Preparation method of high-damping and good-processability gray cast iron for machine tool castings

Abstract

The invention relates to a preparation method of high-damping and good-processability gray cast iron for machine tool castings, and belongs to the technical field of gray cast iron. Pure nickel, pure titanium, a Ca31Si60 silicon-calcium alloy and a FeSi90Al1.5 silicon-iron alloy in a certain mass ratio are creatively used as raw materials, the raw materials are sequentially subjected to mixed smelting, air cooling to the room temperature and crushing operation, then a first nucleating agent is prepared, molten iron obtained in the preparation process of gray cast iron is subjected to in-ladle inoculation treatment through the first nucleating agent, and the molten iron is subjected to in-ladle inoculation treatment to obtain the gray cast iron. Then, a silicon-barium inoculant is used as a second inoculant, 75FeSi is used as a third inoculant, the silicon-barium inoculant and the 75FeSi are synergistically compounded to form a composite inoculant, the composite inoculant is used for carrying out stream inoculation during pouring on the molten iron subjected to primary inoculation, and then conventional cooling treatment is carried out, so that the gray cast iron is obtained. The composite material has the characteristic of high damping and is excellent in processability.

Description

Technical Field

[0001] The invention belongs to the technical field of grey cast iron, and in particular relates to a method for preparing grey cast iron with high damping and good processing performance for machine tool castings. Background Art

[0002] As a metal material, gray cast iron is widely used in various industrial fields due to its good castability, thermal conductivity and other properties. In the machine tool manufacturing industry, gray cast iron has always been the mainstream material for making core components such as bed frames and columns. However, with the continuous development of precision machining technology, this has also put forward higher performance requirements for gray cast iron, that is, it must ensure stability and machining accuracy under high-intensity cutting conditions, and be able to effectively absorb vibration and reduce noise. Based on this, the limitations of traditional gray cast iron have gradually emerged. How to prepare a gray cast iron with high damping and good machining performance is an urgent problem to be solved. Summary of the invention

[0003] In view of the problems existing in the prior art, the purpose of the present invention is to provide a method for preparing gray cast iron with high damping and good processing performance for machine tool castings. The present invention creatively uses pure nickel, pure titanium, Ca31Si60 silicon-calcium alloy and FeSi90Al1.5 silicon-ferroalloy in a certain mass ratio as raw materials, so that they are mixed and smelted in sequence, air-cooled to room temperature, and crushed to prepare a first inoculant, and then the molten iron obtained in the preparation process of the gray cast iron is subjected to an in-package inoculation treatment by the first inoculant, thereby completing the first inoculation of the molten iron, and then a silicon-barium inoculant is used as a second inoculant and 75FeSi is used as a third inoculant. The two are synergistically compounded to form a composite inoculant, and the composite inoculant is used to perform in-stream inoculation on the molten iron that has completed the first inoculation during pouring, and then a conventional cooling treatment is performed to obtain a gray cast iron that not only has the characteristics of high damping but also has excellent processing performance.

[0004] The purpose of the present invention can be achieved by the following technical solutions:

[0005] A method for preparing gray cast iron with high damping and good processing performance for machine tool castings, the preparation method comprising the following steps:

[0006] (1) According to the chemical composition, high-purity pig iron, ferrosilicon, ferromanganese, ferrochrome, ferromolybdenum, pure copper, pure tin, ferrous sulfide and a carburizer are added to a medium frequency induction furnace, and then the temperature is raised to 1470-1520° C. and kept at a constant temperature for 3-5 minutes to obtain molten iron;

[0007] (2) adding a first inoculant to the bottom of the ladle, preheating it, and pouring the molten iron into it for inoculation treatment to obtain component A;

[0008] (3) pouring the component A and adding a composite inoculant to perform inoculant, and air cooling to room temperature to complete the preparation.

[0009] As a preferred technical solution of the present invention, the chemical composition of step (1) comprises, by weight percentage: 1.6-1.8% Si, 3.4-3.5% C, 0.1-0.3% Mn, 0.06-0.1% S, 0.015-0.05% Cu, 0.2-0.3% Cr, 0.1% Sn, 0.15-0.2% Mo and the remainder Fe.

[0010] As a preferred technical solution of the present invention, the recarburizer in step (1) is a graphite recarburizer.

[0011] As a preferred technical solution of the present invention, the heating rate in step (1) is controlled at 15-20°C / min.

[0012] As a preferred technical solution of the present invention, in step (2), the first inoculant is prepared by the following steps:

[0013] Step A: Add 3-4 parts by weight of pure nickel, 6 parts by weight of pure titanium, 8-10 parts by weight of Ca31Si60 and 10-12 parts by weight of FeSi90Al1.5 into a medium frequency induction furnace, then heat to 1700-1750°C, keep constant temperature for 15-20 minutes, air cool to room temperature, and crush to complete the preparation.

[0014] Furthermore, the heating rate in step A is controlled at 15-20°C / min.

[0015] Furthermore, the crushing in step A refers to crushing into particles with a particle size of 1-2 mm.

[0016] As a preferred technical solution of the present invention, the dosage of the first inoculant in step (2) is 0.3-0.4% of the mass of the molten iron.

[0017] As a preferred technical solution of the present invention, the preheating in step (2) refers to preheating to 650-700°C.

[0018] As a preferred technical solution of the present invention, the pouring temperature in step (3) is 1380-1400°C.

[0019] As a preferred technical solution of the present invention, the amount of the composite inoculant in step (3) is 0.1-0.15% of the mass of component A; the composite inoculant is formed by mixing the second inoculant and the third inoculant in a mass ratio of 1:1-1.5; the second inoculant is a silicon-barium inoculant; and the third inoculant is 75FeSi with a particle size of 1-2 mm.

[0020] Beneficial effects of the present invention:

[0021] (1) The present invention creatively uses pure nickel, pure titanium, Ca31Si60 silicon-calcium alloy and FeSi90Al1.5 silicon-ferroalloy in a certain mass ratio as raw materials, and sequentially performs mixed smelting, air cooling to room temperature and crushing operation to prepare a first inoculant, and then uses the first inoculant to perform in-package inoculation treatment on molten iron obtained in the preparation process of gray cast iron, thereby completing the first inoculation of the molten iron, and then uses silicon-barium inoculant as the second inoculant and 75FeSi as the third inoculant, and the two are synergistically compounded to form a composite inoculant, and uses the composite inoculant to perform in-stream inoculation on the molten iron that has completed the first inoculation during pouring, and then undergoes conventional cooling treatment to obtain a gray cast iron that not only has high damping characteristics but also has excellent processing performance.

[0022] (2) The present invention creatively first uses conventional raw materials for mixed smelting to prepare molten iron, and then sequentially performs in-package inoculation with a first inoculant, in-stream inoculation with a composite inoculant, and air cooling to room temperature, thereby preparing a gray cast iron that not only has high damping characteristics but also has excellent processing performance; an appropriate amount of nickel can not only play a role in solid solution strengthening during the inoculation process and occupy the lattice position of the matrix metal, but also reduce the segregation of the various elemental compositions during subsequent crystallization and promote the uniform distribution of the components, thereby improving the various properties of the obtained gray cast iron; the introduction of titanium can refine the grains, provide more crystal nuclei, and have an excellent strengthening effect; Ca31Si60, as a silicon-calcium alloy, has a good inoculating effect itself, which can promote the growth of graphite and thereby obtain more flake graphite, while FeSi90Al1.5 and 75FeSi are both ferrosilicon alloys, which can effectively reduce the tendency of white cast iron and improve the morphology of graphite; as for the silicon-barium inoculant, it can refine the graphite to a certain extent and obtain a more uniform graphite structure.

[0023] (3) The present invention creatively improves the technology of the inoculation treatment of molten iron, so that the gray cast iron finally obtained can obtain more excellent processing performance and damping performance. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] In order to facilitate understanding by those skilled in the art, the present invention is further described below with reference to the accompanying drawings.

[0025] Figure 1 This is a graphite morphology diagram of the gray cast iron prepared in Example 3 of the present invention. DETAILED DESCRIPTION

[0026] In order to further explain the technical means and effects adopted by the present invention to achieve the predetermined invention purpose, the specific implementation methods, structures, features and effects of the present invention are described in detail below in conjunction with the accompanying drawings and preferred embodiments.

[0027] The silicon-barium inoculants in all the embodiments and comparative examples of the present invention were purchased directly from the market from Yangzhou Xinlong Ferroalloy Manufacturing Co., Ltd., with the model number of BaII-1.

[0028] Example 1

[0029] A method for preparing gray cast iron with high damping and good processing performance for machine tool castings, the preparation method comprising the following steps:

[0030] (1) According to the chemical composition, high-purity pig iron, ferrosilicon, ferromanganese, ferrochrome, ferromolybdenum, pure copper, pure tin, ferrous sulfide and a carburizer are added to a medium frequency induction furnace, and then the temperature is raised to 1470° C. and kept at this temperature for 3 minutes to obtain molten iron;

[0031] (2) adding a first inoculant to the bottom of the ladle, preheating it, and pouring the molten iron into it for inoculation treatment to obtain component A;

[0032] (3) pouring the component A and adding a composite inoculant to perform inoculant, and air cooling to room temperature to complete the preparation.

[0033] The chemical composition of step (1) comprises, by weight percentage, 1.6% Si, 3.4% C, 0.1% Mn, 0.06% S, 0.015% Cu, 0.2% Cr, 0.1% Sn, 0.15% Mo and the balance Fe.

[0034] The recarburizer in step (1) is a graphite recarburizer.

[0035] The heating rate in step (1) is controlled at 15°C / min.

[0036] Step (2) The first inoculant is prepared by the following steps:

[0037] Step A: Add 3 parts by weight of pure nickel, 6 parts by weight of pure titanium, 8 parts by weight of Ca31Si60 and 10 parts by weight of FeSi90Al1.5 into a medium frequency induction furnace, then heat to 1700°C, keep constant temperature for 15 minutes, air cool to room temperature, and crush to complete the preparation.

[0038] The heating rate in step A is controlled at 15°C / min.

[0039] The crushing in step A refers to crushing into particles with a particle size of 1 mm.

[0040] In step (2), the dosage of the first inoculant is 0.3% of the mass of the molten iron.

[0041] The preheating in step (2) refers to preheating to 650°C.

[0042] The pouring temperature in step (3) is 1380°C.

[0043] The amount of the composite inoculant in step (3) is 0.1% of the mass of component A; the composite inoculant is a mixture of a second inoculant and a third inoculant in a mass ratio of 1:1; the second inoculant is a silicon-barium inoculant; and the third inoculant is 75FeSi with a particle size of 1 mm.

[0044] Example 2

[0045] A method for preparing gray cast iron with high damping and good processing performance for machine tool castings, the preparation method comprising the following steps:

[0046] (1) According to the chemical composition, high-purity pig iron, ferrosilicon, ferromanganese, ferrochrome, ferromolybdenum, pure copper, pure tin, ferrous sulfide and a carburizer are added to a medium frequency induction furnace, and then the temperature is raised to 1520° C. and kept at this temperature for 5 minutes to obtain molten iron;

[0047] (2) adding a first inoculant to the bottom of the ladle, preheating it, and pouring the molten iron into it for inoculation treatment to obtain component A;

[0048] (3) pouring the component A and adding a composite inoculant to perform inoculant, and air cooling to room temperature to complete the preparation.

[0049] The chemical composition of step (1) comprises, by weight percentage, 1.8% Si, 3.5% C, 0.3% Mn, 0.1% S, 0.05% Cu, 0.3% Cr, 0.1% Sn, 0.2% Mo and the balance Fe.

[0050] The recarburizer in step (1) is a graphite recarburizer.

[0051] The heating rate in step (1) is controlled at 20°C / min.

[0052] Step (2) The first inoculant is prepared by the following steps:

[0053] Step A: Add 4 parts by weight of pure nickel, 6 parts by weight of pure titanium, 10 parts by weight of Ca31Si60 and 12 parts by weight of FeSi90Al1.5 into a medium frequency induction furnace, then heat to 1750°C, keep constant temperature for 20 minutes, air cool to room temperature, and crush to complete the preparation.

[0054] The heating rate in step A is controlled at 20°C / min.

[0055] The crushing in step A refers to crushing into particles with a particle size of 2 mm.

[0056] In step (2), the dosage of the first inoculant is 0.4% of the mass of the molten iron.

[0057] The preheating in step (2) refers to preheating to 700°C.

[0058] The pouring temperature in step (3) is 1400°C.

[0059] The amount of the composite inoculant in step (3) is 0.15% of the mass of component A; the composite inoculant is a mixture of a second inoculant and a third inoculant in a mass ratio of 1:1.5; the second inoculant is a silicon-barium inoculant; and the third inoculant is 75FeSi with a particle size of 2 mm.

[0060] Example 3

[0061] A method for preparing gray cast iron with high damping and good processing performance for machine tool castings, the preparation method comprising the following steps:

[0062] (1) According to the chemical composition, high-purity pig iron, ferrosilicon, ferromanganese, ferrochrome, ferromolybdenum, pure copper, pure tin, ferrous sulfide and a carburizer are added to a medium frequency induction furnace, and then the temperature is raised to 1500° C. and kept constant for 4 minutes to obtain molten iron;

[0063] (2) adding a first inoculant to the bottom of the ladle, preheating it, and pouring the molten iron into it for inoculation treatment to obtain component A;

[0064] (3) pouring the component A and adding a composite inoculant to perform inoculant, and air cooling to room temperature to complete the preparation.

[0065] The chemical composition of step (1) comprises, by weight percentage, 1.7% Si, 3.45% C, 0.2% Mn, 0.08% S, 0.03% Cu, 0.25% Cr, 0.1% Sn, 0.18% Mo and the balance Fe.

[0066] The recarburizer in step (1) is a graphite recarburizer.

[0067] The heating rate in step (1) is controlled at 18°C / min.

[0068] Step (2) The first inoculant is prepared by the following steps:

[0069] Step A: Add 3.5 parts by weight of pure nickel, 6 parts by weight of pure titanium, 9 parts by weight of Ca31Si60 and 11 parts by weight of FeSi90Al1.5 into a medium frequency induction furnace, then heat to 1730°C, keep constant temperature for 18 minutes, air cool to room temperature, and crush to complete the preparation.

[0070] The heating rate in step A is controlled at 18°C / min.

[0071] The crushing in step A refers to crushing into particles with a particle size of 1.5 mm.

[0072] In step (2), the dosage of the first inoculant is 0.35% of the mass of the molten iron.

[0073] The preheating in step (2) refers to preheating to 680°C.

[0074] The pouring temperature in step (3) is 1390°C.

[0075] The amount of the composite inoculant in step (3) is 0.13% of the mass of component A; the composite inoculant is a mixture of a second inoculant and a third inoculant in a mass ratio of 1:1.2; the second inoculant is a silicon-barium inoculant; and the third inoculant is 75FeSi with a particle size of 1.5 mm.

[0076] Comparative Example 1

[0077] Based on Example 3, pure nickel is replaced by pure titanium of equal weight, and the rest remain unchanged.

[0078] Comparative Example 2

[0079] Based on Example 3, pure titanium is replaced with Ca31Si60 of equal weight, and the rest remain unchanged.

[0080] Comparative Example 3

[0081] On the basis of Example 3, Ca31Si60 is replaced with FeSi90Al1.5 of equal weight, and the rest remain unchanged.

[0082] Comparative Example 4

[0083] On the basis of Example 3, FeSi90Al1.5 is replaced with pure nickel of equal weight, and the rest remain unchanged.

[0084] Comparative Example 5

[0085] On the basis of Example 3, the second inoculant was replaced by the third inoculant of equal weight, and the rest remained unchanged.

[0086] Comparative Example 6

[0087] On the basis of Example 3, the third inoculant was changed to the second inoculant of equal weight, and the rest remained unchanged.

[0088] Comparative Example 7

[0089] On the basis of Example 3, the first inoculant was changed to a composite inoculant of equal weight, and the rest remained unchanged.

[0090] Comparative Example 8

[0091] On the basis of Example 3, the composite inoculant was changed to the first inoculant of equal weight, and the rest remained unchanged.

[0092] Test Example 1

[0093] Performance Test:

[0094] The grey cast iron prepared in Example 3 and Comparative Examples 1-8 were respectively subjected to performance tests.

[0095] Table 1. Performance test results

[0096]

[0097]

[0098] From the comparison between Example 3 and Comparative Examples 1-8 in Test Example 1, it can be seen that the grey cast iron prepared by the present invention can obtain more excellent processing performance and damping performance.

[0099] The above description is only a preferred embodiment of the present invention and does not limit the present invention in any form. Although the present invention has been disclosed as a preferred embodiment as above, it is not used to limit the present invention. Any technical personnel in this field can make some changes or modify the technical contents disclosed above into equivalent embodiments without departing from the scope of the technical solution of the present invention. However, any brief modifications, equivalent changes and modifications made to the above embodiments based on the technical essence of the present invention without departing from the content of the technical solution of the present invention are still within the scope of the technical solution of the present invention.

Claims

1. A method for preparing gray cast iron with high damping and good processing performance for machine tool castings, characterized in that: The preparation method comprises the following steps: (1) According to the chemical composition, high-purity pig iron, ferrosilicon, ferromanganese, ferrochrome, ferromolybdenum, pure copper, pure tin, ferrous sulfide and a carburizer are added to a medium frequency induction furnace, and then the temperature is raised to 1470-1520° C. and kept at a constant temperature for 3-5 minutes to obtain molten iron; (2) adding a first inoculant to the bottom of the ladle, preheating it, and pouring the molten iron into it for inoculation treatment to obtain component A; (3) pouring the component A and adding a composite inoculant to perform inoculant, and air cooling to room temperature to complete the preparation.

2. The method for preparing a gray cast iron with high damping and good processing performance for machine tool castings according to claim 1, characterized in that: The chemical composition of step (1) comprises, by weight percentage, 1.6-1.8% Si, 3.4-3.5% C, 0.1-0.3% Mn, 0.06-0.1% S, 0.015-0.05% Cu, 0.2-0.3% Cr, 0.1% Sn, 0.15-0.2% Mo and the balance Fe.

3. The method for preparing a gray cast iron with high damping and good processing performance for machine tool castings according to claim 1, characterized in that: The recarburizer in step (1) is a graphite recarburizer.

4. The method for preparing a gray cast iron with high damping and good processing performance for machine tool castings according to claim 1, characterized in that: Step (2) The first inoculant is prepared by the following steps: Step A: Add 3-4 parts by weight of pure nickel, 6 parts by weight of pure titanium, 8-10 parts by weight of Ca31Si60 and 10-12 parts by weight of FeSi90Al1.5 into a medium frequency induction furnace, then heat to 1700-1750°C, keep constant temperature for 15-20 minutes, air cool to room temperature, and crush to complete the preparation.

5. The method for preparing gray cast iron with high damping and good processing performance for machine tool castings according to claim 4, characterized in that: The heating rate in step A is controlled at 15-20°C / min.

6. The method for preparing a gray cast iron with high damping and good processing performance for machine tool castings according to claim 4, characterized in that: The crushing in step A refers to crushing into particles with a particle size of 1-2 mm.

7. The method for preparing gray cast iron with high damping and good processing performance for machine tool castings according to claim 1, characterized in that: In step (2), the dosage of the first inoculant is 0.3-0.4% of the mass of the molten iron.

8. The method for preparing gray cast iron with high damping and good processing performance for machine tool castings according to claim 1, characterized in that: The preheating in step (2) refers to preheating to 650-700°C.

9. The method for preparing gray cast iron with high damping and good processing performance for machine tool castings according to claim 1, characterized in that: The pouring temperature in step (3) is 1380-1400°C.

10. The method for preparing gray cast iron with high damping and good processing performance for machine tool castings according to claim 1, characterized in that: The amount of the composite inoculant in step (3) is 0.1-0.15% of the mass of component A; the composite inoculant is a mixture of a second inoculant and a third inoculant in a mass ratio of 1:1-1.5; the second inoculant is a silicon-barium inoculant; and the third inoculant is 75FeSi with a particle size of 1-2 mm.

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