A method for producing flat tube strip for high corrosion-resistant automobile radiators by continuous casting and rolling

Abstract

The application relates to the technical field of aluminum alloy production, and particularly discloses a method for producing flat tube strip for high-corrosion-resistance automobile radiators by a continuous casting and rolling method. After once annealing of a continuous casting and rolling blank, the blank is rolled to a thickness of 0.35-0.45 mm by a cold rolling mill, and after the rolling mill, the blank is subjected to secondary annealing in an annealing furnace, and the material is annealed to an O state. After the secondary annealing, the blank is rolled to a thickness of 0.25-0.35 mm of a finished product by one pass in the cold rolling mill. The finished product of the 3003 alloy flat tube strip for automobile radiators produced by the method has greatly improved corrosion resistance and tensile strength, the rolling pass of the produced strip is less, the production process is shorter, the production cost is reduced, and the production is more efficient.

Description

TECHNICAL FIELD

[0001] The application relates to the technical field of aluminum alloy production, and particularly discloses a method for producing flat tube strip for high-corrosion-resistance automobile radiator by using continuous casting and rolling. BACKGROUND

[0002] The heat dissipation pipe is a flow channel for the cooling liquid of the automobile radiator and is one of the three core components of the radiator, and needs to have heat conductivity, corrosion resistance, formability and mechanical strength. Currently, the 3003 aluminum alloy (Al-Mn system) is commonly used for production, and the alloy has good corrosion resistance and can resist corrosion of the cooling liquid. Previously, hot-rolled blank was used for producing the flat tube strip for the automobile radiator, and in recent years, some enterprises have begun to use cast-rolled blank for production. For example, the patent CN 104550306 B discloses a method for producing the 3003 alloy aluminum flat tube strip for the automobile radiator by using continuous casting and rolling. The production process flow is as follows: smelting, continuous casting and rolling, one-pass rolling, high-temperature homogenization heat treatment, cold rolling into finished products, straightening and cleaning, secondary heat treatment, inspection, slitting and packaging, and the finished product is in the H24 state, and the tensile strength of the product is between 140 and 160 Mpa. The production cost of the continuous casting method is lower than that of the hot rolling, but the H24 state strip has high work hardening degree and large grain internal energy, and after the finished product is annealed, part of the internal stress can be eliminated, but the dislocation in the organization is large, the lattice distortion is large, the material stability is poor, the strength fluctuation is prone to occur, the use effect is poor when the customer bends the pipe, and the production scheme needs to be subjected to high-temperature homogenization heat treatment, the heat treatment cost is high, and the cold rolling process has many rolling passes, so that the product has a long production time and still faces the problem of high comprehensive production cost. In addition, the product produced by the scheme has low yield strength and poor corrosion resistance, and the heat dissipation pipe is prone to corrosion penetration when the radiator is used, so that the radiator leaks and the service life is shortened. SUMMARY

[0003] In order to solve the problems in the background art, the application discloses a method for producing flat tube strip for high-corrosion-resistance automobile radiator by using continuous casting and rolling, and the 3003 alloy flat tube strip is produced by using continuous casting and rolling blank, the production process is short, the production cost is reduced, and the corrosion resistance and tensile strength of the finished product are greatly improved.

[0004] In order to achieve the above-mentioned application purposes, the application adopts the following technical scheme:

[0005] A method for producing flat tube strip for high-corrosion-resistance automobile radiator by using continuous casting and rolling, comprising the following steps:

[0006] S1, smelting: the electrolytic aluminum liquid with mass percentage of 45-55% and the recycled aluminum waste with mass percentage of 45-55% are put into a smelting furnace to prepare a melt, the iron agent, the quick-dissolved silicon, the manganese agent, the copper agent, and the titanium agent are sequentially added into the smelting furnace, the alloy components are adjusted to be qualified, after refining, slagging, and standing treatment, the melt is poured out, the melt is smoothly flowed into a flow guide chute, four groups of aluminum-titanium-boron wires are uniformly added into the melt, and the melt is sequentially flowed into a degassing box and a plate filter box for treatment.

[0007] S2, continuous casting and rolling: the treated melt is flowed into a forehearth through a vertical flow stabilizer, the temperature of the forehearth is kept at 685-695℃, the melt in the forehearth is flowed into a casting cavity of a casting machine through a nozzle, the casting speed is 7.2-8.0m / min, and the obtained casting blank is passed through a looper table and is rolled by a three-stand rolling mill.

[0008] S3, cold rolling production: the aluminum coil rolled by the three-stand rolling mill is wound, is directly transferred to an annealing furnace of a cold rolling workshop for primary annealing, is cooled to room temperature after the primary annealing, and is rolled to a thickness of 0.35-0.45mm by a cold rolling mill, is transferred to an annealing furnace for secondary annealing after being discharged from the rolling mill, is annealed to O state by low-temperature annealing, and is rolled to a thickness of 0.25-0.35mm by the cold rolling mill in one pass to form a finished product.

[0009] S4, straightening, cleaning, trimming, and reversing: the rolled finished product is transferred to straightening, cleaning, trimming, and reversing, and the edge of the strip after trimming is smooth without burrs.

[0010] S5, detection and packaging: the sample taken during trimming is subjected to mechanical property detection and bending detection, the longitudinal tensile strength of the aluminum strip finished product is 153Mpa-168Mpa, and the strip does not crack in 90-degree bending in the longitudinal and transverse directions, and the aluminum strip that passes the detection is packaged according to packaging requirements.

[0011] Further, in the method for producing the flat tube strip for high-corrosion-resistance automobile radiators by the continuous casting and rolling method, the mass percentages of the components in step S1 are as follows: Si: 0.1-0.3%, Fe: 0.3-0.6%, Mn: 1.0-1.3%, Cu: 0.06-0.12%, Ti: 0.025-0.045%, other single impurities ≤0.03%, total ≤0.15%, and the balance is Al.

[0012] Further, in the method for producing the flat tube strip for high-corrosion-resistance automobile radiators by the continuous casting and rolling method, in step S2, the thickness of the plate blank at the outlet of the first stand of the three-stand rolling mill is 8.0-9.0mm, the thickness of the plate blank at the outlet of the second stand of the three-stand rolling mill is 4.0-5.0mm, the thickness of the plate blank at the outlet of the third stand of the three-stand rolling mill is 2.5-3.0mm, and the material at the outlet of the third stand of the three-stand rolling mill is wound into a coil.

[0013] Further, in the method for producing the high-corrosion-resistance flat tube strip for automobile radiators by the continuous casting and rolling process, in the primary annealing in step S3, the annealing furnace temperature is 530-580 DEG C, the metal temperature is 420-480 DEG C, and the holding time is 4 hours.

[0014] Further, in the method for producing the high-corrosion-resistance flat tube strip for automobile radiators by the continuous casting and rolling process, in the secondary annealing in step S3, the temperature in the annealing furnace is not higher than 400 DEG C, and the metal temperature is not higher than 330 DEG C.

[0015] Further, in the method for producing the high-corrosion-resistance flat tube strip for automobile radiators by the continuous casting and rolling process, in step S1, after the melt is refined, slagged and rested, the composition of the sample taken from the left and right sides of the furnace door is detected, and the deviation of the content of each alloying element is less than 0.01%.

[0016] Further, in the method for producing the high-corrosion-resistance flat tube strip for automobile radiators by the continuous casting and rolling process, in step S2, the surface emulsion residue and the aluminum ash residue of the aluminum coil after the three-stand rolling are strictly controlled, and the emulsion spots with an area of more than 50 mm*50 mm and the aluminum ash marks visible to the naked eye are not allowed to exist.

[0017] Further, in the method for producing the high-corrosion-resistance flat tube strip for automobile radiators by the continuous casting and rolling process, in step S2, the material at the outlet of the three-stand is wound into a coil on the coiler, and the steel sleeve with an inner diameter of 605 mm and a length of 1600 mm is embedded in the material.

[0018] Further, in the method for producing the high-corrosion-resistance flat tube strip for automobile radiators by the continuous casting and rolling process, in step S4, when the tension leveling, cleaning, edge cutting and uncoiling are carried out, the tension leveling elongation needs to be ensured to be more than 0.35%, and the surface of the aluminum strip after the tension leveling is flat, which is convenient for the downstream customers to cut into narrow strips.

[0019] Compared with the prior art, the method has the following beneficial effects:

[0020] 1. The strip produced by the method has the following advantages: the dislocation in the continuous casting and rolling blank is less, the deformation tensile is small, the rolling processing rate is far greater than that of the cast-rolling blank, the processing rate is increased, the subsequent rolling passes can be reduced, the continuous casting and rolling blank is thinner than the cast-rolling blank, and the rolling passes can also be reduced, the rolling passes of the strip produced by the method are less, the production process is shorter, and the production is more efficient.

[0021] 2. The strip produced by the method has the following advantages: the primary annealing temperature is far lower than the homogenizing annealing temperature of the cast-rolling blank, a large amount of power consumption can be saved, the reduction of the rolling passes also means the reduction of the rolling power consumption, and the production cost is reduced.

[0022] 3. The strip produced by the scheme can be detected by salt spray test for more than 90 hours without perforation, while the strip produced by the background technology using cast rolling material can only be detected for about 48 hours without perforation. The salt spray test data can quantitatively show that the corrosion resistance of the flat tube strip for automobile radiators produced by the continuous casting and rolling process is more excellent, which can prolong the service life of the finished radiator;

[0023] 4. The scheme adopts a twice annealing method to produce H14 state strip. H14 has low work hardening degree, small internal residual stress, more stable microstructure, high yield strength of finished product, good support after making radiator, which can effectively prevent the phenomenon of reducing the flow passage cross-sectional area caused by deformation to affect the heat dissipation efficiency. The elongation of H14 state strip product is much lower than that of H24 state, which is more easily cut into narrow strips by the downstream customer, and the lotus leaf edge problem caused by tearing at the edge will not occur, which is convenient for the downstream customer to make pipe high frequency welding without welding problem. DETAILED DESCRIPTION

[0024] The application will be further explained and described below in conjunction with examples, which cannot limit the protection scope of the application. The purpose of disclosing the application is to protect all technical improvements within the scope of the application. Example 1

[0025] A method for producing flat tube strip for high corrosion resistant automobile radiators by continuous casting and rolling process, the specific steps are:

[0026] S1, smelting: put 45.8% of electrolytic aluminum liquid and 54.2% of recycled aluminum scrap into a smelting furnace to prepare an aluminum melt, and then add iron agent, fast-acting silicon, manganese agent, copper agent and titanium agent into the smelting furnace in sequence to adjust the alloy composition to be qualified, wherein the mass percentage of each component is: Si: 0.12%, Fe: 0.32%, Mn: 1.05%, Cu: 0.07%, Ti: 0.028%, other single impurities ≤0.03%, total ≤0.15%, and the balance is Al; After the melt is refined, skimming and standing, the composition of the sample taken from the left and right sides of the furnace door is detected, and the content deviation of each alloy component is less than 0.01%. After refining, skimming and standing, the furnace is started, and the melt flows smoothly into the flow guide chute. Four groups of aluminum titanium boron wires are uniformly added into the melt, and the melt flows into the degassing tank and the plate filter tank for treatment;

[0027] S2, continuous casting and rolling: the treated melt flows into the forehearth through the vertical flow stabilizer, the temperature of the forehearth is kept at 693℃, the nozzle is connected to the forehearth, the melt in the forehearth flows into the casting cavity of the caster through the nozzle, the inside of the steel strip circulates cooling water to cool the melt, the melt solidifies in the casting cavity to form a cast blank, the stable supply of the melt and the rotation of the upper and lower steel strips continuously cast the cast blank at a casting speed of 7.5 m / min, the cast blank passes through the looper table and is rolled by the three-stand tandem rolling mill, the thickness of the slab at the outlet of the first stand of the three-stand tandem rolling mill is 8.9 mm, the thickness of the slab at the outlet of the second stand of the three-stand tandem rolling mill is 4.8 mm, and the thickness of the slab at the outlet of the third stand of the three-stand tandem rolling mill is 2.9 mm; the aluminum coil after three-stand tandem rolling needs to strictly control the residual emulsion and aluminum ash on the surface, there should be no emulsion spots with an area exceeding 50 mm x 50 mm, and there should be no visible aluminum ash marks, the material at the outlet of the three-stand tandem rolling mill needs to be coiled into a coil, the coil material is provided with a steel sleeve with an inner diameter of 605 mm and a length of 1600 mm, and the steel sleeve facilitates subsequent direct furnace annealing;

[0028] S3, cold rolling production: the aluminum coil coiled after three-stand tandem rolling is directly fed into the annealing furnace in the cold rolling workshop for primary annealing, the annealing furnace temperature is 580℃, the metal temperature is 470℃, and the holding time is 4 hours, after primary annealing, the material is cooled to room temperature and then rolled to a thickness of 0.45 mm by the cold rolling mill, and after the rolling mill, the material is fed into the annealing furnace for secondary annealing, during secondary annealing, the annealing furnace gas temperature is 400℃, and the metal temperature does not exceed 330℃, to ensure that the material is annealed to O state, after annealing, the material is rolled to a thickness of 0.35 mm by one pass of the cold rolling mill to form a finished product;

[0029] S4, straightening, cleaning, trimming and uncoiling: after the finished product is rolled, it is transferred to the straightening, cleaning, trimming and uncoiling station, the straightening elongation needs to be ensured to be more than 0.35%, the aluminum strip surface is flat after straightening, which is convenient for the downstream customer to cut into narrow strips, the edge is smooth and free of burrs after trimming, and there should be no obvious aluminum powder on the surface of the aluminum strip after straightening, cleaning, trimming and uncoiling, and the face tissue should not be blackened when wiping with the face tissue;

[0030] S5, detection and packaging: the sample taken during trimming is subjected to mechanical property detection and bending detection, the thickness and width of the coil are checked to ensure that they are within the tolerance range, the end face should be free of burrs, flanging and impact damage, the longitudinal tensile strength of the aluminum strip finished product is detected to be 162 MPa, the 90-degree bending in the longitudinal and transverse directions is free of cracking, and the comprehensive judgment is qualified, and finally the aluminum strip is packaged according to the packaging requirements. Example 2

[0031] A method for producing flat tube strip material for high-corrosion-resistant automobile radiators by continuous casting and rolling, the specific steps are:

[0032] S1, smelting: the electrolytic aluminum liquid with a mass percentage of 53.5%, 46.5% of the recycled aluminum waste is put into the smelting furnace to prepare the aluminum melt, and the iron agent, fast-acting silicon, manganese agent, copper agent and titanium agent are sequentially added into the smelting furnace, and the alloy components are adjusted to be qualified, wherein the mass percentage of each component is: Si: 0.23%, Fe: 0.56%, Mn: 1.23%, Cu: 0.09%, Ti: 0.038%, other single impurities ≤0.03%, total ≤0.15%, and the balance is Al; after the melt is refined, skimming and standing, the samples are taken from the left and right sides of the furnace door for detection, and the content deviation of each alloy component is less than 0.01%, after refining, skimming and standing treatment, the melt is poured out, and the melt is smoothly poured into the flow guide chute, four groups of aluminum titanium boron wires are uniformly added into the melt, and the melt is poured into the degassing tank and the plate type filter tank for treatment, and then the treated melt is directly poured into the front tank;

[0033] S2, continuous casting and rolling: the melt flows into the front tank through the vertical flow stabilizer, the temperature of the front tank is kept at 686℃, the nozzle is connected with the front tank, the melt in the front tank flows into the casting cavity of the casting machine through the nozzle, the inside of the steel belt circulates cooling water to cool the melt through the cooling steel belt, the melt solidifies to form a casting blank in the casting cavity, and the casting blank is continuously cast out at a casting speed of 7.2m / min through the stable flow of the melt and the rotation of the upper and lower steel belts; the casting blank passes through the looper table and is rolled by the three-stand continuous casting and rolling mill, the thickness of the plate blank at the outlet of the first stand of the three-stand continuous casting and rolling mill is 8.1mm, the thickness of the plate blank at the outlet of the second stand of the three-stand continuous casting and rolling mill is 4.3mm, and the thickness of the plate blank at the outlet of the third stand of the three-stand continuous casting and rolling mill is 2.5mm; the aluminum coil after the three-stand continuous casting and rolling needs to be strictly controlled in terms of surface emulsion residue and aluminum ash residue, the emulsion spots with an area of more than 50mm*50mm cannot appear, and there cannot be visible aluminum ash marks, and the material at the outlet of the three-stand continuous casting and rolling mill needs to be coiled into a coil on the coiler, and the coiled material is provided with a steel sleeve with an inner diameter of 605mm and a length of 1600mm, so that the subsequent annealing can be directly carried out in the furnace;

[0034] S3, cold rolling production: the aluminum coil coiled after the three-stand continuous casting and rolling is directly put into the annealing furnace for primary annealing in the cold rolling workshop, the annealing furnace temperature is 570℃, the metal temperature is 460℃, and the annealing is kept for 4 hours, after the annealing, the material is cooled to room temperature and then rolled to a thickness of 0.35mm by the cold rolling mill, the material is then put into the annealing furnace for secondary annealing after coming out of the rolling mill, during the secondary annealing, the annealing furnace gas temperature is 400℃, and the metal temperature is not more than 330℃, so that the material is annealed to O state, and the material is rolled to a thickness of 0.25mm by one pass of the cold rolling mill after coming out of the annealing furnace;

[0035] S4, straightening, cleaning, trimming and uncoiling: after the rolling, the material is transferred to the straightening, cleaning, trimming and uncoiling, the straightening elongation needs to be more than 0.35%, the surface of the aluminum strip after the straightening is flat, which is convenient for the downstream customers to cut into narrow strips, the edge after the trimming is smooth without burrs, and after the straightening, cleaning, trimming and uncoiling, there cannot be obvious aluminum powder on the surface of the aluminum strip, and the surface of the aluminum strip cannot be blackened by wiping with a face tissue.

[0036] S5, detection and packaging: the sample taken during trimming is subjected to mechanical property detection and bending detection, the thickness and width of the roll are checked to be within the tolerance range, the end face should not have burrs, flanging, and impact injury defects, the longitudinal tensile strength of the aluminum strip product is detected to be 158Mpa, the 90-degree bending in the longitudinal and transverse directions has no cracking, and the comprehensive judgment is qualified, and finally the product is packaged according to the packaging requirements of the aluminum strip. Comparative Example

[0037] According to the method for producing the strip for the 3003 alloy aluminum flat tube for the automobile radiator according to the embodiment disclosed in Chinese patent CN 104550306 B, the strip for the 3003 alloy aluminum flat tube for the automobile radiator is produced, and the tensile strength of the product is 148Mpa.

[0038] Salt spray test

[0039] A sodium chloride solution with a concentration of 50±5g / L is prepared using sodium chloride and deionized water, the pH value of the sodium chloride solution is 6.5-7.2, the prepared sodium chloride solution is placed in a salt spray test chamber, and samples of the finished products of Example 1, Example 2 and the comparative example are cut to a certain size, the sample size is 150mmx150mm, different samples are placed in different salt spray test chambers, the salt spray test chamber is started, the temperature in the salt spray chamber is ensured to be 35±2℃, and at the end of the specified test period, the samples are taken out, the surface of the sample is washed with clean water, then dried with filter paper, and checked and judged.

[0040] Three sample pieces of Example 1, Example 2 and the comparative example are cut respectively, and salt spray tests are performed, and finally the average of the three sample pieces is taken as the experimental result of each sample. During the salt spray test, the experimental conditions of all sample pieces of Example 1, Example 2 and the comparative example are consistent. The salt spray test detection result is that the sample of Example 1 is not perforated for an average of 92 hours, the sample of Example 2 is not perforated for an average of 91 hours, and the sample of the comparative example is not perforated for about 48 hours. The salt spray test detection data can quantitatively show that the continuous casting and rolling production of the flat tube strip for the automobile radiator according to the present scheme has better corrosion resistance, and can prolong the service life of the finished radiator.

[0041] The part of the present application not described in detail is prior art.

[0042] The examples selected in the present text in order to disclose the inventive purpose of the present application are currently considered appropriate, but it should be understood that the present application is intended to include all variations and improvements of the examples that fall within the scope of the present concept and invention.

Claims

1. A method for producing high corrosion-resistant flat tube strips for automotive radiators using continuous casting and rolling, characterized in that, Includes the following steps: S1. Smelting: Electrolytic aluminum liquid with a mass percentage of 45-55% and recycled aluminum waste with a mass percentage of 45-55% are put into a smelting furnace to prepare a melt. Iron agent, quick-dissolving silicon, manganese agent, copper agent and titanium agent are added to the smelting furnace in sequence. The alloy composition is adjusted to meet the requirements. The mass percentage of each component is: Si: 0.1-0.3%, Fe: 0.3-0.6%, Mn: 1.0-1.3%, Cu: 0.06-0.12%, Ti: 0.025-0.045%, other single impurities ≤0.03%, total ≤0.15%, balance is Al. After refining, slag removal and settling treatment, the furnace is opened. The melt flows smoothly into the guide channel. Four sets of aluminum-titanium-boron wires are added to the melt at a uniform speed. The melt flows into the degassing box and plate filter box for treatment in sequence. S2. Continuous Casting and Rolling: After processing, the melt flows into the forebox through a vertical flow stabilizer. The temperature of the forebox is maintained at 685-695℃. The melt in the forebox flows into the casting cavity of the casting machine through the casting nozzle. The casting speed is 7.2-8.0 m / min. The resulting billet enters the three-stand continuous rolling mill for rolling through a looper table. The billet exit thickness of the first stand of the three-stand continuous rolling mill is 8.0-9.0 mm, the billet exit thickness of the second stand of the three-stand continuous rolling mill is 4.0-5.0 mm, and the billet exit thickness of the third stand of the three-stand continuous rolling mill is 2.5-3.0 mm. The material exiting the third stand of the three-stand continuous rolling mill is coiled. S3. Cold Rolling Production: Aluminum coils rolled into coils by three consecutive rolling mills are transferred to the cold rolling workshop and directly into the annealing furnace for primary annealing. During primary annealing, the furnace temperature is 530-580℃, ensuring the metal temperature is 420-480℃, and holding for 4 hours. After primary annealing, the material is cooled to room temperature and then transferred to the cold rolling mill to be rolled to a thickness of 0.35-0.45mm. After exiting the mill, the material is transferred to the annealing furnace for secondary annealing. The secondary annealing adopts low-temperature annealing. During secondary annealing, the temperature inside the annealing furnace does not exceed 400℃, and the metal temperature does not exceed 330℃, ensuring that the material is annealed to the O state. After exiting the furnace after secondary annealing, the material is rolled in the cold rolling mill in one pass to become a finished product with a thickness of 0.25-0.35mm. S4. Straightening, cleaning, trimming, and rewinding: The rolled product is straightened, cleaned, trimmed, and rewinded. After trimming, the strip edge is smooth and burr-free. S5. Inspection and Packaging: The samples taken during the cutting process are subjected to mechanical property testing and bending testing. The longitudinal tensile strength of the finished aluminum strip is 153Mpa~168Mpa, and there is no cracking when bending at 90 degrees in both the transverse and longitudinal directions. The qualified aluminum strips are packaged according to the packaging requirements.

2. The method for producing high corrosion-resistant flat tube strips for automotive radiators using continuous casting and rolling as described in claim 1, characterized in that, In step S1, after the melt is refined, slag removed and allowed to stand, samples are taken from both sides of the furnace door to test the composition, and the content deviation of each alloy component is less than 0.01%.

3. The method for producing high corrosion-resistant flat tube strips for automotive radiators using continuous casting and rolling as described in claim 1, characterized in that, In step S2, the aluminum coils after three consecutive rolling processes need to be strictly controlled for surface emulsion residue and aluminum ash residue. There must be no emulsion spots with an area exceeding 50mm×50mm, and no visible aluminum ash marks.

4. The method for producing high corrosion-resistant flat tube strips for automotive radiators using continuous casting and rolling as described in claim 1, characterized in that, In step S2, the material exiting the three frames needs to be wound into a roll, and the roll material is equipped with a sleeve.

5. The method for producing high corrosion-resistant flat tube strips for automotive radiators using continuous casting and rolling as described in claim 1, characterized in that, In step S4, during the straightening, cleaning, trimming, and rewinding process, the straightening elongation is above 0.35%, and the aluminum strip surface is smooth after straightening.