CN119194311A - A method for preparing a large-diameter thin-walled Al-Mg-Si aluminum alloy round tube - Google Patents
A method for preparing a large-diameter thin-walled Al-Mg-Si aluminum alloy round tube Download PDFInfo
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- 229910000838 Al alloy Inorganic materials 0.000 title claims abstract description 79
- 229910018464 Al—Mg—Si Inorganic materials 0.000 title claims abstract description 26
- 238000000034 method Methods 0.000 title claims abstract description 24
- 238000010438 heat treatment Methods 0.000 claims abstract description 59
- 238000005266 casting Methods 0.000 claims abstract description 56
- 238000000137 annealing Methods 0.000 claims abstract description 38
- 238000001125 extrusion Methods 0.000 claims abstract description 37
- 238000003723 Smelting Methods 0.000 claims abstract description 34
- 238000004321 preservation Methods 0.000 claims abstract description 30
- 238000001816 cooling Methods 0.000 claims abstract description 29
- 238000010791 quenching Methods 0.000 claims abstract description 20
- 230000000171 quenching effect Effects 0.000 claims abstract description 20
- 238000007670 refining Methods 0.000 claims abstract description 19
- 238000005498 polishing Methods 0.000 claims abstract description 16
- 239000000463 material Substances 0.000 claims abstract description 14
- 238000002360 preparation method Methods 0.000 claims abstract description 11
- 238000000265 homogenisation Methods 0.000 claims abstract description 4
- 229910052751 metal Inorganic materials 0.000 claims description 16
- 239000002184 metal Substances 0.000 claims description 16
- 239000000498 cooling water Substances 0.000 claims description 14
- 238000003756 stirring Methods 0.000 claims description 14
- 239000000956 alloy Substances 0.000 claims description 12
- 238000004519 manufacturing process Methods 0.000 claims description 7
- 238000009749 continuous casting Methods 0.000 claims description 6
- 229910052749 magnesium Inorganic materials 0.000 claims description 6
- ZAMOUSCENKQFHK-UHFFFAOYSA-N Chlorine atom Chemical compound [Cl] ZAMOUSCENKQFHK-UHFFFAOYSA-N 0.000 claims description 5
- 239000000460 chlorine Substances 0.000 claims description 5
- 229910052801 chlorine Inorganic materials 0.000 claims description 5
- 238000007872 degassing Methods 0.000 claims description 5
- 229910052804 chromium Inorganic materials 0.000 claims description 2
- 229910052802 copper Inorganic materials 0.000 claims description 2
- 230000005674 electromagnetic induction Effects 0.000 claims description 2
- 239000012535 impurity Substances 0.000 claims description 2
- 239000004615 ingredient Substances 0.000 claims description 2
- 229910052742 iron Inorganic materials 0.000 claims description 2
- 238000011068 loading method Methods 0.000 claims description 2
- 229910052748 manganese Inorganic materials 0.000 claims description 2
- 230000000087 stabilizing effect Effects 0.000 claims description 2
- 229910052725 zinc Inorganic materials 0.000 claims description 2
- 229910052726 zirconium Inorganic materials 0.000 claims description 2
- 238000003466 welding Methods 0.000 description 26
- 230000007547 defect Effects 0.000 description 16
- 229910045601 alloy Inorganic materials 0.000 description 10
- 229910052782 aluminium Inorganic materials 0.000 description 7
- 239000000047 product Substances 0.000 description 7
- 239000000126 substance Substances 0.000 description 7
- XAGFODPZIPBFFR-UHFFFAOYSA-N aluminium Chemical compound [Al] XAGFODPZIPBFFR-UHFFFAOYSA-N 0.000 description 6
- 230000000052 comparative effect Effects 0.000 description 6
- 239000007789 gas Substances 0.000 description 6
- 235000012438 extruded product Nutrition 0.000 description 5
- 239000011777 magnesium Substances 0.000 description 5
- 238000003825 pressing Methods 0.000 description 5
- FYYHWMGAXLPEAU-UHFFFAOYSA-N Magnesium Chemical compound [Mg] FYYHWMGAXLPEAU-UHFFFAOYSA-N 0.000 description 4
- HCHKCACWOHOZIP-UHFFFAOYSA-N Zinc Chemical compound [Zn] HCHKCACWOHOZIP-UHFFFAOYSA-N 0.000 description 4
- 239000013078 crystal Substances 0.000 description 4
- 230000006698 induction Effects 0.000 description 4
- 238000005096 rolling process Methods 0.000 description 3
- UFHFLCQGNIYNRP-UHFFFAOYSA-N Hydrogen Chemical compound [H][H] UFHFLCQGNIYNRP-UHFFFAOYSA-N 0.000 description 2
- 230000006378 damage Effects 0.000 description 2
- 238000000227 grinding Methods 0.000 description 2
- 239000001257 hydrogen Substances 0.000 description 2
- 229910052739 hydrogen Inorganic materials 0.000 description 2
- 238000007373 indentation Methods 0.000 description 2
- 239000000203 mixture Substances 0.000 description 2
- 238000007517 polishing process Methods 0.000 description 2
- 239000002699 waste material Substances 0.000 description 2
- 229910018503 SF6 Inorganic materials 0.000 description 1
- 241001062472 Stokellia anisodon Species 0.000 description 1
- 208000027418 Wounds and injury Diseases 0.000 description 1
- 230000009286 beneficial effect Effects 0.000 description 1
- 238000004891 communication Methods 0.000 description 1
- 238000005336 cracking Methods 0.000 description 1
- 238000009826 distribution Methods 0.000 description 1
- 230000000694 effects Effects 0.000 description 1
- 238000005530 etching Methods 0.000 description 1
- 208000014674 injury Diseases 0.000 description 1
- 239000000155 melt Substances 0.000 description 1
- 239000002245 particle Substances 0.000 description 1
- 239000002994 raw material Substances 0.000 description 1
- 238000010079 rubber tapping Methods 0.000 description 1
- 238000005070 sampling Methods 0.000 description 1
- 239000011265 semifinished product Substances 0.000 description 1
- 238000001179 sorption measurement Methods 0.000 description 1
- 238000005482 strain hardening Methods 0.000 description 1
- 238000006467 substitution reaction Methods 0.000 description 1
- SFZCNBIFKDRMGX-UHFFFAOYSA-N sulfur hexafluoride Chemical compound FS(F)(F)(F)(F)F SFZCNBIFKDRMGX-UHFFFAOYSA-N 0.000 description 1
- 229960000909 sulfur hexafluoride Drugs 0.000 description 1
- 239000011701 zinc Substances 0.000 description 1
Classifications
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- C—CHEMISTRY; METALLURGY
- C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
- C22F—CHANGING THE PHYSICAL STRUCTURE OF NON-FERROUS METALS AND NON-FERROUS ALLOYS
- C22F1/00—Changing the physical structure of non-ferrous metals or alloys by heat treatment or by hot or cold working
- C22F1/04—Changing the physical structure of non-ferrous metals or alloys by heat treatment or by hot or cold working of aluminium or alloys based thereon
- C22F1/043—Changing the physical structure of non-ferrous metals or alloys by heat treatment or by hot or cold working of aluminium or alloys based thereon of alloys with silicon as the next major constituent
-
- C—CHEMISTRY; METALLURGY
- C21—METALLURGY OF IRON
- C21D—MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUS METALS OR ALLOYS; MAKING METAL MALLEABLE, e.g. BY DECARBURISATION OR TEMPERING
- C21D9/00—Heat treatment, e.g. annealing, hardening, quenching or tempering, adapted for particular articles; Furnaces therefor
- C21D9/0006—Details, accessories not peculiar to any of the following furnaces
- C21D9/0018—Details, accessories not peculiar to any of the following furnaces for charging, discharging or manipulation of charge
-
- C—CHEMISTRY; METALLURGY
- C21—METALLURGY OF IRON
- C21D—MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUS METALS OR ALLOYS; MAKING METAL MALLEABLE, e.g. BY DECARBURISATION OR TEMPERING
- C21D9/00—Heat treatment, e.g. annealing, hardening, quenching or tempering, adapted for particular articles; Furnaces therefor
- C21D9/08—Heat treatment, e.g. annealing, hardening, quenching or tempering, adapted for particular articles; Furnaces therefor for tubular bodies or pipes
-
- C—CHEMISTRY; METALLURGY
- C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
- C22C—ALLOYS
- C22C1/00—Making non-ferrous alloys
- C22C1/02—Making non-ferrous alloys by melting
- C22C1/026—Alloys based on aluminium
-
- C—CHEMISTRY; METALLURGY
- C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
- C22C—ALLOYS
- C22C21/00—Alloys based on aluminium
- C22C21/02—Alloys based on aluminium with silicon as the next major constituent
-
- C—CHEMISTRY; METALLURGY
- C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
- C22F—CHANGING THE PHYSICAL STRUCTURE OF NON-FERROUS METALS AND NON-FERROUS ALLOYS
- C22F1/00—Changing the physical structure of non-ferrous metals or alloys by heat treatment or by hot or cold working
- C22F1/04—Changing the physical structure of non-ferrous metals or alloys by heat treatment or by hot or cold working of aluminium or alloys based thereon
- C22F1/05—Changing the physical structure of non-ferrous metals or alloys by heat treatment or by hot or cold working of aluminium or alloys based thereon of alloys of the Al-Si-Mg type, i.e. containing silicon and magnesium in approximately equal proportions
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- Chemical & Material Sciences (AREA)
- Engineering & Computer Science (AREA)
- Mechanical Engineering (AREA)
- Materials Engineering (AREA)
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- Extrusion Of Metal (AREA)
Abstract
The invention discloses a preparation method of a large-diameter thin-wall Al-Mg-Si aluminum alloy round tube, which comprises the following steps of material proportioning, smelting, refining, casting, ingot homogenization heat treatment, preheating, extrusion, on-line quenching, stretching straightening, sawing, polishing the inner wall and annealing, and is characterized in that the heat treatment heat preservation temperature in the annealing process is 390+/-5 ℃, the heat preservation time is 3-6h, the heat preservation is finished and air cooling is carried out along with a furnace, a row of bottom-paved round tubes with the outer diameter of 100-200mm and the wall thickness of 10-40mm are placed on an underframe of an annealing furnace, and the large-diameter thin-wall round tubes are uniformly distributed and placed on the bottom-paved round tubes when the annealing furnace is filled. According to the invention, the bottom laying circular tube is added on the bottom layer of the material frame of the annealing furnace, and the large-diameter thin-wall aluminum alloy circular tube and the bottom laying circular tube are uniformly arranged in a unified orientation mode when the furnace is filled, the length of the bottom laying circular tube is greater than or equal to that of the large-diameter thin-wall aluminum alloy circular tube, and the contact mode of the bottom laying circular tube and the large-diameter thin-wall aluminum alloy circular tube is changed from 'point contact' to 'surface contact', so that the stress area of the bottom of the aluminum alloy circular tube is greatly increased, and the aluminum alloy circular tube is prevented from being concave.
Description
Technical Field
The invention relates to the technical field of aluminum alloy processing, in particular to a preparation method of a large-diameter thin-wall Al-Mg-Si aluminum alloy round tube.
Background
The large-size thin-wall aluminum alloy round tube is commonly used for gas-insulated metal-enclosed switchgear, and is a high-voltage distribution device which adopts sulfur hexafluoride (SF 6) gas with excellent insulating property and arc extinguishing property as insulating and arc extinguishing medium and seals all high-voltage electrical appliance elements in a grounded metal tube. Because the use environment is special and severe, the welding quality has higher requirements on the inner and outer surface quality of the circular tube material, the inner wall of the circular tube must be smooth, and the defects of indentation, concave-convex line injury, die mark and the like are not allowed to exist. The surface of the section bar produced by the Al-Mg-Si aluminum alloy in an extrusion mode is inevitably provided with a plurality of adsorption particles and die marks, and the contact area between the bottom and the load is small due to the round shape of the round tube, so that the contact position is extremely easy to be pressed concave, and the product defect is formed.
And the welding process can occur when the circular tube is produced by adopting a forward extrusion mode, metal is divided into a plurality of strands before entering the die hole of the die and then is converged in the welding chamber entering the die hole, and the metal is welded while being converged under the action of high temperature, high pressure and high vacuum and flows out of the die hole to form the circular tube. How to ensure the quality of welding seams is a main technical problem of extrusion of a combined die, and if welding defects occur at the welding seam position of a circular tube, the welding seam is easy to crack and discard in the service process of the product.
Disclosure of Invention
Aiming at the defects, the invention provides a preparation method of a large-diameter thin-wall Al-Mg-Si aluminum alloy round tube, which aims to solve the problem of concave pressing of an inner cavity of an extruded large-diameter round tube.
In order to achieve the above purpose, the invention adopts the following technical scheme:
a preparation method of a large-diameter thin-wall Al-Mg-Si aluminum alloy round tube comprises the following steps:
(1) Preparing raw and auxiliary materials such as aluminum ingots, intermediate alloys and the like according to alloy components and mass percentages;
(2) Smelting and refining, namely putting raw and auxiliary materials into a smelting furnace to smelt and refine to obtain a melt of the required ingot chemical components;
(3) Casting, namely casting and forming the refined melt to obtain a round ingot required by extrusion production;
(4) Homogenizing heat treatment, namely homogenizing heat treatment is carried out on the cast ingot;
(5) Preheating a die, an ingot and an extrusion cylinder, extruding the preheated ingot on an extruder to obtain a circular tube section bar, carrying out online quenching and stretching straightening on the extruded section bar, and then carrying out sawing interruption to obtain a semi-finished product;
(6) And polishing the inner wall, namely polishing the inner wall of the circular tube by adopting a polishing machine, and eliminating various surface quality defects of the inner wall.
(7) Annealing, namely carrying out annealing heat treatment on the round tube to obtain a large-diameter thin-wall Al-Mg-Si aluminum alloy round tube, wherein the heat preservation temperature of the annealing heat treatment is 390+/-5 ℃, the heat preservation time is 3-6h, the heat preservation is finished along with furnace air cooling, a row of bottom-paved round tubes with the outer diameter of 100-200mm and the wall thickness of 10-40mm are placed on an underframe of an annealing furnace, and the large-diameter thin-wall round tubes are uniformly distributed on the bottom-paved round tubes when the annealing furnace is filled.
Preferably, a certain gap is arranged between every two adjacent bottoming round pipes, and the gap between every two adjacent bottoming round pipes is 50-200mm.
Preferably, the aluminum alloy material comprises the following components in percentage by mass ：Si：0.65％-0.75％,Fe：0.15-0.25％,Cu：≤0.12％,Mn：0.20％-0.35％,Mg：0.50-0.65％,Cr：0.12％-0.20％,Zn：≤0.20％,Ti：≤0.05％,Zr：≤0.05％, percent of Al and unavoidable impurities, wherein each unavoidable element is less than 0.05 percent, and the total amount of the unavoidable elements is less than 0.10 percent.
Preferably, during stretching, stretching cushion blocks are respectively placed in the inner cavities of the head end and the tail end of the aluminum alloy round tube, and the stretching rate is 0.5-2.5%.
Preferably, the metal heat preservation temperature in the ingot homogenization heat treatment is 570+/-10 ℃ and the metal heat preservation time is 7-14h.
Preferably, the ingot is heated by adopting electromagnetic induction gradient, the heating temperature of the head of the ingot is 500-520 ℃ and the temperature gradient of the interval 300mm is reduced by 10 ℃, the heating temperature of the die is 500+/-10 ℃, the heating temperature of the extrusion cylinder is 430+/-10 ℃, the speed of the extruded product is 2.5-6.0m/min, the temperature of the online quenching cooling inlet of the profile is more than or equal to 500 ℃, and the temperature of the online quenching cooling outlet of the profile is less than or equal to 50 ℃.
Preferably, the outer diameter of the aluminum alloy round tube is phi 300-600mm, the wall thickness of the round tube is 5-10mm, and the length of the finished product is 6-12m.
Preferably, the ingredients are put into a smelting furnace for smelting at 720-760 ℃, the smelting temperature is 710-730 ℃ after the smelting is finished, the flow rate of refined chlorine is 0.1-0.3Nm 3/h, an electromagnetic stirring device is adopted for stirring and degassing, deslagging, and standing for 30-45min after the refining is finished for starting casting.
Preferably, the casting speed is 25-40mm/min, the casting temperature is 690-710 ℃, and the casting cooling water temperature is 28-35 ℃.
Preferably, the casting is carried out in a water-cooling semi-continuous casting mode, the casting temperature is 700-730 ℃, the casting cooling water temperature is 28-35 ℃, the casting stabilizing material temperature is 690-710 ℃, the casting speed is 25-40mm/min, the casting cooling water flow is 380-420m 3/h, the diameter of the obtained round ingot is 580mm, the shell layer of the outer ring of the ingot is removed by a wagon machine, the round ingot with the diameter of 566mm is obtained, the length of a single round ingot is 7000-8000mm, and ingot blanks with the length of 1500-1800mm are cut in sections after head and tail waste materials of the ingot are cut off.
Preferably, an automatic grinding machine is adopted to finely grind the inner cavity of the large-diameter thin-wall round pipe, and the roughness of the inner wall surface of the round pipe after grinding is less than or equal to Ra0.5mu m.
Preferably, after the head and tail waste materials are cut off, sampling and detecting the quality of the welding line at the head end of the circular tube, and judging the position of the welding line after alkaline etching of the sample, and detecting the welding condition of the position of the welding line.
Compared with the prior art, the invention has the beneficial effects that:
The large-diameter thin-wall Al-Mg-Si aluminum alloy round tube prepared by the invention has the advantages of thinner wall thickness, low hardness, small bottom contact area and poor bearing capacity, and particularly the surface hardness is reduced from 6HW to below 3HW after annealing treatment, so that the round tube becomes soft. Because the hardness of the aluminum alloy round tube is reduced after heating in the annealing process, the aluminum alloy round tube is influenced by the dead weight of the aluminum alloy round tube, when the bottom of the aluminum alloy round tube is contacted with a work rest of an annealing furnace, the outer surface is extremely easy to generate plastic dent, and a convex bulge is formed in the inner cavity of the aluminum alloy round tube. According to the invention, the bottom laying circular tube is added on the bottom layer of the material frame of the annealing furnace, and the large-diameter thin-wall aluminum alloy circular tube and the bottom laying circular tube are uniformly arranged in a unified orientation mode when the furnace is filled, the length of the bottom laying circular tube is greater than or equal to that of the large-diameter thin-wall aluminum alloy circular tube, and the contact mode of the bottom laying circular tube and the large-diameter thin-wall aluminum alloy circular tube is changed from 'point contact' to 'surface contact', so that the stress area of the bottom of the aluminum alloy circular tube is greatly increased, and the aluminum alloy circular tube is prevented from being concave.
The invention controls the heating temperature of the cast ingot, the temperature of the mould, the temperature of the extrusion cylinder and the extrusion speed, selects proper technological parameters on the premise of ensuring the welding quality and the surface quality of the aluminum alloy round tube, and ensures the product quality and the production efficiency. The welding quality is determined by pressure, time, flow rate and other factors, and theoretically, the higher the temperature is, the better the welding is, but the welding is affected by the speed, meanwhile, the temperature drop requirements of the product section and on-line quenching are required to be considered, and the proper speed is selected on the premise of ensuring the mechanical property. According to the invention, by adopting reasonable parameter control of the ingot heating temperature, the die temperature, the extrusion cylinder temperature and the extrusion speed, poor welding is avoided, so that excellent welding quality and surface quality of the aluminum alloy round tube are obtained, and easy cracking and scrapping in the service process are avoided.
The bottom-laying round pipes are provided with a certain gap, so that furnace gas freely circulates during heating, heating temperature is more uniform, and the phenomenon that soft belts are unqualified in performance and coarse crystals are generated locally is avoided.
According to the invention, when the round tube is stretched and straightened, the stretching cushion blocks are respectively arranged in the inner cavities of the head end and the tail end of the round tube, so that the deformation of the two ends is reduced, the dimensional accuracy is improved, and the yield of the round tube is effectively improved.
The invention adopts specific casting temperature, has higher casting temperature, can effectively reduce the deformation resistance of metal and is easy to extrude and form, so that when a longer casting ingot and a larger extrusion coefficient are used, no blank car or extrusion tool is damaged, meanwhile, the extrusion processing is adopted to generate a work hardening effect, so that a round pipe obtains a certain strength, the concave pressing of a cooling bed belt parting strip in the production process is avoided, and the extrusion is facilitated by adopting high-temperature extrusion in the extrusion, thereby ensuring the diameter and wall thickness dimensional accuracy of the round pipe.
According to the invention, the process parameters of smelting, refining and casting processes are optimized, the obtained aluminum alloy melt is clean, the components are uniform, the hydrogen content is less than or equal to 0.12ml/100Al, the existence of hydrogen embrittlement and various casting structure defects is effectively reduced, and an excellent cast ingot is obtained for extrusion processing.
According to the invention, the inner wall of the whole circular tube is polished by adopting an automatic polisher, so that surface quality defects such as pits, die marks, broken lines and the like possibly occurring on the inner wall of the circular tube are eliminated, point discharge of the circular tube in the service process is avoided, and the safety of products is improved.
The invention provides a preparation method of a large-diameter thin-wall Al-Mg-Si aluminum alloy round pipe, which effectively solves the problems of concave pressing, poor welding and the like of the inner cavity of the extrusion round pipe for extruding the large-diameter thin-wall aluminum alloy by selecting proper ingot casting process, extrusion process, heat treatment process and inner cavity polishing process and adopting reasonable auxiliary tools under the combination of multiple improvements.
Drawings
In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings that are required to be used in the description of the embodiments will be briefly described below.
FIG. 1 is a schematic view of a large diameter thin wall Al-Mg-Si aluminum alloy round tube prepared in examples and comparative examples of the present invention;
FIG. 2 is a schematic view showing the placement of large diameter thin wall aluminum alloy round tubes and bottoming round tubes during annealing according to examples 1 to 3 of the present invention;
FIG. 3 is a schematic view showing the placement of a large diameter thin wall aluminum alloy round tube and a bottoming round tube at the time of annealing in example 4 of the present invention.
Detailed Description
The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present invention. It will be apparent that the described embodiments are only some, but not all, embodiments of the invention. All other embodiments, which can be made by those skilled in the art based on the embodiments of the invention without making any inventive effort, are intended to be within the scope of the invention.
In the description of the present invention, it should be noted that the directions or positional relationships indicated by the terms "center", "upper", "lower", "left", "right", "vertical", "horizontal", "inner", "outer", etc. are based on the directions or positional relationships shown in the drawings, are merely for convenience of describing the present invention and simplifying the description, and do not indicate or imply that the devices or elements referred to must have a specific orientation, be configured and operated in a specific orientation, and thus should not be construed as limiting the present invention.
In the description of the present invention, unless explicitly stated or limited otherwise, the terms "mounted," "connected," and "connected" are to be construed broadly, and may be, for example, fixedly connected, detachably connected, or integrally connected, mechanically connected, electrically connected, directly connected, indirectly connected via an intervening medium, or in communication between two elements. The specific meaning of the above terms in the present invention will be understood in specific cases by those of ordinary skill in the art. In addition, the technical features of the different embodiments of the present invention described below may be combined with each other as long as they do not collide with each other.
Referring to FIG. 1, the outer diameter of the target aluminum alloy round tube is 508mm, the wall thickness is 8mm, and the alloy state is 6005A-H112. Aluminum ingots with the purity of more than 99.70% in industrial grade are adopted as raw materials, and related raw and auxiliary material intermediate alloys are smelted and cast, and the chemical compositions and mass percentages of the alloys in each example and comparative example are shown in the following table:
TABLE 1 chemical compositions and mass percentages (wt%) of alloys of examples and comparative examples
Example 1
The preferred embodiment provides a preparation method of a large-diameter thin-wall Al-Mg-Si aluminum alloy round tube, which comprises the following specific steps:
(1) Batching according to the chemical components and mass percentages corresponding to the table 1.
(2) Smelting and refining, namely putting raw and auxiliary materials such as an aluminum ingot, a magnesium ingot, a zinc ingot, an intermediate alloy and the like into a dome hydraulic inclined smelting furnace together for smelting, fully stirring and skimming, wherein the heat preservation temperature of the smelting furnace is 720-740 ℃, the smelting time is 6 hours, the refining temperature is 710-730 ℃, the refining chlorine flow is 0.1-0.3Nm 3/h, stirring and degassing are carried out by adopting an electromagnetic stirring device, deslagging are carried out, and standing is carried out for 30-45min after refining is finished, and casting is started.
(3) Casting by adopting a water-cooling semi-continuous casting mode, wherein the casting temperature is 690-700 ℃, the casting speed is 27mm/min, the casting cooling water temperature is 28-34 ℃, the casting cooling water flow is 390m 3/h, the diameter of the obtained round ingot is 580mm, and finally the wagon is a round ingot with the diameter of 566 mm. The length of the round ingot is 7000mm, and the ingot is cut into ingot blanks with the length of 1800mm in sections after head and tail scraps are cut off.
(4) Homogenizing heat treatment of the cast ingot, namely, homogenizing heat treatment of the cast ingot, wherein the metal heat preservation temperature is 570+/-10 ℃ and the metal heat preservation time is 14h.
(5) Preheating, namely placing the ingot blank into an induction furnace for heating and preserving heat, wherein the heating temperature is 510 ℃, the temperature at the front end of the ingot is gradually reduced every 300mm by adopting a gradient heating mode, the temperature gradient is 10 ℃ in total, namely 510-500-490-480-470 ℃, the preserving heat time is 15-20min, the heating temperature of the die is 500 ℃ plus or minus 10 ℃, and the heating temperature of the extrusion cylinder is 430 ℃ plus or minus 10 ℃.
(6) And extruding, namely extruding the preheated ingot blank in an extrusion cylinder in an extruder to obtain a circular tube profile, wherein the speed of the extruded product is 5.0m/min, and the online quenching cooling inlet temperature of the profile is 525 ℃.
(7) And (3) carrying out online quenching after extrusion molding, cooling by strong wind, wherein the total capacity of the matched motor is 5.5KW, the quenching air quantity is 70%, and rapidly cooling the profile to below 50 ℃.
(8) Stretching, namely stretching and straightening the quenched circular tube section with the stretching rate of 1.6%, and respectively placing stretching cushion blocks in the inner cavities of the head end and the tail end of the circular tube during stretching.
(9) And (3) polishing the inner wall of the whole round pipe by adopting an automatic polishing machine.
(10) Annealing, namely annealing and preserving the heat at 390+/-5 ℃ for 4 hours, and air cooling along with the furnace after the heat preservation is finished, wherein a row of bottom-paved round tubes with the outer diameter of 150mm and the wall thickness of 20mm are arranged on the underframe of the annealing furnace, and the large-diameter thin-wall aluminum alloy round tubes are uniformly distributed on the bottom-paved round tubes when the annealing furnace is charged. The laying round pipes are directly provided with a certain gap, and the gap between the adjacent laying round pipes is 60mm. The laying round pipe is fixed, such as by a wedge block, so as to avoid rolling of the laying round pipe. Referring to fig. 2, in implementation, a row of bottom-laying round tubes 30 are placed on the annealing furnace underframe 20, the large-diameter thin-wall aluminum alloy round tubes 10 are uniformly distributed on the bottom-laying round tubes, the large-diameter thin-wall aluminum alloy round tubes 10 and the bottom-laying round tubes 30 are uniformly distributed towards each other, the length of the bottom-laying round tubes 30 is greater than or equal to that of the large-diameter thin-wall aluminum alloy round tubes 10, and the contact mode of the two is changed from 'point contact' to 'surface contact', so that the stress area of the bottom of the aluminum alloy round tubes is greatly increased, and the aluminum alloy round tubes are prevented from being concave. The bottom-laying round pipes are provided with a certain gap, so that furnace gas freely circulates during heating, heating temperature is more uniform, and the phenomenon that soft belts are unqualified in performance and coarse crystals are generated locally is avoided.
The surface of the large-diameter thin-wall round tube prepared by the embodiment has no concave-pressing defect after being annealed out of the furnace, the roughness of the inner wall surface is Ra0.4mu m, and the welding is good.
Example 2
The preferred embodiment provides a preparation method of a large-diameter thin-wall Al-Mg-Si aluminum alloy round tube, which comprises the following specific steps:
(1) Batching according to the chemical components and mass percentages corresponding to the table 1.
(2) Smelting and refining, namely putting raw and auxiliary materials such as an aluminum ingot, a magnesium ingot, a zinc ingot, an intermediate alloy and the like into a dome hydraulic inclined smelting furnace together for smelting, fully stirring and skimming, wherein the heat preservation temperature of the smelting furnace is 720-740 ℃, the smelting time is 7 hours, the refining temperature is 710-730 ℃, the refining chlorine flow is 0.1-0.3Nm 3/h, stirring and degassing are carried out by adopting an electromagnetic stirring device, deslagging are carried out, and standing is carried out for 30-45min after refining is finished, and casting is started.
(3) Casting by adopting a water-cooling semi-continuous casting mode, wherein the casting temperature is 690-700 ℃, the casting speed is 30mm/min, the casting cooling water temperature is 29-35 ℃, the casting cooling water flow is 410m 3/h, the diameter of the obtained round ingot is 580mm, and finally the wagon is a round ingot with the diameter of 566 mm. The length of the round ingot is 7000mm, and the ingot is cut into ingot blanks with the length of 1800mm in sections after head and tail scraps are cut off.
(4) Homogenizing heat treatment of the cast ingot, namely, homogenizing heat treatment of the cast ingot, wherein the metal heat preservation temperature is 570+/-10 ℃ and the metal heat preservation time is 14h.
(5) Preheating, namely placing the ingot blank into an induction furnace for heating and preserving heat, wherein the heating temperature is 500 ℃, the temperature at the front end of the ingot is gradually reduced every 300mm by adopting a gradient heating mode, the temperature gradient is 10 ℃ in total, namely 500-490-480-470-460 ℃, the preserving heat time is 15-20min, the heating temperature of the die is 500 ℃ plus or minus 10 ℃, and the heating temperature of the extrusion cylinder is 430 ℃ plus or minus 10 ℃.
(6) And extruding, namely extruding the preheated ingot blank in an extrusion cylinder in an extruder to obtain a circular tube profile, wherein the speed of an extruded product is 6.0m/min, and the online quenching cooling inlet temperature of the profile is 525 ℃.
(7) And (3) carrying out online quenching after extrusion molding, cooling by strong wind, wherein the total capacity of the matched motor is 5.5KW, the quenching air quantity is 60%, and rapidly cooling the profile to below 50 ℃.
(8) Stretching, namely stretching and straightening the quenched circular tube section with the stretching rate of 1.6%, and respectively placing stretching cushion blocks in the inner cavities of the head end and the tail end of the circular tube during stretching.
(9) And (3) polishing the inner wall of the whole round pipe by adopting an automatic polishing machine.
(10) Annealing, namely annealing at the temperature of 390+/-5 ℃ for 3.9 hours, air cooling along with the furnace after the heat preservation is finished, placing a row of bottom-paved round tubes with the outer diameter of 180mm and the wall thickness of 40mm on the underframe of the annealing furnace, and uniformly arranging the large-diameter thin-wall aluminum alloy round tubes on the bottom-paved round tubes when charging the furnace. The laying round pipes are directly provided with a certain gap, and the gap between the adjacent laying round pipes is 80mm. The laying round pipe is fixed, such as by a wedge block, so as to avoid rolling of the laying round pipe. Referring to fig. 2, in implementation, a row of bottom-laying round tubes 30 are placed on the annealing furnace underframe 20, the large-diameter thin-wall aluminum alloy round tubes 10 are uniformly distributed on the bottom-laying round tubes, the large-diameter thin-wall aluminum alloy round tubes 10 and the bottom-laying round tubes 30 are uniformly distributed towards each other, the length of the bottom-laying round tubes 30 is greater than or equal to that of the large-diameter thin-wall aluminum alloy round tubes 10, and the contact mode of the two is changed from 'point contact' to 'surface contact', so that the stress area of the bottom of the aluminum alloy round tubes is greatly increased, and the aluminum alloy round tubes are prevented from being concave. The bottom-laying round pipes are provided with a certain gap, so that furnace gas freely circulates during heating, heating temperature is more uniform, and the phenomenon that soft belts are unqualified in performance and coarse crystals are generated locally is avoided.
The surface of the large-diameter thin-wall round tube prepared by the embodiment has no dent defect after annealing and tapping, more tiny pits appear on the surface of the inner wall of the round tube, the roughness of the inner wall after polishing is Ra0.45 mu m, and the welding is good.
Example 3
The preferred embodiment provides a preparation method of a large-diameter thin-wall Al-Mg-Si aluminum alloy round tube, which comprises the following specific steps:
(1) Batching according to the chemical components and mass percentages corresponding to the table 1.
(2) Smelting and refining, namely putting raw and auxiliary materials such as an aluminum ingot, a magnesium ingot, a zinc ingot, an intermediate alloy and the like into a dome hydraulic inclined smelting furnace together for smelting, fully stirring and skimming, wherein the heat preservation temperature of the smelting furnace is 720-740 ℃, the smelting time is 7 hours, the refining temperature is 710-730 ℃, the refining chlorine flow is 0.1-0.3Nm 3/h, stirring and degassing are carried out by adopting an electromagnetic stirring device, deslagging are carried out, and standing is carried out for 30-45min after refining is finished, and casting is started.
(3) Casting by adopting a water-cooling semi-continuous casting mode, wherein the casting temperature is 690-710 ℃, the casting speed is 30mm/min, the casting cooling water temperature is 27-34 ℃, the casting cooling water flow rate is 420m 3/h, the diameter of the obtained round ingot is 580mm, and finally the wagon is a round ingot with the diameter of 566 mm. The length of the round ingot is 7000mm, and the ingot is cut into ingot blanks with the length of 1800mm in sections after head and tail scraps are cut off.
(4) Homogenizing heat treatment of the cast ingot, namely, homogenizing heat treatment of the cast ingot, wherein the metal heat preservation temperature is 570+/-10 ℃ and the metal heat preservation time is 14h.
(5) Preheating, namely placing the ingot blank into an induction furnace for heating and preserving heat, wherein the heating temperature is 520 ℃, the temperature at the front end of the ingot is gradually reduced every 300mm by adopting a gradient heating mode, the temperature gradient is 10 ℃ in total, namely 520-510-500-490-480 ℃, the preserving heat time is 15-20min, the heating temperature of the die is 500 ℃ plus or minus 10 ℃, and the heating temperature of the extrusion cylinder is 430 ℃ plus or minus 10 ℃.
(6) And extruding, namely extruding the preheated ingot blank in an extrusion cylinder in an extruder to obtain a circular tube profile, wherein the speed of the extruded product is 2.5m/min, and the online quenching cooling inlet temperature of the profile is 525 ℃.
(7) And (3) carrying out online quenching after extrusion molding, cooling by strong wind, wherein the total capacity of the matched motor is 5.5KW, the quenching air quantity is 60%, and rapidly cooling the profile to below 50 ℃.
(8) Stretching, namely stretching and straightening the quenched circular tube section with the stretching rate of 1.6%, and respectively placing stretching cushion blocks in the inner cavities of the head end and the tail end of the circular tube during stretching.
(9) And (3) polishing the inner wall of the whole round pipe by adopting an automatic polishing machine.
(10) Annealing, namely annealing at the heat preservation temperature of 390+/-5 ℃ for 3.9 hours, and cooling with the furnace after heat preservation. A row of bottom-laying round tubes with the outer diameter of 130mm and the wall thickness of 20mm are arranged on the bottom-laying round tubes, and the large-diameter thin-wall aluminum alloy round tubes are uniformly distributed and arranged on the bottom-laying round tubes during furnace loading. The laying round pipes are directly provided with a certain gap, and the gap between the adjacent laying round pipes is 60mm. The laying round pipe is fixed, such as by a wedge block, so as to avoid rolling of the laying round pipe. Referring to fig. 2, in implementation, a row of bottom-laying round tubes 30 are placed on the annealing furnace underframe 20, the large-diameter thin-wall aluminum alloy round tubes 10 are uniformly distributed on the bottom-laying round tubes, the large-diameter thin-wall aluminum alloy round tubes 10 and the bottom-laying round tubes 30 are uniformly distributed towards each other, the length of the bottom-laying round tubes 30 is greater than or equal to that of the large-diameter thin-wall aluminum alloy round tubes 10, and the contact mode of the two is changed from 'point contact' to 'surface contact', so that the stress area of the bottom of the aluminum alloy round tubes is greatly increased, and the aluminum alloy round tubes are prevented from being concave. The bottom-laying round pipes are provided with a certain gap, so that furnace gas freely circulates during heating, heating temperature is more uniform, and the phenomenon that soft belts are unqualified in performance and coarse crystals are generated locally is avoided.
The surface of the large-diameter thin-wall round tube prepared by the embodiment has no concave-pressing defect after being annealed out of the furnace, the roughness of the inner wall surface is Ra0.5mu m, and the welding is good.
Example 4
The present preferred embodiment provides a method for manufacturing a large-diameter thin-walled Al-Mg-Si aluminum alloy round tube, unlike embodiment 3, in this exemplary embodiment, the large-diameter thin-walled aluminum alloy round tube 10 is in a multi-row stacked form, the large-diameter thin-walled aluminum alloy round tube 10 located above is stacked between two large-diameter thin-walled aluminum alloy round tubes 10 located below, the large-diameter thin-walled aluminum alloy round tubes 10 are uniformly arranged in a uniform orientation, the contact mode is "surface contact", the multi-row stacked mode improves the production efficiency, gaps between the large-diameter thin-walled aluminum alloy round tubes are provided, free circulation of furnace gas during heating is achieved, heating temperature rise is more uniform, and partial soft belt performance failure of products and coarse grain generation are avoided.
Comparative example 1
The comparative example provides a preparation method of a large-diameter thin-wall Al-Mg-Si aluminum alloy round tube, which comprises the following specific steps:
(1) Batching according to the chemical components and mass percentages corresponding to the table 1.
(2) Smelting, namely putting raw and auxiliary materials such as an aluminum ingot, a magnesium ingot, a zinc ingot, an intermediate alloy and the like into a dome hydraulic inclined smelting furnace together for smelting, fully stirring, skimming, and keeping the temperature of the smelting furnace at 720-740 ℃ for 7 hours.
(3) Casting by adopting a water-cooling semi-continuous casting mode, wherein the casting temperature is 680-700 ℃, the casting speed is 30mm/min, the casting cooling water temperature is 27-34 ℃, the casting cooling water flow rate is 420m 3/h, the diameter of the obtained round ingot is 580mm, and finally the wagon is a round ingot with the diameter of 566 mm. The length of the round ingot is 7000mm, and the ingot is cut into ingot blanks with the length of 1800mm in sections after head and tail scraps are cut off.
(4) Homogenizing heat treatment of the cast ingot, namely, homogenizing heat treatment of the cast ingot, wherein the metal heat preservation temperature is 570+/-10 ℃ and the metal heat preservation time is 14h.
(5) Preheating, namely placing the ingot blank into an induction furnace for heating and preserving heat, wherein the heating temperature is 480 ℃, the temperature at the front end of the ingot is gradually reduced every 300mm by adopting a gradient heating mode, the temperature gradient is 10 ℃ in total, namely 480-470-460-450-440 ℃, the preserving heat time is 15-20min, the heating temperature of a die is 480+/-10 ℃, and the heating temperature of an extrusion cylinder is 430+/-10 ℃.
(6) And extruding, namely extruding the preheated ingot blank in an extrusion cylinder in an extruder to obtain a circular tube profile, wherein the speed of the extruded product is 7.5m/min, and the online quenching cooling inlet temperature of the profile is 525 ℃.
(7) And (3) carrying out online quenching after extrusion molding, cooling by strong wind, wherein the total capacity of the matched motor is 5.5KW, the quenching air quantity is 80%, and rapidly cooling the profile to below 50 ℃.
(8) Stretching, namely stretching and straightening the quenched round pipe section bar, wherein the stretching rate is 1.6%. At the head end and tail end of the round tube during stretching the inner cavities are respectively provided with a stretching cushion block.
(9) Annealing, namely annealing at the heat preservation temperature of 390+/-5 ℃ for 3.9 hours, and cooling with the furnace after heat preservation.
(10) And (3) polishing the inner wall of the whole round pipe by adopting an automatic polishing machine.
The large-diameter thin-wall round tube prepared by the method has the advantages that the surface of the annealed large-diameter thin-wall round tube is provided with a plurality of concave defects, the concave defects are formed on the contact position of the round tube and a material frame of the annealing furnace, fine cracks are formed on the outer surface of the round tube, a plurality of mold marks are formed on the surface of the inner wall, pitting surfaces are formed on the surface of the inner wall, the roughness of the inner wall after polishing is Ra0.9 mu m, and broken lines cannot be completely eliminated. And a plurality of poor welding positions appear at the welding positions.
In the exemplary embodiment of the invention, the specific ingot casting process, extrusion process, heat treatment process and inner cavity polishing process are adopted in the embodiment 1, the embodiment 2 and the embodiment 3, and specific auxiliary tools are adopted in annealing, so that the inner cavity of the round pipe has no indentation defect under the combination of a plurality of improvements, the roughness of polished walls is less than Ra0.5mu m, and all welding seams of the round pipe are welded well. In comparative example 1, a bottoming round tube is not placed on an annealing furnace burden frame, low-temperature rapid extrusion is adopted, a plurality of concave defects are formed on the surface of the bottoming round tube, the concave defects are formed on the contact position of the round tube and the annealing furnace burden frame, fine cracks are formed on the outer surface of the round tube, a plurality of die marks are formed on the surface of the inner wall, a 'pitting surface' is formed on the surface of the inner wall, the roughness of the inner wall after polishing is Ra0.9 mu m, damage lines cannot be completely eliminated, and a plurality of welding defects are formed on the welding line position.
The foregoing is merely illustrative of the present invention, and the present invention is not limited thereto, and any changes or substitutions easily contemplated by those skilled in the art within the scope of the present invention should be included in the present invention. Therefore, the protection scope of the present invention shall be subject to the protection scope of the claims.
Claims (10)
1. A preparation method of a large-diameter thin-wall Al-Mg-Si aluminum alloy round tube comprises the following steps of proportioning, smelting, refining, casting, ingot homogenization heat treatment, preheating, extrusion, on-line quenching, stretching straightening, sawing, polishing the inner wall and annealing, and is characterized in that the heat treatment heat preservation temperature in the annealing process is 390+/-5 ℃, the heat preservation time is 3-6h, the heat preservation is finished and air-cooled along with a furnace, a row of bottom-paved round tubes with the outer diameter of 100-200mm and the wall thickness of 10-40mm are placed on an annealing furnace chassis, and the large-diameter thin-wall round tubes are uniformly distributed on the bottom-paved round tubes during furnace loading.
2. The method for manufacturing a large-diameter thin-wall Al-Mg-Si aluminum alloy round tube according to claim 1, wherein the round tube with the bottom laid directly has a certain gap.
3. The method for preparing the large-diameter thin-wall Al-Mg-Si aluminum alloy round tube according to claim 1, wherein the aluminum alloy material comprises the following components in percentage by mass ：Si：0.65％-0.75％,Fe：0.15-0.25％,Cu：≤0.12％,Mn：0.20％-0.35％,Mg：0.50-0.65％,Cr：0.12％-0.20％,Zn：≤0.20％,Ti：≤0.05％,Zr：≤0.05％,, the balance of Al and unavoidable impurities, each unavoidable element is less than 0.05%, and the total amount of the unavoidable elements is less than 0.10%.
4. The method for preparing the large-diameter thin-wall Al-Mg-Si aluminum alloy round tube according to claim 1, wherein the stretching cushion blocks are respectively placed in the inner cavities of the head end and the tail end of the aluminum alloy round tube during stretching, and the stretching rate is 0.5-2.5%.
5. The method for preparing the large-diameter thin-wall Al-Mg-Si aluminum alloy round tube according to claim 1, wherein the metal heat preservation temperature in the ingot homogenization heat treatment is 570+/-10 ℃ and the metal heat preservation time is 7-14h.
6. The method for preparing the large-diameter thin-wall Al-Mg-Si aluminum alloy round tube according to claim 5, wherein the casting ingot is heated by electromagnetic induction gradient, the heating temperature of the head of the casting ingot is 500-520 ℃, the temperature gradient of the interval 300mm is reduced by 10 ℃, the heating temperature of a die is 500+/-10 ℃, the heating temperature of an extrusion cylinder is 430+/-10 ℃, the speed of an extrusion product is 2.5-6.0m/min, the temperature of an online quenching cooling inlet of the profile is more than or equal to 500 ℃, and the temperature of an online quenching cooling outlet of the profile is less than or equal to 50 ℃.
7. The method for preparing the large-diameter thin-wall Al-Mg-Si aluminum alloy round tube according to claim 1, wherein the outer diameter of the aluminum alloy round tube is phi 300-600mm, the wall thickness of the round tube is 5-10mm, and the length of the finished product is 6-12m.
8. The method for preparing the large-diameter thin-wall Al-Mg-Si aluminum alloy round tube according to claim 1, wherein ingredients are put into a smelting furnace for smelting in the smelting process, the smelting temperature is 720-760 ℃, the smelting is carried out after the smelting is finished, the refining temperature is 710-730 ℃, the flow rate of refined chlorine is 0.1-0.3Nm 3/h, an electromagnetic stirring device is adopted for stirring, degassing and deslagging, and standing is carried out for 30-45min after the refining is finished to start casting.
9. The method for producing a large diameter thin wall Al-Mg-Si aluminum alloy round tube according to claim 1 or 8, wherein the casting speed is 25-40mm/min, the casting temperature is 690-710 ℃, and the casting cooling water temperature is 28-35 ℃.
10. The method for preparing the large-diameter thin-wall Al-Mg-Si aluminum alloy round tube according to claim 8, wherein the casting is carried out in a water-cooling semi-continuous casting mode, the casting temperature is 700-730 ℃, the casting cooling water temperature is 28-35 ℃, the casting stabilizing material temperature is 690-710 ℃, the casting speed is 25-40mm/min, and the casting cooling water flow is 380-420m 3/h.
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