High-precision high-temperature-resistant automobile exhaust pipe manufacturing process

Abstract

The application relates to an exhaust pipe manufacturing technology, in particular to a high-precision high-temperature-resistant automobile exhaust pipe manufacturing process, which comprises the following steps: step one, raw material formula, by weight percentage, comprises 90.5% of 250-mesh fused quartz silicon powder, 0.1% of carbon fiber, 0.2% of organic monomer, 0.1% of crosslinking agent, 0.1% of initiator and 9% of deionized water, and the materials are heated to 40-60 DEG C and stirred for 1-2 hours; step two, the materials in the stirring tank are injected into a ceramic roller mold, and a method of pouring and vibrating simultaneously is adopted for pouring and forming; step three, the chemical components are as follows according to mass percentage: C: 0.6%-1.5%; Mn: 16%-25%; Al: 6%-12%; V: 0.01%-0.2%; Zr: 0.01%-0.2%; Si: 0.01%-0.5%; Cu: 0.01%-2%; Ni: 0.05%-2%; and the balance is Fe; step four, smelting; step five, thin strip continuous casting; step six, on-line hot rolling of the cast strip; step seven, the ceramic roller poured and formed in step two is placed into the exhaust pipe made of the coiled material; and step eight, cooling and coiling: the hot-rolled steel strip is air mist cooled to 600 DEG C-800 DEG C.

Description

TECHNICAL FIELD

[0001] The present application relates to the manufacturing technology of exhaust pipe, in particular to a high-precision high-temperature-resistant automobile exhaust pipe manufacturing process. BACKGROUND

[0002] The automobile exhaust pipe is located at the rear end of the automobile, and the working environment temperature is very high, so the heat resistance, impact resistance and corrosion resistance are very high. These components are manufactured by steel plate through pressure processing, so the base steel plate is required to have pressure forming property. On the other hand, the environmental temperature used is also increasing year by year, and it is necessary to increase the addition amount of alloy elements such as Cr, Mo, Nb to improve the high temperature strength, oxidation resistance and thermal fatigue properties. When the additive elements increase, the processability of the base steel plate will be reduced by using a simple manufacturing method, so pressure forming is often not performed.

[0003] In order to solve this problem, a lot of efforts have been made in composition and manufacturing method, but the precision and high-temperature resistance of the automobile exhaust pipe still need to be improved. SUMMARY

[0004] In view of the problems mentioned in the background art, the purpose of the present application is to provide a high-precision high-temperature-resistant automobile exhaust pipe manufacturing process to solve the problems mentioned in the background art.

[0005] The above technical purpose of the present application is realized by the following technical scheme: a high-precision high-temperature-resistant automobile exhaust pipe manufacturing process, comprising the following steps:

[0006] Step one, the raw material formula according to weight percentage includes 90.5% of 250 mesh fused quartz silicon powder, 0.1% of carbon fiber, 0.2% of organic monomer, 0.1% of crosslinking agent, 0.1% of initiator and 9% of deionized water; the formula amount of fused quartz silicon powder, carbon fiber, organic monomer, crosslinking agent, initiator and deionized water is added into the stirring tank, and heated to 40-60℃ and stirred for 1-2h;

[0007] Step two, the material in the stirring tank is injected into the ceramic roller mold, and the method of pouring and vibrating at the same time is used for casting forming;

[0008] Step three, the chemical composition is mixed according to mass percentage: C: 0.6%-1.5%; Mn: 16%-25%; Al: 6%-12%; V: 0.01%-0.2%; Zr: 0.01%-0.2%; Si: 0.01%-0.5%; Cu: 0.01%-2%; Ni: 0.05%-2%; the balance is Fe;

[0009] Step four, smelting: the raw materials of step three are heated and smelted into molten steel;

[0010] Step five, thin strip continuous casting:

[0011] The molten steel qualified by smelting is continuously cast into a cast strip through a pair of counter-rotating copper casting rollers;

[0012] Step six, cast strip on-line hot rolling:

[0013] The cast strip is rolled into a thin steel strip through one-pass hot rolling, and the strip temperature after rolling is 800-1050 DEG C and is coiled into an exhaust pipe shape;

[0014] Step seven, the ceramic roller poured and formed in step two is put into the exhaust pipe made of coiled material;

[0015] Step eight, cooling and coiling: the hot-rolled steel strip is cooled to 600-800 DEG C through air mist cooling.

[0016] As preferred, the cross-linking agent is one of diisopropyl phenyl peroxide, benzoyl peroxide, N,N'-methylene bisacrylamide.

[0017] As preferred, the organic monomer is one of acrylamide, methacrylamide, propyltrichlorosilane, gamma-chloropropyltrichlorosilane.

[0018] As preferred, the initiator is one of azobis diisopropyl cyanide, lauroyl peroxide, dicyclohexyl peroxide.

[0019] As preferred, the cast strip thickness is 1.4-2.5 mm.

[0020] As preferred, the cast strip has a yield strength of 1350 MPa or above, a tensile strength of 1600 MPa or above, an elongation of 20% or above, and a density of 6.2-7.2 g / cm 3 .

[0021] As preferred, the cast strip has a fine and uniform austenite and ferrite and precipitated particles and kappa' precipitated phase.

[0022] In summary, the high-precision high-temperature-resistant automobile exhaust pipe manufacturing process of the present application has the following advantages: by adding carbon nanofibers, adjusting the ratio of raw materials, and using isostatic pressing forming method, the density is large, the apparent porosity is low, the compressive strength and bending strength at room temperature are high, especially at a high temperature of 1300 DEG C, the performance is improved, the exhaust pipe structure made of new metal formula has superior performance: yield strength ≥1450 MPa, tensile strength ≥1600 MPa, elongation ≥20%; and in the thin strip continuous casting process, the added alloy elements mainly exist in the solid solution state, which can improve the alloy utilization rate, the performance of the exhaust pipe can be greatly improved through the manufacturing process of the present application, and high precision and high temperature resistance are realized. Attached Figure Description

[0023] Figure 1 This is a schematic diagram of the steps of the present invention. Detailed Implementation

[0024] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0025] refer to Figure 1 In specific implementation, the high-precision high-temperature resistant automotive exhaust pipe manufacturing process of the present invention includes the following steps:

[0026] Step 1: The raw material formula, calculated by weight percentage, includes 90.5% fused silica micropowder that can pass through 250 mesh, 0.1% carbon fiber, 0.2% organic monomer, 0.1% crosslinking agent, 0.1% initiator, and 9% deionized water. Add the formulated amounts of fused silica micropowder, carbon fiber, organic monomer, crosslinking agent, initiator, and deionized water to a mixing tank, heat to 40-60℃, and stir for 1-2 hours.

[0027] The crosslinking agent is one of dicumyl peroxide, benzoyl peroxide, and N,N′-methylenebisacrylamide.

[0028] The organic monomer is selected from one of acrylamide, methacrylamide, propyltrichlorosilane, and γ-chloropropyltrichlorosilane.

[0029] The initiator is one of azobisisoheptanenitrile, lauroyl peroxide, and dicyclohexyl peroxide.

[0030] Step 2: Pour the material from the mixing tank into the ceramic roller mold, and cast it using a method of simultaneous casting and vibration.

[0031] Step 3: Mix the chemical components according to the following mass percentages: C: 0.6%-1.5%; Mn: 16%-25%; Al: 6%-12%; V: 0.01%-0.2%; Zr: 0.01%-0.2%; Si: 0.01%-0.5%; Cu: 0.01%-2%; Ni: 0.05%-2%; with the balance being Fe.

[0032] Step 4, Smelting: The raw materials from Step 3 are heated and smelted into molten steel;

[0033] Step 5: Thin strip continuous casting:

[0034] The qualified molten steel is continuously cast into a cast strip by a pair of counter-rotating copper casting rollers;

[0035] Step six, hot rolling the cast strip on line:

[0036] The cast strip is hot rolled into a thin steel strip by one pass, and the strip temperature after rolling is 800-1050℃ and the strip is coiled into an exhaust pipe shape;

[0037] Step seven, placing the ceramic roller formed by pouring in step two into the exhaust pipe made of the coiled strip;

[0038] Step eight, cooling and coiling: the hot rolled strip is cooled by air mist to 600-800℃.

[0039] The thickness of the cast strip is 1.4-2.5mm.

[0040] The yield strength of the cast strip is above 1350MPa, the tensile strength is above 1600MPa, the elongation is above 20%, and the density is 6.2-7.2g / cm 3 .

[0041] The microstructure of the cast strip is fine and uniform austenite and ferrite, and precipitated particles and κ' precipitated phase.

[0042] The effects of the elements in the high-strength, high-plasticity and low-density steel are as follows:

[0043] C: The main effect of C element is to form κ'-carbide with Mn and Al elements, to form precipitate strengthening and dispersion strengthening, to improve the strength of the steel, and C is an austenite forming element that can promote the formation of austenite and also can reduce the density of the steel, but excessive C content will form excessive κ'-carbide, which will adversely affect the elongation of the alloy.

[0044] Mn: Mn element is an austenite forming element that can promote the formation of austenite, which is very beneficial to the strength and plasticity of the steel, and Mn element can form κ'-carbide with C and Al elements to further improve the strength and plasticity of the steel through precipitate strengthening and dispersion strengthening, and the density of Mn element is slightly lower than that of Fe element, which will not increase the density of the steel, and Mn element is also relatively cheap, but excessive addition of Mn element will cause a large amount of β-Mn phase to precipitate during the aging process, which is a hard phase and will greatly reduce the plasticity of the steel, therefore, the content of Mn is controlled within a range, and the content of the present application is 16%-25%.

[0045] Al: Al element can greatly reduce the density of the steel, and form κ'-carbide with C and Mn elements to further improve the strength and plasticity of the steel through precipitate strengthening and dispersion strengthening, but excessive Al content will increase the cost of the steel, therefore, the content of Al is controlled within a range, and the content of the present application is 6%-12%.

[0046] V:V element can effectively improve the strength and toughness of the steel by forming carbonitride in the steel grade, adding V will increase the cost on the one hand, on the other hand, V will precipitate on the grain boundary to produce cracks on the steel strip, therefore, the concentration of V is controlled in 0.01%-0.2%.

[0047] Zr:Zr element can remove the N element of the steel grade, inhibit the formation of AlN. Zr can also play a role in refining the grain. However, Zr element is relatively expensive, which will increase the cost of steel. Therefore, the content of Zr element is controlled in 0.01%-0.2%.

[0048] Si:Si element can deoxidize, Si element can also reduce the specific gravity of steel, improve the strength of steel, but too high silicon content will reduce the welding performance of steel, therefore, the highest content of Si is allowed to be 0.5%.

[0049] Cu:Cu element can stabilize austenite, and Cu element is cheaper than Ni element, but if Cu content is too high, Cu exists in the form of liquid at the grain boundary at high temperature will cause the interface brittleness, therefore, the concentration of Cu must be within 0.01%-2%.

[0050] Ni:Ni element can stabilize austenite and improve the stacking fault energy, Ni concentrated on the surface of the steel can also improve the corrosion resistance and oxidation resistance of the steel, can inhibit the absorption of H in the corrosion process, therefore, the adding content of Ni is within 0.5%-3%.

[0051] Although the embodiments of the present application have been shown and described, it can be understood by those skilled in the art that various changes, modifications, substitutions and variations can be made to the embodiments without departing from the principles and spirit of the present application, the scope of the present application is defined by the appended claims and their equivalents.

Claims

1. A high-precision high-temperature-resistant automobile exhaust pipe manufacturing process, characterized in that: It comprises the following steps: Step one, the raw material formula includes 90.5% of 250 mesh fused quartz silicon powder, 0.1% of carbon fiber, 0.2% of organic monomer, 0.1% of crosslinking agent, 0.1% of initiator and 9% of deionized water by weight percentage; the formula amount of fused quartz silicon powder, carbon fiber, organic monomer, crosslinking agent, initiator and deionized water is added into the stirring tank, heated to 40-60℃ and stirred for 1-2h; Step two, the material in the stirring tank is injected into the ceramic roller mold, and the method of pouring and vibrating is adopted to form the casting; Step three, the chemical composition is mixed according to the mass percentage of C: 0.6%-1.5%; Mn: 16%-25%; Al: 6%-12%; V: 0.01%-0.2%; Zr: 0.01%-0.2%; Si: 0.01%-0.5%; Cu: 0.01%-2%; Ni: 0.05%-2%; the balance is Fe; Step four, smelting: the raw materials of step three are heated and smelted into molten steel; Step five, thin strip continuous casting: The qualified molten steel is continuously cast into a cast strip through a pair of opposite rotating copper casting rolls; Step six, on-line hot rolling of cast strip: The cast strip is rolled into a thin steel strip through 1 pass hot rolling, and the hot rolled steel strip with a temperature of 800-1050℃ after strip rolling is cooled to 600-800℃ by air mist cooling and coiled into an exhaust pipe shape; Step seven, the ceramic roller formed by pouring in step two is put into the exhaust pipe made of coiled material; The thickness of the cast strip is 1.4-2.5mm; The microstructure of the cast strip is fine and uniform austenite and ferrite, precipitated particles and κ' precipitated phase. The cast strip has a yield strength of 1350 MPa or more, a tensile strength of 1600 MPa or more, an elongation of 20% or more, and a density of 6.2 to 7.2 g / cm 3 ; The crosslinking agent is one of dicumyl peroxide, benzoyl peroxide and N,N'-methylene bisacrylamide.

2. The high precision high temperature resistant automotive exhaust pipe manufacturing process as claimed in claim 1, wherein: The organic monomer is one of acrylamide, methacrylamide, propyltrichlorosilane and γ-chloropropyltrichlorosilane.

3. The high precision high temperature resistant automotive exhaust pipe manufacturing process as claimed in claim 1, wherein: The initiator is one of azobis diisopropyl cyanide, lauryl peroxide and dicyclohexyl peroxide di-carbonate.

4. The high precision high temperature resistant automotive exhaust pipe manufacturing process as claimed in claim 1, wherein: ​

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