CN113088829A - Ferrite system heat-resistant steel for automobile turbine shell and exhaust pipe and preparation method thereof - Google Patents
Ferrite system heat-resistant steel for automobile turbine shell and exhaust pipe and preparation method thereof Download PDFInfo
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Abstract
A ferrite system heat-resistant steel for automobile turbine shells and exhaust pipes and a preparation method thereof adopt the following preparation steps: firstly, the method comprises the following steps: selecting raw materials according to a set proportion of heat-resistant steel: smelting; II, secondly: after the raw materials are melted into molten steel, standing the molten steel for slagging operation; then, deslagging to obtain clean molten feed liquid; thirdly, the method comprises the following steps: pouring the melted material liquid into a pouring ladle, and placing the pouring ladle on an automatic pouring machine for weighing; fourthly, the method comprises the following steps: carrying out pouring operation; sampling in a pouring ladle for spectroscopic analysis, and confirming the content of each element; fifthly: after the pouring is finished, carrying out heat treatment operation on the obtained casting and sample; sixthly, the method comprises the following steps: and (5) inspecting the material and the result of the casting and the sample. The invention can not only make the material obtain excellent high-temperature mechanical property; and moreover, a layer of compact oxide film is formed on the surface of the casting, so that oxygen is prevented from diffusing to the interior to further oxidize the matrix, and the oxidation resistance of the material is improved.
Description
Technical Field
The invention belongs to the field of production and manufacturing of automobile turbine shells and exhaust pipes, and particularly relates to a ferrite system heat-resistant steel for the automobile turbine shells and the exhaust pipes and a preparation method thereof.
Background
At present, with the increasingly strict requirements of national policies on environmental protection, higher requirements are continuously put forward on the requirements on automobile exhaust emission. Therefore, on the premise of ensuring that the engine displacement is not increased, how to improve the power performance of the engine is particularly important. In order to improve the power performance of the engine, the power performance of the engine can be improved only by increasing the temperature of exhaust gas; this results in higher and higher exhaust temperatures. The increase in exhaust gas temperature places increasing demands on the materials used to manufacture the turbine housing and exhaust pipe. It mainly has the following problems:
1. because the turbine shell and the exhaust pipe are manufactured by developing the original medium-silicon molybdenum nodular cast iron into high-nickel nodular cast iron or high-silicon molybdenum nodular (vermicular) cast iron, and the high-nickel nodular cast iron or the high-silicon molybdenum nodular (vermicular) cast iron cannot meet the requirement of the exhaust emission temperature of the automobile, most automobile enterprises require that austenite heat-resistant steel materials are used for manufacturing the turbine shell and the exhaust pipe.
2. As the heat-resistant temperature of the high-silicon molybdenum nodular (vermicular) cast iron is about 830 ℃, the heat-resistant temperature of the high-nickel nodular cast iron is about 950 ℃, and the heat-resistant temperature of the heat-resistant steel is about 1050 ℃. In order to obtain a completely austenitic matrix at room temperature, it is necessary to add a large amount of expensive nickel (and at least 12% by weight of nickel) to the alloy material, thus leading to a considerable increase in production costs.
3. The current fuel used by passenger cars is mainly gasoline and diesel oil, and the fuel is easy to produce a large amount of harmful gas after being combusted, so the fuel is extremely unfavorable for the environment.
4. In recent years, natural gas is a novel automobile fuel, and has attracted great attention in domestic and international markets, and some automobile manufacturers also invest a great deal of manpower and financial resources to research and develop; although the exhaust emission temperature of the engine using natural gas as fuel is about 830 ℃, the turbine shell and the exhaust pipe manufactured by using high silicon molybdenum ball (vermicular) graphite cast iron have serious oxidation phenomenon found on the engine using natural gas as fuel, and the engine using natural gas as fuel can not meet the use requirement because the combustion product of natural gas has great difference with the combustion product of gasoline and diesel oil in chemical composition.
Disclosure of Invention
The invention aims to provide a ferrite heat-resistant steel for automobile turbine shells and exhaust pipes and a preparation method thereof, and aims to solve the technical problems that the materials of the manufactured turbine shells and exhaust pipes obtain complete ferrite matrixes and the high-temperature mechanical properties of the materials are improved.
In order to achieve the above object, the specific technical solution of the ferritic heat-resistant steel for automobile turbine shells and exhaust pipes and the method for manufacturing the same according to the present invention is as follows:
a ferrite heat-resistant steel for automobile turbine shells and exhaust pipes, comprising: the heat-resistant steel comprises the following raw materials: waste steel, foundry returns, micro-carbon ferrochrome, nickel plates, ferrocolumbium, electrolytic manganese and ferrosilicon which account for a set proportion of raw materials of the heat-resistant steel; wherein, the raw materials of the heat-resistant steel also contain ferromolybdenum, ferrovanadium, ferrotungsten, ferrosilicon and carburant in set proportion; the raw materials of the heat-resistant steel are put into an induction furnace for smelting, the raw materials of the heat-resistant steel are gradually melted into molten steel, and then deslagging operation and tapping operation are carried out to obtain clean molten feed liquid;
the proportion of the carburant in the heat-resistant steel is as follows: 0.06 percent;
the heat-resistant steel comprises the following chemical components in percentage by mass: carbon: 0.2 to 0.6; silicon: 1.0-2.5; manganese: 0.5-1.0; phosphorus: less than or equal to 0.040; less than or equal to 0.030 percent of sulfur; chromium: 15.0-20.0; nickel: less than or equal to 1.0; molybdenum: less than or equal to 0.50; vanadium: less than or equal to 0.50; niobium: 1.0-2.0; tungsten: 1.5-2.5, the balance being iron and unavoidable trace elements, which have a completely ferritic matrix with a homogeneous distribution of carbides with high-temperature mechanical properties and a low coefficient of thermal expansion and resistance to high-temperature oxidation.
Further, after the raw materials of the heat-resistant steel are gradually melted into molten steel, the temperature of the molten raw materials is continuously increased after being melted, and when the temperature is increased to 1595 ℃, the molten steel is kept stand for slagging operation.
Further, the waste steel is carbon steel.
Further, the scrap returns are waste castings and a pouring system.
Further, the raw materials account for the heat-resistant steel in proportion as follows: the proportion of the waste steel in the heat-resistant steel is as follows: 47.0 percent, and the proportion of the returned materials in the heat-resistant steel is as follows: 35.0 percent of micro-carbon ferrochrome, wherein the proportion of the micro-carbon ferrochrome in the heat-resistant steel is as follows: 15.13 percent, wherein the nickel plate accounts for the heat-resistant steel in proportion: 0.01 percent, and the ratio of ferrocolumbium to the heat-resistant steel is as follows: 0.88 percent, and the proportion of the electrolytic manganese in the heat-resistant steel is as follows: 0.20 percent, and the ferromolybdenum accounts for the proportion of the heat-resistant steel: 0.04 percent, and the proportion of ferrovanadium in the heat-resistant steel is as follows: 0.11 percent, and the proportion of ferrotungsten in the heat-resistant steel is as follows: 1.0 percent and the ferrosilicon accounts for the heat-resistant steel in proportion: 0.57 percent.
The invention also provides a preparation method of the ferrite system heat-resistant steel for the automobile turbine shell and the exhaust pipe, which is provided with the heat-resistant steel and specifically adopts the following preparation steps:
the first step is as follows: the raw materials are mixed according to a set proportion of heat-resistant steel, namely: selecting waste steel, foundry returns, micro-carbon ferrochrome, nickel plates, ferrocolumbium, electrolytic manganese, ferromolybdenum, ferrovanadium, ferrotungsten, ferrosilicon and carburant: and putting the mixture into a medium-frequency induction furnace for smelting;
the second step is that: heating the raw materials in an induction furnace, gradually melting the raw materials into molten steel, then continuously heating the molten steel in the induction furnace, standing for 3 minutes after the temperature is increased to 1580-1630 ℃, and then carrying out slagging operation; so as to ensure that the added materials are completely melted and have uniform components; after slagging, standing molten steel of a raw material of heat-resistant steel melted in the induction furnace for 3 minutes, and then deslagging to obtain clean molten feed liquid;
the third step: when the temperature in the induction furnace reaches 1600 ℃ -1650 ℃, pouring the melted material liquid into a pouring ladle from the induction furnace, and placing the pouring ladle on an automatic pouring machine with a weighing function, wherein the weight of the melted material liquid is as follows: 450-600 Kg;
the fourth step: when the temperature of the molten material molten in the pouring ladle reaches 1555-1609 ℃, pouring operation is carried out; sampling in a pouring ladle for spectroscopic analysis, and confirming the content of each element;
the fifth step: after the pouring is finished, carrying out heat treatment operation on the obtained casting and sample;
and a sixth step: after heat treatment of the cast and the sample, the material and the result were examined.
Further, the set proportion of the raw materials in the first step is as follows: the proportion of the waste steel in the heat-resistant steel is as follows: 47.0 percent, and the proportion of the returned materials in the heat-resistant steel is as follows: 35.0 percent of micro-carbon ferrochrome, wherein the proportion of the micro-carbon ferrochrome in the heat-resistant steel is as follows: 15.13 percent, wherein the nickel plate accounts for the heat-resistant steel in proportion: 0.01 percent, and the ratio of ferrocolumbium to the heat-resistant steel is as follows: 0.88 percent, and the proportion of the electrolytic manganese in the heat-resistant steel is as follows: 0.20 percent, and the ferromolybdenum accounts for the proportion of the heat-resistant steel: 0.04 percent, and the proportion of ferrovanadium in the heat-resistant steel is as follows: 0.11 percent, and the proportion of ferrotungsten in the heat-resistant steel is as follows: 1.0 percent and the ferrosilicon accounts for the heat-resistant steel in proportion: 0.57 percent, and the proportion of the carburant in the heat-resistant steel is as follows: 0.06% was selected.
Further, in the fifth step, the heat treatment process is as follows:
firstly, stacking the castings on a thermal treatment tool according to a standard, transferring the tool into a thermal treatment furnace after stacking is finished, and covering a furnace door;
starting heat treatment equipment to start heating operation, entering a heat preservation stage after the heating reaches a heat preservation temperature, and entering a cooling stage after the heat preservation is finished;
third, according to material and foundry goods structure, the temperature is as low as possible, cooling rate is slow under the prerequisite of guaranteeing the destressing effect, prevents that the foundry goods from warping in heat treatment: the heat treatment process parameters are as follows: the heat preservation temperature is as follows: 750-850 ℃; the heat preservation time is as follows: more than 3 hours; the cooling speed after the heat preservation is as follows: 250 ℃ per hour or less.
Further, the tensile strength of the heat-resistant steel is: more than or equal to 440 MPa; yield strength: not less than 380 MPa; hardness: HB 190-250; the metallographic structure is as follows: a small amount of carbide is distributed in the ferrite matrix; and (3) under the oxidizing atmosphere of 950 ℃, keeping the temperature for 100 hours, and increasing the weight by oxidation: less than or equal to 3.0mg/m2*h。
The ferrite system heat-resistant steel for the automobile turbine shell and the exhaust pipe and the preparation method thereof have the following advantages:
1. the invention utilizes the reasonable proportion of carbon, silicon, manganese, chromium, niobium, tungsten and other elements to obtain carbides which are uniformly distributed in a ferrite matrix, so that the material obtains excellent high-temperature mechanical properties.
2. According to the invention, a small grain structure is obtained by adding a proper proportion of niobium, so that the material performance is improved; moreover, stable carbide is formed in the elements of niobium, chromium, tungsten and carbon, and is uniformly distributed on a grain boundary, so that the grain boundary strength is greatly improved.
3. According to the invention, the chromium element is matched with the silicon element with a proper content, so that a layer of compact oxide film is formed on the surface of the casting under a high-temperature service condition, and oxygen element is prevented from diffusing to the interior to further oxidize a matrix, thereby improving the oxidation resistance of the material.
4. According to the invention, by utilizing a proper heat treatment process, the turbine shell and the exhaust pipe are more stable in material under the service condition, and the dimensional stability of the casting is further improved.
5. The invention obviously reduces the production cost under the condition of not adding expensive nickel element materials.
Drawings
FIG. 1 is a schematic view of the preparation process of the present invention.
Detailed Description
In order to better understand the purpose, structure and function of the present invention, a ferritic heat-resistant steel for automobile turbine shells and exhaust pipes and a method for manufacturing the same according to the present invention will be described in further detail with reference to the accompanying drawings.
As shown in fig. 1, the present invention is provided with: the heat-resistant steel comprises the following raw materials: waste steel (carbon steel in this embodiment), scrap (waste casting and pouring system in this embodiment), micro-carbon ferrochrome, nickel plate, ferrocolumbium, electrolytic manganese, ferromolybdenum, ferrovanadium, ferrotungsten, ferrosilicon and carburant, which account for a set proportion of raw materials of the heat-resistant steel; the raw material of the heat-resistant steel is put into an induction furnace (in this embodiment, a medium-frequency induction furnace) for smelting, the raw material of the heat-resistant steel is gradually melted into molten steel, the temperature of the molten steel is continuously raised after the raw material is melted, the molten steel is kept still for slagging operation after the temperature is raised to 1595 ℃, and then deslagging operation and tapping operation are carried out, so that a clean molten material liquid is obtained.
The proportion of the carburant in the heat-resistant steel is as follows: 0.06 percent.
The chemical composition mass percent (%) of the heat-resistant steel is as follows: carbon (C): 0.2 to 0.6; silicon (Si): 1.0-2.5; manganese (Mn): 0.5-1.0; phosphorus (P): less than or equal to 0.040; less than or equal to 0.030 percent of sulfur (S); chromium (Cr): 15.0-20.0; nickel (Ni): less than or equal to 1.0; molybdenum (Mo): less than or equal to 0.50; vanadium (V): less than or equal to 0.50; niobium (Nb): 1.0-2.0; tungsten (W): 1.5-2.5, the balance of iron and inevitable trace elements, and has a completely ferrite matrix, a plurality of carbides are uniformly distributed in the completely ferrite matrix, and the completely ferrite matrix has good high-temperature mechanical properties, a low thermal expansion coefficient and excellent high-temperature oxidation resistance.
The set proportion of the raw materials is as follows: the proportion of the waste steel (carbon steel in this example) to the heat-resistant steel is: 47.0 percent, and the proportion of the returned materials in the heat-resistant steel is as follows: 35.0 percent of micro-carbon ferrochrome, wherein the proportion of the micro-carbon ferrochrome in the heat-resistant steel is as follows: 15.13 percent, wherein the nickel plate accounts for the heat-resistant steel in proportion: 0.01 percent, and the ratio of ferrocolumbium to the heat-resistant steel is as follows: 0.88 percent, and the proportion of the electrolytic manganese in the heat-resistant steel is as follows: 0.20 percent, and the ferromolybdenum accounts for the proportion of the heat-resistant steel: 0.04 percent, and the proportion of ferrovanadium in the heat-resistant steel is as follows: 0.11 percent, and the proportion of ferrotungsten in the heat-resistant steel is as follows: 1.0 percent and the ferrosilicon accounts for the heat-resistant steel in proportion: 0.57 percent, and the proportion of the carburant in the heat-resistant steel is as follows: 0.06% was selected: and putting the mixture into a medium-frequency induction furnace for smelting.
Example 1:
the method comprises the following specific steps of gradually melting raw materials of the heat-resistant steel into molten steel:
the first step is as follows: the raw materials are mixed according to a set proportion, namely: the proportion of the waste steel (carbon steel in this example) to the heat-resistant steel is: 47.0 percent, and the proportion of the returned materials in the heat-resistant steel is as follows: 35.0 percent of micro-carbon ferrochrome, wherein the proportion of the micro-carbon ferrochrome in the heat-resistant steel is as follows: 15.13 percent, wherein the nickel plate accounts for the heat-resistant steel in proportion: 0.01 percent, and the ratio of ferrocolumbium to the heat-resistant steel is as follows: 0.88 percent, and the proportion of the electrolytic manganese in the heat-resistant steel is as follows: 0.20 percent, and the ferromolybdenum accounts for the proportion of the heat-resistant steel: 0.04 percent, and the proportion of ferrovanadium in the heat-resistant steel is as follows: 0.11 percent, and the proportion of ferrotungsten in the heat-resistant steel is as follows: 1.0 percent and the ferrosilicon accounts for the heat-resistant steel in proportion: 0.57 percent, and the proportion of the carburant in the heat-resistant steel is as follows: 0.06% was selected: and putting the mixture into a medium-frequency induction furnace for smelting;
the second step is that: heating the raw materials in an induction furnace, gradually melting the raw materials into molten steel, then continuously heating the molten steel in the induction furnace, standing for 3 minutes after the temperature is increased to 1580-1630 ℃, and then carrying out slagging operation; so as to ensure that the added materials are completely melted and have uniform components; after slagging, standing molten steel of a raw material of heat-resistant steel melted in the induction furnace for 3 minutes, and then deslagging to obtain clean molten feed liquid;
the third step: when the temperature in the induction furnace reaches 1600-1650 ℃ (the temperature is according to the baking degree of the pouring ladle, namely, the pouring temperature of the final pouring product is ensured), the melted material liquid is poured into the pouring ladle from the induction furnace, and the pouring ladle is placed on an automatic pouring machine with the weighing function, and at the moment, the weight of the melted material liquid is as follows: 450-600 Kg; the weight is controlled within the range according to the single weight of the casting, the die weight and the size of the pouring ladle.
The fourth step: when the temperature of the molten material after being melted in the pouring ladle reaches 1555 ℃, pouring operation is carried out;
a sample was taken from the ladle and analyzed by spectroscopy, confirming the contents of the elements as in the following Table (1):
the fifth step: after the pouring is finished, the casting and the sample obtained by the pouring are subjected to heat treatment operation, the basic heat treatment operation process is as follows,
firstly, stacking the castings on a thermal treatment tool according to a standard, transferring the tool into a thermal treatment furnace after stacking is finished, and covering a furnace door;
starting heat treatment equipment to start heating operation, entering a heat preservation stage after the heating reaches a heat preservation temperature, and entering a cooling stage after the heat preservation is finished; (the heat preservation and temperature reduction stage is performed according to the specification of the claims);
third, according to material and foundry goods structure, the temperature is as low as possible, cooling rate is slow under the prerequisite of guaranteeing the destressing effect, prevents that the foundry goods from warping in heat treatment: the heat treatment process parameters are as follows: the heat preservation temperature is as follows: 755 ℃; the heat preservation time is as follows: 3.05 hours; the cooling speed after the heat preservation is as follows: 95 ℃/hour;
and a sixth step: after the casting and the sample are subjected to heat treatment, checking the material and the result;
tensile strength: more than or equal to 440 MPa; yield strength: not less than 380 MPa; hardness: HB 190-250; the metallographic structure is as follows: a small amount of carbide is distributed in the ferrite matrix; and (3) under the oxidizing atmosphere of 950 ℃, keeping the temperature for 100 hours, and increasing the weight by oxidation: less than or equal to 3.0mg/m2*h；
The materials of the castings and the samples after heat treatment are inspected, and the inspection results are shown in the following table (2):
remarking: oxidation test conditions: test temperature: 950 ℃ and test time: 100 hours; test atmosphere: air (a)
Example 2:
the first step is as follows: the raw materials are mixed according to a set proportion, namely: the proportion of the waste steel (carbon steel in this example) to the heat-resistant steel is: 15.23 percent, and the proportion of the returned materials in the heat-resistant steel is as follows: 75.0 percent of micro-carbon ferrochrome accounts for the heat-resistant steel in proportion: 7.29 percent, wherein the nickel plate accounts for the heat-resistant steel in proportion: 0.08 percent, and the proportion of ferrocolumbium in the heat-resistant steel is as follows: 0.62 percent, and the proportion of the electrolytic manganese in the heat-resistant steel is as follows: 0.17 percent, and the ferromolybdenum accounts for the proportion of the heat-resistant steel: 0.11 percent, and the proportion of ferrovanadium in the heat-resistant steel is as follows: 0.12 percent, and the proportion of ferrotungsten in the heat-resistant steel is as follows: 0.64 percent of silicon iron accounting for the heat-resistant steel is as follows: 0.64 percent, and the proportion of the carburant in the heat-resistant steel is as follows: 0.10 percent of the raw materials are put into a medium-frequency induction furnace for smelting;
the second step is that: heating the raw materials in an induction furnace, gradually melting the raw materials into molten steel, then continuously heating the molten steel in the induction furnace, standing for 3 minutes after the temperature is raised to 1605 ℃, and then carrying out slagging operation; after slagging, standing molten steel of a raw material of heat-resistant steel melted in the induction furnace for 3 minutes, and then deslagging to obtain clean molten feed liquid;
the third step: when the temperature in the induction furnace reaches 1615 ℃, pouring the melted material liquid into a pouring ladle from the induction furnace, and placing the pouring ladle on an automatic pouring machine with a weighing function, wherein the weight of the melted material liquid is as follows: 495 Kg;
the fourth step: when the temperature of the molten material after being melted in the pouring ladle reaches 1575 ℃, pouring operation is carried out; a sample was taken from the ladle for spectroscopic analysis, and the contents of the elements were confirmed as in the following Table (3):
the fifth step: after pouring, carrying out heat treatment operation on the obtained casting and sample, wherein the heat treatment process parameters are as follows: the heat preservation temperature is as follows: 805 ℃ of water; the heat preservation time is as follows: 4.15 hours; the cooling speed after the heat preservation is as follows: 135 ℃/hour;
and a sixth step: after the casting and the sample are subjected to heat treatment, checking the material and the result;
tensile strength: more than or equal to 440 MPa; yield strength: not less than 380 MPa; hardness: HB 190-250; the metallographic structure is as follows: a small amount of carbide is distributed in the ferrite matrix; and (3) under the oxidizing atmosphere of 950 ℃, keeping the temperature for 100 hours, and increasing the weight by oxidation: less than or equal to 3.0mg/m2 × h;
the casting and the sample are subjected to material quality inspection after heat treatment, and the inspection results are shown in the following table (4):
remarking: oxidation test conditions: test temperature: 950 ℃ and test time: 100 hours; test atmosphere: air (a)
Example 3
Firstly, raw materials are proportioned according to a set proportion: namely: the proportion of the waste steel (carbon steel in this example) to the heat-resistant steel is: 8.94 percent, and the proportion of the returned materials in the heat-resistant steel is as follows: 75.0 percent of micro-carbon ferrochrome accounts for the heat-resistant steel in proportion: 10.63 percent, wherein the nickel plate accounts for the heat-resistant steel in proportion: 0.19 percent, and the ratio of ferrocolumbium to the heat-resistant steel is as follows: 1.21 percent, and the proportion of electrolytic manganese in the heat-resistant steel is as follows: 0.33 percent, and the ferromolybdenum accounts for the proportion of the heat-resistant steel: 0.43 percent, and the proportion of ferrovanadium in the heat-resistant steel is as follows: 0.48 percent, and the proportion of ferrotungsten in the heat-resistant steel is as follows: 1.02 percent and the ferrosilicon accounts for the heat-resistant steel in proportion: 1.50 percent, and the proportion of the carburant in the heat-resistant steel is as follows: 0.27% selection: and putting the mixture into a medium-frequency induction furnace for smelting;
(2) heating the raw materials in an induction furnace, gradually melting the raw materials into molten steel, then continuously heating the molten steel in the induction furnace, standing for 3 minutes after the temperature is increased to 1625 ℃, and then carrying out slagging operation; after slagging, standing molten steel of a raw material of heat-resistant steel melted in the induction furnace for 3 minutes, and then deslagging to obtain clean molten feed liquid;
(3) when the temperature in the induction furnace reaches 1615 ℃, pouring the melted material liquid into a pouring ladle from the induction furnace, and placing the pouring ladle on an automatic pouring machine with a weighing function, wherein the weight of the melted material liquid is as follows: the weight of the feed liquid is as follows: 523 Kg;
(4) when the temperature of the molten material melted in the pouring ladle reaches 1605 ℃, pouring operation is carried out; a sample was taken from the ladle for spectroscopic analysis, and the contents of the elements were confirmed as in the following Table (5):
(5) after pouring, carrying out heat treatment operation on the obtained casting and sample, wherein the heat treatment process parameters are as follows: and (3) heat preservation temperature: 845 ℃; and (3) heat preservation time: 5.0 hours; cooling speed after heat preservation: 205 ℃/hour;
(6) the casting and the sample are subjected to material quality inspection after heat treatment, and the inspection results are shown in the following table (6):
remarking: oxidation test conditions: test temperature: 950 ℃ and test time: 100 hours; test atmosphere: air (a)
Example 4:
the first step is as follows: the raw materials are mixed according to a set proportion, namely: the proportion of the waste steel (carbon steel in this example) to the heat-resistant steel is: 43.5 percent, and the proportion of the returned materials in the heat-resistant steel is as follows: 35.0 percent of micro-carbon ferrochrome, wherein the proportion of the micro-carbon ferrochrome in the heat-resistant steel is as follows: 17.01 percent, and the proportion of the nickel plate in the heat-resistant steel is as follows: 0.20 percent, and the proportion of ferrocolumbium in the heat-resistant steel is as follows: 1.31 percent, and the proportion of electrolytic manganese in the heat-resistant steel is as follows: 0.12 percent, and the ferromolybdenum accounts for the proportion of the heat-resistant steel: 0.13 percent of vanadium iron accounts for the heat-resistant steel in proportion: 0.17 percent, and the proportion of ferrotungsten in the heat-resistant steel is as follows: 1.40% and the ferrosilicon accounts for the heat-resistant steel in proportion: 0.95 percent, and the proportion of the carburant in the heat-resistant steel is as follows: 0.21 percent, putting into a medium-frequency induction furnace for smelting;
the second step is that: heating the raw materials in an induction furnace, gradually melting the raw materials into molten steel, then continuously heating the molten steel in the induction furnace, standing for 3 minutes after the temperature is increased to 1613 ℃, and then carrying out slagging operation; after slagging, standing molten steel of a raw material of heat-resistant steel melted in the induction furnace for 3 minutes, and then deslagging to obtain clean molten feed liquid;
the third step: when the temperature in the induction furnace reaches 1606 ℃, pour the molten feed liquid after the melting into the pouring ladle in the induction furnace to place the pouring ladle on the automatic casting machine that has the function of weighing, this moment, molten feed liquid weight is: 485 Kg;
the fourth step: when the temperature of the molten material after being melted in the pouring ladle reaches 1576 ℃, pouring operation is carried out;
a sample was taken from the ladle for spectroscopic analysis, and the contents of the respective elements were confirmed as in the following Table (7):
the fifth step: after pouring, carrying out heat treatment operation on the obtained casting and sample, wherein the heat treatment process parameters are as follows: the heat preservation temperature is as follows: 765 deg.C; the heat preservation time is as follows: 3.1 hours; the cooling speed after the heat preservation is as follows: 105 ℃/hour;
and a sixth step: after the casting and the sample are subjected to heat treatment, checking the material and the result;
tensile strength: more than or equal to 440 MPa; yield strength: not less than 380 MPa; hardness: HB 190-250; the metallographic structure is as follows: a small amount of carbide is distributed in the ferrite matrix; and (3) under the oxidizing atmosphere of 950 ℃, keeping the temperature for 100 hours, and increasing the weight by oxidation: less than or equal to 3.0mg/m2 × h;
the casting and the sample are subjected to material quality inspection after heat treatment, and the inspection results are shown in the following table (8):
remarking: oxidation test conditions: test temperature: 950 ℃ and test time: 100 hours; test atmosphere: air (a)
Example 5:
the first step is as follows: the raw materials are mixed according to a set proportion, namely: the proportion of the waste steel (carbon steel in this example) to the heat-resistant steel is: 31.11 percent, and the proportion of the returned materials in the heat-resistant steel is as follows: 50.0 percent of micro-carbon ferrochrome accounts for the heat-resistant steel in proportion: 14.30 percent, wherein the nickel plate accounts for the heat-resistant steel in proportion: 0.18 percent, and the proportion of ferrocolumbium in the heat-resistant steel is as follows: 1.26 percent, and the proportion of electrolytic manganese in the heat-resistant steel is as follows: 0.16 percent, and the ferromolybdenum accounts for the heat-resistant steel in proportion: 0.10 percent of vanadium iron accounts for the heat-resistant steel in proportion: 0.09 percent of ferrotungsten accounting for the heat-resistant steel is as follows: 1.13 percent and the ferrosilicon accounts for the heat-resistant steel in proportion: 1.45 percent, and the proportion of the carburant in the heat-resistant steel is as follows: 0.22 percent of the raw materials are put into a medium-frequency induction furnace for smelting;
the second step is that: heating the raw materials in an induction furnace, gradually melting the raw materials into molten steel, then continuously heating the molten steel in the induction furnace, standing for 4 minutes after the temperature is raised to 1601 ℃, and then carrying out slagging operation; after slagging, standing molten steel of a raw material of heat-resistant steel melted in the induction furnace for 3 minutes, and then deslagging to obtain clean molten feed liquid;
the third step: when the temperature in the induction furnace reaches 1630 ℃, the melted material liquid is poured into a pouring ladle from the induction furnace, and the pouring ladle is placed on an automatic pouring machine with a weighing function, wherein the weight of the melted material liquid is as follows: 525 Kg;
the fourth step: when the temperature of the molten material melted in the pouring ladle reaches 1585 ℃, pouring operation is carried out; a sample was taken from the ladle for spectroscopic analysis, and the contents of the elements were confirmed as in the following Table (9):
the fifth step: after pouring, carrying out heat treatment operation on the obtained casting and sample, wherein the heat treatment process parameters are as follows: the heat preservation temperature is as follows: 780 ℃; the heat preservation time is as follows: 5.0 hours; the cooling speed after the heat preservation is as follows: 155 ℃/hour;
and a sixth step: after the casting and the sample are subjected to heat treatment, checking the material and the result;
tensile strength: more than or equal to 440 MPa; yield strength: not less than 380 MPa; hardness: HB 190-250; the metallographic structure is as follows: a small amount of carbide is distributed in the ferrite matrix; and (3) under the oxidizing atmosphere of 950 ℃, keeping the temperature for 100 hours, and increasing the weight by oxidation: less than or equal to 3.0mg/m2*h；
The casting and the sample are subjected to material quality inspection after heat treatment, and the inspection results are shown in the following table (10):
remarking: oxidation test conditions: test temperature: 950 ℃ and test time: 100 hours; test atmosphere: air (a)
Example 6:
the first step is as follows: the raw materials are mixed according to a set proportion, namely: the proportion of the waste steel (carbon steel in this example) to the heat-resistant steel is: 15.12 percent, and the proportion of the returned materials in the heat-resistant steel is as follows: 75.0 percent of micro-carbon ferrochrome accounts for the heat-resistant steel in proportion: 7.40 percent, wherein the nickel plate accounts for the heat-resistant steel in proportion: 0.05 percent, and the ratio of ferrocolumbium to the heat-resistant steel is as follows: 0.68 percent, and the proportion of the electrolytic manganese in the heat-resistant steel is as follows: 0.11 percent, and the ferromolybdenum accounts for the proportion of the heat-resistant steel: 0.06 percent, and the proportion of ferrovanadium in the heat-resistant steel is as follows: 0.07 percent of ferrotungsten accounting for the heat-resistant steel: 0.58 percent and the ferrosilicon accounts for the heat-resistant steel in proportion: 0.80 percent, and the proportion of the carburant in the heat-resistant steel is as follows: 0.13 percent of the raw materials are put into a medium-frequency induction furnace for smelting;
the second step is that: heating the raw materials in an induction furnace, gradually melting the raw materials into molten steel, then continuously heating the molten steel in the induction furnace, standing for 5 minutes after the temperature is increased to 1593 ℃, and then carrying out slagging operation; after slagging, standing molten steel of a raw material of heat-resistant steel melted in the induction furnace for 3 minutes, and then deslagging to obtain clean molten feed liquid;
the third step: when the temperature in the induction furnace reaches 1617 ℃, pouring the melted material liquid into a pouring ladle from the induction furnace, and placing the pouring ladle on an automatic pouring machine with a weighing function, wherein the weight of the melted material liquid is as follows: 493 Kg;
the fourth step: when the temperature of the molten material after being melted in the pouring ladle reaches 1572 ℃, pouring operation is carried out; samples were taken from the ladle and analysed by spectroscopy to confirm the contents of the elements in the following table (11):
the fifth step: after pouring, carrying out heat treatment operation on the obtained casting and sample, wherein the heat treatment process parameters are as follows: the heat preservation temperature is as follows: 775 deg.C; the heat preservation time is as follows: 3.5 hours; the cooling speed after the heat preservation is as follows: 165 ℃/hour;
and a sixth step: after the casting and the sample are subjected to heat treatment, checking the material and the result;
tensile strength: more than or equal to 440 MPa; yield strength: not less than 380 MPa; hardness: HB 190-250; the metallographic structure is as follows: a small amount of carbide is distributed in the ferrite matrix; and (3) under the oxidizing atmosphere of 950 ℃, keeping the temperature for 100 hours, and increasing the weight by oxidation: less than or equal to 3.0mg/m2*h；
The castings and the samples were subjected to the material quality inspection after the heat treatment, and the inspection results are shown in the following table (12):
remarking: oxidation test conditions: test temperature: 950 ℃ and test time: 100 hours; test atmosphere: air (a)
Example 7:
the first step is as follows: the raw materials are mixed according to a set proportion, namely: the proportion of the waste steel (carbon steel in this example) to the heat-resistant steel is: 39.11 percent, and the proportion of the returned materials in the heat-resistant steel is as follows: 35.0 percent of micro-carbon ferrochrome, wherein the proportion of the micro-carbon ferrochrome in the heat-resistant steel is as follows: 19.60 percent, wherein the nickel plate accounts for the heat-resistant steel in proportion: 0.07 percent of ferrocolumbium accounting for the heat-resistant steel: 1.85 percent, and the proportion of electrolytic manganese in the heat-resistant steel is as follows: 0.21 percent, and the ferromolybdenum accounts for the proportion of the heat-resistant steel: 0.30 percent, and the proportion of ferrovanadium in the heat-resistant steel is as follows: 0.27 percent, and the proportion of ferrotungsten in the heat-resistant steel is as follows: 1.54 percent, and the ferrosilicon accounts for the heat-resistant steel in proportion: 1.84 percent, and the proportion of the carburant in the heat-resistant steel is as follows: 0.21 percent, putting into a medium-frequency induction furnace for smelting;
the second step is that: heating the raw materials in an induction furnace, gradually melting the raw materials into molten steel, then continuously heating the molten steel in the induction furnace, standing for 3 minutes after the temperature is increased to 1621 ℃, and then carrying out slagging operation; after slagging, standing molten steel of a raw material of heat-resistant steel melted in the induction furnace for 3 minutes, and then deslagging to obtain clean molten feed liquid;
the third step: when the temperature in the induction furnace reaches 1630 ℃, the melted material liquid is poured into a pouring ladle from the induction furnace, and the pouring ladle is placed on an automatic pouring machine with a weighing function, wherein the weight of the melted material liquid is as follows: 505 Kg;
the fourth step: when the temperature of the molten material after being melted in the pouring ladle reaches 1602 ℃, pouring operation is carried out; samples were taken from the ladle for spectroscopic analysis and the elemental contents were as follows (13):
the fifth step: after pouring, carrying out heat treatment operation on the obtained casting and sample, wherein the heat treatment process parameters are as follows: the heat preservation temperature is as follows: 815 ℃; the heat preservation time is as follows: 4.0 hours; the cooling speed after the heat preservation is as follows: 195 ℃/hour;
and a sixth step: after the casting and the sample are subjected to heat treatment, checking the material and the result;
tensile strength: more than or equal to 440 MPa; yield strength: not less than 380 MPa; hardness: HB 190-250; metallographic phaseThe organization is as follows: a small amount of carbide is distributed in the ferrite matrix; and (3) under the oxidizing atmosphere of 950 ℃, keeping the temperature for 100 hours, and increasing the weight by oxidation: less than or equal to 3.0mg/m2*h；
The castings and the samples are subjected to material quality inspection after heat treatment, and the inspection results are shown in the following table (14):
remarking: oxidation test conditions: test temperature: 950 ℃ and test time: 100 hours; test atmosphere: air (a)
Example 8:
the first step is as follows: the raw materials are mixed according to a set proportion, namely: the proportion of the waste steel (carbon steel in this example) to the heat-resistant steel is: 31.51 percent, and the proportion of returned materials in the heat-resistant steel is as follows: 50.0 percent of micro-carbon ferrochrome accounts for the heat-resistant steel in proportion: 14.20 percent, wherein the nickel plate accounts for the heat-resistant steel in proportion: 0.21 percent, and the proportion of ferrocolumbium in the heat-resistant steel is as follows: 1.35 percent, and the proportion of electrolytic manganese in the heat-resistant steel is as follows: 0.20 percent, and the ferromolybdenum accounts for the proportion of the heat-resistant steel: 0.26 percent, and the proportion of ferrovanadium in the heat-resistant steel is as follows: 0.28 percent, and the proportion of ferrotungsten in the heat-resistant steel is as follows: 1.05 percent and the ferrosilicon accounts for the heat-resistant steel in proportion: 0.75 percent, and the proportion of the carburant in the heat-resistant steel is as follows: 0.19 percent of the raw materials are put into a medium-frequency induction furnace for smelting;
the second step is that: heating the raw materials in an induction furnace, gradually melting the raw materials into molten steel, then continuously heating the molten steel in the induction furnace, standing for 4 minutes after the temperature is raised to 1605 ℃, and then carrying out slagging operation; after slagging, standing molten steel of a raw material of heat-resistant steel melted in the induction furnace for 3 minutes, and then deslagging to obtain clean molten feed liquid;
the third step: when the temperature in the induction furnace reaches 1612 ℃, the molten material liquid after melting is poured into the pouring ladle from the induction furnace, and the pouring ladle is placed on an automatic casting machine with a weighing function, and at the moment, the weight of the molten material liquid is as follows: 499 Kg;
the fourth step: when the temperature of the molten material after being melted in the pouring ladle reaches 1579 ℃, pouring operation is carried out; samples were taken from the ladle and analysed by spectroscopy to confirm the contents of the elements in the following table (15):
the fifth step: after pouring, carrying out heat treatment operation on the obtained casting and sample, wherein the heat treatment process parameters are as follows: the heat preservation temperature is as follows: 835 ℃ C; the heat preservation time is as follows: 4.5 hours; the cooling speed after the heat preservation is as follows: 210 ℃/hour;
and a sixth step: after the casting and the sample are subjected to heat treatment, checking the material and the result;
tensile strength: more than or equal to 440 MPa; yield strength: not less than 380 MPa; hardness: HB 190-250; the metallographic structure is as follows: a small amount of carbide is distributed in the ferrite matrix; and (3) under the oxidizing atmosphere of 950 ℃, keeping the temperature for 100 hours, and increasing the weight by oxidation: less than or equal to 3.0mg/m2 × h;
the castings and the samples were subjected to the material quality inspection after the heat treatment, and the inspection results are shown in the following table (16):
remarking: oxidation test conditions: test temperature: 950 ℃ and test time: 100 hours; test atmosphere: air (a)
Example 9:
the first step is as follows: the raw materials are mixed according to a set proportion, namely: the proportion of the waste steel (carbon steel in this example) to the heat-resistant steel is: 40.83 percent, and the proportion of the returned materials in the heat-resistant steel is as follows: 35.0 percent of micro-carbon ferrochrome, wherein the proportion of the micro-carbon ferrochrome in the heat-resistant steel is as follows: 18.40 percent, and the proportion of the nickel plate in the heat-resistant steel is as follows: 0.27 percent of ferrocolumbium, the proportion of the ferrocolumbium in the heat-resistant steel is as follows: 1.63 percent, and the proportion of electrolytic manganese in the heat-resistant steel is as follows: 0.30 percent, and the ferromolybdenum accounts for the proportion of the heat-resistant steel: 0.44 percent, and the proportion of ferrovanadium in the heat-resistant steel is as follows: 0.40 percent, and the proportion of ferrotungsten in the heat-resistant steel is as follows: 1.43 percent, and the ferrosilicon accounts for the heat-resistant steel in proportion: 1.05 percent, and the proportion of the carburant in the heat-resistant steel is as follows: 0.25 percent of the raw materials are put into a medium-frequency induction furnace for smelting;
the second step is that: heating the raw materials in an induction furnace, gradually melting the raw materials into molten steel, then continuously heating the molten steel in the induction furnace, standing for 3 minutes after the temperature is increased to 1628 ℃, and then carrying out slagging operation; after slagging, standing molten steel of a raw material of heat-resistant steel melted in the induction furnace for 3 minutes, and then deslagging to obtain clean molten feed liquid;
the third step: when the temperature in the induction furnace reaches 1642 ℃, pour the molten feed liquid after melting into the pouring ladle from the induction furnace in to place the pouring ladle on the automatic casting machine that has the function of weighing, this moment, molten feed liquid weight is: 455 Kg;
the fourth step: when the temperature of the molten material after being melted in the pouring ladle reaches 1618 ℃, pouring operation is carried out; samples were taken from the ladle and analysed by spectroscopy to confirm the contents of the elements in the following table (17):
the fifth step: after pouring, carrying out heat treatment operation on the obtained casting and sample, wherein the heat treatment process parameters are as follows: the heat preservation temperature is as follows: 790 ℃; the heat preservation time is as follows: 4.5 hours; the cooling speed after the heat preservation is as follows: 150 ℃/hour;
and a sixth step: after the casting and the sample are subjected to heat treatment, checking the material and the result;
tensile strength: more than or equal to 440 MPa; yield strength: not less than 380 MPa; hardness: HB 190-250; the metallographic structure is as follows: a small amount of carbide is distributed in the ferrite matrix; and (3) under the oxidizing atmosphere of 950 ℃, keeping the temperature for 100 hours, and increasing the weight by oxidation: less than or equal to 3.0mg/m2*h；
The castings and the samples are subjected to material quality inspection after heat treatment, and the inspection results are shown in the following table (18):
remarking: oxidation test conditions: test temperature: 950 ℃ and test time: 100 hours; test atmosphere: air (a)
Example 10:
the first step is as follows: the raw materials are mixed according to a set proportion, namely: the proportion of the waste steel (carbon steel in this example) to the heat-resistant steel is: 15.25 percent, and the proportion of the returned materials in the heat-resistant steel is as follows: 75.0 percent of micro-carbon ferrochrome accounts for the heat-resistant steel in proportion: 7.0 percent, wherein the nickel plate accounts for the heat-resistant steel in proportion: 0.10 percent, and the proportion of ferrocolumbium in the heat-resistant steel is as follows: 0.72 percent, and the proportion of electrolytic manganese in the heat-resistant steel is as follows: 0.10 percent, and the ferromolybdenum accounts for the proportion of the heat-resistant steel: 0.19 percent, and the proportion of ferrovanadium in the heat-resistant steel is as follows: 0.21 percent, and the proportion of ferrotungsten in the heat-resistant steel is as follows: 0.58 percent and the ferrosilicon accounts for the heat-resistant steel in proportion: 0.75 percent, and the proportion of the carburant in the heat-resistant steel is as follows: 0.10 percent of the raw materials are put into a medium-frequency induction furnace for smelting;
the second step is that: heating the raw materials in an induction furnace, gradually melting the raw materials into molten steel, then continuously heating the molten steel in the induction furnace, standing for 3 minutes after the temperature is raised to 1601 ℃, and then carrying out slagging operation; after slagging, standing molten steel of a raw material of heat-resistant steel melted in the induction furnace for 3 minutes, and then deslagging to obtain clean molten feed liquid;
the third step: when the temperature in the induction furnace reaches 1632 ℃, the melted material liquid is poured into a pouring ladle from the induction furnace, and the pouring ladle is placed on an automatic pouring machine with a weighing function, wherein the weight of the melted material liquid is as follows: 462 Kg;
the fourth step: when the temperature of the molten material melted in the pouring ladle reaches 1609 ℃, pouring operation is carried out; samples were taken from the ladle and analysed by spectroscopy to confirm the contents of the elements in the following table (19):
the fifth step: after pouring, carrying out heat treatment operation on the obtained casting and sample, wherein the heat treatment process parameters are as follows: the heat preservation temperature is as follows: 785 ℃; the heat preservation time is as follows: 4.5 hours; the cooling speed after the heat preservation is as follows: 201 ℃/hour;
and a sixth step: after the casting and the sample are subjected to heat treatment, checking the material and the result;
tensile strength: more than or equal to 440 MPa; yield strength: not less than 380 MPa; hardness: HB 190-250; the metallographic structure is as follows: a small amount of carbide is distributed in the ferrite matrix; and (3) under the oxidizing atmosphere of 950 ℃, keeping the temperature for 100 hours, and increasing the weight by oxidation: less than or equal to 3.0mg/m2 × h;
the castings and the samples are subjected to material quality inspection after heat treatment, and the inspection results are shown in the following table (20):
remarking: oxidation test conditions: test temperature: 950 ℃ and test time: 100 hours; test atmosphere: air (a)
The invention relates to a ferrite system heat-resistant steel for automobile turbine shells and exhaust pipes, wherein carbon, silicon, manganese, chromium, niobium, tungsten and other elements are reasonably proportioned to obtain carbides uniformly distributed in a ferrite matrix, so that the material has excellent high-temperature mechanical properties. And by adding a proper proportion of niobium element, a fine grain structure is obtained so as to improve the material performance. And niobium, chromium, tungsten and carbon form stable carbide and are uniformly distributed on the grain boundary, so that the grain boundary strength is greatly improved. And under the condition of high-temperature service, a layer of compact oxide film is formed on the surface of the casting, and the oxide film prevents oxygen from diffusing to the interior to further oxidize the matrix, so that the oxidation resistance of the material is improved.
It is to be understood that the present invention has been described with reference to certain embodiments, and that various changes in the features and embodiments, or equivalent substitutions may be made therein by those skilled in the art without departing from the spirit and scope of the invention. In addition, many modifications may be made to adapt a particular situation or material to the teachings of the invention without departing from the essential scope thereof. Therefore, it is intended that the invention not be limited to the particular embodiment disclosed, but that the invention will include all embodiments falling within the scope of the appended claims.
Claims (9)
1. A ferrite system heat-resistant steel for automobile turbine shells and exhaust pipes is characterized by being provided with: the heat-resistant steel comprises the following raw materials: waste steel, foundry returns, micro-carbon ferrochrome, nickel plates, ferrocolumbium, electrolytic manganese and ferrosilicon which account for a set proportion of raw materials of the heat-resistant steel; wherein, the raw materials of the heat-resistant steel also contain ferromolybdenum, ferrovanadium, ferrotungsten, ferrosilicon and carburant in set proportion; the raw materials of the heat-resistant steel are put into an induction furnace for smelting, the raw materials of the heat-resistant steel are gradually melted into molten steel, and then deslagging operation and tapping operation are carried out to obtain clean molten feed liquid;
the proportion of the carburant in the heat-resistant steel is as follows: 0.06 percent;
the heat-resistant steel comprises the following chemical components in percentage by mass: carbon: 0.2 to 0.6; silicon: 1.0-2.5; manganese: 0.5-1.0; phosphorus: less than or equal to 0.040; less than or equal to 0.030 percent of sulfur; chromium: 15.0-20.0; nickel: less than or equal to 1.0; molybdenum: less than or equal to 0.50; vanadium: less than or equal to 0.50; niobium: 1.0-2.0; tungsten: 1.5-2.5, the balance being iron and unavoidable trace elements, which have a completely ferritic matrix with a homogeneous distribution of carbides with high-temperature mechanical properties and a low coefficient of thermal expansion and resistance to high-temperature oxidation.
2. The ferritic heat-resistant steel for automobile turbine shells and exhaust pipes as claimed in claim 1, wherein the temperature of the molten steel is raised continuously after the raw material of the heat-resistant steel is gradually melted into the molten steel, and the molten steel is left to stand for slagging operation after the temperature is raised to 1595 ℃.
3. The ferritic heat-resistant steel for automobile turbine shells and exhaust pipes as set forth in claim 1, wherein the scrap steel is carbon steel.
4. The ferritic heat-resistant steel for automobile turbine shells and exhaust pipes as set forth in claim 1, wherein the scrap is a waste casting and a gating system.
5. The ferritic heat-resistant steel for automobile turbine shells and exhaust pipes as set forth in claim 1, wherein the raw material accounts for the heat-resistant steel in a proportion of: the proportion of the waste steel in the heat-resistant steel is as follows: 47.0 percent, and the proportion of the returned materials in the heat-resistant steel is as follows: 35.0 percent of micro-carbon ferrochrome, wherein the proportion of the micro-carbon ferrochrome in the heat-resistant steel is as follows: 15.13 percent, wherein the nickel plate accounts for the heat-resistant steel in proportion: 0.01 percent, and the ratio of ferrocolumbium to the heat-resistant steel is as follows: 0.88 percent, and the proportion of the electrolytic manganese in the heat-resistant steel is as follows: 0.20 percent, and the ferromolybdenum accounts for the proportion of the heat-resistant steel: 0.04 percent, and the proportion of ferrovanadium in the heat-resistant steel is as follows: 0.11 percent, and the proportion of ferrotungsten in the heat-resistant steel is as follows: 1.0 percent and the ferrosilicon accounts for the heat-resistant steel in proportion: 0.57 percent.
6. The method for producing a ferritic heat-resistant steel for automobile turbine shells and exhaust pipes according to claim 1, wherein the heat-resistant steel according to claims 1 to 5 is provided, and the following production steps are specifically employed:
the first step is as follows: the raw materials are mixed according to a set proportion of heat-resistant steel, namely: selecting waste steel, foundry returns, micro-carbon ferrochrome, nickel plates, ferrocolumbium, electrolytic manganese, ferromolybdenum, ferrovanadium, ferrotungsten, ferrosilicon and carburant: and putting the mixture into a medium-frequency induction furnace for smelting;
the second step is that: heating the raw materials in an induction furnace, gradually melting the raw materials into molten steel, then continuously heating the molten steel in the induction furnace, standing for 3 minutes after the temperature is increased to 1580-1630 ℃, and then carrying out slagging operation; so as to ensure that the added materials are completely melted and have uniform components; after slagging, standing molten steel of a raw material of heat-resistant steel melted in the induction furnace for 3 minutes, and then deslagging to obtain clean molten feed liquid;
the third step: when the temperature in the induction furnace reaches 1600 ℃ -1650 ℃, pouring the melted material liquid into a pouring ladle from the induction furnace, and placing the pouring ladle on an automatic pouring machine with a weighing function, wherein the weight of the melted material liquid is as follows: 450-600 Kg;
the fourth step: when the temperature of the molten material molten in the pouring ladle reaches 1555-1609 ℃, pouring operation is carried out; sampling in a pouring ladle for spectroscopic analysis, and confirming the content of each element;
the fifth step: after the pouring is finished, carrying out heat treatment operation on the obtained casting and sample;
and a sixth step: after heat treatment of the cast and the sample, the material and the result were examined.
7. The method for producing a ferritic heat-resistant steel for automobile turbine shells and exhaust pipes as set forth in claim 6, wherein the set proportions of the raw materials in the first step are as follows: the proportion of the waste steel in the heat-resistant steel is as follows: 47.0 percent, and the proportion of the returned materials in the heat-resistant steel is as follows: 35.0 percent of micro-carbon ferrochrome, wherein the proportion of the micro-carbon ferrochrome in the heat-resistant steel is as follows: 15.13 percent, wherein the nickel plate accounts for the heat-resistant steel in proportion: 0.01 percent, and the ratio of ferrocolumbium to the heat-resistant steel is as follows: 0.88 percent, and the proportion of the electrolytic manganese in the heat-resistant steel is as follows: 0.20 percent, and the ferromolybdenum accounts for the proportion of the heat-resistant steel: 0.04 percent, and the proportion of ferrovanadium in the heat-resistant steel is as follows: 0.11 percent, and the proportion of ferrotungsten in the heat-resistant steel is as follows: 1.0 percent and the ferrosilicon accounts for the heat-resistant steel in proportion: 0.57 percent, and the proportion of the carburant in the heat-resistant steel is as follows: 0.06% was selected.
8. The method for producing a ferritic heat-resistant steel for automobile turbine shells and exhaust pipes as set forth in claim 6, wherein in said fifth step, the heat treatment process is as follows:
the method includes the steps that a casting is stacked on a thermal treatment tool according to a standard, the tool is transferred into a thermal treatment furnace after stacking is completed, and a furnace door is covered;
secondly, starting heat treatment equipment to start heating up operation, entering a heat preservation stage after the heating up reaches a heat preservation temperature, and entering a cooling stage after the heat preservation is finished;
according to the materials and the casting structure, the temperature is as low as possible and the cooling rate is slow on the premise of ensuring the stress relief effect, and the casting is prevented from deforming in the heat treatment process: the heat treatment process parameters are as follows: the heat preservation temperature is as follows: 750-850 ℃; the heat preservation time is as follows: more than 3 hours; the cooling speed after the heat preservation is as follows: 250 ℃ per hour or less.
9. The method for producing a ferritic heat-resistant steel for automobile turbine shells and exhaust pipes as claimed in claim 6, wherein the tensile strength of the heat-resistant steel is: more than or equal to 440 MPa; yield strength: not less than 380 MPa; hardness: HB 190-250; the metallographic structure is as follows: a small amount of carbide is distributed in the ferrite matrix; and (3) under the oxidizing atmosphere of 950 ℃, keeping the temperature for 100 hours, and increasing the weight by oxidation: less than or equal to 3.0mg/m2*h。
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|---|---|---|---|---|
| CN113953461A (en) * | 2021-11-03 | 2022-01-21 | 上海艾诺特殊钢铸造有限公司 | Process for casting screwed pipe of paper machine |
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| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN113953461A (en) * | 2021-11-03 | 2022-01-21 | 上海艾诺特殊钢铸造有限公司 | Process for casting screwed pipe of paper machine |
| CN115821149A (en) * | 2022-11-30 | 2023-03-21 | 南阳飞龙汽车零部件有限公司 | Method for solving cracks of cast steel products |
| CN115821149B (en) * | 2022-11-30 | 2024-04-09 | 南阳飞龙汽车零部件有限公司 | Method for solving cracks of cast steel products |
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