CN112322962B

CN112322962B - Vermicular graphite cast iron and preparation method thereof

Info

Publication number: CN112322962B
Application number: CN202011230035.6A
Authority: CN
Inventors: 郭进京; 孙世贵; 付君义; 刘永锋
Original assignee: ZYNP Corp
Current assignee: ZYNP Corp
Priority date: 2020-11-06
Filing date: 2020-11-06
Publication date: 2022-04-12
Anticipated expiration: 2040-11-06
Also published as: CN112322962A

Abstract

The invention provides vermicular graphite cast iron which comprises 3.60-3.95 wt% of C, 2.20-2.80 wt% of Si, 0.20-0.70 wt% of Mn, 0.50-1.20 wt% of Cu, 0.03-0.07 wt% of Sn, 0.03-0.07 wt% of Ti, 0.005-0.020 wt% of Mg, less than or equal to 0.015 wt% of S, less than or equal to 0.06 wt% of P and the balance of Fe. The application also provides a preparation method of the vermicular graphite cast iron, which obtains a blank through centrifugal casting, so that the tensile strength is stable and reaches above 550MPa, the hardness can reach 260-330 HBW, the mechanical property is higher than that of common alloy gray cast iron, the corrosion resistance is good, the production process is simple, the cost is low, and the vermicular graphite cast iron has higher use value and economic value.

Description

Vermicular graphite cast iron and preparation method thereof

Technical Field

The invention relates to the technical field of cast iron, in particular to vermicular cast iron and a preparation method thereof.

Background

Vermicular cast iron has emerged as a new cast iron material in the 60's of the 20 th century. China is one of the earliest countries for studying vermicular cast iron. Generally, vermicular cast iron is produced by adding a vermiculizer (magnesium or rare earth) prior to casting, followed by solidification.

According to the requirements of high detonation pressure, wear resistance and corrosion resistance of the current market and the requirements of the market and future development, the vermicular graphite cast iron is a good choice, the vermicular graphite cast iron can better realize the effects that the high strength is far higher than that of gray cast iron, and the cutting performance is better than that of nodular cast iron.

In the prior art, the method of manufacturing the vermicular cast iron by adopting centrifugal casting is still a development stage, and the carbide and the ferrite of the vermicular cast iron produced in a laboratory are many and are mainly eliminated by heat treatment.

Disclosure of Invention

The technical problem to be solved by the invention is to provide the vermicular cast iron which has the characteristics of high strength, high wear resistance, corrosion resistance and low friction coefficient.

In view of this, the present application provides a vermicular cast iron, comprising:

preferably, the content of C is 3.70-3.90 wt%, and the content of Si is 2.60-2.80 wt%.

Preferably, the content of Mn is 0.50-0.6 wt%, and the content of Cu is 0.70-1.00 wt%.

Preferably, the content of Sn is 0.04-0.06 wt%, and the content of Ti is 0.035-0.060 wt%.

Preferably, the content of S is 0.003-0.015 wt%, and the content of P is less than or equal to 0.02 wt%.

The application also provides a preparation method of the vermicular cast iron, which comprises the following steps:

smelting alloy raw materials according to the alloy components of the vermicular cast iron of claim 1 to obtain molten iron;

carrying out vermicularizing treatment and secondary inoculation on the molten iron, and then carrying out centrifugal casting to obtain a blank;

and cooling and shot blasting the blank to obtain the vermicular graphite cast iron.

Preferably, the smelting temperature is 1400-1600 ℃; the temperature of the centrifugal casting is 650-900 ℃, the rotating speed of the centrifugal casting is 900-1100 r/min, and the demolding temperature of the centrifugal casting is 650-900 ℃; the cooling is air cooling firstly and then air cooling, and the cooling speed is 60-80 ℃/min.

Preferably, the vermicular treatment is carried out by adopting a sandwich covering and punching method, and the sandwich covering and punching method comprises plant ash, a vermiculizer, an inoculant and scrap iron in sequence.

Preferably, the vermiculizing inoculant and the secondary inoculant are independently selected from a common inoculant or a silicon-strontium inoculant, and the vermiculizing inoculant is selected from a low-magnesium low-rare earth vermiculizer; the inoculant for the vermiculization treatment and the inoculant for the secondary inoculation are 0.50-1.50 wt% of the molten iron, and the vermiculizer is 0.30-0.80 wt% of the molten iron.

The application also provides an article prepared from the vermicular cast iron or the vermicular cast iron prepared by the preparation method.

The application provides vermicular graphite cast iron which comprises 3.60-3.95 wt% of C, 2.20-2.80 wt% of Si, 0.20-0.70 wt% of Mn, 0.50-1.20 wt% of Cu, 0.03-0.07 wt% of Sn, 0.03-0.07 wt% of Ti, 0.005-0.020 wt% of Mg, less than or equal to 0.015 wt% of S, less than or equal to 0.06 wt% of P and the balance of Fe. According to the invention, the addition of alloy elements such as Mn, Cu, Sn and the like can obtain the best cast pearlite structure, the graphite is refined, the matrix is strengthened, and the addition of Ti interferes with graphite spheroidization, so that vermicular graphite is more favorably formed; the invention obtains the best cast iron performance mainly by matching and combining various elements, the copper and the tin are mutually combined, the ferrite content is reduced, the cast pearlite content is improved, and the pearlite form is refined, thereby improving the strength, the elastic modulus, the corrosion resistance and the like of the cast iron.

Experimental results show that through optimization design of alloy components and a casting process, the strength of cast iron is greatly improved, the cost is relatively low, the process is simple, the hardness is 260-330 HB, and the tensile strength is greater than 550MPa, the cast matrix of the cast iron is fine lamellar pearlite and a small amount of ferrite (less than or equal to 30%), the graphite is vermicular (more than or equal to 80%), the structure is stable, the size stability of the cylinder sleeve is easy to guarantee, and the corrosion resistance is greatly improved. The cast iron of the invention has low alloy content, so the comprehensive cost is far lower than that of other high-alloy cast irons.

Drawings

FIG. 1 is a metallographic photograph of the graphite morphology of vermicular cast iron prepared in example 1 of the present invention;

FIG. 2 is a metallographic photograph of the matrix structure of vermicular cast iron prepared in example 1 of the present invention;

FIG. 3 is a metallographic photograph of the graphite morphology of vermicular cast iron prepared in example 2 of the present invention;

FIG. 4 is a metallographic photograph of the matrix structure of vermicular cast iron prepared in example 2 of the present invention;

FIG. 5 is a metallographic photograph of the graphite morphology of vermicular cast iron prepared in example 3 of the present invention;

FIG. 6 is a metallographic photograph of the matrix structure of vermicular cast iron prepared in example 3 of the present invention.

Detailed Description

For a further understanding of the invention, reference will now be made to the preferred embodiments of the invention by way of example, and it is to be understood that the description is intended to further illustrate features and advantages of the invention, and not to limit the scope of the claims.

In view of the development status of the vermicular cast iron, the application provides low-cost and high-strength centrifugal casting as-cast pearlite vermicular cast iron, and the vermicular cast iron cylinder sleeve prepared from the low-cost and high-strength centrifugal casting as-cast pearlite vermicular cast iron has high strength, high wear resistance, corrosion resistance and low friction coefficient, and is low in manufacturing cost and free of heat treatment. Specifically, the embodiment of the invention discloses vermicular cast iron, which comprises the following components:

in the present application, the mass of C is 3.60 to 3.95 wt%, and in specific embodiments, the content of C is 3.70 to 3.90 wt%, too low carbon may cause many carbides, and too high carbon may cause graphite floating. The method is different from the design of higher carbon equivalent of common vermicular cast iron, and effectively avoids the phenomenon of more carbides in an as-cast structure under the condition of metal mold centrifugal casting with higher cooling speed.

The content of S is less than or equal to 0.015 wt%, in a specific embodiment, the content of S is 0.003-0.015%, too low sulfur can cause too few graphite nucleation cores, and too high sulfur can consume too much vermiculizer to cause poor vermiculizing effect. The method controls low sulfur and phosphorus content, and is more favorable for forming vermicular graphite.

The content of the Si is 2.20-2.80 wt%, in a specific embodiment, the content of the Si is 2.60-2.80 wt%, the final silicon is high mainly due to the fact that the inoculation amount is large, the inoculation amount is small, excessive ledeburite is easy to appear, but the silicon cannot be too high, and the ferrite is too much.

The Mn content is 0.20-0.70 wt%, and in specific embodiments, the Mn content is 0.50-0.60 wt%. The Cu content is 0.50-1.20 wt%, in a specific embodiment, the Cu content is 0.70-1.00 wt%, more specifically, the Cu content is 0.80-0.90 wt%, and higher copper is a main guarantee for obtaining more pearlite.

The Sn content is 0.30 to 0.70 wt%, in a specific embodiment, the Sn content is 0.040 to 0.060 wt%, more preferably 0.045 wt%, and a small amount of Sn is also used to obtain a large amount of pearlite.

The content of Ti is 0.03-0.07 wt%, in a specific embodiment, the content of Ti is 0.035-0.060 wt%, and a small amount of Ti interferes with the generation of graphite nodules, so that the creep rate is improved.

The content of Mg is 0.005-0.020 wt%, and in specific embodiments, the content of Mg is 0.007-0.015 wt%. The method controls the content of residual magnesium (0.02-0.035% in the conventional method and 0.005-0.020% in the invention) which is lower than the content of the residual magnesium produced by the conventional vermicular cast iron, and is more suitable for producing the vermicular cast iron by centrifugal casting of a metal mold with higher cooling speed.

In view of this, the present application also provides a method for preparing compacted graphite iron, comprising the steps of:

smelting the alloy raw material according to the alloy components of the vermicular graphite cast iron to obtain molten iron;

and carrying out air cooling, shot blasting, rough machining and finish machining on the blank to obtain the vermicular graphite cast iron.

The alloy raw materials are not particularly limited, and those skilled in the art can adopt simple substances or alloys containing relevant alloy elements according to the required cast iron components.

In the present invention, the melting is a melting well known to those skilled in the art, and the specific embodiment thereof is not particularly limited in the present application; in the application, the smelting temperature is 1480-1550 ℃, and in a specific embodiment, the smelting temperature is 1490-1520 ℃, and more specifically, the smelting temperature is 1500-1510 ℃.

This application will then the molten iron carries out vermicularizing treatment and secondary inoculation, vermicularizing treatment adopts "sandwich" to cover and rush into the method and goes on, the method is rush into to cover the plant ash, vermiculizer, inoculant and the iron fillings that include in proper order "sandwich", and above-mentioned vermicularizing treatment mode can strengthen the absorption of vermiculizer. The vermiculizer is a common low-magnesium low-rare earth vermiculizer (such as an Eken compact 5503, Ningxia cast peak ZFCV4 and the like), and can be purchased from the market. The content of the vermiculizer is 0.30-0.80 wt% of the molten iron, and the small amount of the vermiculizer is easy to cause insufficient vermiculization to form flake graphite, so that the strength is greatly reduced; when the amount of the vermicular agent is too large, spheroidization is caused, and nodular graphite is formed, so that the performances such as heat conductivity, shock absorption and the like are reduced. The plant ash mainly prevents the vermiculizer from sticking the ladle bottom, and the scrap iron mainly plays a role in covering and delaying the vermiculization reaction time. The inoculant for the vermiculization treatment and the inoculant for the secondary inoculation are respectively a common inoculant or a silicon-strontium inoculant, the content of the inoculants is 0.50-1.50 wt% of the molten iron, the inoculant for the vermiculization treatment accounts for 85 wt%, and the inoculant for the secondary inoculation accounts for 15 wt%; too high an inoculant amount will result in a higher ferrite content in the matrix.

The method comprises the step of centrifugally pouring molten iron after the vermicular treatment and the secondary inoculation treatment to obtain a blank, wherein the centrifugal pouring temperature is 1360-1450 ℃, in a specific embodiment, the centrifugal pouring temperature is 1380-1420 ℃, and more specifically, the centrifugal pouring temperature is 1400 ℃. In the invention, the rotational speed of the centrifugal casting is 900-1100 r/min, and in a specific embodiment, the rotational speed of the centrifugal casting is 970-1030 r/min. In the invention, the mold-releasing temperature of the centrifugal casting is 650-900 ℃, in a specific embodiment, the mold-releasing temperature of the centrifugal casting is 650-850 ℃, and more specifically, the mold-releasing temperature of the centrifugal casting is 750-820 ℃.

Cooling, shot blasting, rough machining and finish machining are finally carried out on the blank to obtain the vermicular graphite cast iron; in the invention, the cooling is preferably carried out by air cooling after blowing the air by using a fan or compressed air to the temperature of 550-650 ℃, more preferably 580-620 ℃, and most preferably 600 ℃. In the invention, the cooling speed in the cooling process is 60-80 ℃/min. After the above cooling, a vermicular cast iron is obtained.

The application also provides an article prepared from the vermicular cast iron prepared by the preparation method of the scheme.

In the present application, the article is in particular a vermicular cast iron cylinder liner.

In order to obtain a vermicular cast iron product with precise size, the vermicular cast iron is subjected to rough machining, and the rough machining method is not particularly limited, and a cylinder sleeve with a required shape can be obtained by adopting a rough machining method well known to a person skilled in the art.

After rough machining, the rough machined vermicular cast iron is subjected to finish machining, and the method for finish machining is not particularly limited, and the cylinder liner with the required dimensional accuracy can be obtained by adopting the method for finish machining which is well known to the skilled person.

The cast iron provided by the invention is easy to produce, only the most common casting process is adopted, the qualified cast iron can be produced, the complexity of the casting process is equivalent to the casting difficulty of other alloy gray cast irons, the cast iron components only contain a small amount of copper and tin noble metals, but the content of the noble metals is much lower than that of other alloy gray cast irons with the same strength, and therefore, the material cost is greatly reduced.

The invention provides a cylinder liner, which is made of the high-strength cast pearlite vermicular graphite cast iron in the technical scheme, and the preparation method of the cylinder liner is consistent with that of the high-strength cast pearlite vermicular graphite cast iron in the technical scheme, and is not repeated herein.

The tensile strength of the cast iron provided by the invention is more than 550MPa and is far higher than the highest mark HT350 (the tensile strength is not lower than 350MPa) of gray cast iron and bainite alloy cast iron (not less than 400MPa), and the corrosion resistance even reaches the standard corrosion average corrosion depth of less than 10 mu m (the common alloy gray cast iron is about 50-190 mu m).

Compared with the prior art, the strength of the cast iron is greatly improved by optimally designing alloy components and a casting process, the cost is relatively low, the process is simple, the hardness is 260-330 HB, the tensile strength is more than 550MPa, the cast matrix of the cast iron is fine lamellar pearlite and a small amount of ferrite (less than or equal to 30 percent), the graphite is vermicular (more than or equal to 80 percent), the structure is stable, the size stability of the cylinder sleeve is easily ensured, and the corrosion resistance is greatly improved. The cast iron of the invention has low alloy content, so the comprehensive cost is far lower than that of other high-alloy cast irons.

For further understanding of the present invention, the vermicular cast iron and the preparation method thereof provided by the present invention are described in detail below with reference to the following examples, and the scope of the present invention is not limited by the following examples.

Example 1

Smelting alloy elements to obtain molten iron, wherein the smelting temperature is controlled to be 1500-1510 ℃;

the obtained molten iron is subjected to vermicular treatment, covered by a sandwich method, vermicular by a flushing method, the bag needs to be properly dried, the vermicular agent cannot be sticky due to too much heat, plant ash is firstly used, then the vermicular agent is about 0.35-0.60 percent, then the vermicular agent is covered by a proper amount (about 0.80-1.20 percent) of ferrosilicon inoculant, and a layer of scrap iron is added on the vermicular agent, and attention is paid to: each layer of covering is properly impacted; the inoculant adopted in the vermicularizing treatment is a ferrosilicon inoculant of Ningxia cast peaks, and the vermicularizing agent is an Eken compact 5503;

centrifugally casting the obtained molten iron into a blank after secondary inoculation, wherein the casting temperature is controlled to be 1380-1420 ℃, the centrifugal rotating speed is 1000r/min in the casting process, and the blank is discharged at 800 ℃;

and cooling the obtained blank to 600 ℃ by blowing cooling through a fan, and then air cooling, wherein the cooling speed in the cooling period is about 60-80 ℃/min.

And (4) after rough machining, finish machining the cooled blank into a finished cylinder sleeve product.

Detecting the components of the cylinder sleeve by adopting a photoelectric direct-reading spectrometer according to GB/T24234-2009 'cast iron multi-element determination spark discharge atomic emission spectrometry', wherein the detection result is that the cylinder sleeve comprises the following components: c: 3.84 wt%, Si: 2.60 wt%, P: 0.022 wt%, S: 0.008 wt%, Mn: 0.548 wt%, Cu: 0.873 wt%, Sn: 0.058 wt%, Ti: 0.040 wt%, residual Mg: 0.007 wt% and the balance Fe. FIG. 1 is a metallographic photograph (x 100) of the graphite morphology of vermicular cast iron prepared in example 1 of the present invention; FIG. 2 is a metallographic photograph (x 100) of the matrix structure of vermicular cast iron prepared in example 1 of the present invention.

The cylinder liner prepared in example 1 is subjected to mechanical property detection according to GB/T231.1-2018 part 1 of Brinell hardness test of metal material: the standard test of the test method comprises the following test results: HBW: 278;

adopting a universal material testing machine WDW-300, and according to GB/T228.1-2010 part 1 of metal material tensile test: the standard detection of the room temperature test method comprises the following detection results: tensile strength: 595 MPa;

according to the standard detection of GB/T22315-2008 ' test method for elastic modulus and Poisson's ratio of metal material ', the detection result is as follows: elastic modulus of cylinder liner: 147 GPa;

according to the standard detection of the gray cast iron cylinder sleeve corrosion resistance test method, the average corrosion depth is 4.2 mu m.

Example 2

Smelting alloy raw materials to obtain molten iron; controlling the smelting temperature to be 1500-1510 ℃;

carrying out vermicularizing treatment on the obtained molten iron, wherein a vermicularizing agent is Ningxia cast peak ZFCV4, an inoculant is Ningxia cast peak ferrosilicon inoculant, the sandwich covering is adopted as described in example 1, and the vermicularizing treatment is carried out by using a flushing method;

centrifugally casting the obtained molten iron into a blank after secondary inoculation, wherein the casting temperature is controlled to 1390-1420 ℃, and the centrifugal rotating speed is 1020 r/min; demolding at 810 ℃;

cooling the obtained blank to 620 ℃ by a fan, and then air-cooling, wherein the cooling speed is more than 60-80 ℃/min during cooling;

According to the method of the embodiment 1, the components of the cylinder sleeve prepared in the embodiment 2 of the invention are detected, and the detection result is as follows: c: 3.79 wt%, Si: 2.51 wt%, P: 0.020 wt%, S: 0.007 wt%, Mn: 0.556 wt%, Cu: 0.878 wt%, Sn: 0.057 wt%, Ti: 0.055 wt%, residual Mg: 0.010 wt%, the balance being Fe.

FIG. 3 is a metallographic photograph (x 100) of the graphite morphology of the vermicular cast iron prepared according to the present example of the invention; FIG. 4 is a metallographic photograph (x 100) of the matrix structure of the vermicular cast iron prepared according to the present example of the invention.

According to the detection method of the embodiment 1, the mechanical property of the cylinder sleeve prepared in the embodiment 2 of the invention is detected, and the detection result is as follows: HBW: 285, tensile strength: 612MPa, modulus of elasticity: 150GPa, average corrosion depth of 4.1 μm.

Example 3

Smelting alloy raw materials to obtain molten iron; controlling the smelting temperature to be 1490-1510 ℃;

carrying out vermicularizing treatment on the molten iron, wherein a vermicularizing agent is Ningxia cast peak ZFCV4, and an inoculant is Ningxia cast peak silicon-strontium inoculant; using a "sandwich" cover as described in example 1, a vermicular treatment was performed using the punch-in method;

centrifugally casting the obtained molten iron into a blank after secondary inoculation, wherein the casting temperature is controlled to be 1400-1420 ℃, and the centrifugal rotating speed is 1030 r/min; demolding at 835 ℃;

cooling the obtained blank to 590 ℃ by a fan, and then air-cooling, wherein the cooling speed is about 60-80 ℃/min during the cooling period;

According to the method of the embodiment 1, the components of the cylinder sleeve prepared in the embodiment 3 of the invention are detected, and the detection result is as follows: c: 3.70 wt%, Si: 2.52 wt%, P: 0.004 wt%, S: 0.008 wt%, Mn: 0.54 wt%, Cu: 0.890 wt%, Sn: 0.045 wt%, Ti: 0.045 wt%, residual Mg: 0.015 wt%, the balance being Fe.

FIG. 5 is a metallographic photograph (x 100) of the graphite morphology of the vermicular cast iron prepared according to the present example of the invention; FIG. 6 is a metallographic photograph (x 100) of the matrix structure of the vermicular cast iron prepared according to the present example of the invention.

According to the method of the embodiment 1, the mechanical property of the cylinder sleeve prepared in the embodiment 3 of the invention is detected, and the detection result is as follows: HBW305, tensile strength: 625MPa, modulus of elasticity: 154GPa, an average depth of corrosion of 3.6 μm.

Example 4

The preparation method and parameters are the same as in example 1, except that: the contents of the alloy elements are shown in table 1, wherein the numbers 1 and 2 in table 1 are in accordance with the requirements of conventional residual magnesium, and the numbers 3 and 4 are in accordance with the requirements of the invention; detecting the tissue morphology of the prepared cylinder sleeve, wherein the tissue morphology is shown in table 2;

TABLE 1 data Table of alloy compositions (wt%) of Cylinder liners Nos. 1 to 4

Numbering	C	S	Si	P	Mn	Cu	Sn	Mg
									1	3.72	0.021	2.39	0.000	0.710	0.800	0.037	0.024
2	3.71	0.017	2.41	0.006	0.700	0.800	0.038	0.023
									3	3.69	0.002	2.53	0.000	0.650	0.840	0.044	0.009
4	3.64	0.002	2.55	0.000	0.64	0.840	0.047	0.010

TABLE 2 microscopic structure morphology table of cylinder sleeve prepared by numbering 1-4

Numbering

Detection site

Vermicular form

Spherical shape

Pearlite

Ferrite

Ledeburite body

1

Inner wall

70％

30％

50％

20％

30％

1

Intermediate (II)

90％

10％

80％

20％

1

Outer wall

20％

80％

20％

2

Inner wall

90％

10％

40％

20％

40％

2

Intermediate (II)

70％

30％

50％

20％

30％

2

Outer wall

20％

80％

40％

10％

50％

3

Inner wall

80％

20％

80％

20％

3

Intermediate (II)

80％

20％

80％

20％

3

Outer wall

80％

20％

80％

20％

4

Inner wall

90％

10％

70％

30％

4

Intermediate (II)

90％

10％

70％

30％

4

Outer wall

90％

10％

70％

30％

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

1. A vermicular cast iron comprising:

2. the compacted graphite iron according to claim 1, wherein the C content is 3.70-3.90 wt%.

3. The compacted graphite iron according to claim 1, wherein the Mn content is 0.50 to 0.6 wt%, and the Cu content is 0.70 to 1.00 wt%.

4. The vermicular cast iron according to claim 1, wherein the content of Sn is 0.04-0.06 wt%, and the content of Ti is 0.035-0.060 wt%.

5. The compacted graphite iron according to claim 1, wherein the P content is ≤ 0.02 wt%.

6. The method of preparing compacted graphite iron of claim 1, comprising the steps of:

7. The preparation method of claim 6, wherein the smelting temperature is 1400-1600 ℃; the temperature of the centrifugal casting is 650-900 ℃, the rotating speed of the centrifugal casting is 900-1100 r/min, and the demolding temperature of the centrifugal casting is 650-900 ℃; the cooling is air cooling firstly and then air cooling, and the cooling speed is 60-80 ℃/min.

8. The method according to claim 6, wherein the vermicular treatment is performed by a "sandwich" cover-and-punch method, which comprises plant ash, vermiculizer, inoculant and scrap iron in sequence.

9. The method of claim 8, wherein the creep-treating inoculant and the secondary inoculant are independently selected from the group consisting of a conventional inoculant and a silicon-strontium inoculant, and the creep-treating inoculant is selected from the group consisting of a low-magnesium low-rare earth creep agent; the inoculant for the vermiculization treatment and the inoculant for the secondary inoculation are 0.50-1.50 wt% of the molten iron, and the vermiculizer is 0.30-0.80 wt% of the molten iron.

10. An article prepared from the vermicular cast iron according to any one of claims 1 to 5 or the vermicular cast iron prepared by the preparation method according to any one of claims 6 to 9.