CN111604496A - Investment casting process for heat-resistant steel connecting pipe shell - Google Patents
Investment casting process for heat-resistant steel connecting pipe shell Download PDFInfo
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- B22D—CASTING OF METALS; CASTING OF OTHER SUBSTANCES BY THE SAME PROCESSES OR DEVICES
- B22D47/00—Casting plants
- B22D47/02—Casting plants for both moulding and casting
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- B22—CASTING; POWDER METALLURGY
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- B22C1/00—Compositions of refractory mould or core materials; Grain structures thereof; Chemical or physical features in the formation or manufacture of moulds
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- B—PERFORMING OPERATIONS; TRANSPORTING
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- B22C1/16—Compositions of refractory mould or core materials; Grain structures thereof; Chemical or physical features in the formation or manufacture of moulds characterised by the use of binding agents; Mixtures of binding agents
- B22C1/18—Compositions of refractory mould or core materials; Grain structures thereof; Chemical or physical features in the formation or manufacture of moulds characterised by the use of binding agents; Mixtures of binding agents of inorganic agents
- B22C1/186—Compositions of refractory mould or core materials; Grain structures thereof; Chemical or physical features in the formation or manufacture of moulds characterised by the use of binding agents; Mixtures of binding agents of inorganic agents contaming ammonium or metal silicates, silica sols
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B22—CASTING; POWDER METALLURGY
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- B22C7/00—Patterns; Manufacture thereof so far as not provided for in other classes
- B22C7/02—Lost patterns
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B22—CASTING; POWDER METALLURGY
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- B22C9/02—Sand moulds or like moulds for shaped castings
- B22C9/04—Use of lost patterns
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B22—CASTING; POWDER METALLURGY
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- B22C9/12—Treating moulds or cores, e.g. drying, hardening
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- B22C—FOUNDRY MOULDING
- B22C9/00—Moulds or cores; Moulding processes
- B22C9/22—Moulds for peculiarly-shaped castings
- B22C9/24—Moulds for peculiarly-shaped castings for hollow articles
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- C21D—MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUS METALS OR ALLOYS; MAKING METAL MALLEABLE, e.g. BY DECARBURISATION OR TEMPERING
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- G01N21/31—Investigating relative effect of material at wavelengths characteristic of specific elements or molecules, e.g. atomic absorption spectrometry
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
- G01N1/00—Sampling; Preparing specimens for investigation
- G01N1/28—Preparing specimens for investigation including physical details of (bio-)chemical methods covered elsewhere, e.g. G01N33/50, C12Q
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Abstract
The invention discloses a heat-resistant steel connecting pipe shell investment casting process, which comprises the following steps: s1, paraffin is injected and molded to obtain a wax pattern, and the wax pattern is assembled by welding and bonding an electric soldering iron; s2, taking silica sol as a bonding agent, doping zirconium powder filler, an anti-cracking agent, a wetting agent and a defoaming agent to prepare slurry, immersing a wax mould into the slurry for slurry hanging, spreading a zircon refractory material to form a shell, and repeatedly operating for 4 times after hardening to obtain the mould shell; s3, placing the formwork in a dewaxing furnace, introducing steam until paraffin completely flows out, placing the formwork in a molding machine for sand filling, and roasting to obtain a high-strength formwork; s4, putting the raw material of the heat-resistant steel connecting pipe into a smelting furnace, and preserving heat to obtain molten metal; s5, detecting components; s6, pouring; s7, heat treatment; and S8, inspecting the casting, namely completing the investment casting process of the heat-resistant steel connecting pipe shell. The investment casting process provided by the invention can produce high-quality castings, the casting yield is high, and the phenomena of inclusion and cold shut are not easy to occur.
Description
Technical Field
The invention relates to the technical field of investment casting, in particular to an investment casting process for a heat-resistant steel connecting pipe shell.
Background
The heat-resistant steel has higher strength and chemical stability under high temperature conditions, and is widely applied to parts working under high temperature conditions such as power machinery, boilers, steam turbines and the like. In addition to high temperatures, high strength and resistance to high-temperature oxidation corrosion, these components also require, depending on the application, adequate toughness, good workability and weldability, and a certain structural stability. Therefore, the heat-resistant steel is one of the common materials for castings, but because some castings with structures have more complex structures, thin-wall connecting pipe castings have higher quality requirements, and if the traditional casting process is used, the produced connecting pipe castings are easy to have the phenomena of inclusion, cold shut and the like, and the quality cannot meet the requirements. Based on the defects in the prior art, the invention provides a fired mold casting process for a shell of a heat-resistant steel connecting pipe.
Disclosure of Invention
The invention aims to solve the problems that the phenomena of inclusion and cold shut are easy to occur in the production process of the existing connecting pipe casting, and the quality of the produced casting is not ideal, and provides a heat-resistant steel connecting pipe shell investment casting process.
A heat-resistant steel connecting pipe shell investment casting process comprises the following steps:
s1, manufacturing a wax mould: selecting semi-solid paraffin as a wax mould material, injecting the semi-solid paraffin into a wax mould by using a paraffin injection machine, then forming to obtain a wax pattern, carrying out piece-by-piece hot welding on the wax pattern by using a flat-head electric soldering iron in a manual mode, and welding, adhering and assembling the wax pattern into a wax mould;
s2, preparing a formwork: taking silica sol as a bonding agent, adding zirconium powder filler, an anti-cracking agent, a wetting agent and a defoaming agent, stirring for 8-10 hours to prepare slurry, immersing the wax mold prepared in the step S1 into the slurry for slurry coating, then scattering zircon refractory material to form a shell, coating a layer of hardened shell outside the wax mold after the shell is hardened, and repeatedly coating 4 layers of hardened shells outside the wax mold to obtain the mold shell;
s3, dewaxing and roasting: placing the formwork prepared in the step S2 in a dewaxing furnace, introducing steam with the temperature of 145-155 ℃ into the dewaxing furnace until paraffin in the formwork is melted and completely flows out, cleaning an inner cavity of the formwork with hot water at 50-60 ℃, simultaneously washing off a wax film adhered to the outer wall of the formwork, drying, placing the formwork in a molding machine for sand filling, then heating to 1000 ℃, roasting at 1000 ℃ for 25-35 min, and cooling to obtain a high-strength formwork;
s4, smelting: presetting the furnace temperature of a smelting furnace to be 1555-1565 ℃, starting heating, monitoring the furnace temperature once every 30min, putting the raw material of the heat-resistant steel connecting pipe into the smelting furnace after the furnace temperature of the smelting furnace reaches the preset temperature, and preserving the heat for 40-60 min to obtain molten metal;
s5, component detection: taking the molten metal by using a small ladle, pouring the molten metal into a metal mold for manufacturing a spectrum detection sample, cooling to obtain the sample, turning the cross section of the sample flat by using a lathe, detecting components by using a direct-reading spectrometer, performing the next step if the detection result meets the casting requirement of the heat-resistant steel connecting pipe, and adjusting the components of the molten metal in the step S4 according to the detection result if the detection result does not meet the casting requirement of the heat-resistant steel connecting pipe until the component detection result meets the casting requirement of the heat-resistant steel connecting pipe;
s6, pouring: keeping the temperature of the molten metal meeting the casting requirement of the heat-resistant steel connecting pipe according to the component detection result in the step S5 at 1555-1565 ℃ for 10min, standing, removing floating slag by using a slag removing spoon after impurities are completely precipitated, and then pouring the molten metal into the high-strength formwork prepared in the step S3, wherein the speed is in the principle of slow first and fast second, and the pouring time is 25S, so that a casting is obtained;
s7, heat treatment: placing the casting obtained in the step S6 into a cage, wherein the preset annealing furnace temperature is 1055-1065 ℃, starting to heat up an annealing furnace, placing the casting and the cage into the annealing furnace when the annealing furnace temperature is raised to the preset temperature, keeping the temperature at 1055-1065 ℃ for 40-60 min, taking out the material, and naturally cooling the material to room temperature by contacting with air to obtain the heat-resistant steel connecting pipe shell;
s8, casting inspection: and (5) flaw detection is carried out on the heat-resistant steel connecting pipe shell obtained in the step S7 by using X-ray, no defect is found, and the size of the casting meets the requirement, so that the investment casting process of the heat-resistant steel connecting pipe shell is completed.
Preferably, in step S1, the injection pressure is 15kg/cm2The temperature is 58-62 ℃.
Preferably, in step S2, the mass ratio of the silica sol to the zirconium powder filler to the anti-cracking agent to the wetting agent to the defoaming agent is 5: 16 to 20: 0.01 to 0.02: 8 to 10: 8 to 12, and more preferably, the mass ratio of the silica sol to the zirconium powder filler to the anti-cracking agent to the wetting agent to the defoaming agent is 5: 18: 0.015: 9: 10.
Preferably, the anti-cracking agent is one of N-phenyl-2-naphthylamine, N-diphenyl-p-phenylenediamine, N-p-phenylmethyl-2-naphthylamine and N-isopropyl-N-phenyl-p-phenylenediamine; the wetting agent is a compound of heptadecyl imidazoline, polyoxyethylene fatty alcohol ether and propylene glycol, and the mass ratio of the heptadecyl imidazoline to the polyoxyethylene fatty alcohol ether to the propylene glycol is 10: 6-8: 3-5; the defoaming agent is fatty acid glyceride or polydimethylsiloxane.
Preferably, in step S2, the curing temperature is 20 to 25 ℃, the relative humidity is 55 to 65%, and the curing time is 1 to 2 hours, and more preferably, the curing temperature is 23 ℃, the relative humidity is 60%, and the curing time is 1.5 hours.
Preferably, in step S5, the metal mold is preheated to 195 to 205 ℃ in advance in a heat treatment furnace.
Preferably, in step S7, the temperature of the annealing furnace is monitored every 1 hour during the temperature rise, the temperature of the casting is monitored every 5 minutes after the casting is placed in the annealing furnace, and the temperature of the annealing furnace is monitored every 10 minutes during the cooling process.
Compared with the prior art, the invention has the beneficial effects that:
1. the investment casting process provided by the invention has the advantages that the process is complete, the content is detailed, the whole process of investment casting is formed by wax pattern manufacturing, formwork preparation, dewaxing roasting, smelting, component detection, pouring, heat treatment and casting inspection, the thin-wall part heat-resistant steel connecting pipe shell with complex casting structure and high quality requirement can be manufactured by the investment casting process provided by the invention, and the problems that the phenomena of inclusion and cold shut are easy to occur in the production process of the connecting pipe shell and the quality of the produced casting is not ideal can be effectively solved;
2. the shell of the connecting pipe manufactured by the investment casting process has high precision, high quality, good quality and excellent heat resistance, and the phenomena of inclusion and cold shut are not easy to occur, so that the comprehensive performance of the shell of the connecting pipe is good;
3. when the formwork is prepared, the silica sol is used as the adhesive, and the zirconium powder filler, the anti-cracking agent, the wetting agent and the defoaming agent are added in a reasonable proportion, so that the integral precision and the product percent of pass of the casting are improved, compared with the casting produced by using the traditional formwork, the percent of pass is improved by 10.6-13.2%, the production cost of the casting can be effectively reduced, the economic benefit is good, and the formwork is worthy of popularization.
Detailed Description
The present invention will be further illustrated with reference to the following specific examples.
Example 1
The invention provides a heat-resistant steel connecting pipe shell investment casting process which comprises the following steps:
s1 wax pattern production: selecting semi-solid paraffin as wax mould material, injecting the semi-solid paraffin into the wax mould by a paraffin injection machine, and forming to obtain wax mould, wherein the injection pressure is 15kg/cm2The temperature is 58 ℃, wax patterns are welded one by using a flat-head electric soldering iron in a manual mode, and the wax patterns are assembled by welding and bonding;
s2, preparing a formwork: taking silica sol as a bonding agent, adding zirconium powder filler, an anti-cracking agent, a wetting agent and a defoaming agent, stirring for 8 hours to prepare slurry, immersing the wax mold prepared in the step S1 into the slurry for slurry coating, then scattering zircon refractory material to form a shell, coating a layer of hardened shell outside the wax mold after the shell is hardened, and repeatedly coating 4 layers of hardened shells outside the wax mold to obtain the mold shell;
the mass ratio of the silica sol to the zirconium powder filler to the anti-cracking agent to the wetting agent to the defoaming agent is 5: 20: 0.02: 10: 12; the anti-cracking agent is N-phenyl-2-naphthylamine; the wetting agent is a compound of heptadecyl imidazoline, polyoxyethylene fatty alcohol ether and propylene glycol, and the mass ratio of the heptadecyl imidazoline to the polyoxyethylene fatty alcohol ether to the propylene glycol is 10: 6: 3; the defoaming agent is fatty glyceride;
the hardening temperature is 20 ℃, the relative humidity is 65%, and the time is 2 h;
s3, dewaxing and roasting: placing the formwork prepared in the step S2 in a dewaxing furnace, introducing steam with the temperature of 145 ℃ into the dewaxing furnace until paraffin in the formwork is melted and completely flows out, cleaning the inner cavity of the formwork with hot water at 50 ℃, simultaneously washing off a wax film adhered to the outer wall of the formwork, drying, placing the formwork in a molding machine for filling sand, then heating to 1000 ℃, roasting for 25min at 1000 ℃, and cooling to obtain a high-strength formwork;
s4, smelting: presetting the furnace temperature of a smelting furnace to 1555 ℃, starting heating, monitoring the furnace temperature every 30min, putting the raw material of the heat-resistant steel connecting pipe into the smelting furnace after the furnace temperature of the smelting furnace reaches the preset temperature, and preserving the heat for 60min to obtain molten metal;
s5, component detection: taking the molten metal by using a small ladle, pouring the molten metal into a metal mold which is preheated to 195 ℃ in a heat treatment furnace in advance and used for manufacturing a spectrum detection sample, cooling to obtain the sample, turning the cross section of the sample flat by using a lathe, detecting the components by using a direct-reading spectrometer, carrying out the next step if the detection result meets the casting requirement of the heat-resistant steel connecting pipe, and if the detection result does not meet the casting requirement of the heat-resistant steel connecting pipe, adjusting the components of the molten metal in the step S4 according to the detection result until the component detection result meets the casting requirement of the heat-resistant steel connecting pipe;
s6, pouring: keeping the temperature of the molten metal meeting the casting requirement of the heat-resistant steel connecting pipe with the component detection result in the step S5 at 1555 ℃ for 10min, standing, removing floating slag by using a slag removing spoon after impurities are completely precipitated, and then pouring the molten metal into the high-strength formwork prepared in the step S3, wherein the speed is in the principle of slow first, fast second and slow second, and the pouring time is 25S, so that a casting is obtained;
s7, heat treatment: placing the casting obtained in the step S6 into a cage, setting the temperature of an annealing furnace to 1055 ℃, starting to heat the annealing furnace, placing the casting and the cage into the annealing furnace when the temperature of the annealing furnace is raised to the preset temperature, keeping the temperature at 1055 ℃ for 60min, taking out the material, contacting with air, and naturally cooling to room temperature to obtain the heat-resistant steel connecting pipe shell;
monitoring the furnace temperature every 1h in the heating process of the annealing furnace, monitoring the furnace temperature every 5min after the casting is placed into the annealing furnace, and monitoring the furnace temperature every 10min in the cooling process of the annealing furnace;
s8, casting inspection: and (5) flaw detection is carried out on the heat-resistant steel connecting pipe shell obtained in the step S7 by using X-ray, no defect is found, and the size of the casting meets the requirement, so that the investment casting process of the heat-resistant steel connecting pipe shell is completed.
Example 2
The invention provides a heat-resistant steel connecting pipe shell investment casting process which comprises the following steps:
s1, manufacturing a wax mould: selecting semi-solid paraffin as wax mould material, injecting the semi-solid paraffin into the wax mould by a paraffin injection machine, and forming to obtain wax mould, wherein the injection pressure is 15kg/cm2The temperature is 60 ℃, wax patterns are welded one by using a flat-head electric soldering iron in a manual mode, and the wax patterns are assembled by welding and bonding;
s2, preparing a formwork: silica sol is used as a bonding agent, zirconium powder filler, an anti-cracking agent, a wetting agent and a defoaming agent are added, stirring is carried out for 9 hours to prepare slurry, the wax mold prepared in the step S1 is immersed into the slurry for slurry coating, then zircon refractory material is scattered to form a shell, a layer of hardened shell is coated outside the wax mold after the shell is hardened, and 4 layers of hardened shells are repeatedly coated outside the wax mold to obtain the mold shell;
the mass ratio of the silica sol to the zirconium powder filler to the anti-cracking agent to the wetting agent to the defoaming agent is 5: 18: 0.015: 9: 10; the anti-cracking agent is N-p-benzyl-2-naphthylamine; the wetting agent is a compound of heptadecyl imidazoline, polyoxyethylene fatty alcohol ether and propylene glycol, and the mass ratio of the heptadecyl imidazoline to the polyoxyethylene fatty alcohol ether to the propylene glycol is 10: 7: 4; the defoaming agent is fatty glyceride;
the hardening temperature is 25 ℃, the relative humidity is 65%, and the time is 1 h;
s3, dewaxing and roasting: placing the formwork prepared in the step S2 in a dewaxing furnace, introducing steam with the temperature of 150 ℃ into the dewaxing furnace until paraffin in the formwork is melted and completely flows out, cleaning the inner cavity of the formwork with hot water at 55 ℃, simultaneously washing off a wax film adhered to the outer wall of the formwork, drying, placing the formwork in a molding machine for filling sand, then heating to 1000 ℃, roasting for 30min at 1000 ℃, and cooling to obtain a high-strength formwork;
s4, smelting: presetting the furnace temperature of a smelting furnace to 1560 ℃, starting heating, monitoring the furnace temperature every 30min, putting the raw material of the heat-resistant steel connecting pipe into the smelting furnace when the furnace temperature of the smelting furnace reaches the preset temperature, and preserving the heat for 50min to obtain molten metal;
s5, component detection: taking the molten metal by using a small ladle, pouring the molten metal into a metal die which is preheated to 200 ℃ in a heat treatment furnace in advance and used for manufacturing a spectrum detection sample, cooling to obtain the sample, turning the cross section of the sample flat by using a lathe, detecting the components by using a direct-reading spectrometer, carrying out the next step if the detection result meets the casting requirement of the heat-resistant steel connecting pipe, and if the detection result does not meet the casting requirement of the heat-resistant steel connecting pipe, adjusting the components of the molten metal in the step S4 according to the detection result until the component detection result meets the casting requirement of the heat-resistant steel connecting pipe;
s6, pouring: keeping the temperature of the molten metal meeting the casting requirement of the heat-resistant steel connecting pipe with the component detection result in the step S5 at 1560 ℃ for 10min, standing, removing floating slag by using a slag removing spoon after impurities are completely precipitated, and then pouring the molten metal into the high-strength formwork prepared in the step S3, wherein the speed is the principle of slow first and then fast and then slow, and the pouring time is 25S, so that a casting is obtained;
s7, heat treatment: placing the casting obtained in the step S6 into a cage, wherein the preset annealing furnace temperature is 1060 ℃, starting to heat up an annealing furnace, placing the casting and the cage into the annealing furnace when the annealing furnace temperature is raised to the preset temperature, keeping the temperature at 1060 ℃ for 50min, taking out the material, contacting with air, and naturally cooling to room temperature to obtain the heat-resistant steel connecting pipe shell;
monitoring the furnace temperature every 1h in the heating process of the annealing furnace, monitoring the furnace temperature every 5min after the casting is placed into the annealing furnace, and monitoring the furnace temperature every 10min in the cooling process of the annealing furnace;
s8, casting inspection: and (5) flaw detection is carried out on the heat-resistant steel connecting pipe shell obtained in the step S7 by using X-ray, no defect is found, and the size of the casting meets the requirement, so that the investment casting process of the heat-resistant steel connecting pipe shell is completed.
Example 3
The invention provides a heat-resistant steel connecting pipe shell investment casting process which comprises the following steps:
s1, manufacturing a wax mould: selecting semi-solid paraffin as wax mould material, injecting the semi-solid paraffin into the wax mould by a paraffin injection machine, and forming to obtain wax mould, wherein the injection pressure is 15kg/cm2And the temperature is 62 ℃, the wax pattern is welded piece by using a flat-head electric soldering iron in a manual mode, and the wax pattern is assembled by welding and bonding;
s2, preparing a formwork: taking silica sol as a bonding agent, adding zirconium powder filler, an anti-cracking agent, a wetting agent and a defoaming agent, stirring for 10 hours to prepare slurry, immersing the wax mold prepared in the step S1 into the slurry for slurry coating, then spreading a zircon refractory material to form a shell, coating a layer of hardened shell outside the wax mold after the shell is hardened, and repeatedly coating 4 layers of hardened shells outside the wax mold to obtain the mold shell;
the mass ratio of the silica sol to the zirconium powder filler to the anti-cracking agent to the wetting agent to the defoaming agent is 5: 16: 0.01: 8; the anti-cracking agent is N-isopropyl-N-phenyl p-phenylenediamine; the wetting agent is a compound of heptadecyl imidazoline, polyoxyethylene fatty alcohol ether and propylene glycol, and the mass ratio of the heptadecyl imidazoline to the polyoxyethylene fatty alcohol ether to the propylene glycol is 10: 8: 5; the defoaming agent is polydimethylsiloxane;
the hardening temperature is 25 ℃, the relative humidity is 55%, and the time is 1 h;
s3, dewaxing and roasting: placing the formwork prepared in the step S2 in a dewaxing furnace, introducing steam with the temperature of 155 ℃ into the dewaxing furnace until paraffin in the formwork is melted and completely flows out, cleaning the inner cavity of the formwork with hot water at the temperature of 60 ℃, simultaneously washing a wax film adhered to the outer wall of the formwork, drying, placing the formwork in a molding machine for filling sand, then heating to 1000 ℃, roasting for 35min at the temperature of 1000 ℃, and cooling to obtain a high-strength formwork;
s4, smelting: presetting the furnace temperature of a smelting furnace to 1565 ℃, starting heating, monitoring the furnace temperature every 30min, putting the raw material of the heat-resistant steel connecting pipe into the smelting furnace when the furnace temperature of the smelting furnace reaches the preset temperature, and preserving the heat for 40min to obtain molten metal;
s5, component detection: taking the molten metal by using a small ladle, pouring the molten metal into a metal die which is preheated to 205 ℃ in a heat treatment furnace in advance and used for manufacturing a spectrum detection sample, cooling to obtain the sample, turning the cross section of the sample flat by using a lathe, detecting the components by using a direct-reading spectrometer, carrying out the next step if the detection result meets the casting requirement of the heat-resistant steel connecting pipe, and if the detection result does not meet the casting requirement of the heat-resistant steel connecting pipe, adjusting the components of the molten metal in the step S4 according to the detection result until the component detection result meets the casting requirement of the heat-resistant steel connecting pipe;
s6, pouring: keeping the temperature of the molten metal meeting the casting requirement of the heat-resistant steel connecting pipe with the component detection result in the step S5 at 1565 ℃ for 10min, standing, removing floating slag by using a slag removing spoon after impurities are completely precipitated, and then pouring the molten metal into the high-strength formwork prepared in the step S3, wherein the speed is the principle of slow first and then fast and then slow, and the pouring time is 25S, so that a casting is obtained;
s7, heat treatment: placing the casting obtained in the step S6 into a cage, setting the temperature of a preset annealing furnace to be 1065 ℃, starting to heat up the annealing furnace, placing the casting and the cage into the annealing furnace when the temperature of the annealing furnace rises to the preset temperature, keeping the temperature at 1065 ℃ for 40min, taking out the material, contacting with air, and naturally cooling to room temperature to obtain the heat-resistant steel connecting pipe shell;
monitoring the furnace temperature every 1h in the heating process of the annealing furnace, monitoring the furnace temperature every 5min after the casting is placed into the annealing furnace, and monitoring the furnace temperature every 10min in the cooling process of the annealing furnace;
s8, casting inspection: and (5) flaw detection is carried out on the heat-resistant steel connecting pipe shell obtained in the step S7 by using X-ray, no defect is found, and the size of the casting meets the requirement, so that the investment casting process of the heat-resistant steel connecting pipe shell is completed.
In examples 1 to 3 of the present invention, the heat-resistant steel connecting pipe material was 1Cr20Ni14Si 2.
In the casting test of step S8, no defect was detected by X-ray inspection of the heat-resistant steel connecting tube shells obtained in examples 1 to 3, and the sizes of the obtained heat-resistant steel connecting tube shells were all satisfactory. The connecting pipe shell body prepared by the simultaneous comparative example (the connecting pipe is produced by using the traditional investment casting process) is subjected to flaw detection by X-ray, and the defects exist; compared with the product yield of the two, the product yield of the invention in the embodiment 1, the embodiment 2 and the embodiment 3 is respectively 10.6 percent, 13.2 percent and 11.3 percent higher than that of the comparative example.
The above description is only for the preferred embodiment of the present invention, but the scope of the present invention is not limited thereto, and any person skilled in the art should be considered to be within the technical scope of the present invention, and the technical solutions and the inventive concepts thereof according to the present invention should be equivalent or changed within the scope of the present invention.
Claims (7)
1. The investment casting process of the heat-resistant steel connecting pipe shell is characterized by comprising the following steps of:
s1, manufacturing a wax mould: selecting semi-solid paraffin as a wax mould material, injecting the semi-solid paraffin into a wax mould by using a paraffin injection machine, then forming to obtain a wax pattern, carrying out piece-by-piece hot welding on the wax pattern by using a flat-head electric soldering iron in a manual mode, and welding, adhering and assembling the wax pattern into a wax mould;
s2, preparing a formwork: taking silica sol as a bonding agent, adding zirconium powder filler, an anti-cracking agent, a wetting agent and a defoaming agent, stirring for 8-10 hours to prepare slurry, immersing the wax mold prepared in the step S1 into the slurry for slurry coating, then scattering zircon refractory material to form a shell, coating a layer of hardened shell outside the wax mold after the shell is hardened, and repeatedly coating 4 layers of hardened shells outside the wax mold to obtain the mold shell;
s3, dewaxing and roasting: placing the formwork prepared in the step S2 in a dewaxing furnace, introducing steam with the temperature of 145-155 ℃ into the dewaxing furnace until paraffin in the formwork is melted and completely flows out, cleaning an inner cavity of the formwork with hot water at 50-60 ℃, simultaneously washing off a wax film adhered to the outer wall of the formwork, drying, placing the formwork in a molding machine for sand filling, then heating to 1000 ℃, roasting at 1000 ℃ for 25-35 min, and cooling to obtain a high-strength formwork;
s4, smelting: presetting the furnace temperature of a smelting furnace to be 1555-1565 ℃, starting heating, monitoring the furnace temperature once every 30min, putting the raw material of the heat-resistant steel connecting pipe into the smelting furnace after the furnace temperature of the smelting furnace reaches the preset temperature, and preserving the heat for 40-60 min to obtain molten metal;
s5, component detection: taking the molten metal by using a small ladle, pouring the molten metal into a metal mold for manufacturing a spectrum detection sample, cooling to obtain the sample, turning the cross section of the sample flat by using a lathe, detecting components by using a direct-reading spectrometer, performing the next step if the detection result meets the casting requirement of the heat-resistant steel connecting pipe, and adjusting the components of the molten metal in the step S4 according to the detection result if the detection result does not meet the casting requirement of the heat-resistant steel connecting pipe until the component detection result meets the casting requirement of the heat-resistant steel connecting pipe;
s6, pouring: keeping the temperature of the molten metal meeting the casting requirement of the heat-resistant steel connecting pipe according to the component detection result in the step S5 at 1555-1565 ℃ for 10min, standing, removing floating slag by using a slag removing spoon after impurities are completely precipitated, and then pouring the molten metal into the high-strength formwork prepared in the step S3, wherein the speed is in the principle of slow first and fast second, and the pouring time is 25S, so that a casting is obtained;
s7, heat treatment: placing the casting obtained in the step S6 into a cage, wherein the preset annealing furnace temperature is 1055-1065 ℃, starting to heat up an annealing furnace, placing the casting and the cage into the annealing furnace when the annealing furnace temperature is raised to the preset temperature, keeping the temperature at 1055-1065 ℃ for 40-60 min, taking out the material, and naturally cooling the material to room temperature by contacting with air to obtain the heat-resistant steel connecting pipe shell;
s8, casting inspection: and (5) flaw detection is carried out on the heat-resistant steel connecting pipe shell obtained in the step S7 by using X-ray, no defect is found, and the size of the casting meets the requirement, so that the investment casting process of the heat-resistant steel connecting pipe shell is completed.
2. The investment casting process of a heat resistant steel connecting pipe shell as claimed in claim 1, wherein the injection pressure is 15kg/cm in step S12The temperature is 58-62 ℃.
3. The investment casting process for the heat-resistant steel connecting pipe shell according to claim 1, wherein in the step S2, the mass ratio of the silica sol, the zirconium powder filler, the anti-cracking agent, the wetting agent and the defoaming agent is 5: 16-20.01-0.02: 8-10: 8-12.
4. The investment casting process of a heat-resistant steel connecting pipe shell as claimed in claim 1 or 3, wherein the anti-cracking agent is one of N-phenyl-2-naphthylamine, N-diphenyl-p-phenylenediamine, N-p-phenylmethyl-2-naphthylamine, N-isopropyl-N-phenyl-p-phenylenediamine; the wetting agent is a compound of heptadecyl imidazoline, polyoxyethylene fatty alcohol ether and propylene glycol, and the mass ratio of the heptadecyl imidazoline to the polyoxyethylene fatty alcohol ether to the propylene glycol is 10: 6-8: 3-5; the defoaming agent is fatty acid glyceride or polydimethylsiloxane.
5. The investment casting process of a heat-resistant steel connecting pipe shell as claimed in claim 1, wherein in step S2, the hardening temperature is 20-25 ℃, the relative humidity is 55-65%, and the hardening time is 1-2 h.
6. The investment casting process of a heat-resistant steel connecting pipe shell as claimed in claim 1, wherein in step S5, the metal mold is preheated to 195-205 ℃ in a heat treatment furnace in advance.
7. The investment casting process for connecting tube shells of heat-resistant steel as claimed in claim 1, wherein in step S7, the temperature of the annealing furnace is monitored every 1h during the temperature rise of the annealing furnace, the temperature of the annealing furnace is monitored every 5min after the casting is placed in the annealing furnace, and the temperature of the annealing furnace is monitored every 10min during the cooling process.
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