CN118308653A - Bottom pouring chassis casting and preparation process thereof - Google Patents
Bottom pouring chassis casting and preparation process thereof Download PDFInfo
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- CN118308653A CN118308653A CN202410401625.2A CN202410401625A CN118308653A CN 118308653 A CN118308653 A CN 118308653A CN 202410401625 A CN202410401625 A CN 202410401625A CN 118308653 A CN118308653 A CN 118308653A
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- 229910045601 alloy Inorganic materials 0.000 claims description 40
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- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 claims description 32
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- QVGXLLKOCUKJST-UHFFFAOYSA-N atomic oxygen Chemical compound [O] QVGXLLKOCUKJST-UHFFFAOYSA-N 0.000 claims description 10
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- XEEYBQQBJWHFJM-UHFFFAOYSA-N iron Substances [Fe] XEEYBQQBJWHFJM-UHFFFAOYSA-N 0.000 claims description 10
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Abstract
The invention provides a bottom pouring chassis casting and a preparation process thereof, and belongs to the technical field of bottom pouring chassis for casting. The bottom casting chassis casting comprises the following components in percentage by mass ：C:0.23％-0.30％、Si:0.60％-0.80％、Mn:0.50％-0.75％、P≤0.020％、S≤0.015％、Cr:0.10％-0.25％、Ni:0.55％-0.75％、Mo:0.15％-0.35％、V≤0.05％、Al：0.01％-0.02％、Cu≤0.20％,As≤0.025％、Sn≤0.025％、Sb≤0.010％、H≤0.0002％、O≤0.0050％、N≤0.0100％, and the balance of Fe and unavoidable impurities. The bottom pouring chassis casting under the chemical composition formula has good casting performance, weldability and processability, reduces the defect generation rate of blanks, has crack resistance in a rapid cooling and rapid heating use state, can be repeatedly subjected to repair welding and machining use, and has the service life of more than 200 times.
Description
Technical Field
The invention belongs to the technical field of bottom pouring chassis for casting, and particularly relates to a bottom pouring chassis casting and a preparation process thereof.
Background
The bottom pouring chassis for the large steel ingot is used as one of important components of the metallurgical accessory, and the heavy machinery industry has discontinuous production mode due to various types and sizes of manufactured products, and the working environment needs to be subjected to repeated rapid cooling and rapid heating. And the casting process is directly contacted with high-temperature molten steel, the bottom is easy to crack, scald and other defects, the service life of the steel cannot be generally 20-40 times through repair welding or machining, the consumption of ton steel is high, and the use cost of the smelting process accessory is high.
The bottom casting chassis is made of gray cast iron, and has the advantages of low cost and good castability. However, the bottom pouring chassis made of gray cast iron generates microcracks under the action of multiple stresses in the use process, and the microcracks are expanded in the use process, so that the inner wall of the water gap of the chassis is cracked and peeled off to generate pits, the lifting lug is easy to break after mechanical collision, and the lifting lug can only be scrapped when the cracking is serious or too many due to poor repairing property of the cast iron. Meanwhile, the chassis with cracks and pits is easy to remain slag inclusion or inject refractory materials at the cracks, the cleaning labor intensity is high, and meanwhile, the purity of the later-stage casting steel ingot is influenced.
The chassis of the patent CN205869413U is used for prolonging the service life, fireproof paint is smeared in the chassis, the steel casting process is decomposed to influence the surface quality of the steel ingot, and the structure is not suitable for bottom pouring steel ingot casting. The patent CN203649342U, CN209157074U, CN202621851U is used for replacing parts nearby the bottom pouring channel as consumable materials periodically in a combined mode, so that the service life of the chassis is prolonged, the use cost is reduced slightly, and the problem of chassis cracking is not fundamentally solved.
In view of this, the invention is specifically proposed.
Disclosure of Invention
The invention provides a bottom pouring chassis casting and a preparation process thereof, aiming at solving the technical problems that a bottom pouring chassis for a steel ingot is easy to crack, short in service life, high in use cost and the like.
The technical scheme of the invention is as follows:
The invention provides a bottom pouring chassis casting, which comprises the following components in percentage by mass ：C:0.23％-0.30％、Si:0.60％-0.80％、Mn:0.50％-0.75％、P≤0.020％、S≤0.015％、Cr:0.10％-0.25％、Ni:0.55％-0.75％、Mo:0.15％-0.35％、V≤0.05％、Al：0.01％-0.02％、Cu≤0.20％,As≤0.025％、Sn≤0.025％、Sb≤0.010％、H≤0.0002％、O≤0.0050％、N≤0.0100％, and the balance of Fe and unavoidable impurities.
In one embodiment ,C:0.25％-0.28％、Si:0.65％-0.75％、Mn:0.50％-0.60％、P≤0.010％、S≤0.005％、Cr:0.15％-0.20％、Ni:0.55％-0.65％、Mo：0.15％-0.25％、V≤0.05％、Al:0.015％-0.020％、Cu≤0.10％、As≤0.020％、Sn≤0.020％、Sb≤0.005％、H≤0.0002％、O≤0.0050％、N≤0.0100％;
Preferably ,C:0.25％-0.28％、Si:0.66％-0.75％、Mn:0.52％-0.58％、P:0.006％-0.008％、S:0.001％-0.003％、Cr:0.150％-0.200％、Ni:0.550％-0.640％、Mo:0.170％-0.230％、V:0.005％-0.006％、Al:0.015％-0.019％、Cu:0.020％-0.040％、As:0.003％-0.005％、Sn:0.002％-0.004％、Sb:0.002％、H:0.00015％、O:0.004％-0.005％、N:0.007％-0.008％.
In a specific embodiment, the bottom pouring chassis casting comprises a chassis main body, a working surface of the chassis main body is provided with a hemispherical bottom water gap, the bottom of the bottom water gap is communicated with a bottom pouring channel, the bottom pouring channel extends to the other working surface of the chassis main body, lifting lugs are symmetrically arranged on the edge of the chassis main body, the lifting lugs are flush with the working surface of the chassis main body, provided with the bottom water gap, and the thickness of the lifting lugs is smaller than that of the chassis main body.
Preferably, the bottom pouring channel is in a shape of a truncated cone with a small upper part and a large lower part.
In one embodiment, the thickness of the bottom pouring chassis casting is h=260 mm-500mm, the diameter of the outer circle of the bottom pouring chassis casting is 4H-6H, the diameter of the bottom nozzle is 1H-2H, the height of the bottom pouring channel is 0.3H-0.6H, the thickness of the lifting lug is 0.5H-0.6H, and the width of the lifting lug is 0.8H-1H.
The invention also provides a preparation process of the bottom pouring chassis casting, which comprises the following steps:
(1) Smelting: smelting molten steel according to the components of the bottom pouring chassis casting and the mass percentages of the components for standby;
(2) Pouring: pouring the molten steel prepared in the step (1) into a casting mold, and demolding to obtain a chassis blank;
(3) And (3) heat treatment: sequentially carrying out quenching treatment and tempering treatment on the chassis blank prepared in the step (2), and discharging the chassis blank from a furnace to obtain the finished product;
The quenching treatment includes: firstly heating to 230-270 ℃ for heat preservation not less than 3 hours, then heating to 630-670 ℃ for heat preservation not less than 3 hours at the heating rate of 40-50 ℃/h, then heating to 990-1010 ℃ for heat preservation not less than 9 hours at the heating rate of 50-60 ℃/h, spray cooling for 20-40 minutes, starting air cooling at the temperature not more than 450 ℃, starting air cooling at the temperature not more than 250 ℃, and feeding into a furnace for tempering at the temperature not more than 150 ℃;
The tempering treatment includes: heating to 230-270 ℃ for heat preservation not less than 3h, heating to 650-670 ℃ for heat preservation not less than 11h at the heating rate of 40-50 ℃/h, cooling to 380-420 ℃ for heat preservation not less than 3h at the cooling rate of 30-40 ℃/h, cooling, and discharging the workpiece at the temperature not more than 230 ℃.
In the present invention, the casting mold is manufactured by a conventional method according to the dimensional structure of the bottom pouring tray casting.
In a specific embodiment, the smelting of step (1) comprises:
(1) Smelting in an electric furnace: after the waste steel is melted by oxygen blowing and carbon spraying of an alkaline electric arc furnace, slag is exchanged and P is removed, and the tapping temperature of crude water is more than or equal to 1700 ℃ for tapping;
(2) Ladle refining: after refining the ladle bottom pad deoxidizing protective agent HSi, carrying out power transmission and heating on the crude water in the step (1) at a station, blowing argon in the whole ladle bottom, adding a slag forming material to control the slag basicity CaO/SiO 2 to be 2-3, then adding a powdery deoxidizer to carry out diffusion deoxidizing operation, adding alloy ferrosilicon, alloy ferromanganese, alloy ferrochromium, nickel plate or alloy ferronickel and alloy ferromolybdenum according to standard components after the slag color is adjusted to be white or gray, and then carrying out power transmission and heating on molten steel to be more than or equal to 1650 ℃ and entering a vacuum station;
(3) Vacuum treatment: starting timing at the vacuum degree of less than or equal to 1 Torr, keeping the vacuum time of more than or equal to 15min, fine adjusting the components and the temperature after the vacuum is finished, continuously performing diffusion deoxidation operation, feeding aluminum wires and/or aluminum iron for final deoxidation before tapping, and tapping at the tapping temperature of 1560-1600 ℃;
wherein, the impurity elements V of the crude water in the step (1) are controlled to be less than or equal to 0.05 percent, cu to be less than or equal to 0.20 percent, as to be less than or equal to 0.025 percent, sn to be less than or equal to 0.025 percent, sb to be less than or equal to 0.010 percent and P to be less than or equal to 0.020 percent.
In a specific embodiment, the scrap steel is at least two of carbon scrap steel, a briquetting and a scrap steel ingot mould, and preferably, the scrap steel is carbon scrap steel or a combination of the briquetting and the scrap steel ingot mould, wherein the mass ratio of the carbon scrap steel or the briquetting to the scrap steel ingot mould is 10-15:1; preferably, the mass ratio of the carbon scrap steel or the briquetting to the scrap steel ingot mould is 12-15:1; the addition amount of the deoxidizing protective agent HSi is 3-4kg/t; the slag-forming material is lime and fluorite, and the mass ratio of the lime to the fluorite is 3-4:1; the powdery deoxidizer is C-P and CaSi-P; the total addition amount of the powdery deoxidizer is 10-30kg/t; the vacuum treatment time is 15-20min, the argon flow is 120-140L/min during the vacuum treatment, the soft argon blowing time from the end of vacuum to tapping is controlled to be 20-50 min, the soft argon blowing flow is 20-40L/min, and the addition amount of the final deoxidized aluminum wire and/or aluminum iron is calculated according to the Al content of 0.025-0.030%, and the residual is not considered.
When crude water is smelted in an electric furnace, foam slag is required to be produced for better removal of impurities and gas, pig iron (high carbon content and easier production of foam slag) is generally added, but the price of pig iron is higher, the inventor adopts a scrap ingot mould (high carbon content of cast iron) to produce foam slag, but the scrap mould has the problem of higher residual elements, and the ratio of the carbon scrap steel to the carbon scrap steel is controlled by adding carbon scrap steel or a briquetting, so that the crude water obtained by smelting finally can meet the requirements.
In a specific embodiment, the casting mold adopts a sand box for molding, and the surface of a cavity of the sand box is brushed with high-temperature-resistant water-based paint and dried; removing oxygen in the cavity before casting; a steel flow protection device is arranged under a ladle nozzle during pouring, so that secondary oxidation of molten steel is reduced; and adding a proper amount of heating agent and rice husk into the casting riser after casting, preserving heat, slowly cooling in a casting pit for 5-8 days, sequentially pouring into a box, shakeout, annealing at low temperature, and cutting to remove the casting riser and the inner runner to obtain the chassis blank.
Preferably, the number of times of brushing the high temperature resistant water-based paint on the surface of the cavity is 3, the thickness of the paint is controlled to be 0.3-0.4mm, the paint is dried, nitrogen is filled into the chassis cavity for more than 30min before casting, and the filling time is more than or equal to 60min.
In a specific embodiment, during quenching treatment, firstly heating to 240-260 ℃ for 3-4 hours, then heating to 640-660 ℃ for 3-4 hours at the heating rate of 50 ℃/h, then heating to 1000-1010 ℃ for 9-10 hours at the heating rate of 50 ℃/h, spray cooling for 30-40 minutes, air cooling at the temperature of 450 ℃ or less, air cooling at the temperature of 250 ℃ or less, and tempering at the temperature of 150 ℃ or less;
During tempering, the temperature is raised to 240-260 ℃ for 3-4h, then the temperature is raised to 660-670 ℃ for 11-12 h at the heating rate of 40 ℃/h, then the temperature is cooled to 400-420 ℃ for 3-4h at the cooling rate of 40 ℃/h, then the furnace is cooled, and the temperature of the workpiece is less than or equal to 230 ℃ and is discharged from the furnace.
The heat treatment process is quenching and tempering, comprises quenching treatment and high-temperature tempering treatment, and aims to obtain good comprehensive mechanical properties of a workpiece through proper process parameters, and has high strength and good plastic toughness. Therefore, when the novel energy-saving cooling device is used under the working condition of rapid cooling and rapid heating, the chassis is not easy to deform.
In one specific embodiment, the method further comprises: and (4) flaw detection and treatment.
In the present invention, flaw detection and processing include: and after the bottom chassis casting is processed, carrying out UT and MT flaw detection on the upper working surface and the lower working surface of the bottom pouring chassis casting according to JB/T5000.14 standard. UT requires single defect less than or equal to phi 3mm, and extension defect is not allowed; MT inspection requires a linear display record of greater than 0.3mm, and the linear defect length is less than or equal to 2mm. If the defect exceeds the standard, the defect position is immediately subjected to defect elimination treatment, repair welding and stress relief annealing.
Compared with the prior art, the invention has the following beneficial effects:
The bottom pouring chassis casting under the chemical composition formula has good casting performance and welding performance, and reduces the defect generation rate of blanks; the bottom pit adopts a semicircular bottom water gap shape, so that inclusion floating is facilitated, the quality of a water gap end of a produced steel ingot is improved, stress concentration is avoided, and the risk of cracking around the bottom pit is reduced; the molten steel used for chassis casting is manufactured by adopting an alkaline arc furnace, a ladle refining furnace and a vacuum degassing process, so that the residual element level and the gas content of the chassis can be effectively reduced, the inclusion level of the chassis is reduced, and the service life is prolonged; the secondary oxidation prevention measures of the chassis before and during pouring further reduce the secondary oxidation of molten steel and improve the purity; grain refinement and structure transformation during heat treatment are carried out to obtain stable ferrite, pearlite and sorbite. The bottom pouring chassis casting has the capability of crack resistance in a rapid cooling and rapid heating use state, can be repeatedly subjected to repair welding and machining, can be used for prolonging the use times, and can be used for more than 200 times.
Drawings
FIG. 1 is a schematic cross-sectional view of a bottom pour tray casting of the present invention;
FIG. 2 is a three-dimensional schematic view of a bottom pour tray casting of the present invention;
FIG. 3 is a pictorial representation of a physical blank of the bottom pour tray casting of the present invention;
FIG. 4 is a schematic illustration of the use of the bottom pour tray casting of the present invention;
FIG. 5 is a graph showing the grain size results (100X 500) of the bottom-pouring chassis casting prepared in example 1;
FIG. 6 is a graph of the grain size results (100X 500) of the bottom-pouring tray casting prepared in example 2;
Wherein 1-chassis body; 2-bottom nozzle; 3-bottom pouring channel; 4-lifting lugs; 5-ingot mould; 6-a bottom plate; 7-middle pouring tube.
Detailed Description
The present invention will be described in further detail with reference to the drawings and examples, in order to make the objects, technical solutions and advantages of the present invention more apparent. It should be understood that the specific embodiments described herein are for purposes of illustration only and are not intended to limit the scope of the invention.
Referring to fig. 1-4, the structure of a bottom pouring chassis casting in the following embodiment includes a chassis main body 1, a working surface of the chassis main body 1 is provided with a hemispherical bottom water gap 2, the bottom of the bottom water gap 2 is communicated with a bottom pouring channel 3, the bottom pouring channel 3 extends to another working surface of the chassis main body 1, the bottom pouring channel 3 is in a shape of a truncated cone with a small top and a large bottom, two groups of lifting lugs 4 are symmetrically arranged at the edge of the chassis main body 1, the two groups of lifting lugs 4 are vertically arranged, the lifting lugs 4 are flush with the working surface of the chassis main body 1 provided with the bottom water gap 2, and the thickness of the lifting lugs 4 is smaller than that of the chassis main body 1.
The thickness H=260 mm-500mm of the bottom pouring chassis casting, the diameter of the outer circle of the bottom pouring chassis casting is 4H-6H, the diameter of the bottom water gap 2 is 1H-2H, the height of the bottom pouring channel 3 is 0.3H-0.6H, the thickness of the lifting lug is 0.5H-0.6H, and the width of the lifting lug is 0.8H-1H.
Example 1 provides a process for preparing a bottom-pouring chassis casting
1. And (3) after the electric furnace burden scrap ingot mould is melted by oxygen blowing and carbon spraying by using an alkaline electric arc furnace, changing slag and removing P, and tapping at the electric furnace tapping temperature of 1705 ℃. Adding lime and fluorite (the mass ratio is 3-4:1) into a 150t refined steel ladle bottom pad HSi 3kg/t pre-deoxidizer to perform slagging, controlling the slag basicity CaO/SiO 2 to be 2.5, then performing diffusion deoxidization operation by adopting C-P, caSi-P, adjusting the total consumption of the diffusion deoxidizer CaSi-P15 kg/t steel and C-P10 kg/t steel, adding alloy ferrosilicon, alloy ferromanganese, alloy ferrochromium, nickel plate or alloy ferronickel and alloy ferromolybdenum according to standard components after the color of the steel slag is adjusted to be white or off-white, and then feeding the molten steel to heat to 1660 ℃ and entering a vacuum station; argon flow is 120L/min, vacuum degree is less than or equal to 1 torr, and the vacuum is maintained for 15min. After the vacuum is finished, the argon flow is 30L/min, the holding time is 30min, and the addition amount of the final deoxidized aluminum wire and/or aluminum iron is calculated according to the Al content of 0.025-0.030%, and the residue is not considered. Pouring refined molten steel into the die cavity at the tapping temperature of 1580 ℃. The smelting chemical components comprise the balance of Fe according to mass percent ：C：0.25％、Si：0.66％、Mn：0.52％、P：0.008％、S：0.002％、Cr：0.16％、Ni：0.56％、Mo：0.19％、V:0.006％、Al：0.018％、Cu：0.03％、As：0.004％、Sn：0.003％、Sb：0.002％,H：0.00015％、O：0.0046％、N：0.0078％,.
2. The overall thickness H=280 mm of the chassis, and the diameter D1=1600 mm of the chassis; bottom nozzle diameter d2=280 mm; the height B=120 mm of the bottom pouring channel (design of casting blind holes, later processing), the thickness=140 mm of the lifting lug, the width=280 mm of the lifting lug, the unilateral allowance control is carried out on a 20mm design blank picture and a pouring channel, an external chill is arranged above the lifting lug, the lifting lug defect is prevented, a casting riser is arranged opposite to the shape of a water gap at the bottom of a chassis, the quality of a working face is prevented from being influenced, and two internal runners of one riser are arranged. The diameter of the casting riser is 800mm, and the height is 1000mm. Brushing high temperature resistant water-based paint on the surface of the molding cavity for 3 times, controlling the thickness to be 0.3-0.4mm, and drying. Nitrogen is filled into the chassis cavity more than or equal to 30min before pouring, the air filling time is more than or equal to 60min, and the ladle nozzle is fully drained before pouring, and the drainage times are more than or equal to 3 times. And (5) adding a proper amount of heating agent and rice husk to the casting riser after casting the workpiece, preserving heat, slowly cooling in a casting pit for 5 days, and pouring into a box and a furnace.
3. And (3) after the chassis blank is box-broken and shakeout, annealing at a low temperature, and starting performance heat treatment after cutting a riser and an ingate. During quenching treatment, firstly, heat is preserved for 3 hours at 250 ℃, then the temperature is preserved for 3 hours at the temperature rising speed of 50 ℃/h to 650 ℃, then the temperature is preserved for 9 hours at the temperature rising speed of 50 ℃/h to 1000 ℃, spray cooling is carried out for 30 minutes, air cooling is started at the temperature of less than or equal to 450 ℃, air cooling is started at the temperature of less than or equal to 250 ℃, and the temperature of less than or equal to 150 ℃ is fed into a furnace for tempering. During tempering, the temperature is firstly increased to 250 ℃, the heat preservation is carried out for 3 hours, then the temperature is controlled to be 40 ℃/h at the heating rate, the heat preservation time is firstly increased to 660 ℃ for 11 hours, then the temperature is reduced to 400 ℃ at the cooling rate of 40 ℃/h, the heat preservation time is 3 hours, and the furnace is cooled until the temperature of a workpiece is less than or equal to 230 ℃ and is discharged.
4. Machining and checking the flaw detection. After the machining is finished according to the drawing, carrying out UT flaw detection on the upper working surface and the lower working surface of the chassis according to JB/T5000.14 standard, and recording the flaw with the exceeding standard of phi 3 mm; MT examination shows no > 2mm linearity, and no defect elimination treatment is needed.
Example 2 provides a process for preparing a bottom-pouring chassis casting
1. Electric furnace batching scrap ingot mould: briquetting=1:12, after oxygen blowing, carbon spraying and melting by using an alkaline electric arc furnace, changing slag and removing P, and tapping at 1700 ℃ in an electric furnace. Adding lime and fluorite (the mass ratio is 3-4:1) into a 150t refined steel ladle bottom pad HSi 3kg/t pre-deoxidizer to perform slagging, controlling the slag basicity CaO/SiO 2 to be 2.5, then performing diffusion deoxidization operation by adopting C-P, caSi-P, adjusting the total consumption of the diffusion deoxidizer CaSi-P15 kg/t steel and C-P10 kg/t steel, adding alloy ferrosilicon, alloy ferromanganese, alloy ferrochromium, nickel plate or alloy ferronickel and alloy ferromolybdenum according to standard components after the color of the steel slag is adjusted to be white or off-white, and then feeding the molten steel to heat to 1665 ℃ and entering a vacuum station; argon flow is 120L/min, vacuum degree is less than or equal to 1 torr, and the vacuum is maintained for 15min. After the vacuum is finished, the argon flow is 30L/min and the holding time is 30min during soft blowing, and the addition amount of the final deoxidized aluminum wire and/or aluminum iron is calculated according to the Al content of 0.025-0.030%, and the residue is not considered. Pouring refined molten steel into the die cavity at the tapping temperature of 1582 ℃. The smelting chemical components comprise the balance of Fe according to mass percent ：C：0.26％、Si：0.68％、Mn：0.53％、P：0.007％、S：0.001％、Cr：0.15％、Ni：0.55％、Mo：0.17％、V:0.005％、Al：0.016％、Cu：0.03％、As：0.003％、Sn：0.002％、Sb：0.002％,H：0.00015％、O：0.0042％、N：0.0075％,.
2. The overall thickness H=280 mm of the chassis, and the diameter D1=1600 mm of the chassis; bottom nozzle diameter d2=280 mm; the height B=120 mm of the bottom pouring channel (design of casting blind holes, later processing), the thickness=140 mm of the lifting lug, the width=280 mm of the lifting lug, the unilateral allowance control is carried out on a 20mm design blank picture and a pouring channel, an external chill is arranged above the lifting lug, the lifting lug defect is prevented, a casting riser is arranged opposite to the shape of a water gap at the bottom of a chassis, the quality of a working face is prevented from being influenced, and two internal runners of one riser are arranged. The diameter of the casting riser is 800mm, and the height is 1000mm. Brushing high temperature resistant water-based paint on the surface of the molding cavity for 3 times, controlling the thickness to be 0.3-0.4mm, and drying. Nitrogen is filled into the chassis cavity more than or equal to 30min before pouring, the air filling time is more than or equal to 60min, and the ladle nozzle is fully drained before pouring, and the drainage times are more than or equal to 3 times. And (5) adding a proper amount of heating agent and rice husk to the riser after casting the workpiece, preserving heat, slowly cooling in a casting pit for 5 days, and pouring into a box and then charging into a furnace.
3. And (3) after the chassis blank is box-broken and shakeout, annealing at a low temperature, and starting performance heat treatment after cutting a riser and an ingate. During quenching treatment, firstly, heat is preserved for 3 hours at 250 ℃, then the temperature is preserved for 3 hours at the temperature rising speed of 50 ℃/h to 650 ℃, then the temperature is preserved for 9 hours at the temperature rising speed of 50 ℃/h to 1000 ℃, spray cooling is carried out for 30 minutes, air cooling is carried out at the temperature of less than or equal to 450 ℃, air cooling is carried out at the temperature of less than or equal to 250 ℃, and the temperature of less than or equal to 150 ℃ is carried out in an oven for tempering. During tempering, the temperature is firstly increased to 250 ℃, the heat preservation is carried out for 3 hours, then the temperature is controlled to be 40 ℃/h at the heating rate, the heat preservation time is firstly increased to 660 ℃ for 11 hours, then the temperature is reduced to 400 ℃ at the cooling rate of 40 ℃/h, the heat preservation time is 3 hours, and the furnace is cooled until the temperature of a workpiece is less than or equal to 230 ℃ and is discharged.
4. Machining and checking the flaw detection. After the machining is finished according to the drawing, carrying out UT flaw detection on the upper working surface and the lower working surface of the chassis according to JB/T5000.14 standard, and recording the flaw with the exceeding standard of phi 3 mm; MT examination shows no > 2mm linearity, and no defect elimination treatment is needed.
Example 3 provides a process for preparing a bottom-pouring chassis casting
1. Electric furnace batching scrap ingot mould: carbon scrap=1:13, after oxygen blowing, carbon spraying and melting by using an alkaline electric arc furnace, slag replacement and P removal are carried out, and tapping is carried out at the tapping temperature of 1708 ℃ of an electric furnace. Adding lime and fluorite (the mass ratio is 3-4:1) into a 150t refined steel ladle bottom pad HSi 3kg/t pre-deoxidizer to perform slagging, controlling the slag basicity CaO/SiO 2 to be 3, then performing diffusion deoxidization operation by adopting C-P, caSi-P, adjusting the total consumption of the diffusion deoxidizer CaSi-P15 kg/t steel and C-P10 kg/t steel, adding alloy ferrosilicon, alloy ferromanganese, alloy ferrochromium, nickel plate and/or alloy ferronickel and alloy ferromolybdenum according to standard components after the steel slag color is adjusted to be white or off-white, and then feeding the molten steel to heat to 1668 ℃ and entering a vacuum station; argon flow is 120L/min, vacuum degree is less than or equal to 1 torr, and the vacuum is maintained for 15min. After the vacuum is finished, the argon flow is 30L/min and the holding time is 30min during soft blowing, and the addition amount of the final deoxidized aluminum wire and/or aluminum iron is calculated according to the Al content of 0.025-0.030%, and the residue is not considered. And pouring refined molten steel into the cavity at the tapping temperature of 1575 ℃. The smelting chemical components comprise the balance of Fe according to mass percent ：C：0.26％、Si：0.70％、Mn：0.53％、P：0.007％、S：0.003％、Cr：0.17％、Ni：0.60％、Mo：0.18％、V:0.005％、Al：0.015％、Cu：0.04％、As：0.005％、Sn：0.004％、Sb：0.002％,H：0.00015％、O：0.0045％、N：0.0076％,.
2. The overall thickness h=300 mm of the chassis and the diameter d1=1800 mm of the chassis; bottom nozzle diameter d2=400 mm; the bottom pouring channel height b=120 mm (as cast blind hole design, post-processing); lug thickness = 150mm, lug width = 300mm, unilateral surplus control is at 20mm design blank diagram and pouring channel, and the lug top sets up outer chiller, prevents the lug defect, and the casting riser setting is in chassis bottom mouth of a river shape opposite, avoids influencing working face quality, sets up two ingates of a riser. The diameter of the casting riser is 800mm, and the height is 1000mm. Brushing high temperature resistant water-based paint on the surface of the molding cavity for 3 times, controlling the thickness to be 0.3-0.4mm, and drying. Nitrogen is filled into the chassis cavity more than or equal to 30min before pouring, the air filling time is more than or equal to 60min, and the ladle nozzle is fully drained before pouring, and the drainage times are more than or equal to 3 times. And (5) adding a proper amount of heating agent and rice husk to the riser after casting the workpiece, preserving heat, slowly cooling in a casting pit for 6 days, and pouring into a box and then charging into a furnace.
3. And (3) after the chassis blank is box-broken and shakeout, annealing at a low temperature, and starting performance heat treatment after cutting a riser and an ingate. During quenching treatment, firstly, heat is preserved for 3 hours at 250 ℃, then the temperature is preserved for 3 hours at the temperature rising speed of 50 ℃/h to 650 ℃, then the temperature is preserved for 9 hours at the temperature rising speed of 50 ℃/h to 1000 ℃, spray cooling is carried out for 30 minutes, air cooling is carried out at the temperature of less than or equal to 450 ℃, air cooling is carried out at the temperature of less than or equal to 250 ℃, and the temperature of less than or equal to 150 ℃ is carried out in an oven for tempering. During tempering, the temperature is firstly increased to 250 ℃, the heat preservation is carried out for 3 hours, then the temperature is controlled to be 40 ℃/h at the heating rate, the heat preservation time is firstly increased to 660 ℃ for 11 hours, then the temperature is reduced to 400 ℃ at the cooling rate of 40 ℃/h, the heat preservation time is 3 hours, and the furnace is cooled until the temperature of a workpiece is less than or equal to 230 ℃ and is discharged.
4. Machining and checking the flaw detection. After the machining is finished according to the drawing, carrying out UT flaw detection on the upper working surface and the lower working surface of the chassis according to JB/T5000.14 standard, and recording the flaw with the exceeding standard of phi 3 mm; MT examination shows no > 2mm linearity, and no defect elimination treatment is needed.
Example 4 provides a process for preparing a bottom-pouring chassis casting
1. Electric furnace batching scrap ingot mould: carbon scrap=1:13, after oxygen blowing, carbon spraying and melting by using an alkaline electric arc furnace, slag replacement and P removal are carried out, and tapping is carried out at the electric furnace tapping temperature of 1705 ℃. Adding lime and fluorite (the mass ratio is 3-4:1) into a 150t refined steel ladle bottom pad HSi 3kg/t pre-deoxidizer to perform slagging, controlling the slag basicity CaO/SiO 2 to be 3, then performing diffusion deoxidization operation by adopting C-P, caSi-P, adjusting the total consumption of the diffusion deoxidizer CaSi-P15 kg/t steel and C-P10 kg/t steel, adding alloy ferrosilicon, alloy ferromanganese, alloy ferrochromium, nickel plate or alloy ferronickel and alloy ferromolybdenum according to standard components after the color of the steel slag is adjusted to be white or off-white, and then feeding the molten steel to heat to 1662 ℃ and entering a vacuum station; argon flow is 120L/min, vacuum degree is less than or equal to 1 torr, and the vacuum is maintained for 15min. After the vacuum is finished, the argon flow is 30L/min and the holding time is 30min during soft blowing, and the addition amount of the final deoxidized aluminum wire and/or aluminum iron is calculated according to the Al content of 0.025-0.030%, and the residue is not considered. And pouring refined molten steel into the die cavity at the tapping temperature of 1583 ℃. The smelting chemical components comprise the balance of Fe according to mass percent ：C：0.27％、Si：0.72％、Mn：0.55％、P：0.008％、S：0.002％、Cr：0.18％、Ni：0.61％、Mo：0.19％、V:0.005％、Al：0.017％、Cu：0.03％、As：0.004％、Sn：0.004％、Sb：0.002％,H：0.00015％、O：0.0048％、N：0.0072％,.
2. The overall thickness h=300 mm of the chassis and the diameter d1=1800 mm of the chassis; bottom nozzle diameter d2=400 mm; the bottom pouring channel height b=120 mm (as cast blind hole design, post-processing); lug thickness = 150mm, lug width = 300mm, unilateral surplus control is at 20mm design blank diagram and pouring channel, and the lug top sets up outer chiller, prevents the lug defect, and the casting riser setting is in chassis bottom mouth of a river shape opposite, avoids influencing working face quality, sets up two ingates of a riser. The diameter of the casting riser is 800mm, and the height is 1000mm. Brushing high temperature resistant water-based paint on the surface of the molding cavity for 3 times, controlling the thickness to be 0.3-0.4mm, and drying. Nitrogen is filled into the chassis cavity more than or equal to 30min before pouring, the air filling time is more than or equal to 60min, and the ladle nozzle is fully drained before pouring, and the drainage times are more than or equal to 3 times. And (5) adding a proper amount of heating agent and rice husk to the riser after casting the workpiece, preserving heat, slowly cooling in a casting pit for 6 days, and pouring into a box and then charging into a furnace.
3. And (3) after the chassis blank is box-broken and shakeout, annealing at a low temperature, and starting performance heat treatment after cutting a riser and an ingate. During quenching treatment, firstly, heat is preserved for 3 hours at 250 ℃, then the temperature is preserved for 3 hours at the temperature rising speed of 50 ℃/h to 650 ℃, then the temperature is preserved for 9 hours at the temperature rising speed of 50 ℃/h to 1000 ℃, spray cooling is carried out for 30 minutes, air cooling is carried out at the temperature of less than or equal to 450 ℃, air cooling is carried out at the temperature of less than or equal to 250 ℃, and the temperature of less than or equal to 150 ℃ is carried out in an oven for tempering. During tempering, the temperature is firstly increased to 250 ℃, the heat preservation is carried out for 3 hours, then the temperature is controlled to be 40 ℃/h at the heating rate, the heat preservation time is firstly increased to 660 ℃ for 11 hours, then the temperature is reduced to 400 ℃ at the cooling rate of 40 ℃/h, the heat preservation time is 3 hours, and the furnace is cooled until the temperature of a workpiece is less than or equal to 230 ℃ and is discharged.
4. Machining and checking the flaw detection. After the machining is finished according to the drawing, carrying out UT flaw detection on the upper working surface and the lower working surface of the chassis according to JB/T5000.14 standard, and recording the flaw with the exceeding standard of phi 3 mm; MT examination shows no > 2mm linearity, and no defect elimination treatment is needed.
Example 5 provides a process for preparing a bottom-pouring chassis casting
1. Electric furnace batching scrap ingot mould: carbon scrap=1:15, after oxygen blowing, carbon spraying and melting by using an alkaline electric arc furnace, slag replacement and P removal are carried out, and tapping is carried out at the tapping temperature of 1701 ℃ of an electric furnace. Adding lime and fluorite (the mass ratio is 3-4:1) into a 150t refined steel ladle bottom pad HSi 3kg/t pre-deoxidizer to perform slagging, controlling the slag basicity CaO/SiO 2 to be 3, then performing diffusion deoxidization operation by adopting C-P, caSi-P, adjusting the total consumption of the diffusion deoxidizer CaSi-P15 kg/t steel and C-P10 kg/t steel, adding alloy ferrosilicon, alloy ferromanganese, alloy ferrochromium, nickel plate and/or alloy ferronickel and alloy ferromolybdenum according to standard components after the steel slag color is adjusted to be white or off-white, and then feeding the molten steel to heat to 1666 ℃ and entering a vacuum station; argon flow is 120L/min, vacuum degree is less than or equal to 1 torr, and the vacuum is maintained for 20min. After the vacuum is finished, the argon flow is 30L/min and the holding time is 30min during soft blowing, and the addition amount of the final deoxidized aluminum wire and/or aluminum iron is calculated according to the Al content of 0.025-0.030%, and the residue is not considered. And pouring refined molten steel into the die cavity at the tapping temperature of 1585 ℃. The smelting chemical components comprise the balance of Fe according to mass percent ：C：0.27％、Si：0.73％、Mn：0.57％、P：0.006％、S：0.001％、Cr：0.18％、Ni：0.63％、Mo：0.22％、V:0.005％、Al：0.018％、Cu：0.02％、As：0.003％、Sn：0.002％、Sb：0.002％,H：0.00015％、O：0.0040％、N：0.0065％,.
2. Chassis overall thickness h=400 mm, chassis diameter d1=2400 mm; bottom nozzle diameter d2=400 mm; the bottom pouring channel height b=220 mm (as cast blind hole design, post-processing); lug thickness = 200mm, lug width = 340mm, unilateral surplus control is at 20mm design blank diagram and pouring channel, and the lug top sets up outer chiller, prevents the lug defect, and the casting riser setting is in chassis bottom mouth of a river shape opposite, avoids influencing working face quality, sets up two ingates of a riser. The diameter of the casting riser is 800mm, and the height is 1000mm. Brushing high temperature resistant water-based paint on the surface of the molding cavity for 3 times, controlling the thickness to be 0.3-0.4mm, and drying. Nitrogen is filled into the chassis cavity more than or equal to 30min before pouring, the air filling time is more than or equal to 60min, and the ladle nozzle is fully drained before pouring, and the drainage times are more than or equal to 3 times. And (3) adding a proper amount of heating agent and rice husk to the riser after casting the workpiece, preserving heat, slowly cooling in a casting pit for 8 days, and pouring into a box and then charging into a furnace.
3. And (3) after the chassis blank is box-broken and shakeout, annealing at a low temperature, and starting performance heat treatment after cutting a riser and an ingate. During quenching treatment, firstly, the temperature is kept for 4 hours at 250 ℃, then the temperature is kept for 4 hours at the temperature rising speed of 50 ℃/h to 650 ℃, then the temperature is kept for 10 hours at the temperature rising speed of 50 ℃/h to 1000 ℃, the spray cooling is carried out for 30 minutes, the air cooling is started at the temperature of less than or equal to 450 ℃, the air cooling is started at the temperature of less than or equal to 250 ℃, and the temperature of less than or equal to 150 ℃ is fed into a furnace for tempering. During tempering, the temperature is firstly increased to 250 ℃, the heat preservation is carried out for 3 hours, then the temperature is controlled to be 40 ℃/h at the heating rate, the heat preservation time is firstly increased to 660 ℃ for 12 hours, then the temperature is reduced to 400 ℃ at the cooling rate of 40 ℃/h for 4 hours, and the furnace is cooled until the temperature of the workpiece is less than or equal to 230 ℃ and is discharged.
4. Machining and checking the flaw detection. After the machining is finished according to the drawing, carrying out UT flaw detection on the upper working surface and the lower working surface of the chassis according to JB/T5000.14 standard, and recording the flaw with the exceeding standard of phi 3 mm; MT examination shows no > 2mm linearity, and no defect elimination treatment is needed.
Example 6 provides a process for preparing a bottom-pouring chassis casting
1. Electric furnace batching scrap ingot mould: briquetting=1:15, after oxygen blowing, carbon spraying and melting by using an alkaline electric arc furnace, changing slag and removing P, and tapping at the electric furnace tapping temperature of 1702 ℃. Adding lime and fluorite (the mass ratio is 3-4:1) into a 150t refined steel ladle bottom pad HSi 3kg/t pre-deoxidizer to perform slagging, controlling the slag basicity CaO/SiO 2 to be 3, then performing diffusion deoxidization operation by adopting C-P, caSi-P, adjusting the total consumption of the diffusion deoxidizer CaSi-P15 kg/t steel and C-P10 kg/t steel, adding alloy ferrosilicon, alloy ferromanganese, alloy ferrochromium, nickel plate and/or alloy ferronickel and alloy ferromolybdenum according to standard components after the steel slag color is adjusted to be white or off-white, and then feeding the molten steel to the temperature of 1670 ℃ and entering a vacuum station; argon flow is 120L/min, vacuum degree is less than or equal to 1 torr, and the vacuum is maintained for 20min. After the vacuum is finished, the argon flow is 30L/min and the holding time is 30min during soft blowing, and the addition amount of the final deoxidized aluminum wire and/or aluminum iron is calculated according to the Al content of 0.025-0.030%, and the residue is not considered. And pouring refined molten steel into the die cavity at the tapping temperature of 1588 ℃. The smelting chemical components comprise the balance of Fe according to mass percent ：C：0.28％、Si：0.75％、Mn：0.58％、P：0.007％、S：0.002％、Cr：0.20％、Ni：0.64％、Mo：0.23％、V:0.005％、Al：0.019％、Cu：0.03％、As：0.004％、Sn：0.003％、Sb：0.002％,H：0.00015％、O：0.0043％、N：0.0069％,.
2. Chassis overall thickness h=400 mm, chassis diameter d1=2400 mm; bottom nozzle diameter d2=400 mm; the bottom pouring channel height b=220 mm (as cast blind hole design, post-processing); lug thickness = 200mm, lug width = 340mm, unilateral surplus control is at 20mm design blank diagram and pouring channel, and the lug top sets up outer chiller, prevents the lug defect, and the casting riser setting is in chassis bottom mouth of a river shape opposite, avoids influencing working face quality, sets up two ingates of a riser. The diameter of the casting riser is 800mm, and the height is 1000mm. Brushing high temperature resistant water-based paint on the surface of the molding cavity for 3 times, controlling the thickness to be 0.3-0.4mm, and drying. Nitrogen is filled into the chassis cavity more than or equal to 30min before pouring, the air filling time is more than or equal to 60min, and the ladle nozzle is fully drained before pouring, and the drainage times are more than or equal to 3 times. And (3) adding a proper amount of heating agent and rice husk to the riser after casting the workpiece, preserving heat, slowly cooling in a casting pit for 8 days, and pouring into a box and then charging into a furnace.
3. And (3) after the chassis blank is box-broken and shakeout, annealing at a low temperature, and starting performance heat treatment after cutting a riser and an ingate. During quenching treatment, firstly, the temperature is kept for 4 hours at 250 ℃, then the temperature is kept for 4 hours at the temperature rising speed of 50 ℃/h to 650 ℃, then the temperature is kept for 10 hours at the temperature rising speed of 50 ℃/h to 1000 ℃, the spray cooling is carried out for 30 minutes, the air cooling is started at the temperature of less than or equal to 450 ℃, the air cooling is started at the temperature of less than or equal to 250 ℃, and the temperature of less than or equal to 150 ℃ is fed into a furnace for tempering. During tempering, the temperature is firstly increased to 250 ℃, the heat preservation is carried out for 3 hours, then the temperature is controlled to be 40 ℃/h at the heating rate, the heat preservation time is firstly increased to 660 ℃ for 12 hours, then the temperature is reduced to 400 ℃ at the cooling rate of 40 ℃/h for 4 hours, and the furnace is cooled until the temperature of the workpiece is less than or equal to 230 ℃ and is discharged.
4. Machining and checking the flaw detection. After the machining is finished according to the drawing, carrying out UT flaw detection on the upper working surface and the lower working surface of the chassis according to JB/T5000.14 standard, and recording the flaw with the exceeding standard of phi 3 mm; MT examination shows no > 2mm linearity, and no defect elimination treatment is needed.
The bottom pouring chassis casting of the invention can be used for pouring steel ingots with the bottom pouring speed below 60t, and the performances, the tissues and the service life of the chassis are shown in tables 1-3 and figures 5-6. The production practice is applied in batches, the service life is up to more than 200 times, and compared with 20-40 times of cast iron chassis, the service life is prolonged. Particularly, after cracks appearing in the later period of use can be eliminated and welded, the upper end face and the lower end face are slightly deformed, and the steel can be continuously used after being processed smoothly (the single processing amount is less than or equal to 2 mm) in a mechanical processing mode, so that the consumption of ton steel of a chassis can be greatly reduced, and the smelting and manufacturing cost of bottom pouring steel ingots is further reduced.
Table 1 results of analysis of mechanical properties of examples
| Sequence number | Rp0.2(MPa) | Rm(MPa) | Z(％) | A(％) | HBW | KV2(J) |
| Example 1 | 305 | 524 | 48 | 29 | 154、153、156 | 26、40、31 |
| Example 2 | 310 | 527 | 45 | 25.5 | 156、152、156 | 24、26、25 |
| Example 3 | 315 | 503 | 47 | 22 | 157、155、155 | 25、27、25 |
| Example 4 | 334 | 550 | 66 | 27 | 161、161、161 | 21、24、23 |
| Example 5 | 365 | 556 | 61 | 27 | 169、167、164 | 27、30、25 |
| Example 6 | 372 | 572 | 41 | 26.5 | 167、167、174 | 28、20、22 |
| Cast iron 1 | 156 | 194 | 2 | 3 | 170、170、170 | 2、2、3 |
| Cast iron 2 | 156 | 186 | 1.5 | 2.5 | 164、161、161 | 3、3、3 |
Wherein rp0.2: represents the stress at which the specific plastic elongation is 0.2%;
Rm: tensile strength. Stress corresponding to the corresponding maximum force;
A%: elongation after break. The ratio of the residual elongation of the post-break gauge length to the original gauge length, expressed in%;
Z%: shrinkage of the area. The ratio of the maximum reduction in cross-sectional area of the specimen after fracture to the original cross-sectional area is expressed in%;
HBW: brinell hardness measured using a cemented carbide indenter;
KV 2: k is the impact absorption energy, V is the notch type, and subscript 2 is the pendulum blade radius.
Cast iron 1 and cast iron 2 are derived from the purchase of cast iron chassis by me company, and are attached cast test blocks provided by the suppliers. The cast iron 1 comprises the following components: 3.76%, si:1.14%, mn:0.82%, P:0.12%, S:0.073% and the balance of Fe and unavoidable impurities. The cast iron 2 comprises the following components: 3.69%, si:1.16%, mn:0.79%, P:0.13%, S:0.058% of Fe and the balance of unavoidable impurities.
TABLE 2 results of Chassis tissue analysis comparison
| Sequence number | Type(s) | Microstructure of microstructure | Ferrite grain size | Ferrite content |
| Example 1 | High power | Ferrite + pearlite + sorbite | 7.5 | 60％ |
| Example 2 | High power | Ferrite + pearlite + sorbite | 7.5 | 60％ |
| Example 3 | High power | Ferrite + pearlite + sorbite | 7.5 | 60％ |
| Example 4 | High power | Ferrite + pearlite + sorbite | 7.5 | 60％ |
| Example 5 | High power | Ferrite + pearlite + sorbite | 7.5 | 60％ |
| Example 6 | High power | Ferrite + pearlite + sorbite | 7.5 | 60％ |
| Cast iron 1 | High power | Flaky graphite + pearlite + ferrite | / | 2％ |
| Cast iron 2 | High power | Flaky graphite + pearlite + ferrite | / | 2％ |
TABLE 3 statistics of actual number of uses and status of chassis
The foregoing description of the preferred embodiments of the invention is not intended to be limiting, but rather is intended to cover all modifications, equivalents, and alternatives falling within the spirit and principles of the invention.
Claims (10)
1. A bottom pouring chassis casting is characterized in that the components of the bottom pouring chassis casting and the mass percentage of each component are ：C:0.23％-0.30％、Si:0.60％-0.80％、Mn:0.50％-0.75％、P≤0.020％、S≤0.015％、Cr:0.10％-0.25％、Ni:0.55％-0.75％、Mo:0.15％-0.35％、V≤0.05％、Al：0.01％-0.02％、Cu≤0.20％,As≤0.025％、Sn≤0.025％、Sb≤0.010％、H≤0.0002％、O≤0.0050％、N≤0.0100％,, and the rest content is Fe and unavoidable impurities.
2. A bottom-pouring chassis casting according to claim 1, characterized in that ,C:0.25％-0.28％、Si:0.65％-0.75％、Mn:0.50％-0.60％、P≤0.010％、S≤0.005％、Cr:0.15％-0.20％、Ni:0.55％-0.65％、Mo：0.15％-0.25％、V≤0.05％、Al:0.015％-0.020％、Cu≤0.10％、As≤0.020％、Sn≤0.020％、Sb≤0.005％、H≤0.0002％、O≤0.0050％、N≤0.0100％; is preferred ,C:0.25％-0.28％、Si:0.66％-0.75％、Mn:0.52％-0.58％、P:0.006％-0.008％、S:0.001％-0.003％、Cr:0.150％-0.200％、Ni:0.550％-0.640％、Mo:0.170％-0.230％、V:0.005％-0.006％、Al:0.015％-0.019％、Cu:0.020％-0.040％、As:0.003％-0.005％、Sn:0.002％-0.004％、Sb:0.002％、H:0.00015％、O:0.004％-0.005％、N:0.006％-0.008％.
3. A bottom pouring chassis casting according to claim 1, characterized in that the bottom pouring chassis casting comprises a chassis main body (1), a working surface of the chassis main body (1) is provided with a hemispherical bottom water gap (2), the bottom of the bottom water gap (2) is communicated with a bottom pouring channel (3), the bottom pouring channel (3) extends to the other working surface of the chassis main body (1), lifting lugs (4) are symmetrically arranged on the edge of the chassis main body (1), the lifting lugs (4) are flush with the working surface of the chassis main body (1) provided with the bottom water gap (2), and the thickness of the lifting lugs (4) is smaller than that of the chassis main body (1).
4. A bottom pouring tray casting according to claim 3, characterized in that the thickness H = 260-500 mm of the bottom pouring tray casting, the diameter of the outer circle of the bottom pouring tray casting is 4H-6H, the diameter of the bottom nozzle (2) is 1H-2H, the height of the bottom pouring channel (3) is 0.3H-0.6H, the thickness of the lifting lug is 0.5H-0.6H, and the width of the lifting lug is 0.8H-1H.
5. A process for preparing a bottom-pouring chassis casting as claimed in any one of claims 1 to 4, comprising the steps of:
(1) Smelting: smelting molten steel according to the components of the bottom pouring chassis casting and the mass percentages of the components for standby;
(2) Pouring: pouring the molten steel prepared in the step (1) into a casting mold, and demolding to obtain a chassis blank;
(3) And (3) heat treatment: sequentially carrying out quenching treatment and tempering treatment on the chassis blank prepared in the step (2), and discharging the chassis blank from a furnace to obtain the finished product;
The quenching treatment includes: firstly heating to 230-270 ℃ for heat preservation not less than 3 hours, then heating to 630-670 ℃ for heat preservation not less than 3 hours at the heating rate of 40-50 ℃/h, then heating to 990-1010 ℃ for heat preservation not less than 9 hours at the heating rate of 50-60 ℃/h, spray cooling for 20-40 minutes, starting air cooling at the temperature not more than 450 ℃, starting air cooling at the temperature not more than 250 ℃, and feeding into a furnace for tempering at the temperature not more than 150 ℃;
The tempering treatment includes: heating to 230-270 ℃ for heat preservation not less than 3h, heating to 650-670 ℃ for heat preservation not less than 11h at the heating rate of 40-50 ℃/h, cooling to 380-420 ℃ for heat preservation not less than 3h at the cooling rate of 30-40 ℃/h, cooling, and discharging the workpiece at the temperature not more than 230 ℃.
6. The process for preparing a bottom-pouring chassis casting according to claim 5, wherein said smelting of step (1) comprises:
(1) Smelting in an electric furnace: after the waste steel is melted by oxygen blowing and carbon spraying of an alkaline electric arc furnace, slag is exchanged and P is removed, and the tapping temperature of crude water is more than or equal to 1700 ℃ for tapping;
(2) Ladle refining: after refining the ladle bottom pad deoxidizing protective agent HSi, carrying out power transmission and heating on the crude water in the step (1) at a station, blowing argon in the whole ladle bottom, adding a slag forming material to control the slag basicity CaO/SiO 2 to be 2-3, then adding a powdery deoxidizer to carry out diffusion deoxidizing operation, adding alloy ferrosilicon, alloy ferromanganese, alloy ferrochromium, nickel plate or alloy ferronickel and alloy ferromolybdenum according to standard components after the slag color is adjusted to be white or gray, and then carrying out power transmission and heating on molten steel to be more than or equal to 1650 ℃ and entering a vacuum station;
(3) Vacuum treatment: starting timing at the vacuum degree of less than or equal to 1 Torr, keeping the vacuum time of more than or equal to 15min, fine adjusting the components and the temperature after the vacuum is finished, continuously performing diffusion deoxidation operation, feeding aluminum wires and/or aluminum iron for final deoxidation before tapping, and tapping at the tapping temperature of 1560-1600 ℃;
wherein, the impurity elements V of the crude water in the step (1) are controlled to be less than or equal to 0.05 percent, cu to be less than or equal to 0.20 percent, as to be less than or equal to 0.025 percent, sn to be less than or equal to 0.025 percent, sb to be less than or equal to 0.010 percent and P to be less than or equal to 0.020 percent.
7. The process for preparing the bottom pouring chassis casting according to claim 6, wherein the steel scraps are at least two of carbon steel scraps, briquettes and steel scraps ingot molds, and preferably the steel scraps are carbon steel scraps or a combination of briquettes and steel scraps ingot molds, wherein the mass ratio of the carbon steel scraps or briquettes to the steel scraps ingot molds is 10-15:1; preferably, the mass ratio of the carbon scrap steel or the briquetting to the scrap steel ingot mould is 12-15:1; the addition amount of the deoxidizing protective agent HSi is 3-4kg/t; the slag-forming material is lime and fluorite, and the mass ratio of the lime to the fluorite is 3-4:1; the powdery deoxidizer is C-P and CaSi-P; the total addition amount of the powdery deoxidizer is 10-30kg/t; the vacuum treatment time is 15-20min, the argon flow is 120-140L/min during the vacuum treatment, the soft argon blowing time from the end of vacuum to tapping is controlled to be 20-50 min, the soft argon blowing flow is 20-40L/min, and the addition amount of the final deoxidized aluminum wire and/or aluminum iron is calculated according to the Al content of 0.025-0.030%, and the residual is not considered.
8. The process for preparing a bottom pouring chassis casting according to claim 5, wherein the casting mold adopts a sand box molding, and the surface of a cavity of the sand box is brushed with a high-temperature-resistant water-based coating and dried; removing oxygen in the cavity before casting; a steel flow protection device is arranged under a ladle nozzle during pouring, so that secondary oxidation of molten steel is reduced; and adding a proper amount of heating agent and rice husk into the casting riser after casting, preserving heat, slowly cooling in a casting pit for 5-8 days, sequentially pouring into a box, shakeout, annealing at low temperature, and cutting to remove the casting riser and the inner runner to obtain the chassis blank.
9. A process for preparing a bottom-pouring chassis casting according to claim 5, wherein,
During quenching treatment, firstly heating to 240-260 ℃ for 3-4 h, then heating to 640-660 ℃ for 3-4 h at the heating rate of 50 ℃/h, then heating to 1000-1010 ℃ for 9-10 h at the heating rate of 50 ℃/h, spray cooling for 30-40 min, starting air cooling at the temperature of less than or equal to 450 ℃, starting air cooling at the temperature of less than or equal to 250 ℃, and entering a furnace for tempering at the temperature of less than or equal to 150 ℃;
During tempering, the temperature is raised to 240-260 ℃ for 3-4h, then the temperature is raised to 660-670 ℃ for 11-12 h at the heating rate of 40 ℃/h, then the temperature is cooled to 400-420 ℃ for 3-4h at the cooling rate of 40 ℃/h, then the furnace is cooled, and the temperature of the workpiece is less than or equal to 230 ℃ and is discharged from the furnace.
10. The process for preparing a bottom-pouring chassis casting according to claim 5, further comprising: and (4) flaw detection and treatment.
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CN118308653A true CN118308653A (en) | 2024-07-09 |
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