LU501341B1 - High-toughness and high-hardness ductile iron material used under ultra-low temperature and preparation method thereof - Google Patents

High-toughness and high-hardness ductile iron material used under ultra-low temperature and preparation method thereof Download PDF

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Publication number
LU501341B1
LU501341B1 LU501341A LU501341A LU501341B1 LU 501341 B1 LU501341 B1 LU 501341B1 LU 501341 A LU501341 A LU 501341A LU 501341 A LU501341 A LU 501341A LU 501341 B1 LU501341 B1 LU 501341B1
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spheroidizing
inoculation
temperature
alloy
ultra
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LU501341A
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German (de)
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Yingdong Qu
Guanglong Li
Wei Zhang
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Univ Shenyang Technology
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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
    • C—CHEMISTRY; METALLURGY
    • C21—METALLURGY OF IRON
    • C21C—PROCESSING OF PIG-IRON, e.g. REFINING, MANUFACTURE OF WROUGHT-IRON OR STEEL; TREATMENT IN MOLTEN STATE OF FERROUS ALLOYS
    • C21C1/00—Refining of pig-iron; Cast iron
    • C21C1/10—Making spheroidal graphite cast-iron
    • C—CHEMISTRY; METALLURGY
    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22C—ALLOYS
    • C22C33/00—Making ferrous alloys
    • C22C33/08—Making cast-iron alloys
    • C—CHEMISTRY; METALLURGY
    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22C—ALLOYS
    • C22C33/00—Making ferrous alloys
    • C22C33/08—Making cast-iron alloys
    • C22C33/10—Making cast-iron alloys including procedures for adding magnesium
    • C—CHEMISTRY; METALLURGY
    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22C—ALLOYS
    • C22C37/00—Cast-iron alloys
    • C22C37/06—Cast-iron alloys containing chromium
    • C22C37/08—Cast-iron alloys containing chromium with nickel
    • 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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  • Chemical & Material Sciences (AREA)
  • Engineering & Computer Science (AREA)
  • Materials Engineering (AREA)
  • Metallurgy (AREA)
  • Organic Chemistry (AREA)
  • Mechanical Engineering (AREA)
  • Refinement Of Pig-Iron, Manufacture Of Cast Iron, And Steel Manufacture Other Than In Revolving Furnaces (AREA)

Abstract

The invention relates to a high toughness and high hardness ductile iron material used under ultra-low temperature conditions, which is mainly applied to the manufacture of mechanical product parts castings used under ultra-low temperature conditions, which is characterized in that: the chemical composition of the material is calculated by weight percentage: C2.7%-2.9%, Si1.8%-2.0%, Mn1%-5%, P0.01%-0.08%, S0.01%-0.02%, Ni20%-28%, Cr0.5%-3.0%, Cu0.5%-1.5%, Mg0.06-0.09%, the rest is Fe. The purpose of the application is to overcome the disadvantages of poor casting performance, poor impact toughness, low hardness and wear resistance, and poor machining performance of materials that are traditionally suitable for ultra-low temperature conditions, and can provide new materials for the design of mechanical parts used at ultra-low temperatures, choose.

Description

DESCRIPTION 1000188 High-toughness and high-hardness ductile iron material used under ultra-low temperature and preparation method thereof
TECHNICAL FIELD The invention relates to a high-toughness and high-hardness ductile iron material used at ultra-low temperature, which is mainly used for manufacturing mechanical product parts castings used at ultra-low temperature.
BACKGROUND Nodular cast iron is a common material for castings of mechanical product parts used at room temperature. Its main components are C, Si, Mn, Cr, Ni, Mo, Cu and other elements. The matrix is divided into ferrite, pearlite, austenite, Martensite, bainite, etc.; the main preparation process is the smelting of raw iron liquid, alloy composition adjustment, spheroidization and inoculation treatment. In recent years, the preparation of ductile iron materials used in supercritical conditions, such as high temperature, low temperature, strong friction, high impact and high strength, has increasingly become the main research direction in the world's mechanical field. In the field of ultra-low temperature mechanical product parts castings, alloy austenitic cast steel materials (such as 1Cr18Ni9Ti, etc.) are most widely used today. However, due to the casting performance of cast steel materials and the limitations of heat treatment and later machining, such materials are being manufactured When castings with more complex shapes are prone to serious casting defects, and the machining and heat treatment work hours are also longer; at the same time, the high wear resistance of this material can meet the higher hardness requirements under ultra-low temperature conditions. Therefore, the invention provides a new material selection for the design of parts of such mechanical products.
SUMMARY Objective of the invention: the invention is a high toughness and high hardness ductile iron material used under ultra-low temperature conditions. The matrix of the material is ductile iron, which not only maintains high mechanical properties, but also has the wear resistance and wear resistance of ductile iron itself. The advantages of good casting performance overcome the disadvantages of poor casting performance, 1000188 poor impact toughness, low hardness and wear resistance, and poor machining performance of materials that are traditionally suitable for ultra-low temperature conditions. It can provide new designs for mechanical parts used at ultra-low temperatures. The choice of materials.
Technical solution: the invention is implemented through the following technical solutions: A high-toughness and high-hardness ductile iron material used at ultra-low temperature, characterized in that the chemical composition of the material is calculated by weight percentage: C2.7%-2.9%, Sil.8%-2.0%, Mn1%-5%, P0.01%-0.08%, S0.01%-0.02%, Ni20%-28%, Cr0.5%-3.0%, Cu0.5%-1.5%, Mg0.06-0.09%, the rest is Fe.
The performance range of this material at ultra-low temperature: at-150°C, the Vickers hardness value Hv is 180-380, the impact value is 20-37J/mm2, and the Vickers hardness value Hv is 130-260 at room temperature. The impact value is 25-30J/mm?.
A method for preparing a ductile iron material with high toughness and high hardness used at ultra-low temperature as described above, which is characterized in that the method is carried out as follows: (1) preparation of raw molten iron: the P content of pig iron and scrap steel raw materials is controlled within 0.01%-0.08%, and the content of S is controlled within S 0.01%-0.02%; the composition of the raw materials must be clearly known and added and controlled within 35%-50% of the total ; (2) adjustment of alloy composition: the adjustment of alloy composition includes the order of addition of alloy raw materials, carbon equivalent and carbon silicon content adjustment; use intermediate frequency electric furnace smelting to adjust the alloy composition according to the above chemical composition ratio and ensure the uniformity of the alloy elements in the molten iron; the carbon equivalent and carbon silicon content are adjusted according to the above carbon silicon content range; the order of adding alloy raw materials is: Ni, Mn, Cr, Cu, Si;
(3) spheroidizing treatment: Ni-Mg alloy spheroidizing agent with a Mg content 50734) of 20% to 30% is used in the spheroidizing process, and the mass fraction is 0.5% to
1.5%, and the addition method is flushing into the bottom of the bag; the spheroidizing temperature is 1460°C-1540°C; the molten iron is spheroidized in accordance with the specified spheroidizing agent, spheroidizing agent addition amount, spheroidizing method and spheroidizing temperature; (4) inoculation treatment: after the molten iron smelting process, the ferrosilicon inoculant is used to inoculate the molten iron once; the chemical composition of the ferrosilicon inoculant is 70% to 78% by weight, and the rest is Fe; the mass fraction is
0.5%-1.5%; the adding method is inoculation with flow, and the inoculation temperature is 1350°C-1380°C.
Advantages and effects: the invention is a high toughness and high hardness ductile iron material used under ultra-low temperature conditions. Its significant advantages include the following three points:
1. This material can guarantee its high toughness and high hardness performance under ultra-low temperature conditions, and its performance is less sensitive to temperature changes. Its mechanical performance indicators are detailed above.
2. The matrix of this material is ductile cast iron, which has good casting performance and is suitable for manufacturing complex-shaped casting products. At the same time, it has good mechanical processing and heat treatment performance.
3. The alloy composition of this material is rich, which can be adapted to various surface treatments such as subsequent carburizing and nitriding.
The invention of this material can provide new material options for the design of mechanical parts used at ultra-low temperatures.
BRIEF DESCRIPTION OF THE FIGURES Figure 1 shows the matrix tissue of the invention under an optical microscope magnified 100 times.
Figure 2 is an impact performance curve from room temperature to-160°C in the performance interval of the invention.
The sample is a V-notched sample that meets the GB/T229-2007 Charpy 1000188 Pendulum Impact Test Method for Metallic Materials.
Figure 3 1s a hardness performance curve from room temperature to-120°C in the performance interval of the invention.
The sample is a smooth surface with a Imm rough surface from the bottom layer of the as-cast state without heat treatment.
DESCRIPTION OF THE INVENTION the invention will be specifically described below in conjunction with specific embodiments: Example 1: The material of the invention is prepared according to the preparation process described in the technical scheme of the invention. The selected charge is not recharged. The chemical composition of the molten iron is as follows by weight percentage: C2.7%, Sil.9% , Mn3%, P0.04%, S0.02%, Ni26%, Cr0.5%, Cu0.5%, Mg0.09%, the rest is Fe; the spheroidizing process uses a Ni-Mg alloy spheroidizing agent with a Mg content of 23%, the addition amount is 1%, the addition method is the bottom of the bag flushing method, the spheroidizing temperature is 1470°C; the Si content is used in one inoculation process 75% of ferrosilicon is processed, and the second inoculation uses Si75%, Al0.5%, Zr2%, Sr3%, Ca0.2% ferrosilicon, zirconium, and strontium inoculant, the addition amount is 1.5%, and the addition method is random flow Inoculation, adding temperature is 1370 °C. The material of the invention prepared according to the above process, referring to the GB/T229-2007 standard, is subjected to a low-temperature impact test on the material, and a low-temperature Vickers hardness tester is used to perform a low-temperature hardness test. The test data is: at-150°C; the Vickers hardness value Hv is 192, and the impact value is 36]/mm?; at room temperature, the Vickers hardness value Hv is 141, and the impact value is 29J/mm?.
Example 2: The material of the invention is prepared according to the preparation process described in the technical scheme of the invention, in which a comparative test is carried out to change the spheroidizing process in the same smelting as the test (1), and the chemical composition of the molten iron is as follows
The weight percentages are: C2.7%, Sil.9%, Mn3%, P0.04%, S0.02%, Ni26%, 10501361 Cr0.5%, Cu0.5%, Mg0.09%, and the rest is Fe; the spheroidizing process uses the rare earth silicon-magnesium alloy spheroidizing agent of Rel.5%, S145%, and Mg7%, the addition amount is 1%, the addition method 1s the bottom of the bag flushing method, and the spheroidizing temperature is 1470°C; one incubation process The silicon ferrosilicon with 75% Si content is used for treatment, and the second inoculation adopts Si75%, Al0.5%, Zr2%, Sr3%, Ca0.2% ferrosilicon zirconium strontium inoculant, and the addition amount is 1.5%. The joining method is inoculation with the flow, and the joining temperature is 1370°C. The material of the invention prepared according to the above process, referring to the GB/T229-2007 standard, is subjected to a low-temperature impact test on the material, and a low-temperature Vickers hardness tester is used to perform a low-temperature hardness test. The test data is: under-150°C; the Vickers hardness value Hv is 165, and the impact value is 17J/mm2; at room temperature, the Vickers hardness value Hv is 107, and the impact value is 24J/mm*.
Example 3: The material of the invention is prepared according to the preparation process described in the technical scheme of the invention, in which a comparative test is carried out to change the secondary inoculation treatment process in the same smelting as the (1) test, in which the chemical composition of the molten iron The percentages by weight are: C2.7%, S11.9%, Mn3%, P0.04%, S0.02%, Ni26%, Cr0.5%, Cu0.5%, Mg0.09%, and the rest is Fe; the spheroidizing process uses a Ni-Mg alloy spheroidizing agent with a Mg content of 23%, the addition amount is 1%, the addition method is the bottom of the bag flushing method, the spheroidizing temperature is 1470°C; the Si content is used in one incubation process 75% of ferrosilicon is treated, and the second inoculation is treated with Si75% ferrosilicon inoculant, the addition amount is 1%, the addition method is flow inoculation, and the addition temperature is 1370°C. The material of the invention prepared according to the above process, referring to the GB/T229-2007 standard, carries out a low-temperature impact test on the material, and uses a low-temperature Vickers hardness tester to perform a low-temperature hardness test. The test data is:
under-150 °C; the Vickers hardness value Hv is 193, and the impact value is 21J/mm?2; 10501361 at room temperature, the Vickers hardness value Hv is 145, and the impact value is 23J/mm?.
Example 4: The material of the invention is prepared according to the preparation process described in the technical scheme of the invention, and the selected charge 1s not recharged. The chemical composition of the molten iron is as follows: C2.9%, Sil.8% , Mn4%, P0.04%, S0.02%, Ni28%, Cr1.5%, Cul. 2%, Mg0.09%, the rest is Fe; the spheroidizing process uses a Ni-Mg alloy spheroidizing agent with a Mg content of 23%, the addition amount is 1%, the addition method is the bottom of the bag flushing method, the spheroidizing temperature is 1490 °C; the Si content is used in one inoculation process 75% of ferrosilicon is processed, and the second inoculation uses S175%, Al0.5%, Zr2%, Sr3%, Ca0.2% ferrosilicon, zirconium, and strontium inoculant, the addition amount is 1.5%, and the addition method is random flow Inoculation, adding temperature is 1360 °C. The material of the invention prepared according to the above process, referring to the GB/T229-2007 standard, is subjected to a low-temperature impact test on the material, and a low-temperature Vickers hardness tester is used to perform a low-temperature hardness test. The test data is: at-150°C; the Vickers hardness value Hv is 358, and the impact value is 23J/mm2; at room temperature, the Vickers hardness value Hv is 246, and the impact value is 27J/mm°.
Example 5: The material of the invention is prepared according to the preparation process described in the technical scheme of the invention. The selected charge is not recharged. The chemical composition of the molten iron is as follows: C2.9%, Si1.8% , Mn4%, P0.04%, S0.02%, Ni28%, Cr2.5%, Cu0.5%, Mg0.09%, the rest is Fe; the spheroidizing process uses a Ni-Mg alloy spheroidizing agent with a Mg content of 23%, the addition amount is 1%, the addition method is the bottom of the bag flushing method, the spheroidizing temperature is 1490 °C; the Si content is used in one inoculation process 75% of ferrosilicon is processed, and the second inoculation uses Si75%, Al0.5%, Zr2%, Sr3%, Ca0.2% ferrosilicon, zirconium, and strontium inoculant, the addition amount is 1.5%, and the addition method is random flow Inoculation, adding temperature is 1360 °C. The material of the invention 1000188 prepared according to the above process, referring to the GB/T229-2007 standard, is subjected to a low-temperature impact test on the material, and a low-temperature Vickers hardness tester is used to perform a low-temperature hardness test. The test data is: at-150°C; the Vickers hardness value Hv is 382, and the impact value is 20J/mm?; at room temperature, the Vickers hardness value Hv is 256, and the impact value is 25J/mm*.
Example 6: The material of the invention is prepared according to the preparation process described in the technical scheme of the invention. The selected charge is not recharged. The chemical composition of the molten iron is as follows: C2.7%, Sil.8% by weight , Mn4%, P0.04%, S0.02%, Ni28%, Cr0.5%, Cu0.5%, Mg0.09%, the rest is Fe; the spheroidizing process uses a Ni-Mg alloy spheroidizing agent with a Mg content of 30%, the addition amount is 1%, the addition method is the bottom of the bag flushing method, the spheroidizing temperature is 1470°C; the Si content is used in one incubation process 75% of ferrosilicon is processed, and the second inoculation uses Si75%, A10.5%, Zr2%, Sr3%, Ca0.2% ferrosilicon zirconium strontium inoculant, the addition amount is 1.5%, and the addition method is random flow Inoculation, adding temperature is 1370 °C. The material of the invention prepared according to the above process, referring to the GB/T229-2007 standard, is subjected to a low-temperature impact test on the material, and a low-temperature Vickers hardness tester is used to perform a low-temperature hardness test. The test data is: at-150°C; the Vickers hardness value Hv is 187, and the impact value is 37J/mm°; at room temperature, the Vickers hardness value Hv is 156, and the impact value is 30J/mm?.
Example 7: The material of the invention is prepared according to the preparation process described in the technical scheme of the invention. The selected charge is not recharged. The chemical composition of the molten iron is as follows by weight percentage: C2.7%, Sil.8% , Mn4%, P0.04%, S0.02%, Ni28%, Cr0.5%, Cu0.5%, Mg0.09%, the rest is Fe; the spheroidizing process uses a Ni-Mg alloy spheroidizing agent with a Mg content of 30%, the addition amount is 1%, the addition method is the bottom of the bag flushing method, the spheroidizing 1000188 temperature is 1470°C; the Si content is used in one incubation process 75% of ferrosilicon is processed, and the molten iron is poured directly without second incubation.
The material of the invention prepared according to the above process,
with reference to the GB/T229-2007 standard, is subjected to a low-temperature impact test on the material, and a low-temperature Vickers hardness tester is used to perform a low-temperature hardness test to obtain the test data: at-150°C; the Vickers hardness value Hv is 181, and the impact value is 20J/mm?; at room temperature, the
Vickers hardness value Hv is 136, and the impact value is 23J/mm?.

Claims (2)

CLAIMS LU501341
1. A preparation method of high toughness and high hardness ductile iron material used at ultra-low temperature, characterized in that: the chemical composition of the material is calculated by weight percentage: C 2.7%-2.9%, Si
1.8%-2.0%, Mn 1%-5%, P 0.01%-0.08%, S 0.01%-0.02%, Ni 20%-28%, Cr
0.5%-3.0%, Cu0.5%-1.5%, Mg0.06-0.09%, the rest are Fe; the method is carried out as follows: (1) preparation of raw molten iron: the P content of pig iron and scrap steel raw materials is controlled within 0.01%-0.08%, and the content of S is controlled within S 0.01%-0.02%; the composition of the raw materials must be clearly known and added and controlled within 35%-50% of the total ; (2) adjustment of alloy composition: the adjustment of alloy composition includes the order of addition of alloy raw materials, carbon equivalent and carbon silicon content adjustment; use intermediate frequency electric furnace smelting to adjust the alloy composition according to the above chemical composition ratio and ensure the uniformity of the alloy elements in the molten iron; the carbon equivalent and carbon silicon content are adjusted according to the above carbon silicon content range; the order of adding alloy raw materials is: Ni, Mn, Cr, Cu, Si; (3) spheroidizing treatment: Ni-Mg alloy spheroidizing agent with a Mg content of 20% to 30% is used in the spheroidizing process, and the mass fraction is 0.5% to
1.5%, and the addition method is flushing into the bottom of the bag; the spheroidizing temperature is 1460°C-1540°C; the molten iron is spheroidized in accordance with the specified spheroidizing agent, spheroidizing agent addition amount, spheroidizing method and spheroidizing temperature; (4) inoculation treatment: after the molten iron smelting process, the ferrosilicon inoculant is used to inoculate the molten iron once; the chemical composition of the ferrosilicon inoculant is that Si 70% -78% by weight, and the rest is Fe; the mass fraction is 0.5%-1.5%; the adding method is inoculation with flow, and the inoculation temperature is 1350°C-1380°C.
2. The method for preparing high-toughness and high-hardness ductile iron 50734)
material used at ultra-low temperature according to claim 1, characterized in that: in step (4), the second inoculation is performed after the first inoculation process; in the secondary inoculation process, Si-Fe-Zr-Sr inoculant is used; it consists of the following chemical components in percentage by weight: Si 70%-78%, Al 0.2%-0.5%, Zr 0.5%-3%, Sr 0.5%-3%, Ca 0.2%-0.5%, and the balance of Fe; the adding amount is 0.5%-1.5%, the adding method is stream inoculation, and the inoculation temperature is 1350°C-1380°C.
LU501341A 2022-01-27 2022-01-27 High-toughness and high-hardness ductile iron material used under ultra-low temperature and preparation method thereof LU501341B1 (en)

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Application Number Priority Date Filing Date Title
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