CN106676386A - Thermal treatment method of cast iron cylinder sleeve - Google Patents

Abstract

The invention discloses a heat treatment method for a cast iron cylinder liner. The weight percentage of the cast iron cylinder liner is C3.0-3.4%, Si1.65-2.15%, Mn0.75-1.0%, Cr0.3- 0.6%, P<0.2%, S<0.06%, and the balance is Fe. The method includes batching, preheating, smelting, quick analysis before furnace, final deoxidation, nodular ink treatment and inoculation treatment, pouring and pearlitization treatment. The method has a simple smelting process, and by controlling the addition of carbon, silicon, and chromium in the cast iron, spheroidizing treatment and pearlitizing treatment, high-performance friction-reducing nodular cast iron can be cast, while reducing production costs, and is especially suitable for casting cast iron cylinder liners.

Description

A heat treatment method for cast iron cylinder liner

technical field

The invention relates to the technical field of ferrous metal production, in particular to a heat treatment method for cast iron cylinder liners.

Background technique

my country has been producing nodular cast iron since 1950, and has developed rich rare earth resources since the 1970s. Therefore, on the basis of magnesium nodular cast iron, my country's unique rare earth nodular cast iron has been developed and has become an important casting material. Chromium-containing nodular cast iron is an excellent wear-reducing material, which has the characteristics of high hardness and prolonging the service life of castings. When used as anti-friction cast iron, the chromium content is generally below 0.5% to avoid free carbides. Therefore, the development of chromium-containing antifriction ductile iron to prolong the service life of castings. In addition, in order to improve the wear resistance of chromium-containing nodular cast iron piston rings, pearlitization treatment is required.

Contents of the invention

The purpose of the present invention is to address the above problems, to propose a cast iron cylinder liner and its preparation method, by controlling the addition of carbon, silicon, chromium in cast iron, spheroidizing treatment and pearlitizing treatment, casting high-performance anti-friction nodular graphite cast iron.

The technical scheme that the present invention solves its technical problem adopts is: comprise following several steps:

The first step: ingredients: steel scrap, recycled materials, pig iron, ferromanganese, ferrosilicon, and ferrochrome according to C3.0～3.4%, Si1.65～2.15%, Mn0.75～1.0%, Cr0.3～0.6% , P<0.2%, S<0.06%, and the balance is Fe weight percentage;

Step 2: Preheating: Put the optimized calculated steel scrap, recycled material and pig iron into the medium frequency induction furnace for preheating;

The third step: smelting: After melting the steel scrap, recycled material, and pig iron in the intermediate frequency induction furnace, put in a deoxidizer whose amount is 18-28% of the furnace charge, and whose composition is 70% lime + 30% fluorite for pre-deoxidation, and then put in For baked ferromanganese, ferrosilicon and ferrochrome, when the temperature of molten iron rises to 1420-1480°C, add 0.1% slag remover to remove slag once, and then cover with heat preservation agent to wait for sampling analysis;

Step 4: Quick analysis before the furnace: Take the molten iron and analyze it with a front-of-the-furnace spectrometer combined with carbon-silicon thermal analysis for rapid analysis, and adjust the chemical composition according to the analysis results;

Step 5: Final deoxidation: raise the temperature of the molten iron to 1460-1650°C, and put in 0.1-0.3% aluminum in the molten iron for final deoxidation;

Step 6: Spheroidization treatment and inoculation treatment: The molten iron flows from the intermediate frequency induction furnace to the ladle, and the spheroidization treatment, inoculation treatment and secondary slag removal treatment are performed in the ladle, and the amount added is 1.2 to 1.4 of the molten iron amount %Nodulizer, the particle size of the nodulizer is 8-26mm, and the nodulizer is FeSiMg Re3; add 1-1.2% inoculant whose amount is the amount of molten iron, the particle size of the inoculant is 4-8 mm, and the inoculant is 75 ferrosilicon; add 0.1% slag removal agent whose amount is the amount of molten iron, and spheroidize Immediately after that, remove the slag and pour the triangular test piece and spectrometer to analyze and detect the spheroidization and chemical composition of the molten iron before pouring;

Step 7: Pouring: The pouring temperature is 1480-1500°C. When the ladle is pouring, add a secondary inoculant with an amount of 0.08-0.16% of the molten iron. The particle size of the inoculant is 2-6mm, and the inoculant is 75 Ferrosilicon to obtain chromium-containing nodular cast iron cylinder liner castings;

The eighth step: pearlitization treatment.

In the eighth step of pearlitization treatment, the casting is loaded into a heat treatment furnace below 200°C, heated to 920-940°C, kept for 4-6 hours, cooled to 720-740°C, kept for 5-6 hours, Cool to 500 ℃ and air-cool to obtain chromium-containing nodular cast iron cylinder liner parts.

The beneficial effects of the invention are: the smelting process is simple, and by controlling the amount of carbon, silicon, and chromium added in the cast iron, spheroidizing treatment and pearlitizing treatment, high-performance anti-friction nodular cast iron can be cast, and the production cost can be reduced at the same time, which is especially suitable for casting Cast iron cylinder liner.

detailed description

Example 1:

A kind of heat treatment method of cast iron cylinder liner of this example, comprises following several steps:

The first step: ingredients: steel scrap, recycled materials, pig iron, ferromanganese, ferrosilicon, and ferrochrome according to C3.0%, Si1.65%, Mn0.75%, Cr0.3%, P<0.2%, S< 0.06%, and the balance is batched in the form of Fe weight percentage;

Step 2: Preheating: Put the optimized calculated steel scrap, recycled material and pig iron into the medium frequency induction furnace for preheating;

The third step: smelting: After melting the steel scrap, recycled materials, and pig iron in the intermediate frequency induction furnace, put in a deoxidizer whose amount is 18% of the furnace charge, and whose composition is 70% of lime + 30% of fluorite for pre-deoxidation, and then put into baking For the processed ferromanganese, ferrosilicon and ferrochrome, when the temperature of molten iron rises to 1420°C, add 0.1% slag remover to remove slag once, and then cover the heat preservation agent and wait for sampling and analysis;

Step 4: Quick analysis before the furnace: Take the molten iron and analyze it with a front-of-the-furnace spectrometer combined with carbon-silicon thermal analysis for rapid analysis, and adjust the chemical composition according to the analysis results;

The fifth step: final deoxidation: the temperature of molten iron is raised to 1460°C, and aluminum whose amount is 0.1% of molten iron is put in for final deoxidation;

Step 6: Spheroidization treatment and inoculation treatment: The molten iron flows from the intermediate frequency induction furnace to the ladle, and the spheroidization treatment, inoculation treatment and secondary slag removal treatment are carried out in the ladle, and the amount of 1.2% balls is added to the amount of molten iron. Nodulizer, the particle size of the nodulizer is 8mm, and the nodulizer is FeSiMg Re3; add 1% inoculant whose amount is the amount of molten iron, the particle size of the inoculant is 4 mm, and the inoculant is 75 ferrosilicon; add 0.1% slag removal agent whose amount is the amount of molten iron, and remove slag immediately after the nodularization reaction The pouring triangular test piece and the spectrometer analyze and detect the spheroidization and chemical composition of the molten iron before pouring;

Step 7: Pouring: The pouring temperature is 1480°C. When the ladle is pouring, 0.08% of the secondary inoculant is added with the amount of molten iron. The particle size of the inoculant is 2 mm, and the inoculant is 75 ferrosilicon to obtain chromium-containing Ductile iron cylinder liner castings;

Step 8: Pearlitization treatment: Put the casting into a heat treatment furnace below 200°C, raise the temperature to 920°C, keep it for 4 hours, cool it to 720°C, keep it for 5 hours, cool it to 500°C and take it out of the furnace for air cooling to obtain a chromium-containing ductile iron cylinder Set of parts.

Example 2:

A kind of heat treatment method of cast iron cylinder liner of this example, comprises following several steps:

The first step: ingredients: steel scrap, recycled materials, pig iron, ferromanganese, ferrosilicon, and ferrochrome according to C3.2%, Si1.9%, Mn0.85%, Cr0.45%, P<0.2%, S< 0.06%, and the balance is batched in the form of Fe weight percentage;

Step 2: Preheating: Put the optimized calculated steel scrap, recycled material and pig iron into the medium frequency induction furnace for preheating;

The third step: smelting: After melting the steel scrap, recycled material, and pig iron in the intermediate frequency induction furnace, put in a deoxidizer whose amount is 23% of the furnace charge, and whose composition is 70% lime + 30% fluorite for pre-deoxidation, and then put into baking For the processed ferromanganese, ferrosilicon and ferrochrome, when the temperature of the molten iron rises to 1450°C, add 0.1% slag remover to remove slag once, and then cover the heat preservation agent and wait for sampling analysis;

Step 4: Quick analysis before the furnace: Take the molten iron and analyze it with a front-of-the-furnace spectrometer combined with carbon-silicon thermal analysis for rapid analysis, and adjust the chemical composition according to the analysis results;

Step 5: Final deoxidation: raise the temperature of molten iron to 1505°C, and put in aluminum whose amount is 0.2% of molten iron for final deoxidation;

Step 6: Spheroidization treatment and inoculation treatment: The molten iron flows from the intermediate frequency induction furnace to the ladle, and the spheroidization treatment, inoculation treatment and secondary slag removal treatment are carried out in the ladle, and the amount is 1.3% of the molten iron amount. Nodulizer, the particle size of the nodulizer is 17mm, and the nodulizer is FeSiMg Re3; add 1.1% inoculant whose amount is the amount of molten iron, the particle size of the inoculant is 6 mm, and the inoculant is 75 ferrosilicon; add 0.1% slag removal agent whose amount is the amount of molten iron, and remove slag immediately after the nodularization reaction The pouring triangular test piece and the spectrometer analyze and detect the spheroidization and chemical composition of the molten iron before pouring;

Step 7: Pouring: The pouring temperature is 1490°C. When the ladle is pouring, 0.12% of the secondary inoculant whose amount is the amount of molten iron is added along with the pouring. The particle size of the inoculant is 4 mm, and the inoculant is 75 ferrosilicon to obtain chromium-containing Ductile iron cylinder liner castings;

Step 8: Pearlitization treatment: Put the casting into a heat treatment furnace below 200°C, raise the temperature to 930°C, keep it for 5 hours, cool it to 730°C, keep it for 5.5 hours, cool it to 500°C and leave it for air cooling to obtain chromium-containing ductile iron Cylinder parts.

Example 3:

A kind of heat treatment method of cast iron cylinder liner of this example, comprises following several steps:

The first step: ingredients: steel scrap, recycled materials, pig iron, ferromanganese, ferrosilicon, and ferrochrome according to C3.4%, Si2.15%, Mn1.0%, Cr0.6%, P<0.2%, S< 0.06%, and the balance is batched in the form of Fe weight percentage;

Step 2: Preheating: Put the optimized calculated steel scrap, recycled material and pig iron into the medium frequency induction furnace for preheating;

The third step: smelting: After melting the steel scrap, recycled materials, and pig iron in the intermediate frequency induction furnace, put in a deoxidizer whose amount is 28% of the furnace charge, and whose composition is 70% lime + 30% fluorite for pre-deoxidation, and then put into baking For the processed ferromanganese, ferrosilicon and ferrochrome, when the temperature of molten iron rises to 1480°C, add 0.1% slag remover to remove slag once, and then cover the heat preservation agent and wait for sampling analysis;

Step 4: Quick analysis before the furnace: Take the molten iron and analyze it with a front-of-the-furnace spectrometer combined with carbon-silicon thermal analysis for rapid analysis, and adjust the chemical composition according to the analysis results;

The fifth step: final deoxidation: the temperature of molten iron is raised to 1650°C, and aluminum whose amount is 0.3% of molten iron is put into it for final deoxidation;

Step 6: Nodularization treatment and inoculation treatment: The molten iron flows from the intermediate frequency induction furnace to the ladle, and the nodularization treatment, inoculation treatment and secondary slag removal treatment are carried out in the ladle, and the amount of 1.4% balls added is 1.4% of the molten iron amount. Nodulizer, the particle size of the nodulizer is 26mm, and the nodulizer is FeSiMg Re3; add 1.2% inoculant whose amount is the amount of molten iron, the particle size of the inoculant is 8 mm, and the inoculant is 75 ferrosilicon; add 0.1% slag remover whose amount is the amount of molten iron, and remove slag immediately after the nodularization reaction The pouring triangular test piece and the spectrometer analyze and detect the spheroidization and chemical composition of the molten iron before pouring;

Step 7: Pouring: The pouring temperature is 1500°C. During the pouring of the ladle, 0.16% of the secondary inoculant is added with the amount of molten iron. The particle size of the inoculant is 6 mm, and the inoculant is 75 ferrosilicon to obtain chromium-containing Ductile iron cylinder liner castings;

Step 8: Pearlitization treatment: put the casting into a heat treatment furnace below 200°C, raise the temperature to 940°C, keep warm for 6 hours, cool to 740°C, keep warm for 6 hours, cool to 500°C and leave the furnace for air cooling to obtain a chromium-containing ductile iron cylinder Set of parts.

The specific embodiments of the present invention have been described above, but these descriptions can not be interpreted as limiting the scope of the present invention, and the protection scope of the present invention is defined by the appended claims, and any modification on the basis of the claims of the present invention , equivalent replacements and improvements, etc., all fall within the protection scope of the present invention.

Claims (2)

1. a kind of heat treatment method of Cast iron liner, it is characterised in that：Including following several steps：

The first step：Dispensing：By steel scrap, foundry returns, the pig iron, ferromanganese, ferrosilicon, ferrochrome press C3.0~3.4%, Si1.65~2.15%, Mn0.75~1.0%, Cr0.3~0.6%, P ＜ 0.2%, S ＜ 0.06%, the mode of balance of Fe percentage by weights carries out dispensing；

Second step：Preheating：By optimization calculate steel scrap, foundry returns, the pig iron input intermediate frequency furnace in preheated；

3rd step：Melting：By the steel scrap in intermediate frequency furnace, foundry returns, the pig iron fusing after, put into its quantity for furnace charge 18~ 28%, composition carries out pre-deoxidation for the deoxidizer of Calx 70%+ fluorites 30%, then puts into ferromanganese, ferrosilicon and ferrochrome that baking is processed, When bonded hard ferrite magnet is warming up to 1420~1480 DEG C, add 0.1% deslagging agent once to remove the gred, be then covered by be sampled point of heat preserving agent etc. Analysis；

4th step：Both analysis：Take iron liquid stokehold spectrometer analysis quickly to be analyzed with reference to carbon silicon heat analysis, according to Analysis result adjusts chemical composition；

5th step：Final deoxidizing：Bonded hard ferrite magnet is warming up to into 1460~1650 DEG C, the aluminum that its quantity is iron liquid 0.1~0.3% is put into Carry out final deoxidizing；

6th step：Spheroidising and inoculation：Iron liquid flows to casting ladle from intermediate frequency furnace, carry out in casting ladle spheroidising, Inoculation and secondary except Slag treatment, adds 1.2~1.4% nodulizers that its quantity is iron liquid amount, and the granularity of nodulizer is 8~ 26mm, nodulizer is FeSiMgRe3；Adding 1~1.2% inovulant that its quantity is iron liquid amount, the granularity of inovulant is 4~ 8mm, inovulant is 75 ferrosilicon；Add 0.1% deslagging agent that its quantity is iron liquid amount, cast triangle of skimming at once after spheroidizing reacion Test piece and spectrometer analysis detect that liquid iron balling and chemical composition are poured into a mould after qualified；

7th step：Cast：1480~1500 DEG C of pouring temperature, as cast adds its quantity for iron liquid amount when casting ladle is poured into a mould 0.08~0.16% post inoculant, the granularity of inovulant is 2~6mm, and inovulant is 75 ferrosilicon, obtains the cylinder of spheroidal graphite cast-iron containing chromium Set foundry goods；

8th step：Pearliteization process.

2. the heat treatment method of a kind of Cast iron liner according to claim 1, it is characterised in that：In the 8th described step pearl During body of light process is processed, below 200 DEG C of foundry goods ﹤ is fitted in heat-treatment furnace, is warming up to 920~940 DEG C, is incubated 4~6h stoves It is cooled to 720~740 DEG C, is incubated 5~6h, stove is cooled to 500 DEG C of air coolings of coming out of the stove, obtains the cylinder sleeve part of spheroidal graphite cast-iron containing chromium.