Aluminum alloy bar and hot rolling method of aluminum alloy bar

Abstract

The invention provides an aluminum alloy bar and a hot rolling method of the aluminum alloy bar. The hot rolling method comprises the steps that three-dimensional scanning is conducted on a hot continuous rolling mill, the nominal diameter Dn of each roller and the diameter dn of an inscribed circle of a wire are obtained, the reduction ratio kn is obtained, and the pass sectional area Sn is obtained through calculation; calculating the flow Ln according to the flow ratio Fn; calculating to obtain a roller rotating speed rn and a simulated motor rotating speed omega n; the aluminum alloy ingot is subjected to 1-n passes of hot rolling at the rotating speed omega n, and an aluminum alloy bar is obtained; the flow ratio of the soft aluminum alloy is 0.95-1.10, and the flow ratio of the hard aluminum alloy is 0.90-1.05. According to the method, by establishing the incidence relation between the parameters of all the passes of rollers in the aluminum alloy hot continuous rolling mill and combining the inherent attributes of the soft aluminum alloy and the hard aluminum alloy, the rotating speed of all the roller motors suitable for rolling materials at present is rapidly calculated and obtained, the method can be directly applied to actual hot rolling, the material forming quality and production efficiency are improved, and the production cost is reduced. And the parameter exploration cost is reduced.

Description

Technical Field

[0001] The present invention relates to the technical field of aluminum alloys, and in particular, to an aluminum alloy bar and a hot rolling method for an aluminum alloy bar. Background Art

[0002] In the traditional preparation method of aluminum alloys, aluminum alloy bars are usually produced by extrusion. Limited by equipment, the production efficiency is low, and the weight of a single bar is about 20-50 kg, which cannot meet the needs of continuous production. When directly hot rolling large ingots with a hot tandem rolling mill for aluminum alloy bars, bars or coiled wire materials without joints and with a weight of more than 200 kg can be produced. The production efficiency is high and the forming speed is fast. At present, it has become the mainstream production method for high-end wire bars. The hot tandem rolling mill for aluminum alloy bars is composed of 8 horizontal and vertical rolls and 14 Y-shaped rolls. In the actual rolling production process, the rolling matching speeds of the rolls are obtained by experience. However, for aluminum alloys of different grades, due to differences in structure and properties, it is necessary to conduct multiple single-bar experiments to match the rolling speeds of each roll. The experimental efficiency is low, resulting in serious waste of human resources, raw materials, and energy, and the parameter exploration efficiency is low. On the other hand, even if the bar can be smoothly rolled and flowed, due to unreasonable speed matching between some rolls, the macro or microstructural uniformity will change, gradually accumulate, resulting in surface folding, mid-course wire breakage, and rolling cracking, affecting production efficiency and quality.

[0003] Hot tandem rolling is the mainstream production method for aluminum alloy bars. However, the properties of aluminum alloys of different grades are different. Soft alloys such as 1xxx series aluminum alloys are soft and have a high elongation rate, while hard alloys such as 2xxx, 5xxx, and 7xxx series bars have heat treatment strengthening or work hardening effects, with high strength and low elongation rate, and poor forming effects. When rolling soft alloys, the material is prone to overflow from the roll gap, resulting in surface quality problems such as folding and stacking. When hot rolling hard alloys, due to the gradually decreasing elongation rate, mid-course wire breakage or end cracking is likely to occur, making it difficult to continue production. Summary of the Invention

[0004] The main object of the present invention is to provide an aluminum alloy bar and a hot rolling method for an aluminum alloy bar, so as to solve the problems in the prior art that it is difficult to balance the forming quality of soft and hard aluminum alloys in the hot rolling method of aluminum alloy bars and a large amount of preliminary parameter exploration is required.

[0005] To achieve the above object, according to one aspect of the present invention, a hot rolling method for an aluminum alloy bar is provided. The hot rolling method is carried out in a hot tandem rolling mill and includes the following steps: Step S1, preparing an aluminum alloy ingot by using an aluminum ingot and an intermediate alloy according to the component ratio of the aluminum alloy bar; Step S2, determining the simulated motor speed ω of the nth pass roll during hot rolling n ; Step S21, performing three-dimensional scanning on the hot tandem rolling mill to obtain the nominal diameter D of each rolln 、The inscribed circle diameter d of each rolling mill wire n , and at the same time obtain the reduction ratio k of each rolling mill n , calculate the pass cross-sectional area S of the hot continuous rolling mill n ; Step S22, according to the flow ratio F of the hot continuous rolling mill n , calculate the flow rate L of the hot continuous rolling mill n ; Step S23, calculate the roll speed r of the hot continuous rolling mill n and the simulated motor speed ω n ; Step S3, feed the aluminum alloy ingot into the hot continuous rolling mill, and use the simulated motor speed ω n as the actual motor speed, and perform hot rolling for 1 to n passes to obtain aluminum alloy bars; when the aluminum alloy bars are soft aluminum alloys, the flow ratio is 0.95 to 1.10; when the aluminum alloy bars are hard aluminum alloys, the flow ratio is 0.90 to 1.05.

[0006] Further, in step S2, the pass cross-sectional area S n is calculated by formula (1):

[0007] S n = π × d n 2 ÷ 4 (1).

[0008] Further, in step S2, the flow rate L n is calculated by formula (2):

[0009] L n = L n-1 × F n (2); where L n-1 is the flow rate of the previous pass, and L1 is 430000 to 440000 mm 2 / s.

[0010] Further, in step S2, the roll speed r n is calculated by formula (3):

[0011] r n = L n ÷ S n ÷ (D n ÷ 2) (3).

[0012] Further, in step S2, the simulated motor speed ω n is calculated by formula (4):

[0013] ω n = r n × k n × 30 ÷ π (4).

[0014] Further, the hard aluminum alloy includes one or more of 5xxx series aluminum alloy, 2xxx series aluminum alloy, 6xxx series aluminum alloy, and 7xxx series aluminum alloy; and / or the soft aluminum alloy includes 1xxx series aluminum alloy.

[0015] Further, in step S22, according to the alloy series of the aluminum alloy bar, the flow ratio F of the hot continuous rolling mill is determined n ; when the alloy series of the aluminum alloy bar is 1xxx series aluminum alloy, F n is 1.05 - 1.10; when the alloy series of the aluminum alloy bar is 2xxx series aluminum alloy, 6xxx series aluminum alloy, or 7xxx series aluminum alloy, F n is 0.95 - 1.05; when the alloy series of the aluminum alloy bar is 5xxx series aluminum alloy, F n is 0.90 - 0.95.

[0016] Further, after step S23, step S2 further includes the following steps: digitally model the hot continuous rolling mill to obtain a digital model of the hot continuous rolling mill; run the digital model of the hot continuous rolling mill at the simulated motor speed ω n to obtain a simulated aluminum alloy bar, and visually observe the forming state of the simulated aluminum alloy bar under the current conditions: when there are no forming defects in the simulated aluminum alloy bar, use the simulated motor speed ω n as the actual motor speed for hot rolling; when there are forming defects in the simulated aluminum alloy bar, repeat steps S22 and S23, adjust the flow ratio until there are no more forming defects in the simulated aluminum alloy bar. At this time, the motor speed is the second simulated motor speed, and use the second simulated motor speed as the actual motor speed for hot rolling; forming defects include stacking, tensile fracture, and open - mouth cracking.

[0017] Further, when stacking appears in the simulated aluminum alloy bar, adjust the flow ratio to 1.05 - 1.10; when tensile fracture or open - mouth cracking appears in the simulated aluminum alloy bar, adjust the flow ratio to 0.90 - 0.95.

[0018] Further, in step S1, according to the ingredient ratio of the aluminum alloy bar, mix the aluminum ingot and the master alloy, and perform semi - continuous casting to obtain an aluminum alloy cast bar; perform homogenization heat treatment and milling on the aluminum alloy cast bar in sequence to obtain an aluminum alloy ingot.

[0019] According to another aspect of the present invention, an aluminum alloy bar is provided, which is obtained by using the above - mentioned hot rolling method of the present invention.

[0020] Furthermore, the grain boundary width of the aluminum alloy bar is 15 - 30 μm, the total area percentage of Brass texture, Copper texture, and S texture is 10 - 30%, the area percentage of Cube texture is 50 - 70%, and the grain core-surface difference is ≤ 1.0 grade; and / or the elongation of the aluminum alloy bar is 10 - 30%, and the tensile strength range of the whole coil of 200 - 3000 kg is 2 - 15 MPa.

[0021] Applying the technical solution of the present invention, by establishing the correlation relationship between the roll parameters of each pass in the hot continuous rolling mill of aluminum alloy, combining the inherent properties of soft aluminum alloy and hard aluminum alloy, confirming the flow ratio of the rolling passes before and after the roll, and quickly obtaining the rotational speeds of each roll motor suitable for the current rolling material through calculation, it can be directly applied to the actual hot rolling process, significantly improving the material forming quality and production efficiency, and reducing the cost of parameter exploration through experiments. Brief Description of the Drawings

[0022] The attached drawings forming a part of this application are used to provide a further understanding of the present invention. The schematic embodiments and descriptions thereof of the present invention are used to explain the present invention and do not constitute an improper limitation of the present invention. In the drawings:

[0023] Figure 1 Shows the hot rolling process flow chart according to an embodiment of the present invention;

[0024] Figure 2 Shows the hot rolling process flow chart according to Embodiment 1 of the present invention;

[0025] Figure 3 Shows the digital model of the hot rolling equipment according to Embodiment 1 of the present invention;

[0026] Figure 4 Shows the grain morphology according to Embodiment 1 of the present invention;

[0027] Figure 5 Shows the grain morphology according to Comparative Example 1;

[0028] Figure 6 Shows the defect morphology according to Comparative Example 1;

[0029] Figure 7 Shows the stacking defects generated by hot rolling in the digital model according to Comparative Example 2;

[0030] Figure 8 Shows the stacking defects generated by hot rolling in the actual production according to Comparative Example 2. Detailed Description of the Embodiments

[0031] It should be noted that, without conflict, the embodiments in this application and the features in the embodiments can be combined with each other. The present invention will be described in detail below with reference to the drawings and in combination with the embodiments.

[0032] As described in the background art of the present invention, in the prior art, there are problems that the hot rolling method of aluminum alloy bars is difficult to balance the forming quality of soft aluminum alloy and hard aluminum alloy, and a large amount of preliminary parameter exploration is required. To solve the above problems, in a typical embodiment of the present invention, a hot rolling method of aluminum alloy bars is provided. The hot rolling method is carried out in a hot tandem mill and includes the following steps: Step S1, according to the component ratio of the aluminum alloy bars, an aluminum ingot and an intermediate alloy are prepared into an aluminum alloy ingot; Step S2, determine the simulated motor speed ω of the nth pass roll during the hot rolling process n ; Step S21, perform three-dimensional scanning on the hot tandem mill to obtain the nominal diameter D of each roll n , the inscribed circle diameter d of each roll wire n , and at the same time obtain the reduction ratio k of each roll n , and calculate the pass cross-sectional area S of the hot tandem mill n ; Step S22, according to the flow ratio F of the hot tandem mill n , calculate the flow rate L of the hot tandem mill n ; Step S23, calculate the roll speed r n and the simulated motor speed ω n of the hot tandem mill; Step S3, feed the aluminum alloy ingot into the hot tandem mill, and use the simulated motor speed ω n as the actual motor speed to perform hot rolling for 1 to n passes to obtain aluminum alloy bars; when the aluminum alloy bars are soft aluminum alloy, the flow ratio is 0.95 to 1.10; when the aluminum alloy bars are hard aluminum alloy, the flow ratio is 0.90 to 1.05.

[0033] Among them, soft aluminum alloy refers to aluminum alloy with a hardness HB ≤ 50 N / mm 2 after hot rolling, and hard aluminum alloy refers to aluminum alloy with a hardness HB > 50 N / mm 2 after hot rolling.

[0034] The present invention designs a calculation process based on material properties and hot tandem mill parameters. By collecting D n , d n , k n , calculating S n , determining F n , calculating L n , r n , ω n, to obtain the optimal motor speed settings for the rollers in each hot rolling pass. The present invention establishes the correlation relationships among the rotational speeds of the rollers, the rotational speeds of the roller motors, the pass interfaces, and the bar flow rates in the hot continuous rolling mill of aluminum alloy. By combining the inherent properties of soft and hard aluminum alloys, the flow rate ratio of the rolling passes before and after the rollers is confirmed. By calculation, the rotational speeds of the roller motors suitable for the current rolling material are quickly obtained, significantly improving the material forming quality and production efficiency, and reducing the cost of experimental parameter exploration. At the same time, by reasonably controlling parameters such as the bar rolling flow rate, the accumulation of energy caused by long-term friction between the material and the roller is avoided, and the formation of coarse grain defects is prevented, which is beneficial to obtaining aluminum alloy rolling bars with fine grain size and appropriate grain boundary width and without coarse grain ring defects; it can also obtain a reasonable matching of deformation orientation texture and recrystallization texture, significantly improving the material uniformity and ductility. Among them, the reduction ratio k of each roller n can be obtained from the nameplate of the motor used. The hot rolling process flow chart of an embodiment of the present invention is as shown in Figure 1 shown.

[0035] Typically but not limited to, when the aluminum alloy bar is a soft aluminum alloy, the flow rate ratio is 0.95, 0.96, 0.97, 0.98, 0.99, 1.00, 1.01, 1.02, 1.03, 1.04, 1.05, 1.06, 1.07, 1.08, 1.09, 1.10 or a range value composed of any two of these values.

[0036] Typically but not limited to, when the aluminum alloy bar is a hard aluminum alloy, the flow rate ratio is 0.90, 0.91, 0.92, 0.93, 0.94, 0.95, 0.96, 0.97, 0.98, 0.99, 1.00, 1.01, 1.02, 1.03, 1.04, 1.05 or a range value composed of any two of these values.

[0037] In a preferred embodiment, in step S2, the pass cross-sectional area S n is calculated by formula (1):

[0038] S n = π×d n 2 ÷4 (1).

[0039] In formula (1), in actual production, even if the roller is designed to be circular, since the aluminum alloy to be rolled will not fully fill the roll gap, when the actual aluminum alloy ingot / bar / wire passes through the roller, it will not completely present a circular cross-section. At this time, the inscribed circle diameter d of the aluminum alloy bar passing through the roller is collected n , and the pass area calculated by the formula is relatively more accurate.

[0040] In a preferred embodiment, in step S2, the flow rate L nCalculated by formula (2):

[0041] L n = L n-1 × F n (2); where L n-1 is the flow rate of the previous pass, and L1 is 430,000 - 440,000 mm 2 / s.

[0042] In formula (2), the flow rate L of each pass n is obtained by multiplying the flow rate L of the previous pass n-1 by the flow rate ratio F set according to the type of aluminum alloy to be prepared n where the flow rate L1 of the first pass is obtained by considering the rolling capacity of the comprehensive equipment and the actual ingot size factors.

[0043] In a preferred embodiment, in step S2, the roll speed r n is calculated by formula (3):

[0044] r n = L n ÷ S n ÷ (D n ÷ 2)(3).

[0045] In formula (3), L n ÷ S n gives the actual flow velocity of the bar, and the flow velocity ÷ (D n ÷ 2) gives the roll speed r n .

[0046] In a preferred embodiment, in step S2, the simulated motor speed ω n is calculated by formula (4):

[0047] ω n = r n × k n × 30 ÷ π(4).

[0048] In formula (4), the roll speed r n is in the unit of rad / s, that is, the angular velocity of the roll rotation per second. Since 2π × arc velocity = angular velocity, the unit of the motor speed is r / min, that is, 2π × ω n = r n × k n × 60, and the conversion is obtained.

[0049] As described above, the hot rolling method of the present invention can take into account the forming quality of both soft and hard aluminum alloy bars, and is a hot rolling method that can be commonly used for aluminum alloys of various hardnesses. In a preferred embodiment, the hard aluminum alloy includes one or more of 5xxx series aluminum alloy, 2xxx series aluminum alloy, 6xxx series aluminum alloy, and 7xxx series aluminum alloy; and / or the soft aluminum alloy includes 1xxx series aluminum alloy.

[0050] In a preferred embodiment, the matching relationship between each pass and the motor in the hot continuous rolling mill is as follows: 1 motor drives 1 pass, or 1 motor drives 2 passes, or 1 motor drives a passes, where a is 3 to 7. When using 1 motor to drive 2 passes or a passes, the reduction ratio k of each roll is used n to control the motor speed and match the speeds of each roll. The above conditions are beneficial to making the hot rolling method of the present invention adapt to various equipment conditions. In order to reduce costs or facilitate maintenance, some equipment can operate in a manner of using a single motor to drive multiple rolls. The motor herein refers to the electrical equipment that drives the rolls.

[0051] In a preferred embodiment, in step S22, according to the alloy series of the aluminum alloy bar, the flow ratio F of the hot continuous rolling mill is determined n ; when the alloy series of the aluminum alloy bar is 1xxx series aluminum alloy, F n is 1.05 to 1.10; when the alloy series of the aluminum alloy bar is 2xxx series aluminum alloy, 6xxx series aluminum alloy, or 7xxx series aluminum alloy, F n is 0.95 to 1.05; when the alloy series of the aluminum alloy bar is 5xxx series aluminum alloy, F n is 0.90 to 0.95.

[0052] For 1xxx series aluminum alloy, since this type of aluminum alloy cannot be processed and strengthened or heat-treated and strengthened, it belongs to the category of soft alloys, and stacking and overflowing of the roll gap are likely to occur during the rolling process. Therefore, it is preferred that F n is 1.05 to 1.10 to give the bar a slightly larger tensile stress to avoid stacking and make the bar roll smoothly in the roller path.

[0053] For 2xxx series aluminum alloy, 6xxx series aluminum alloy, or 7xxx series aluminum alloy, the above types of aluminum alloys are medium-high composition alloys that can be heat-treated and strengthened and belong to the category of hard alloys. Therefore, it is preferred that F n is 0.95 to 1.05 to give the bar a moderate tensile stress to avoid defects such as stacking, tensile fracture, and open-mouth cracking.

[0054] For 5xxx series aluminum alloy, this type of aluminum alloy is a medium composition alloy that can be work-hardened, and with the increase of the processing amount, the hardening degree is significantly improved, and head-end open-mouth cracking defects are likely to occur. Therefore, it is preferred that F nis 0.90 to 0.95 to apply slight compressive stress to the bar and achieve simultaneous rolling and defect bridging.

[0055] Typical but non-limiting, when the alloy series of the aluminum alloy bar is 1xxx series aluminum alloy, F n is 1.05, 1.06, 1.07, 1.08, 1.09, 1.10 or a range value composed of any two of these numerical values.

[0056] Typical but non-limiting, when the alloy series of the aluminum alloy bar is 2xxx series aluminum alloy, 6xxx series aluminum alloy or 7xxx series aluminum alloy, F n is 0.95, 0.96, 0.97, 0.98, 0.99, 1.00, 1.01, 1.02, 1.03, 1.04, 1.05 or a range value composed of any two of these numerical values.

[0057] Typical but non-limiting, when the alloy series of the aluminum alloy bar is 5xxx series aluminum alloy, F n is 0.90, 0.91, 0.92, 0.93, 0.94, 0.95 or a range value composed of any two of these numerical values.

[0058] In a preferred embodiment, after step S23, step S2 further includes the following steps: performing digital modeling on the hot continuous rolling mill to obtain a digital model of the hot continuous rolling mill; using the simulated motor speed ω n to run the digital model of the hot continuous rolling mill to obtain a simulated aluminum alloy bar, and visually observing the forming state of the simulated aluminum alloy bar under the current conditions: when there are no forming defects in the simulated aluminum alloy bar, using the simulated motor speed ω n as the actual motor speed for hot rolling; when there are forming defects in the simulated aluminum alloy bar, repeating step S22 and step S23, adjusting the flow ratio until there are no more forming defects in the simulated aluminum alloy bar. At this time, the motor speed is the second simulated motor speed, and using the second simulated motor speed as the actual motor speed for hot rolling; the forming defects include stacking, tensile fracture and open-mouth cracking. The morphologies of stacking, tensile fracture and open-mouth cracking are conventional defect morphologies that can be understood by those skilled in the art.

[0059] In view of the production problems such as stacking, tensile fracture, and opening crack that are likely to occur during the hot rolling process of aluminum alloy bars, the present invention uses digital modeling means to simulate the hot rolling forming state of the material under the current flow ratio setting. When the above-mentioned defects occur in the alloy bars, the flow ratio is continuously adjusted to an appropriate range to achieve the smooth forming of the material during hot rolling. By first screening and obtaining appropriate parameters through digital simulation and then verifying them through actual production, the experimental cost can be greatly reduced, and the cracking ratio during the material production process can be decreased. The present invention establishes the flow relationship of aluminum alloy bars between each rolling mill, integrates the material properties, calculates the optimal flow ratio by using digital simulation means, designs the matching speed of each rolling mill, and then sets the motor speed in the system, so as to better ensure the smooth rolling and forming of the alloy bars, and improve the production quality and efficiency.

[0060] Among them, the process of digital modeling of the hot tandem mill can be carried out using conventional modeling software in the art. For example, first use Auto CAD to draw the three-dimensional scanned rolling mill, then import it into Deform to build a model, and input relevant rolling parameters to carry out digital simulation to obtain the digital model of the hot tandem mill. The relevant rolling parameters include the starting rolling temperature, rolling speed, and final rolling temperature. The rolling speed is the simulated motor speed ω n , and the starting rolling temperature and the final rolling temperature can be set according to the type of aluminum alloy bars. For example, the starting rolling temperature is 400 - 500 °C, and the final rolling temperature is 150 - 250 °C.

[0061] When stacking occurs to the material, increase the flow ratio to apply a slightly larger tensile stress to the bars, so that the bars can be smoothly rolled in the roller path; when tensile fracture or opening crack occurs to the material, it indicates that the rolling speed at the rear end is too fast. Therefore, decrease the flow ratio to apply a slight compressive stress to carry out rolling and defect healing simultaneously. Based on this, in a preferred embodiment, when stacking occurs to the aluminum alloy simulated bars, adjust the flow ratio to 1.05 - 1.10; when tensile fracture or opening crack occurs to the aluminum alloy simulated bars, adjust the flow ratio to 0.90 - 0.95.

[0062] In a preferred embodiment, in step S1, mix the aluminum ingot and the master alloy according to the component ratio of the aluminum alloy bars, and carry out semi-continuous casting to obtain an aluminum alloy cast bar; perform homogenization heat treatment and surface milling on the aluminum alloy cast bar in sequence to obtain an aluminum alloy ingot; the diameter φ of the aluminum alloy ingot is 125 - 145 mm. Among them, the semi-continuous casting, homogenization heat treatment, and surface milling processes can use conventional parameters in the art. For example, melt the aluminum ingot and the master alloy at 660 - 750 °C to smelt an aluminum alloy cast bar; keep the aluminum alloy cast bar at 450 - 550 °C for 24 - 48 h for homogenization heat treatment, and then mill off the surface oxide layer to obtain the surface-milled aluminum alloy ingot.

[0063] In another typical embodiment of the present invention, an aluminum alloy bar is further provided. The aluminum alloy bar is obtained by using the hot rolling method described above in the present invention, which can take into account the forming quality of both soft and hard aluminum alloys during the hot rolling process of the aluminum alloy bar, and does not require a large amount of preliminary parameter exploration.

[0064] Due to the reasonable control of the rolling flow of the bar during the hot rolling process of the aluminum alloy bar of the present invention, the energy accumulation and the generation of coarse grain defects caused by the long-term or frictional contact between the material and the roll are avoided. The obtained aluminum alloy rolled bar has a moderate grain boundary width, a small difference between the core and the surface of the grains, a small grain size, no coarse grain ring defects, can obtain a reasonable deformation orientation texture and a recrystallization texture matching, and controls a moderate elongation rate. The difference in the tensile strength of the whole coil is small, significantly improving the material uniformity and excellent forming quality. In a preferred embodiment, the grain boundary width of the aluminum alloy bar is 15 - 30 μm, the total area percentage of Brass texture, Copper texture and S texture is 10 - 30%, the area percentage of Cube texture is 50 - 70%, and the difference between the core and the surface of the grains is ≤ 1.0 level; and / or the elongation rate of the aluminum alloy bar is 10 - 30%, and the difference in the tensile strength of the whole coil of 200 - 3000 kg is 2 - 15 MPa.

[0065] Among them, the difference in the tensile strength of the whole coil of 200 - 3000 kg means that when using the hot rolling method of the aluminum alloy bar of the present invention in a hot tandem mill, an aluminum alloy bar with a single weight of 200 - 3000 kg can be prepared, and the difference between the maximum and minimum values of the tensile strength of the whole coil is 3 - 15 MPa. This parameter can characterize the material uniformity and processing stability of the hot rolling method. The smaller the difference, the better the material uniformity and processing stability of the hot rolling method.

[0066] The following further describes the present application in detail with specific embodiments, and these embodiments should not be construed as limiting the scope claimed in the present application.

[0067] Example 1

[0068] To prepare a 1060 aluminum alloy bar, which belongs to a soft aluminum alloy, the hot rolling method is as follows. The hot rolling process flow chart is shown in Figure 2 :

[0069] Step S1, mix the aluminum ingot and the intermediate alloy according to the component ratio of the aluminum alloy bar, and perform semi-continuous casting to obtain an aluminum alloy cast bar; perform homogenization heat treatment and surface milling on the aluminum alloy cast bar in sequence to obtain an aluminum alloy ingot; the diameter φ of the aluminum alloy ingot is 145 mm;

[0070] Step S2, determine the simulated motor speed ω of the nth pass roll during the hot rolling process n ;

[0071] Step S21: Use the RigelScan Max intelligent handheld laser 3D scanner to perform three-dimensional scanning on the hot strip mill to obtain the nominal diameter D of each roll n and the inscribed circle diameter d of the wire for each roll n . At the same time, obtain the reduction ratio k of each roll from the motor nameplate n . According to the formula S n = π × d n 2 ÷4, calculate the pass cross-sectional area S of the hot strip mill n ;

[0072] Step S22: According to the properties of 1060 aluminum alloy bars, determine that the initial flow ratio of the hot strip mill is 1.05 - 1.10 (verified by digital modeling that the best F n = 1.05) under the experimental conditions of this experiment. According to the formula L n = L n-1 ×F n , calculate the flow rate L of the hot strip mill n ;

[0073] Step S23: According to the formula r n = L n ÷S n ÷(D n ÷2), ω n = r n ×k n ×30÷π, further calculate the roll speed r n and the simulated motor speed ω n of the hot strip mill;

[0074] For digital modeling of the hot strip mill, first use Auto CAD to draw the rolls scanned in three dimensions, and then import them into Deform to build a model. Input relevant rolling parameters (rolling speed, i.e., the simulated motor speed ω n , the starting rolling temperature is 440 °C, and the final rolling temperature is 200 °C), and then digital simulation can be carried out to obtain the digital model of the hot strip mill. As shown in Figure 3 , the rolled bar advances along the preset rolling direction in the roll path formed by the rolls, thereby performing rolling; Run the digital model of the hot strip mill at the simulated motor speed ω n to obtain the forming state of the aluminum alloy simulated bar under the current conditions. Observe visually and check when the digital model of the hot strip mill finishes running: When there are no forming defects in the aluminum alloy simulated bar, at the simulated motor speed ω nHot rolling is carried out at the actual motor speed; when forming defects appear in the aluminum alloy simulated bar, steps S22 and S23 are repeated to adjust the flow ratio: when stacking occurs in the aluminum alloy simulated bar, the flow ratio is adjusted to 1.05 - 1.10; when tensile fracture or open - mouth cracking occurs in the aluminum alloy simulated bar, the flow ratio is adjusted to 0.90 - 0.95; until no forming defects appear in the aluminum alloy simulated bar. At this time, the parameters of each pass in the hot - rolling process are shown in Table 1, and the optimal simulated motor speed for each pass is calculated.

[0075] Step S3: Feed the aluminum alloy ingot into the hot continuous rolling mill, and use the optimal simulated motor speed ω for each pass n as the actual motor speed, and carry out hot rolling for n passes to obtain the aluminum alloy bar.

[0076]

[0077] Among them, for passes 1 to 8, there is one motor for each pass; for passes 9 to 14, one motor drives, and the motor speed is controlled by different reduction ratios to match the rotational speeds of each roll; for passes 15 to 22, one motor drives two passes.

[0078] Example 2

[0079] The difference from Example 1 is that digital modeling is not carried out, and directly use the simulated motor speed ω calculated for each pass n as the actual motor speed for each pass, and carry out hot rolling for n passes to obtain the aluminum alloy bar.

[0080] Example 3

[0081] The difference from Example 2 is that to prepare a 1060 aluminum alloy bar, the flow ratio F of the hot continuous rolling mill in step S22 n = 1.08.

[0082] Example 4

[0083] The difference from Example 2 is that to prepare a 1060 aluminum alloy bar, the flow ratio F of the hot continuous rolling mill in step S22 n = 1.10.

[0084] Example 5

[0085] To prepare a 2024 aluminum alloy bar, which belongs to a hard aluminum alloy, the hot - rolling method is as follows:

[0086] Step S1: Mix the aluminum ingot and the master alloy according to the component ratio of the aluminum alloy bar, and carry out semi - continuous casting to obtain an aluminum alloy cast bar; the aluminum alloy cast bar is subjected to homogenization heat treatment and milling in sequence to obtain an aluminum alloy ingot; the diameter φ of the aluminum alloy ingot is 145 mm;

[0087] Step S2, determine the simulated motor speed ω of the roll at the nth pass during hot rolling n ;

[0088] Step S21, use the RigelScan Max intelligent handheld laser 3D scanner to perform three-dimensional scanning on the hot strip mill to obtain the nominal diameter D of each roll n , the inscribed circle diameter d of each roll wire n . At the same time, obtain the reduction ratio k of each roll from the motor nameplate n . According to the formula S n = π × d n 2 ÷4, calculate the pass cross-sectional area S of the hot strip mill n ;

[0089] Step S22, according to the properties of the 2024 aluminum alloy rod, determine that the initial flow ratio of the hot strip mill is 0.95 - 1.05 (the best F under the experimental conditions of this experiment is verified through digital modeling n = 1.0). According to the formula L n = L n-1 ×F n , calculate the flow rate L of the hot strip mill n ;

[0090] Step S23, according to the formula r n = L n ÷S n ÷(D n ÷2), ω n = r n ×k n ×30÷π, further calculate the roll speed r n and the simulated motor speed ω n ;

[0091] Perform digital modeling on the hot strip mill. First, use Auto CAD to draw the rolled rolls scanned in three dimensions, and then import them into Deform to build a model. Input relevant rolling parameters (rolling speed, i.e., the simulated motor speed ω n , the starting rolling temperature is 440°C, and the final rolling temperature is 200°C), and then digital simulation can be carried out to obtain the digital model of the hot strip mill; run the digital model of the hot strip mill with the simulated motor speed ω n to obtain the forming state of the aluminum alloy simulated rod under the current conditions. Observe visually and check when the digital model of the hot strip mill runs to completion: when there are no forming defects in the aluminum alloy simulated rod, use the simulated motor speed ω nHot rolling is carried out at the actual motor speed; when forming defects appear in the aluminum alloy simulated bar, steps S22 and S23 are repeated to adjust the flow ratio: when stacking appears in the aluminum alloy simulated bar, the flow ratio is adjusted to 1.05 - 1.10; when tensile fracture or open-mouth cracking appears in the aluminum alloy simulated bar, the flow ratio is adjusted to 0.90 - 0.95; until no forming defects appear in the aluminum alloy simulated bar, at this time, the parameters of each pass in the hot rolling process are shown in Table 2, and the optimal simulated motor speed of each pass is calculated.

[0092] Step S3, feed the aluminum alloy ingot into the hot tandem mill, and carry out hot rolling for n passes at the optimal simulated motor speed ω n of each pass as the actual motor speed to obtain an aluminum alloy bar.

[0093]

[0094] Among them, for passes 1 to 8, there is one motor for each pass; for passes 9 to 14, they are driven by one motor, and the motor speed is controlled by different reduction ratios to match the rotational speeds of each rolling mill roll; for passes 15 to 22, they are driven by one motor for two passes.

[0095] Example 6

[0096] The difference from Example 5 is that digital modeling is not carried out, and the simulated motor speed ω n calculated for each pass is directly used as the actual motor speed of each pass to carry out hot rolling for n passes to obtain an aluminum alloy bar.

[0097] Example 7

[0098] The difference from Example 6 is that to prepare a 6061 aluminum alloy bar, the flow ratio F n of the hot tandem mill in step S22 is 0.95.

[0099] Example 8

[0100] The difference from Example 6 is that to prepare a 7075 aluminum alloy bar, the flow ratio F n of the hot tandem mill in step S22 is 1.05.

[0101] Example 9

[0102] To prepare a 5056 aluminum alloy bar, which belongs to a hard aluminum alloy, the hot rolling method is as follows:

[0103] Step S1, mix the aluminum ingot and the master alloy according to the composition ratio of the aluminum alloy bar, carry out semi-continuous casting to obtain an aluminum alloy cast bar; the aluminum alloy cast bar is successively subjected to homogenization heat treatment and surface milling to obtain an aluminum alloy ingot; the diameter φ of the aluminum alloy ingot is 145 mm;

[0104] Step S2, determine the simulated motor speed ω of the roll in the nth pass during hot rolling n ;

[0105] Step S21, use a RigelScan Max intelligent handheld laser 3D scanner to perform three-dimensional scanning on the hot strip mill to obtain the nominal diameter D of each roll n , the inscribed circle diameter d of each roll wire n , and at the same time obtain the reduction ratio k of each roll from the motor nameplate n , according to the formula S n = π × d n 2 ÷4, calculate the pass cross-sectional area S of the hot strip mill n ;

[0106] Step S22, according to the properties of 5056 aluminum alloy bars, determine that the initial flow ratio of the hot strip mill is 0.90 - 0.95 (the best F under the experimental conditions of this experiment is verified through digital modeling n = 0.9), according to the formula L n = L n-1 ×F n , calculate the flow rate L of the hot strip mill n ;

[0107] Step S23, according to the formula r n = L n ÷S n ÷(D n ÷2), ω n = r n ×k n ×30÷π, further calculate the roll speed r n and the simulated motor speed ω n ;

[0108] Perform digital modeling on the hot strip mill. First, use Auto CAD to draw the rolls scanned in three dimensions, and then import them into Deform to build a model. Input relevant rolling parameters (rolling speed, i.e., the simulated motor speed ω n , the starting rolling temperature is 440°C, and the final rolling temperature is 200°C), then digital simulation can be carried out to obtain the digital model of the hot strip mill; run the digital model of the hot strip mill at the simulated motor speed ω n to obtain the forming state of the aluminum alloy simulated bar under the current conditions. Observe visually and check when the digital model of the hot strip mill finishes running: when there are no forming defects in the aluminum alloy simulated bar, at the simulated motor speed ω nPerform hot rolling with the actual motor speed; when forming defects occur in the aluminum alloy simulated bar, repeat steps S22 and S23 to adjust the flow ratio: when stacking occurs in the aluminum alloy simulated bar, adjust the flow ratio to 1.05 - 1.10; when tensile fracture or opening crack occurs in the aluminum alloy simulated bar, adjust the flow ratio to 0.90 - 0.95; until no forming defects appear in the aluminum alloy simulated bar. At this time, the parameters of each pass in the hot rolling process are shown in Table 3, and the optimal simulated motor speed of each pass is calculated.

[0109] Step S3: Feed the aluminum alloy ingot into the hot tandem mill and perform n - pass hot rolling at the optimal simulated motor speed ω n of each pass as the actual motor speed to obtain an aluminum alloy bar.

[0110]

[0111] Among them, for passes 1 to 8, there is one motor for each pass; for passes 9 to 14, they are driven by one motor, and the motor speed is controlled by different reduction ratios to match the speeds of each rolling mill roll; for passes 15 to 22, they are driven by one motor for two passes.

[0112] Example 10

[0113] The difference from Example 9 is that digital modeling is not carried out, and the simulated motor speed ω n calculated for each pass is directly used as the actual motor speed of each pass to perform n - pass hot rolling to obtain an aluminum alloy bar.

[0114] Example 11

[0115] The difference from Example 10 is that when preparing a 5056 aluminum alloy bar, the flow ratio F n of the hot tandem mill in step S22 is 0.93.

[0116] Example 12

[0117] The difference from Example 10 is that when preparing a 5056 aluminum alloy bar, the flow ratio F n of the hot tandem mill in step S22 is 0.95.

[0118] Comparative Example 1

[0119] The difference from Example 1 is that when preparing a 1060 aluminum alloy bar, the flow ratio F n of the hot tandem mill is fixed at 1.2, and the parameters of each pass in this working condition are shown in Table 4.

[0120]

[0121] Among them, for passes 1 to 8, there is one motor for each pass; for passes 9 to 14, they are driven by one motor, and the motor speed is controlled by different reduction ratios to match the speeds of each rolling mill; for passes 15 to 22, two passes are driven by one motor.

[0122] Comparative Example 2

[0123] The difference from Example 1 is that to prepare 1060 aluminum alloy bars, the flow ratio F of the hot continuous rolling mill is fixed n = 0.85, and the parameters of each process in the hot rolling process under this working condition are shown in Table 5.

[0124]

[0125] Among them, for passes 1 to 8, there is one motor for each pass; for passes 9 to 14, they are driven by one motor, and the motor speed is controlled by different reduction ratios to match the speeds of each rolling mill; for passes 15 to 22, two passes are driven by one motor.

[0126] Performance test:

[0127] The aluminum alloy bars actually prepared in the above examples and comparative examples were tested, and the results are shown in Table 6.

[0128] Grain boundary width: The grain morphology was analyzed by EBSD (electron backscatter diffraction), and the intercept method was used for statistics with reference to GB / T 3246.1.

[0129] Area percentages of Brass texture, Copper texture, S texture, and Cube texture: Automatically analyzed by EBSD software.

[0130] Difference between the core and surface of grains: The grain morphology was analyzed by EBSD, and the intercept method was used for statistics with reference to GB / T 3246.1.

[0131] Elongation: Tested according to the standard of GB / T 228.

[0132] Single coil weight: Weighed by an electronic scale.

[0133] Range of tensile strength of the whole coil: Tested according to the standard of GB / T 228.

[0134]

[0135] It can be seen that in Comparative Example 1, due to the excessive flow ratio, the running speed of the rolling mill during the rolling process is much greater than the tension-bearing capacity of the bar, resulting in the breakage of the bar during the hot rolling process and the inability to form smoothly. In Comparative Example 2, since the 1060 alloy is a soft alloy and the flow ratio is too low during the rolling process, the bar is subjected to a large compressive stress and cannot flow forward smoothly and overflow the roll gap during rolling, resulting in the stacking of the bar during the hot rolling process and the inability to form smoothly.

[0136] The grain morphology of Example 1 of the present invention is shown in Figure 4 , and the grain morphology of Comparative Example 1 is shown in Figure 5 . The defect morphology of Comparative Example 1 is shown in Figure 6 . Figure 4 It can be seen that in Figure 4 , a small amount of dynamic recrystallization is formed in the rolling structure, which helps to increase the proportion of Cube texture, thereby improving the elongation and forming performance of the hot-rolled bar, providing a good basis for subsequent cold forming, and the performance difference of the finished material is relatively small. Figure 5 No obvious recrystallization is seen in Figure 5 . At this time, the proportion of Cube texture in the material is relatively low, the elongation is low, the forming performance is insufficient, and the performance difference of the finished material is relatively large. Figure 6 It can be seen in Figure 6 that the bars without reasonable rolling process adjustment show rolling fracture and intermediate hole morphology.

[0137] The stacking defects generated during hot rolling in the digital model of Comparative Example 2 are shown in Figure 7 , and the morphology of the stacking defects generated during hot rolling in actual production is shown in Figure 8 . It can be seen that in the simulation process of Comparative Example 2, the material overflows the roll gap, resulting in easy formation of stacking during the subsequent pass rolling process, which is consistent with Figure 8 the actual rolling performance.

[0138] As can be seen from the above, compared with the comparative examples, each embodiment of the present invention establishes the correlation relationship between the roll parameters of each pass in the hot continuous rolling mill of aluminum alloy, combines the inherent properties of soft aluminum alloy and hard aluminum alloy, confirms the flow ratio of the rolling passes before and after the roll, and can quickly obtain the rotational speed of each roll motor suitable for the current rolling material through calculation, which can be directly applied to the actual hot rolling process, significantly improving the forming quality and production efficiency of the material and reducing the cost of experimental parameter exploration.

[0139] In addition, it can be seen that when all process parameters are within the preferred range of the present invention, the comprehensive effect is better.

[0140] The above are only the preferred embodiments of the present invention and are not used to limit the present invention. For those skilled in the art, the present invention can have various changes and modifications. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. A hot rolling method for an aluminum alloy bar, characterized in that, The hot rolling method is carried out in a hot strip mill and includes the following steps: Step S1: Prepare an aluminum alloy ingot by mixing aluminum ingots and master alloys according to the composition ratio of the aluminum alloy bar; Step S2, determine the simulated motor speed ω of the roll at the nth pass during the hot rolling process n ; Step S21: Conduct three-dimensional scanning on the hot continuous rolling mill to obtain the nominal diameter D of each roll n , the inscribed circle diameter d of each roll wire n , and simultaneously obtain the reduction ratio k of each roll n , and calculate the pass sectional area S of the hot continuous rolling mill n ; Step S22, calculate the flow rate L of the hot strip mill according to the flow rate ratio F of the hot strip mill n n ;​ Step S23, calculate the roll speed r of the hot strip mill n , and the simulated motor speed ω n ; Step S3: Feed the aluminum alloy ingot into the hot tandem mill and perform hot rolling in 1 to n passes at the simulated motor speed ω n as the actual motor speed to obtain the aluminum alloy bar When the aluminum alloy bar is a soft aluminum alloy, the flow ratio is 0.95 - 1.10; When the aluminum alloy bar is a hard aluminum alloy, the flow ratio is 0.90 - 1.

05.

2. The hot rolling method according to claim 1, wherein, In the said step S2, The cross-sectional area S of the pass n is calculated by formula (1): S n = π × d n 2 ÷ 4 (1); and / or The flow rate L n is calculated by Equation (2): L n = L n-1 × F n (2); where L n-1 is the flow rate of the previous pass, and L1 is 430,000 - 440,000 mm 2 / s.

3. The hot rolling method according to claim 1 or 2, characterized in that, In the said step S2, The roll speed r n is calculated by formula (3): r n =L n ÷S n ÷(D n ÷2)(3); and / or The simulated motor speed ω n is calculated by formula (4): ω n = r n × k n × 30 ÷ π (4).

4. The hot rolling method according to claim 1 or 2, characterized in that, The hard aluminum alloy includes one or more of 5xxx series aluminum alloys, 2xxx series aluminum alloys, 6xxx series aluminum alloys and 7xxx series aluminum alloys; and / or The soft aluminum alloy includes 1xxx series aluminum alloys.

5. The hot rolling method according to claim 1 or 2, characterized in that, In the step S22, the flow ratio F of the hot tandem rolling mill is determined according to the alloy series of the aluminum alloy bar n ; When the alloy series of the aluminum alloy bar is 1xxx series aluminum alloy, F n is 1.05 to 1.10; When the alloy series of the aluminum alloy bar is 2xxx series aluminum alloy, 6xxx series aluminum alloy or 7xxx series aluminum alloy, F n is 0.95 to 1.05; When the alloy series of the aluminum alloy bar is 5xxx series aluminum alloy, F n is 0.90 to 0.

95.

6. The hot rolling method according to claim 1 or 2, characterized in that, After the step S23, the step S2 further includes the following steps: digitally modeling the hot rolling mill to obtain a digital model of the hot rolling mill; with the simulated motor speed ω n Running the digital model of the hot rolling mill to obtain an aluminum alloy simulated bar, and visually observing the forming state of the aluminum alloy simulated bar under the current conditions: When there are no forming defects in the aluminum alloy simulated bar, the hot rolling is carried out at the simulated motor speed ω n as the actual motor speed; When forming defects occur in the aluminum alloy simulation bar, repeat step S22 and step S23, adjust the flow ratio until the forming defects no longer occur in the aluminum alloy simulation bar. At this time, the motor speed is the second simulated motor speed, and use the second simulated motor speed as the actual motor speed for the hot rolling; The forming defects include stacking, tensile fracture and open - mouth cracking.

7. The hot rolling method according to claim 6, characterized in that, When stacking occurs in the aluminum alloy simulation bar, adjust the flow ratio to 1.05 - 1.10; When tensile fracture or open - mouth cracking occurs in the aluminum alloy simulation bar, adjust the flow ratio to 0.90 - 0.

95.

8. The hot rolling method according to claim 1 or 2, characterized in that In step S1, mix the aluminum ingots and the master alloys according to the composition ratio of the aluminum alloy bar, carry out semi - continuous casting to obtain an aluminum alloy cast bar; and then subject the aluminum alloy cast bar to homogenization heat treatment and surface milling in sequence to obtain the aluminum alloy ingot.

9. An aluminum alloy bar, characterized in that, Obtained by using the hot rolling method according to any one of claims 1 to 8.

10. The aluminum alloy bar according to claim 9, characterized in that, The grain boundary width of the aluminum alloy bar is 15 - 30 μm, the total area percentage of Brass texture, Copper texture and S texture is 10 - 30%, the area percentage of Cube texture is 50 - 70%, and the grain core - surface difference ≤ 1.0 grade; and / or The elongation of the aluminum alloy bar is 10 - 30%, and the tensile strength range of a whole coil of 200 - 3000 kg is 2 - 15 MPa.

Images