invention are also suitable.
As a preferred embodiment of the present invention, the temperature of the preheating in the step (2) is 550 ℃ to 600 ℃, for example 550 ℃, 555 ℃, 560 ℃, 565 ℃, 570 ℃, 575 ℃, 580 ℃, 585 ℃, 590 ℃, 595 ℃ or 600 ℃, etc., and is not limited to the values listed, and other values not listed in the present range are also applicable.
Preferably, the preheating time is 90-120min, such as 90min, 95min, 100min, 105min, 110min, 115min or 120min, etc., and is not limited to the recited values, and other values not recited in the present range are also applicable.
Preferably, the austenitizing temperature in step (2) is 880- & ltSUB & gt 900- & gt, and may be 880 ℃, 882 ℃, 884 ℃, 886 ℃, 888 ℃, 890 ℃, 892 ℃, 894 ℃, 896 ℃, 898 ℃, 900 ℃ or the like, for example, and is not limited to the recited values, and other values not recited in the present range are also applicable.
Preferably, the austenitizing in step (2) is performed for a period of 120-150min, such as 120min, 125min, 130min, 135min, 140min, 145min or 150min, and the like, and is not limited to the values listed, and other values not listed in the present disclosure are also applicable.
Preferably, the carbon potential in austenitizing in step (2) is 1.0.
Preferably, the medium for the salt bath quenching in the step (2) is molten salt.
Preferably, the salt bath quenching temperature in step (2) is 360-.
Preferably, the salt bath quenching in step (2) has a holding time of 100-.
The molten salt used in the invention can be a mixed solution of potassium nitrite and sodium nitrite, and the mixing proportion is 40 percent to 60 percent to 40 percent.
In the present invention, the carbon potential is controlled during the austenitizing stage, which is a key factor of the necessary control. During the heat treatment, the austenite on the surface layer of the casting has the decarburization phenomenon. The carbon potential is controlled to prevent decarburization of the surface of the casting, so that austempered ductile iron meeting mechanical properties is obtained under the above heat treatment conditions.
As a preferred technical scheme of the invention, the method comprises the following steps:
(1) carrying out spheroidizing inoculation on the molten iron by adopting a flushing spheroidizing method, pouring after inoculation is finished, and cooling after pouring is finished to obtain nodular cast iron; wherein the adding amount of a nodulizer in the spheroidizing inoculation is 1.2-1.4% of the mass of molten iron, and the nodulizer is a rare earth magnesium nodulizer; the particle size of the rare earth magnesium nodulizer is 10-30 mm; the adding amount of the ferrosilicon inoculant in the spheroidizing inoculation is 0.6-0.8% of the mass of molten iron; the particle size of the ferrosilicon inoculant is 8-20 mm; in the pouring process, bismuth-containing inoculant is adopted for stream inoculation, and the addition amount of the bismuth-containing inoculant is 0.01-0.10% of the mass of molten iron;
(2) sequentially preheating the nodular cast iron obtained in the step (1) at the temperature of 550-600 ℃, austenitizing at the temperature of 880-900 ℃ and at the carbon potential of 1.0, preserving heat for 150min, performing salt bath quenching at the temperature of 360-390 ℃ and preserving heat for 150min, and obtaining the austempered nodular cast iron after the salt bath quenching is finished.
According to the invention, through research and control on the preparation process of the isothermal quenching nodular cast iron, a series of heat treatments are carried out on the poured nodular cast iron, so that the performance of the nodular cast iron material subjected to isothermal quenching treatment reaches the standard, and the problem of deformation possibly caused by large-size castings (the length of an axle housing exceeds 2m) is solved.
In a third aspect, the invention provides an integrated axle housing, which is prepared from the austempered ductile iron of the first aspect.
Preferably, integration axle housing includes the axle housing body, be provided with spindle nose and support on the axle housing body, the axle housing body the spindle nose with steel sheet support is integrated into one piece for casting shaping.
In a fourth aspect, the invention further provides a preparation method of the integrated axle housing in the third aspect, which is characterized by comprising the following steps:
(1) carrying out spheroidizing inoculation on the molten iron by adopting a flushing spheroidizing method, pouring after inoculation is finished, and cooling after pouring is finished to obtain nodular cast iron; wherein the adding amount of a nodulizer in the spheroidizing inoculation is 1.2-1.4% of the mass of molten iron, and the nodulizer is a rare earth magnesium nodulizer; the particle size of the rare earth magnesium nodulizer is 10-30 mm; the adding amount of the ferrosilicon inoculant in the spheroidizing inoculation is 0.6-0.8% of the mass of molten iron; the particle size of the ferrosilicon inoculant is 8-20 mm; in the pouring process, bismuth-containing inoculant is adopted for stream inoculation, and the addition amount of the bismuth-containing inoculant is 0.01-0.10% of the mass of molten iron; wherein the sand mould adopted in the pouring is an integrated axle housing sand mould;
(2) sequentially preheating the nodular cast iron integrated axle housing obtained in the step (1) at the temperature of 550-600 ℃, austenitizing at the temperature of 880-900 ℃ and at the carbon potential of 1.0, preserving heat for 150min, performing salt bath quenching at the temperature of 360-390 ℃ and preserving heat for 150min, and obtaining the isothermal quenching nodular cast iron integrated axle housing after the salt bath quenching is finished.
According to the invention, the application of the austempered ductile iron material in the integrated axle housing is realized through the material selection and the integrated design of the axle housing. Meanwhile, the defects of deformation, performance and the like of the isothermal quenching nodular cast iron in the application of the axle housing are overcome through component selection of the nodular cast iron raw material, research on the preparation method of the isothermal quenching nodular cast iron and reasonable design of the integrated axle housing. According to the invention, the integrated axle housing is prepared by firstly designing the integrated axle housing and the casting process and simultaneously determining the element composition in the austempered ductile iron according to the performance required by the axle housing in the practical application process and the problems of more oil leakage at the welding part, deformation at the axle head part and the like existing in the existing axle housing, so that the prepared integrated axle housing meets the use performance, and the problems of oil leakage caused by welding and deformation caused by the integral forming of the axle head part and the axle housing in the existing axle housing are solved.
Compared with the prior art, the invention at least has the following beneficial effects:
(1) through research on the raw materials and the preparation method thereof in the axle housing manufacturing process, the problem of insufficient performance of the isothermal quenching nodular cast iron in the axle housing manufacturing process is solved.
(2) The isothermal nodular cast iron material is adopted to manufacture the integrated axle housing, so that the integrated casting of products such as a half-axle sleeve, a steel plate bracket and the like is realized, the manufacturing process is saved, and the problems that the oil leakage phenomenon of the cast steel axle housing of the type is more and the deformation exists after the axle head part is welded are solved.
(3) Compared with the existing cast steel axle housing, the integrated axle housing prepared by the isothermal quenching nodular cast iron has the tensile strength and the yield strength which are 1.8 times and 2.3 times of those of the existing cast steel axle housing, and meanwhile, the whole vehicle equipped with the axle housing reduces the weight by 140kg (the weight reduction ratio is 24.6%).
Drawings
FIG. 1 is a metallographic (graphite) photograph of austempered ductile iron of example 1;
FIG. 2 is a photograph of the metallographic phase (matrix) of austempered ductile iron of example 1;
FIG. 3 is a metallographic (graphite) photograph of austempered ductile iron of example 2;
FIG. 4 is a photograph of the metallographic phase (matrix) of austempered ductile iron of example 2;
FIG. 5 is a metallographic (graphite) photograph of austempered ductile iron in example 3;
FIG. 6 is a metallographic (matrix) photograph of austempered ductile iron of example 3;
fig. 7 is a metallographic (graphite) photograph of austempered ductile iron of application example 1;
FIG. 8 is a photograph of the metallographic phase (matrix) of austempered ductile iron of application example 1;
FIG. 9 is a schematic view of an integrated axle housing.
The present invention is described in further detail below. The following examples are merely illustrative of the present invention and do not represent or limit the scope of the claims, which are defined by the claims.
Detailed Description
To better illustrate the invention and to facilitate the understanding of the technical solutions thereof, typical but non-limiting examples of the invention are as follows:
example 1
The isothermal quenching nodular cast iron comprises the following components in percentage by weight: c3.60wt%, Si 2.31 wt%, Mn 0.22 wt%, P0.017 wt%, S0.013 wt%, Cu 0.70 wt%, Mo0.10wt%, Mg 0.035 wt%, and the balance of Fe.
The preparation method of the austempered ductile iron comprises the following steps:
(1) carrying out spheroidizing inoculation on the molten iron by adopting a flushing spheroidizing method, pouring after inoculation is finished, and cooling after pouring is finished to obtain nodular cast iron; wherein the adding amount of a nodulizer in the spheroidizing inoculation is 1.2 percent of the mass of molten iron, and the nodulizer is Mg6RE2Rare earth magnesium nodulizer with particle size of 10-30 mm; the adding amount of the ferrosilicon inoculant in the spheroidizing inoculation is 0.6 percent of the mass of the molten iron, and the ferrosilicon inoculant is FeSi75Al1.5Ferrosilicon B with the granularity of 8-20 mm; in the pouring process, stream inoculation is carried out by adopting a bismuth-containing inoculant, the addition amount of the bismuth-containing inoculant is 0.08 percent of the mass of molten iron, and the bismuth-containing inoculant is FOSECONINOCULIN 400 bismuth-containing inoculant;
(2) sequentially preheating the nodular cast iron obtained in the step (1) at 580 ℃ for 105min, austenitizing at 890 ℃ and 1 carbon potential and preserving heat for 135min, carrying out salt bath quenching at 375 ℃ and preserving heat for 125min, and obtaining the austempered nodular cast iron after the salt bath quenching is finished.
The mechanical property indexes of the obtained austempered ductile iron are shown in table 1, the metallographic photographs of the obtained austempered ductile iron are shown in figures 1 and 2, and figure 1 is a metallographic (graphite) photograph of the austempered ductile iron (graphite: grade 3 in spheroidization rate, grade 6 in spherical diameter and 100 x); FIG. 2 is a photograph of the metallographic phase (matrix) of austempered ductile iron (matrix: austenite and bainite, 500X).
Example 2
The isothermal quenching nodular cast iron comprises the following components in percentage by weight: c3.75wt%, Si 2.47 wt%, Mn 0.40 wt%, P0.025 wt%, S0.013 wt%, Cu 0.80 wt%, Mo0.20wt%, Mg 0.052 wt%, and the balance being Fe.
The preparation method of the austempered ductile iron comprises the following steps:
(1) carrying out spheroidizing inoculation on the molten iron by adopting a flushing spheroidizing method, pouring after inoculation is finished, and cooling after pouring is finished to obtain nodular cast iron; wherein the adding amount of a nodulizer in the spheroidizing inoculation is 1.4 percent of the mass of molten iron, and the nodulizer is Mg6RE2Rare earth magnesium nodulizer with particle size of 10-30 mm; the adding amount of the ferrosilicon inoculant in the spheroidizing inoculation is 0.80 percent of the mass of the molten iron, and the ferrosilicon inoculant is FeSi75Al1.5Ferrosilicon B with the granularity of 8-20 mm; in the pouring process, stream inoculation is carried out by adopting a bismuth-containing inoculant, the addition amount of the bismuth-containing inoculant is 0.10 percent of the mass of molten iron, and the bismuth-containing inoculant is FOSECO INOCULIN 400 bismuth-containing inoculant;
(2) sequentially preheating the nodular cast iron obtained in the step (1) at 580 ℃ for 105min, austenitizing at 900 ℃ and 1.0 carbon potential and preserving heat for 150min, carrying out salt bath quenching at 360 ℃ and preserving heat for 150min, and obtaining the austempered nodular cast iron after the salt bath quenching is finished.
The mechanical property indexes of the obtained austempered ductile iron are shown in table 1, the metallographic photos are shown in fig. 3 and 4, and fig. 3 is the metallographic (graphite) photo of the austempered ductile iron (graphite: grade 3 in spheroidization rate, grade 6 in sphere diameter and 100 x); FIG. 4 is a photograph of the metallographic phase (matrix) of austempered ductile iron (matrix: austenite and bainite, 500X).
Example 3
The isothermal quenching nodular cast iron comprises the following components in percentage by weight: c3.67wt%, Si2.41 wt%, Mn 0.32 wt%, P0.019 wt%, S0.012 wt%, Cu 0.75 wt%, Mo0.15wt%, Mg 0.043 wt%, and the balance of iron.
The preparation method of the austempered ductile iron comprises the following steps:
(1) carrying out spheroidizing inoculation on the molten iron by adopting a flushing spheroidizing method, pouring after inoculation is finished, and cooling after pouring is finished to obtain nodular cast iron; wherein the adding amount of a nodulizer in the spheroidizing inoculation is 1.30 percent of the mass of molten iron, and the nodulizer is Mg6RE2Rare earth magnesium nodulizer with particle size of 10-30 mm; the adding amount of the ferrosilicon inoculant in the spheroidizing inoculation is 0.70 percent of the mass of the molten iron, and the ferrosilicon inoculant is FeSi75Al1.5Ferrosilicon B with the granularity of 8-20 mm; in the pouring process, stream inoculation is carried out by adopting a bismuth-containing inoculant, the addition amount of the bismuth-containing inoculant is 0.09 percent of the mass of molten iron, and the bismuth-containing inoculant is FOSECO INOCULIN 400 bismuth-containing inoculant;
(2) sequentially preheating the nodular cast iron obtained in the step (1) at 580 ℃ for 120min, austenitizing at 880 ℃ and 1.0 carbon potential and preserving heat for 120min, performing salt bath quenching at 390 ℃ and preserving heat for 100min, and obtaining the austempered nodular cast iron after the salt bath quenching is finished.
The mechanical property indexes of the obtained austempered ductile iron are shown in table 1, the metallographic photos are shown in fig. 5 and 6, and fig. 1 is the metallographic (graphite) photo of the austempered ductile iron (graphite: grade 3 in spheroidization rate, grade 6 in sphere diameter and 100 x); FIG. 2 is a photograph of the metallographic phase (matrix) of austempered ductile iron (matrix: austenite and bainite, 500X).
TABLE 1 mechanical Properties of austempered ductile iron in the examples of the present invention
Application example 1
An integrated axle housing and a preparation method thereof, wherein the integrated axle housing comprises the following components in percentage by weight: c3.67wt%, Si2.41 wt%, Mn 0.32 wt%, P0.019 wt%, S0.012 wt%, Cu 0.75 wt%, Mo0.15wt%, Mg 0.043 wt%, and the balance of iron.
The preparation method of the integrated axle housing comprises the following steps:
(1) carrying out spheroidizing inoculation on the molten iron by adopting a flushing spheroidizing method, pouring after inoculation is finished, and cooling after pouring is finished to obtain a nodular cast iron integrated axle housing; wherein the adding amount of a nodulizer in the spheroidizing inoculation is 1.30 percent of the mass of molten iron, and the nodulizer is Mg6RE2Rare earth magnesium nodulizer with particle size of 10-30 mm; the adding amount of the ferrosilicon inoculant in the spheroidizing inoculation is 0.70 percent of the mass of the molten iron, and the ferrosilicon inoculant is FeSi75Al1.5Ferrosilicon B with the granularity of 8-20 mm; in the pouring process, stream inoculation is carried out by adopting a bismuth-containing inoculant, the addition amount of the bismuth-containing inoculant is 0.09 percent of the mass of molten iron, and the bismuth-containing inoculant is FOSECO INOCULIN 400 bismuth-containing inoculant; wherein the sand mould adopted in the pouring is an integrated axle housing sand mould;
(2) and (2) sequentially preheating the nodular cast iron integrated axle housing obtained in the step (1) at 580 ℃ for 120min, austenitizing at 880 ℃ and 1.0 carbon potential and preserving heat for 120min, performing salt bath quenching at 390 ℃ and preserving heat for 100min, and obtaining the integrated axle housing after the salt bath quenching is finished.
The mechanical performance indexes of the integrated axle housing are shown in table 2, the metallographic photos are shown in fig. 7 and 8, and fig. 7 is the metallographic (graphite) photo of the integrated axle housing (graphite: grade 3 spheroidization rate, grade 6 spherical diameter, 100 x); fig. 8 is a photograph of the metallographic phase (matrix) of the integrated axle housing (matrix: austenite and bainite, 500 ×), and fig. 9 is a schematic view of the integrated axle housing produced.
TABLE 2 mechanical Properties of austempered ductile iron integrated axle housing of application example in the present invention
In the present invention, the test methods of tensile strength and elongation after fracture in mechanical properties in examples and application examples were performed in accordance with the regulations of GB/T228.1, and the test method of hardness was performed in accordance with the regulations of GB/T231.1.
As can be seen from the embodiment and the application example, the austempered ductile iron and the integrated axle housing prepared from the austempered ductile iron have excellent mechanical properties, and can meet the axle housing strength of the axle housing in practical application.
The applicant declares that the present invention illustrates the detailed structural features of the present invention through the above embodiments, but the present invention is not limited to the above detailed structural features, that is, it does not mean that the present invention must be implemented depending on the above detailed structural features. It should be understood by those skilled in the art that any modifications of the present invention, equivalent substitutions of selected components of the present invention, additions of auxiliary components, selection of specific modes, etc., are within the scope and disclosure of the present invention.
The preferred embodiments of the present invention have been described in detail, however, the present invention is not limited to the specific details of the above embodiments, and various simple modifications may be made to the technical solution of the present invention within the technical idea of the present invention, and these simple modifications are within the protective scope of the present invention.
It should be noted that the various technical features described in the above embodiments can be combined in any suitable manner without contradiction, and the invention is not described in any way for the possible combinations in order to avoid unnecessary repetition.
In addition, any combination of the various embodiments of the present invention is also possible, and the same should be considered as the disclosure of the present invention as long as it does not depart from the spirit of the present invention.
Claims (10)
1. The austempered ductile iron is characterized by comprising the following components in percentage by weight: 3.60 to 3.75 weight percent of C, 2.30 to 2.50 weight percent of Si, 0.20 to 0.40 weight percent of Mn, less than or equal to 0.06 weight percent of P, less than or equal to 0.03 weight percent of S, 0.70 to 0.80 weight percent of Cu, 0.10 to 0.20 weight percent of Mo, 0.03 to 0.06 weight percent of Mg, and the balance of Fe.
2. The austempered ductile iron of claim 1 comprising the following components in weight percent: 3.65 to 3.70 weight percent of C, 2.35 to 2.45 weight percent of Si, 0.25 to 0.35 weight percent of Mn, less than or equal to 0.06 weight percent of P, less than or equal to 0.03 weight percent of S, 0.72 to 0.78 weight percent of Cu, 0.12 to 0.16 weight percent of Mo, 0.04 to 0.05 weight percent of Mg, and the balance of Fe;
preferably, the austempered ductile cast iron comprises the following components in percentage by weight: 3.67 percent of C, 2.41wt percent of Si, 0.32 percent of Mn, less than or equal to 0.06 percent of P, less than or equal to 0.03 percent of S, 0.75 percent of Cu, 0.15 percent of Mo, 0.047 percent of Mg0, and the balance of iron.
3. The method for producing austempered ductile iron according to claim 1 or 2, characterized by comprising the steps of:
(1) carrying out spheroidizing inoculation on molten iron by adopting a flushing spheroidizing method, pouring after inoculation is finished, and cooling after pouring is finished to obtain nodular cast iron;
(2) and (2) sequentially carrying out preheating, austenitizing and salt bath quenching on the nodular cast iron obtained in the step (1), and obtaining the austempered nodular cast iron after the salt bath quenching is finished.
4. The method according to claim 3, wherein the molten iron of step (1) is prepared by melting raw materials including scrap steel, a carburant, ferrosilicon, ferromanganese, copper, and ferromolybdenum proportionally using an intermediate frequency furnace.
5. The method of claim 3 or 4, wherein the nodulizer is added in the nodulizing inoculant of step (1) in an amount of 1.2-1.4% by mass of the molten iron;
preferably, the nodulizer is a rare earth magnesium nodulizer;
preferably, the particle size of the rare earth magnesium nodulizer is 10-30mm, preferably 15-25 mm;
preferably, the adding amount of the ferrosilicon inoculant in the spheroidizing inoculation of the step (1) is 0.6-0.8 percent of the mass of the molten iron;
preferably, the ferrosilicon inoculant has a particle size of 8-20mm, preferably 10-15 mm.
6. The process according to any one of claims 3 to 5, wherein in the step (1) the casting is stream-inoculated with a bismuth-containing inoculant;
preferably, the addition amount of the bismuth-containing inoculant is 0.01-0.10% of the mass of the molten iron.
7. The method according to any one of claims 3 to 6, wherein the temperature for preheating in step (2) is 550-600 ℃;
preferably, the preheating time is 90-120 min;
preferably, the temperature for austenitizing in the step (2) is 880-900 ℃;
preferably, the austenitizing in the step (2) is carried out for 150 min;
preferably, the carbon potential in austenitizing in step (2) is 1.0;
preferably, the medium for the salt bath quenching in the step (2) is molten salt;
preferably, the temperature of the salt bath quenching in the step (2) is 360-390 ℃;
preferably, the heat preservation time of the salt bath quenching in the step (2) is 100-.
8. The method of any one of claims 3 to 7, wherein the method comprises the steps of:
(1) carrying out spheroidizing inoculation on the molten iron by adopting a flushing spheroidizing method, pouring after inoculation is finished, and cooling after pouring is finished to obtain nodular cast iron; wherein the adding amount of a nodulizer in the spheroidizing inoculation is 1.2-1.4% of the mass of molten iron, and the nodulizer is a rare earth magnesium nodulizer; the particle size of the rare earth magnesium nodulizer is 10-30 mm; the adding amount of the ferrosilicon inoculant in the spheroidizing inoculation is 0.6-0.8% of the mass of molten iron; the particle size of the ferrosilicon inoculant is 8-20 mm; in the pouring process, bismuth-containing inoculant is adopted for stream inoculation, and the addition amount of the bismuth-containing inoculant is 0.01-0.10% of the mass of molten iron;
(2) sequentially preheating the nodular cast iron obtained in the step (1) at the temperature of 550-600 ℃, austenitizing at the temperature of 880-900 ℃ and at the carbon potential of 1.0, preserving heat for 150min, performing salt bath quenching at the temperature of 360-390 ℃ and preserving heat for 150min, and obtaining the austempered nodular cast iron after the salt bath quenching is finished.
9. An integrated axle housing, characterized in that it is prepared from austempered ductile iron according to any one of claims 1 or 2;
preferably, integration axle housing includes the axle housing body, be provided with spindle nose and steel sheet support on the axle housing body, the axle housing body the spindle nose with the support is integrated into one piece casting shaping.
10. The method of making an integrated axle housing of claim 9 including the steps of:
(1) carrying out spheroidizing inoculation on the molten iron by adopting a flushing spheroidizing method, pouring after inoculation is finished, and cooling after pouring is finished to obtain nodular cast iron; wherein the adding amount of a nodulizer in the spheroidizing inoculation is 1.2-1.4% of the mass of molten iron, and the nodulizer is a rare earth magnesium nodulizer; the particle size of the rare earth magnesium nodulizer is 10-30 mm; the adding amount of the ferrosilicon inoculant in the spheroidizing inoculation is 0.6-0.8% of the mass of molten iron; the particle size of the ferrosilicon inoculant is 8-20 mm; in the pouring process, bismuth-containing inoculant is adopted for stream inoculation, and the addition amount of the bismuth-containing inoculant is 0.01-0.10% of the mass of molten iron; wherein the sand mould adopted in the pouring is an integrated axle housing sand mould;
(2) sequentially preheating the nodular cast iron integrated axle housing obtained in the step (1) at the temperature of 550-600 ℃, austenitizing at the temperature of 880-900 ℃ and at the carbon potential of 1.0, preserving heat for 150min, performing salt bath quenching at the temperature of 360-390 ℃ and preserving heat for 150min, and obtaining the isothermal quenching nodular cast iron integrated axle housing after the salt bath quenching is finished.
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| CN112322849A (en) * | 2020-11-10 | 2021-02-05 | 十堰澳贝科技有限公司 | Heat treatment process for ADI material of reference seat |
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| CN113564451A (en) * | 2021-07-01 | 2021-10-29 | 杭州新松机器人自动化有限公司 | Preparation method and application of novel austempered ductile iron with high contact fatigue resistance |
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