KR102216865B1 - Alluminum alloy material for intergrated bumper beam unit and manufacturing method using the same - Google Patents

Abstract

The present invention relates to an aluminum alloy material for an integrated bumper beam unit, based on the total composition weight, Si 0.9 to 1.8% by weight, Fe 0.10 to 0.16% by weight, Cu 0.70 to 1.20% by weight, Mn 0.60 to 1.11% by weight, Mg An aluminum alloy material containing 0.80 to 1.40 wt%, Cr 0.03 to 0.05 wt%, Zn 0.02 to 0.04 wt%, and titanium 0.01 to 0.03 wt%, the balance being Al and inevitable impurities, the mechanical properties after T6 tempering Of course, it discloses an invention that has confirmed that it is a useful material that can easily manufacture an integrated bumper beam unit in which a bumper beam and a stave are integrated by showing physical properties that can secure rigidity.

Description

Aluminum alloy material for integrated bumper beam unit and manufacturing method of integrated bumper beam unit using the same {ALLUMINUM ALLOY MATERIAL FOR INTERGRATED BUMPER BEAM UNIT AND MANUFACTURING METHOD USING THE SAME}

The present invention relates to an aluminum alloy material for an integral bumper beam unit, and more particularly, an aluminum alloy material for an integral bumper beam unit that enables easy manufacturing of a bumper beam and a stave integrally, and an integral bumper beam unit manufactured therefrom. It is about.

The promising way to improve automobile fuel efficiency is light weight technology, which can be said to be due to high efficiency and low cost compared to other fuel efficiency improvement technologies. Fuel economy improvement technology is largely classified into engine/drive system efficiency improvement, driving resistance reduction, and weight reduction. Engine efficiency improvement has reached the technical limit through many studies, and driving resistance reduction technology is known to have relatively inadequate improvement effect.

However, against the backdrop of the growth of luxury cars and intelligent cars, the average vehicle weight is increasing with the addition of safety, convenience, and emotional equipment. Accordingly, interest in innovative lightweight measures to offset the increase in weight is increasing.

An example of a vehicle weight reduction plan is to reduce the weight of materials and parts, thereby increasing engine efficiency and maximizing the performance of the vehicle, thereby improving fuel economy.This is an effective method for improving the environment by preventing global warming and reducing emissions. When the weight is reduced by 10%, it improves fuel efficiency by 3.8% and reduces exhaust gas CO by 4.5% and NOx by 8.8%.

Another way to reduce weight of automobiles is structural optimization technology such as design review and component modularization, and lightweight material technology such as improvement of existing material properties and application of new materials. Materials used for this are metal materials such as steel, Al, and Mg, and polymer materials, and the advantages of these materials are maximized and applied to parts in the right place to achieve weight reduction.

Vehicle weight is a key factor that determines fuel efficiency, and vehicle weight reduction can additionally improve overall vehicle performance, such as reducing driving resistance, improving braking performance, and improving steering stability, as well as reducing fuel consumption and exhaust gas emissions.

Automobiles can be classified into body, chassis, powertrain, etc., and research and application related to weight reduction are actively carried out in body parts composed of a combination of about 300 or so plates.

In terms of automobile weight reduction, research is being conducted in two directions: developing new lightweight materials with excellent physical properties and improving mechanical properties of existing materials, and lightweight metal materials currently being studied are aluminum and magnesium, which have excellent weight reduction effects. There are high-strength and ultra-high-strength steels that have high strength by improving the mechanical properties of lightweight metals and existing steel materials.

Since automotive parts have different required properties depending on the part used, it is very important to apply materials suitable for the required properties of each part in the right place.

In general, materials such as high-tensile steel, aluminum, and magnesium, which are used to reduce the weight of automobile bodies, have characteristics of incombustibility and incompatibility with low molding limits in common. Therefore, when developing a component using lightweight metal, it is necessary to comprehensively consider the mechanical properties of the material, the geometric shape of the molded part, the required strength of the molded part, and the quality such as the possibility of weight reduction, and molding cost. Aluminum weighs about a third of iron and has excellent light weight, high specific strength and specific rigidity, excellent corrosion resistance, workability, thermoelectric conductivity, and has various advantages that do not cause brittle fracture at low temperatures. Therefore, aluminum is used as a lightweight material for typical automobiles. In selecting materials for automobile parts, not only simple weight reduction but also price competitiveness is important in terms of marketability, and aluminum has superior competitiveness compared to other lightweight materials. In addition, it is known that aluminum is excellent in recyclability, so that about 85% or more of aluminum alloys applied to automobiles can be recycled. The disadvantages of aluminum materials include low stiffness, difficulty in welding, and an increase in the price of steel (for the same performance, the price is twice as high when using roughly 1/2 of the steel material), and aluminum is a cylinder head and engine block. , And has been mainly used in various cases.

Aluminum applications are gradually increasing in automotive chassis parts such as subframes and suspensions. Global OEMs in Europe and Japan, such as Mercedes Benz, BMW, Audi and Honda, are leading the development of aluminum subframes, and extrusion molding method, casting method, hydroforming, hot gas molding to secure formability and process efficiency when manufacturing aluminum subframes. Various molding methods are being applied.

On the other hand, the vehicle bumper is to prevent physical damage to the vehicle by elastically deforming during a low and medium speed collision of the vehicle.When it collides with another vehicle or a fixture, it absorbs the shock to promote the safety of the occupant. It is a shock absorber disposed at the front and rear of the vehicle to minimize deformation of the vehicle body at the same time.

As shown in FIG. 1, the bumper 10 is fixed to the side member 31 on the vehicle body side by mounting the staves 23 on both rear sides of the bumper beam 21 arranged in the vehicle width direction from the front and rear of the vehicle. The bumper beam unit 25 is disposed in front of the bumper beam 21 and an energy absorber 27 that absorbs an impact force, and a bumper cover 29 that surrounds the bumper beam 21 and the energy absorber 27 Consists of

Here, in the conventional bumper beam unit 25, as shown in FIG. 2, the staves 23 are welded through separate flanges 41 on both rear sides of the bumper beam 21, and the staves 23 ) Is directly assembled to the side member 31 on the vehicle body side. In addition, the bumper beam unit 25 has a separate towing for selectively mounting a towing hook on the bumper beam 21 in order to connect a cable to the vehicle body or connect a trailer or a carrier to tow when the vehicle is rescued or towed. It is a situation in which the pipe 43 is attached.

In the bumper beam unit 25 assembled in the vehicle body as described above, the bumper beam 21 is manufactured and applied using an aluminum material in accordance with the recent trend of reducing weight of the vehicle.

However, it is difficult to achieve sufficient weight reduction of the vehicle only by manufacturing the bumper beam 21 using such an aluminum material, and furthermore, the stave 23 is in a situation in which a steel material is usually used, so that the stave 23 It can be said that it is preferable in terms of weight reduction that the entire bumper beam unit 25 including) is made of a lightweight material and is integrally manufactured.

However, in order to apply a new material to the bumper beam, which is an important structural component, it is necessary to determine the appropriate shape and dimensions to have excellent structural performance through computational structural analysis in the early stages of design, and to analyze and understand it. In order to manufacture, the shape and dimensions determined in this way must be implemented and manufactured through an easy method, and the original mechanical performance must also be maintained.

As a conventional technology related to weight reduction of the bumper beam unit, there may be mentioned the technology described in Korean Patent Publication No. 2015-0141454, in which a bumper stave and a flange plate are formed by extrusion of aluminum, and the set shape is formed through bending and cutting. It describes a bumper stay unit for a vehicle and a method of manufacturing the same, which reduces components, reduces cost, and realizes weight reduction by making it integrally so as to have it.

An object of the present invention is to provide an aluminum alloy material for an integrated bumper beam unit capable of securing rigidity while being able to easily extrude a bumper beam and a stave through extrusion molding.

The present invention also aims to provide an integrated bumper beam unit capable of securing impact rigidity while being lighter than the conventional bumper beam unit and a method of manufacturing the same.

One embodiment of the present invention, in terms of the total composition weight, Si 0.9 to 1.8% by weight, Fe 0.10 to 0.16% by weight, Cu 0.70 to 1.20% by weight, Mn 0.60 to 1.11% by weight, Mg 0.80 to 1.40% by weight, Cr It provides an aluminum alloy material for an integrated bumper beam unit, comprising 0.03 to 0.05% by weight, 0.02 to 0.04% Zn, and 0.01 to 0.03% by weight of titanium, and the balance consisting of Al and inevitable impurities.

The aluminum alloy material of the present invention according to a preferred embodiment may be a mechanical property after T6 tempering, having a tensile strength of 410 MPa or more, a yield strength of 360 MPa or more, and an elongation of 12% or more.

Another embodiment of the present invention provides an integrated bumper beam unit made of an aluminum alloy material according to the above embodiments.

In another embodiment of the present invention, (a) casting an aluminum alloy at 600 to 710° C. (S1); (b) homogenizing the cast aluminum alloy at 500 to 600° C. for 3 to 10 hours (S2); (c) preheating the homogenized aluminum alloy at 480 to 510°C, extruding, and then press quenching (S3); (d) heat-treating the extruded aluminum alloy at 90 to 110° C. for 30 to 120 minutes T1 (S4); (e) press bending the T1 heat-treated aluminum alloy (S5); And (f) subjecting the press-bent aluminum alloy to T6 heat treatment at 170 to 200°C for 5 to 7 hours (S6), wherein the aluminum alloy includes 0.9 to 1.8% by weight of Si, based on the total composition weight, Fe 0.10 to 0.16 wt%, Cu 0.70 to 1.20 wt%, Mn 0.60 to 1.11 wt%, Mg 0.80 to 1.40 wt%, Cr 0.03 to 0.05 wt%, Zn 0.02 to 0.04 wt%, titanium 0.01 to 0.03 wt% And, it provides a method of manufacturing an aluminum alloy integrated bumper beam unit using the remainder consisting of Al and inevitable impurities.

In the manufacturing method according to a preferred embodiment, in the step of heat-treating T1 (S4), the temperature is raised to a temperature of 90 to 110° C. at a temperature increasing rate of 0.1° C./s, and then the constant temperature is maintained for 30 to 120 minutes, It can be carried out by air cooling at room temperature.

The aluminum alloy material according to the present invention exhibits a similar degree of stiffness compared to the 7000 series alloy known as a high-strength aluminum alloy material in terms of mechanical properties after T6 tempering, and the extrudability is remarkably improved, so that the conventional bumper beam and the stave are separately manufactured and assembled. It is possible to easily manufacture a bumper beam unit through extrusion processing in one piece using a single aluminum alloy material instead of the old one, which can ultimately contribute to weight reduction of the vehicle and the effect of improving fuel economy.

1 to 2 show an exploded view and an assembly view of bumper members including a bumper beam for a conventional vehicle,
3 schematically illustrates a heat treatment process in the manufacturing process of an aluminum alloy integrated bumper beam according to the present invention.
4 is a process flow diagram schematically showing a process of processing and assembling a conventional bumper beam.
5 is a process flow diagram schematically showing the processing and assembly process of the integrated bumper beam according to the present invention.
6 is a product photograph of the integrated bumper beam unit manufactured in the present invention, and FIG. 7 is a longitudinal sectional view of a portion indicated by an arrow.

Hereinafter, the present invention will be described in more detail with reference to the drawings.

Bumper beams are mainly high-strength 6000 series aluminum alloys or 7000 series aluminum alloys to ensure ease of manufacture and high rigidity. In the case of 6000 series aluminum alloys, the effect of aging hardening by controlling the precipitation phase of magnesilicate (Mg ₂ Si) As a result, high-strength properties of the average tensile strength of 334 MPa and yield strength of 298 MPa are obtained, but the overall weight of the alloy is increased by increasing the thickness of the material to secure the stiffness of the product. In recent years, a 7000 series aluminum alloy having properties of a tensile strength of 400 MPa, a yield strength of 350 MPa, and an elongation of 10% is mainly used.

However, additional weight reduction is required to improve fuel efficiency of automobiles, and at the same time, high toughness for improving the strength of the bumper beam material and impact absorption is also required, and thus a need to have a higher elongation has emerged.

However, in order to secure high strength of 400 MPa or more, the elongation of the 7000 series aluminum alloy, which is mainly used, decreases to within 10%, so that additional weight reduction, high strength, and high elongation cannot be simultaneously pursued. In addition, for high strength, the content of Mn and Zn must be increased. In this case, the extrudability is lowered, making it difficult to manufacture the extruded shape, as well as a problem of lowering productivity and increasing manufacturing cost.

Therefore, it is possible to manufacture extruded profiles with high productivity due to excellent extrudability, and the tensile strength and yield strength can be increased while increasing the elongation by more than 10%, and thus, research on alloy materials that can enable high strength, high impact resistance, and weight reduction. The present inventors have already applied for this (Korean Patent Application No. 10-2017-0110368).

Here, in manufacturing an integrated bumper beam unit in which an aluminum bumper beam and a stale are integrated, an A6000-based material is used, but it is uniformly distributed in physical properties (hardness, strength) through aging hardening suppression heat treatment (T1) before bending the bumper beam. It describes the manufacturing method to have.

However, in the case of the A6061 or A6063 aluminum alloy discussed here, it is insufficient to view that it ultimately achieved sufficient high strength even in the mechanical properties after T5 or T6 tempering.

Accordingly, the present inventors have conducted extensive research on the influence of alloying elements capable of improving extrudability while securing strength in manufacturing an integrated bumper beam unit in which a bumper beam and a stave are integrated.

As a result, in 6000 series aluminum alloy, when the content ratio of Mg and Si is increased, the strength can be improved, and the components of Mn and Cr function as major elements to inhibit recrystallization growth, and the Cu component improves the hardness to precipitate β-phase. It was confirmed to accelerate.

In the case of aluminum alloy materials of the following composition, high strength and formability can be secured in extrusion molding of the integrated bumper beam unit, and mechanical properties that can achieve high strength even with thin films are identified. It was confirmed to be expressed;

By weight of the total composition, Si 0.9 to 1.8% by weight, Fe 0.10 to 0.16% by weight, Cu 0.70 to 1.20% by weight, Mn 0.60 to 1.11% by weight, Mg 0.80 to 1.40% by weight, Cr 0.03 to 0.05% by weight, Zn 0.02 An aluminum alloy material containing from 0.04% by weight to 0.01% by weight of titanium and from 0.01 to 0.03% by weight of titanium, and the remainder consisting of Al and inevitable impurities.

In the aluminum alloy material for an integrated bumper beam unit of the present invention, the effects of major elemental components that affect mechanical properties are as follows.

Si, together with Mg, is partially dissolved in the aluminum alloy matrix and solid-solution strengthened. In addition, during the artificial aging treatment at a relatively high temperature, it exhibits aging hardenability to form aging precipitates that contribute to the improvement of strength, thereby obtaining high strength and high strength required to satisfy mechanical properties required as a vehicle bumper beam unit. It is an essential element for When the Si content is too small, the absolute amount is insufficient, so that the solid solution strengthening and aging hardenability are insufficient. As a result, the required high strength and high proof strength cannot be obtained. On the other hand, when the content of Si is too large, it cannot be dissolved in the matrix, and thus coarse crystallized matter and precipitate are formed, which causes a decrease in strength, elongation, etc., and also lowers extrusion workability. Therefore, the Si content is preferably 0.9 to 1.8% by weight.

Mn has the effect of suppressing recrystallization and minimizing crystal grains by forming Al-(Fe, Mn, Cr)-based nano-dimensional fine dispersed particles during homogenization heat treatment, and a part of Mn is dissolved in the aluminum alloy plate matrix. Employment strengthening can occur. Therefore, the content of Mn is set to 0.60 to 1.11% by weight.

Mg is necessary for solid solution strengthening like Si, and to form aging precipitates that contribute to strength improvement with Si during the artificial aging treatment, exhibiting aging hardenability, and satisfying mechanical properties required as a bumper beam unit for a vehicle, It is an essential element for obtaining high strength and high strength. When the Mg content is too small, the absolute amount is insufficient, so that the solid solution strengthening and aging hardenability are insufficient. As a result, the required high strength and high proof strength cannot be obtained. On the other hand, when the Mg content is too large, the strength becomes too high and cannot be dissolved in the matrix, thereby forming coarse crystals and precipitates, resulting in a decrease in strength, elongation, and the like, and extrusion workability is also reduced. Therefore, the Mg content is in the range of 0.8 to 1.4% by weight.

Cr is an element that is usually regulated as an impurity, but it acts as a major element for inhibiting recrystallization growth like Mn, and its content is in the range of 0.03 to 0.05% by weight.

Cu, like Mg and Si, contributes to the improvement of strength and proof strength. When the Cu content is too small, the effect is not sufficiently obtained, and high strength and high yield strength required to satisfy the mechanical properties required as an integral bumper beam unit cannot be obtained. On the other hand, when the Cu content is too large, the strength and proof strength are rather reduced. Further, the extrusion processability is greatly reduced. Therefore, the Cu content is in the range of 0.7 to 1.2%.

In the case of such an aluminum alloy material, as a mechanical property after T6 tempering, a tensile strength of 410 MPa or more, a yield strength of 360 Pa or more, and an elongation of 12% or more may be satisfied. In particular, in the above and below, the mechanical properties after T6 tempering means, after casting an aluminum alloy at 700° C., the cast aluminum alloy is homogenized at 540° C. for 10 hours, and the homogenized aluminum alloy at 500° C. After preheating, extrusion, press quenching, the extruded aluminum alloy was naturally aged for 5 days at a temperature of 25°C, and then the temperature was raised to 100°C at a temperature increase rate of 0.1°C/s. After the T1 heat treatment for 1.5 hours, press-bending the T1 heat-treated aluminum alloy, and then T6 heat treatment at 175°C for 4 hours to define the mechanical properties.

In the above and below description, T6 tempering means performing a peak aging treatment after solution treatment and quenching treatment of the aluminum alloy material.

A preferred example of a method of manufacturing an integrated bumper beam unit through extrusion using such an aluminum alloy material is: (a) casting an aluminum alloy at 600 to 710° C. (S1); (b) homogenizing the cast aluminum alloy at 500 to 600° C. for 3 to 10 hours (S2); (c) preheating the homogenized aluminum alloy at 480 to 510°C, extruding, and then press quenching (S3); (d) heat-treating the extruded aluminum alloy at 90 to 110° C. for 30 to 120 minutes T1 (S4); (e) press bending the T1 heat-treated aluminum alloy (S5); And (f) heat-treating the press-bent aluminum alloy at 170 to 200°C for 5 to 7 hours (S6).

The method of manufacturing an aluminum alloy integrated bumper beam according to the present invention will be described in detail as follows.

3 schematically illustrates a heat treatment process in the manufacturing process of an aluminum alloy integrated bumper beam according to the present invention. With this reference, the manufacturing process of the aluminum alloy integrated bumper beam will be described.

First, an aluminum alloy having the above composition is cast at 600 to 710°C (S1).

In general, 6000 series aluminum alloy is a heat treatment alloy containing Mg and Si as main additive components. The above-described aluminum alloy used as the material of the integrated aluminum bumper beam unit in the present invention has variations in mechanical properties of the material according to the natural aging after extrusion, like other alloy materials, resulting in a deviation in bending dimensions during press bending, a later process. This can cause a decrease in equipment productivity, such as a change in press reduction conditions. Therefore, in the present invention, this problem can be solved by a T1 heat treatment process performed under specific conditions to be described later, and by applying this to the manufacture of an integrated bumper beam unit, dispersion of material properties can be minimized and a homogeneous product can be obtained.

Next, the cast aluminum alloy is homogenized at 500 to 600° C. for 3 to 10 hours (S2).

The homogenized aluminum alloy is preheated at 480 to 510°C, extruded, and then press quenched (S3).

The extruded aluminum alloy is subjected to T1 heat treatment at 90 to 110° C. for 30 to 120 minutes (S4). Specifically, after the natural aging hardening, the temperature is raised to a temperature of 90 to 110° C. at a temperature increase rate of 0.1° C./s, maintained at a constant temperature for 30 to 120 minutes, and then air-cooled at room temperature to perform primary heat treatment. .

In general, in the case of heat-treated alloys (A6000, 7000 series), 3 to 5 at about 500 to 550° C. in order to dissolve the components such as Mg and Si inside the aluminum alloy into a complete solid solution through a solution treatment (around 500°C). Isothermal heat treatment is performed for a period of time. Most of these processes require an additional process of heat treatment in an additional large heat treatment furnace immediately after extrusion.

However, the heat treatment according to the present invention omits the solution treatment process and follows a press heat treatment process similar to the solution treatment process by rapidly cooling at an outlet temperature (around 550°C) immediately after extrusion. However, when the product is extruded, the physical properties of the product are affected by conditions such as the outlet temperature and the extrusion speed, so it is important to reduce defects by reducing the quality dispersion and manufacturing a uniform product in order to satisfy the quality standard when producing a large number of products. Do.

Therefore, in the present invention, T1 heat treatment was introduced in order to uniformly distribute the quality of the product immediately after the press heat treatment. In the case of aluminum bending molding, the T1 heat treatment condition was introduced to minimize the product shape and dimensions after press bending according to the material properties of the material.

In general, T1 heat treatment refers to natural aging after cooling in high-temperature processing, but residual stress due to quenching exists inside due to the variation of the cooling rate of the material, so to remove it, it is 100℃ lower than the aging treatment temperature for 0.5 to 1.5 hours. The examples were conducted under the conditions of, and as a result of comparing their tensile strength, yield strength, and elongation, it was confirmed that the conditions of 100°C and 1.5 hours were optimal.

Then, the T1 heat-treated aluminum alloy is press-bent (S5).

The press-bent aluminum alloy is subjected to T6 heat treatment at 170 to 200°C for 5 to 7 hours (S6). This T6 heat treatment process is hardened by precipitation of solute atoms during artificial aging conditions and has a material strength performance of 360 MPa class of maximum tensile strength.

The above-described manufacturing process of a bumper beam is a manufacturing process of an integrated bumper beam that can obtain an effect of effectively shortening a process step in a conventional mass-produced bumper beam process.

Referring to FIGS. 4 and 5, FIG. 4 is a process flow diagram schematically showing a process of processing and assembling a conventional bumper beam, and FIG. 5 schematically illustrates a process and assembly process of an integrated bumper beam according to the present invention. It is the process flow diagram shown.

As shown in Figure 4, the conventional bumper beam process must go through a total of 23 steps from processing and welding/assembly process steps.

However, as shown in FIG. 5, the manufacturing process of the integrated bumper beam according to the present invention is a total of five steps, and the number of parts is one, and processes such as processing and welding with counterpart parts are unnecessary, so the number of processes and cost reduction, etc. The remarkable effect of can be obtained.

According to another aspect of the present invention, it is possible to provide an aluminum alloy integrated bumper beam unit manufactured by the above-described manufacturing method.

Hereinafter, the present invention will be described in detail based on examples, of course, that the present invention is not limited by these examples.

<Example>

After casting the aluminum alloy of the composition shown in Table 1 at 700°C, the cast aluminum alloy was homogenized at 540°C for 10 hours. The homogenized aluminum alloy was preheated at 500° C., extruded, and then press quenched. Then, the extruded aluminum alloy was naturally aged for 5 days at a temperature of 25° C., heated to 100° C. at a temperature rising rate of 0.1° C./s, and then subjected to T1 heat treatment for 1.5 hours. After press bending the T1 heat-treated aluminum alloy, T6 heat treatment was performed at 175° C. for 4 hours (a total of 5 hours including 1 hour of heating) to produce an aluminum alloy integrated bumper beam.

It goes without saying that the alloy components in Table 1 below contain inevitable trace amounts of impurities.

Alloy component (% by weight) Si Fe Cu Mn Mg Cr Zn Ti Al Example 1 0.65 0.20 0.34 0.14 0.87 0.18 0.02 0.01 Balance Example 2 1.12 0.13 0.86 0.86 1.01 0.04 0.03 0.02 Balance

After T6 tempering, the mechanical properties, that is, tensile strength, yield strength, and elongation were evaluated, and the results are shown in Table 2 below.

Tensile strength (MPa) Yield strength (MPa) Elongation (%) Example 1 322 292 9 Example 2 411 361 15

From the results of Table 2, in the case of the aluminum alloy of Example 2, the yield strength of 361 MPa, the tensile strength of 411 MPa, and the elongation of 15% were secured, compared to the aluminum alloy of Example 1 in manufacturing an integrated bumper beam unit. It can be seen that the extrusion processability will also be excellent while achieving high strength.

On the other hand, in order to check the mechanical properties of the alloy according to Example 2 compared to the A7000-based alloy having excellent strength among aluminum alloy materials, an alloy material was obtained through T7 tempering with an alloy having the composition shown in Table 3 below.

Usually, heat treatment of 7000 series aluminum alloy usually requires long-term maintenance with T7 (overaging) stabilization treatment, and the T7 temper here is 6 hours at 144°C in addition to heat treatment at 100°C for 6 hours (including 1 hour of heating). Maximum strength characteristics can be secured through heat treatment conditions of (including 1 hour of heating).

Alloy component (% by weight) Si Fe Cu Mn Mg Cr Zn Ti Al Example 3 0.04 0.11 0.48 0.14 1.30 0.01 4.83 0.03 Balance

After T7 tempering, the mechanical properties, that is, tensile strength, yield strength, and elongation were evaluated, and the results are shown in Table 4 below.

Tensile strength (MPa) Yield strength (MPa) Elongation (%) Example 3 460 371 15

From the results of Table 4, it can be seen that in the case of the alloy of Example 2, the result is comparable in strength to that of the alloy of Example 3.

As a result, it can be seen that the alloy of Example 2 can achieve the high-strength characteristics of 7000-based aluminum, and is also excellent in mechanical properties that can affect extrudability, and thus will be useful for manufacturing an integrated bumper beam unit.

On the other hand, the tensile strength, yield strength, and elongation of each sample completed until T4 heat treatment (before press molding) using the alloy material of Example 2 are shown in Table 5 below.

Heat treatment Tensile strength (MPa) Yield strength (MPa) Elongation (%) Example 2 T4 349.7 192.3 18.3

From the results of Table 5, it can be seen that the alloy material of Example 2 has excellent elongation after T4 heat treatment.

In the case of the alloy material of Example 2, as the mechanical properties after T4 heat treatment show the results shown in Table 5 above, stretching is advantageous after press molding, and there was no occurrence of problems such as cracks in forming the flange after press molding. It was confirmed visually.

Meanwhile, an integrated bumper beam unit of the shape shown in FIG. 6 was manufactured for simple evaluation of extrudability. 7 shows a longitudinal cross-section of the arrow portion of FIG. 6, and extrudability was evaluated by checking the dimensional deviation of the extruded cross-section.

As a result, in the case of using the alloy material of Example 2, when extruding at a die temperature of 430°C at an extrusion speed of about 1.0 to 2.0 mm/s, the deviation of the curvature dimension (top) in the dimension of the cross section was obtained to be 1t or less. It was confirmed that desirable extrudability was expressed in manufacturing the unit.

Claims (5)

delete delete delete (a) casting an aluminum alloy at 600 to 710°C (S1);
(b) homogenizing the cast aluminum alloy at 500 to 600° C. for 3 to 10 hours (S2);
(c) preheating the homogenized aluminum alloy at 480 to 510°C, extruding, and then press quenching (S3);
(d) heat-treating the extruded aluminum alloy at 90 to 110° C. for 30 to 120 minutes T1 (S4);
(e) press bending the T1 heat-treated aluminum alloy (S5); And
(f) T6 heat treatment of the press-bent aluminum alloy at 170 to 200°C for 5 to 7 hours (S6),
As the aluminum alloy, in terms of the total composition weight, Si 0.9 to 1.8 wt%, Fe 0.10 to 0.16 wt%, Cu 0.70 to 1.20 wt%, Mn 0.60 to 1.11 wt%, Mg 0.80 to 1.40 wt%, Cr 0.03 to 0.05 Using weight%, Zn 0.02 to 0.04% by weight, titanium 0.01 to 0.03% by weight, and the balance consisting of Al and inevitable impurities,
Method of manufacturing an aluminum alloy integrated bumper beam unit.
The method of claim 4, wherein the T1 heat treatment step (S4) is performed by raising the temperature to a temperature of 90 to 110°C at a temperature increase rate of 0.1°C/s, maintaining a constant temperature for 30 to 120 minutes, and then performing air cooling at room temperature. Method of manufacturing an aluminum alloy integrated bumper beam unit, characterized in that carried out by a method.

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