KR102487222B1 - High-strength aluminum rolled plate manufacturing method and high-strength aluminum rolled plate using the same - Google Patents

Abstract

The present invention a) in weight percent, copper (Cu) 5.1 to 5.9, magnesium (Mg) 0.6 to 0.9, manganese (Mn) 0.25 to 0.6, silver (Ag) 0.15 to 0.25, zirconium (Zr) 0.07 to 0.13, silicon Melting an aluminum alloy material consisting of (Si) 0.04 to 0.1, iron (Fe) 0.09 to 0.15, titanium (Ti) greater than 0 and less than 0.1, vanadium (V) 0.02 to 0.05, and the balance aluminum (Al) and unavoidable impurities b) casting the molten aluminum alloy, c) homogenizing the cast alloy, d) reheating the homogenized aluminum alloy, e) hot rolling the reheated aluminum alloy. , f) solution treatment of the hot-rolled aluminum alloy, g) cold-rolling of the solution treatment-treated aluminum rolled sheet, h) first aging treatment of the cold-rolled aluminum sheet, and i ) It relates to a method for producing a high-strength aluminum alloy rolled sheet material, characterized in that it comprises the step of second aging treatment of the first aged aluminum rolled sheet material.

Description

High-strength aluminum rolled plate manufacturing method and high-strength aluminum rolled plate using the same}

The present invention relates to a method for manufacturing a high-strength aluminum alloy rolled sheet including a process heat treatment (solution heat treatment - cold rolling - first aging treatment - second aging treatment) and a high-strength aluminum alloy rolled sheet using the same.

Metals used in various military materials must have excellent productivity such as molding and welding to support productivity, and must have excellent bulletproof performance and durability.

In general, steel materials have been used in almost all military materials due to low manufacturing cost and high strength requirements, but recently, light weight and high mobility are required, and the demand for lightweight metals that can replace steel materials is increasing.

Among them, aluminum alloys are being studied most representatively. Depending on the alloy elements, aluminum alloys range from medium and high-strength aluminum alloys such as 5000 series (Al-Mg) and 6000 series (Al-Mg-Si), 2000 series (Al-Cu) and 7000 series (Al-Zn- Various alloys are used as armor materials, ranging from high-strength aluminum alloys such as Mg-based).

For example, the Agency for Defense Development, 'aluminum alloy composite powder and its manufacturing method' (Korean Registered Patent Publication No. 10-2032802), 'Mischmetal-Added Titanium-Aluminum Alloy-Based Alloy' (Korean Registered Patent Publication No. 10-1842922 Research on aluminum alloy materials such as Ho) is actively in progress, and Kobe Steel of Japan is also conducting research on 'aluminum alloy manufacturing method' (Japanese Patent Registration No. 6750964).

However, aluminum alloys are expensive in the manufacturing process, so it is still difficult to completely replace steel materials. In particular, in order to manufacture 2xxx series high-strength aluminum alloy rolled sheets, dedicated equipment for stretching is essential. There are considerable difficulties.

Republic of Korea Patent Registration No. 10-2032802 (2019.10.10.) Republic of Korea Patent Registration No. 10-1842922 (2018.03.22.) Japanese Patent Registration No. 6750964 (2020.09.20.)

In order to solve the above problems, the present invention provides a method for manufacturing a high-strength aluminum alloy rolled sheet material that replaces the stretching process through processing heat treatment (solution heat treatment - cold rolling - first aging treatment - second aging treatment) The purpose.

In addition, the purpose of providing a method for producing a high-strength aluminum alloy rolled sheet having a tensile strength of 510 MPa or more, a yield strength of 480 MPa or more and an elongation of 6.5% or more at the same time by optimizing cold rolling, first aging treatment and second aging treatment conditions to be

One embodiment of the present invention for achieving the above object is a) by weight %, copper (Cu) 5.1 to 5.9, magnesium (Mg) 0.6 to 0.9, manganese (Mn) 0.25 to 0.6, silver (Ag) 0.15 to 0.25 , zirconium (Zr) 0.07 to 0.13, silicon (Si) 0.04 to 0.1, iron (Fe) 0.09 to 0.15, titanium (Ti) greater than 0 and 0.1 or less, vanadium (V) 0.02 to 0.05 and the balance aluminum (Al) and unavoidable Melting an aluminum alloy material composed of impurities, b) casting the molten aluminum alloy, c) homogenizing the cast alloy, d) reheating the homogenized aluminum alloy, e) Hot rolling the reheated aluminum alloy, f) solution heat treating the hot rolled aluminum alloy, g) cold rolling the solution heat treated aluminum rolled sheet, h) the cold rolled aluminum sheet It relates to a method for manufacturing a high-strength aluminum alloy rolled sheet material comprising the step of first aging treatment and i) the step of second aging treatment of the first aged aluminum rolled sheet material.

In the above embodiment, step d) may be performed at 450 to 500° C. for 10 to 15 hours.

In one embodiment, step e) may be performed at a reduction ratio of 60 to 90%.

In the above embodiment, step f) may be maintained at 500 to 550 ° C for 0.5 to 10 hours.

In the above embodiment, step g) may be performed at a cold reduction ratio of 1.5 to 20%.

In the above embodiment, the step i) includes (i-1) holding at 160 to 200 ° C. for 1 to 20 hours and (i-2) air-cooling the rolled sheet material having performed the step (i-1) steps may be included.

Another embodiment of the present invention, in weight percent, copper (Cu) 5.1 to 5.9, magnesium (Mg) 0.6 to 0.9, manganese (Mn) 0.25 to 0.6, silver (Ag) 0.15 to 0.25, zirconium (Zr) 0.07 to 0.13, silicon (Si) 0.04 to 0.1, iron (Fe) 0.09 to 0.15, titanium (Ti) greater than 0 and 0.1 or less, vanadium (V) 0.02 to 0.05, and the balance of aluminum (Al) and unavoidable impurities, It relates to a high-strength aluminum alloy rolled sheet material in which the content of copper (Cu) and magnesium (Mg) satisfies the following relational expression 1.

[Relationship 1]

7.5 ≤ [Cu]/[Mg] ≤ 9.5

(In the above relational expression 1, [Cu] is the weight% of copper (Cu), and [Mg] is the weight% of magnesium (Mg).)

In the above embodiment, the elongation of the aluminum alloy rolled sheet may be 6.5% or more.

In the above embodiment, the yield strength of the aluminum alloy rolled sheet may be 480 to 600 MPa.

In the above embodiment, the tensile strength of the aluminum alloy rolled sheet may be 510 to 700 MPa.

According to the method for manufacturing a high-strength aluminum alloy rolled sheet according to the present invention, the yield strength of 480 to 600 MPa and the yield strength of 510 to 700 MPa through processing heat treatment (solution heat treatment - cold rolling - first aging treatment - second aging treatment) It is possible to manufacture a high-strength aluminum alloy rolled sheet having a tensile strength and an elongation of 6.5% or more.

1 is a process chart for explaining a manufacturing method of a high-strength aluminum alloy rolled sheet according to an embodiment of the present invention.
Figure 2 is a graph showing the change in strength after solution treatment of a high-strength aluminum alloy according to an embodiment of the present invention.
3 is a photograph showing the surface state of a high-strength aluminum alloy rolled sheet according to an embodiment of the present invention.
Figure 4 is a graph for comparing the maximum tensile strength and treatment completion time of the high-strength aluminum alloy rolled sheet according to the second aging treatment time according to an embodiment of the present invention.
5 and 6 are photographs of the microstructure of a high-strength aluminum alloy rolled sheet manufactured according to an embodiment of the present invention.

Hereinafter, a high-strength aluminum alloy rolled sheet material and manufacturing method according to the present invention will be described in detail. The drawings introduced below are provided as examples so that the spirit of the present invention can be sufficiently conveyed to those skilled in the art. Therefore, the present invention may be embodied in other forms without being limited to the drawings presented below, and the drawings presented below may be exaggerated to clarify the spirit of the present invention. At this time, unless there is another definition in the technical terms and scientific terms used, they have meanings commonly understood by those of ordinary skill in the art to which this invention belongs, and the gist of the present invention in the following description and accompanying drawings Descriptions of well-known functions and configurations that may be unnecessarily obscure are omitted.

One embodiment of the present invention is a 2xxx-based high-strength aluminum alloy rolled sheet material, more preferably including copper (Cu), magnesium (Mg), manganese (Mn), silver (Ag), zirconium (Zr), and silicon (Si ), relates to a high-strength aluminum alloy rolled sheet material containing any one or more of iron (Fe) titanium (Ti) and vanadium (V).

The existing 2xxx series of high-strength aluminum alloy rolled sheets required stretching after solution heat treatment in the manufacturing process to secure straightness and improve mechanical properties. This has caused an increase in the cost of equipment investment due to the addition of equipment for stretching in addition to the usual rolling equipment, and a reduction in productivity due to the additional process. In addition, when the high-strength aluminum alloy rolled sheet is manufactured through the stretching method, the surface quality is reduced due to the orange peel phenomenon in which orange peel-like irregularities are formed on the surface.

In order to solve this problem, the present invention greatly improves productivity by replacing the stretching process by applying processing heat treatment (solution heat treatment - cold rolling - first aging treatment - second aging treatment), cold rolling, first aging treatment and By optimizing the second aging treatment conditions, it is possible to provide a high-strength aluminum alloy rolled sheet having a tensile strength of 510 to 700 MPa, a yield strength of 480 to 600 MPa, and an elongation of 6.5% or more at the same time.

Hereinafter, the composition range of the high-strength aluminum alloy rolled sheet according to an embodiment of the present invention will be described in detail. Hereinafter, unless otherwise specified, units are % by weight.

According to one embodiment, the high-strength aluminum alloy rolled sheet is, by weight, copper (Cu) 5.1 to 5.9, magnesium (Mg) 0.6 to 0.9, manganese (Mn) 0.25 to 0.6, silver (Ag) 0.15 to 0.25, zirconium (Zr) 0.07 to 0.13, silicon (Si) 0 to 0.1, iron (Fe) 0 to 0.15, titanium (Ti) 0 to 0.1, vanadium (V) 0 to 0.05, and the balance aluminum alloy (Al) and unavoidable impurities It can be done.

Copper (Cu) is included in an amount of 5.1 to 5.9% by weight.

The copper (Cu) may react with the aluminum alloy (Al) and precipitate as a compound such as CuAl ₂ at the grain boundary of the 2xxx-based aluminum alloy. Through this, it is possible to improve the strength and fatigue resistance of the aluminum alloy rolled sheet. In order to make this action useful, it is preferable to add 5.1% by weight or more of copper (Cu). If the amount of copper (Cu) is less than 5.1% by weight, the amount of the above-mentioned precipitate decreases, and thus the effect on the improvement of tensile strength by the main reinforcing phase may be insignificant. On the other hand, when the copper (Cu) content exceeds 5.9% by weight, the precipitate becomes coarse and the volume fraction of the precipitated phase at the grain boundary increases, causing a significant decrease in elongation. For this reason, the copper (Cu) is preferably included in 5.1 to 5.9% by weight.

Magnesium (Mg) is included in an amount of 0.6 to 0.9% by weight.

The magnesium (Mg) may combine with copper (Cu) and silver (Ag) components in aluminum alloys to affect precipitation of an omega (Ω) phase in an Al-Cu-Mg-Ag-based alloy system. In particular, the ratio (Cu/Mg) of the magnesium (Mg) to the copper (Cu) is important, because mechanical properties can be improved by changing aging precipitation behavior according to the content ratio of Cu/Mg. As described above, when considering that 5.1 to 5.9% by weight of copper (Cu) is added in the high-strength aluminum alloy rolled sheet according to an embodiment of the present invention, it is preferable that 0.6% by weight or more of magnesium (Mg) is added. However, if the amount of magnesium (Mg) is less than 0.6% by weight, the amount of age hardening of the aluminum alloy rolled sheet may be significantly reduced, and conversely, if the content of magnesium (Mg) exceeds 0.9% by weight, the strength is improved but the corrosion resistance and weldability may be reduced. For this reason, it is preferable that 0.6 to 0.9% by weight of magnesium (Mg) is included.

Manganese (Mn) is included in an amount of 0.25 to 0.6% by weight.

The manganese (Mn) may be dispersed as fine particles in the high-strength aluminum alloy rolled sheet material to hinder the movement of dislocations (Grain). Through this, it is possible to enhance the strength of the high-strength aluminum alloy rolled sheet. In order to make this action useful, it is preferable to add 0.25% by weight or more of manganese (Mn). If the amount of manganese (Mn) is less than 0.25% by weight, the amount of dispersed particles is significantly reduced and the mechanical properties are weakened. As a result, elongation decreases and brittleness increases. For this reason, it is preferable that the manganese (Mn) is contained in an amount of 0.25 to 0.6% by weight.

Silver (Ag) is included in an amount of 0.15 to 0.25% by weight.

When the silver (Ag) is added to the Al-Cu-Mg-based alloy, an omega (Ω) phase, which is a stable precipitated phase, may be precipitated in the matrix. This improves the mechanical properties of the high-strength aluminum alloy rolled sheet, and at the same time, it is possible to maintain high strength even in high-speed deformation. In order to make this action useful, the silver (Ag) is preferably added in an amount of 0.15% by weight or more. When the silver (Ag) is added in an amount of less than 0.15% by weight, the above-mentioned effect is not significant, and conversely, when the amount of the silver (Ag) exceeds 0.25% by weight, the manufacturing cost increases excessively compared to the degree to which the effect increases, resulting in an increase in production cost. there is a problem. For this reason, the amount of silver (Ag) is preferably 0.15 to 0.25% by weight.

Zirconium (Zr) is included in an amount of 0.07 to 0.13% by weight.

The zirconium (Zr) is an element contributing to grain refinement of the high-strength aluminum alloy rolled sheet material, and serves to increase the recrystallization temperature of the high-strength aluminum alloy rolled sheet material and lower the growth rate of crystal grains during the recrystallization process. In addition, the zirconium (Zr) can contribute to an increase in strength by suppressing local deformation or slip at grain boundaries. In order to make this action useful, the zirconium (Zr) is preferably added in an amount of 0.07% by weight or more. If the zirconium (Zr) is less than 0.07% by weight, it is difficult to implement the above-mentioned effect. Conversely, when the zirconium (Zr) content exceeds 0.13% by weight, quench sensitivity is increased, and thus tensile strength and fracture toughness may be reduced when the thickness of the plate material is increased. For this reason, the zirconium (Zr) is preferably included in an amount of 0.07 to 0.13% by weight.

Titanium (Ti) is included in less than 0.1% by weight (excluding 0%).

Like the zirconium (Zr), the titanium (Ti) is an element that contributes to grain refinement of the high-strength aluminum alloy rolled sheet. The titanium (Ti) may be added to the high-strength aluminum alloy rolled sheet through the Al-5Ti-1B rod and may provide an effect of preventing cracking of the slab during casting. In order to make this action useful, the titanium (Ti) may be added in an amount of 0% by weight or more, more preferably 0.015% by weight or more. However, when the amount of titanium (Ti) exceeds 0.1% by weight, TiB ₂ particles act as inclusions, causing a problem of deteriorating fracture toughness and fatigue characteristics. For this reason, it is preferable that the titanium (Ti) is included in 0.1% by weight in a range exceeding 0.

In addition, the high-strength aluminum alloy rolled sheet according to an embodiment of the present invention may improve strength and crack resistance by including appropriate amounts of silicon (Si), iron (Fe), titanium (Ti), and vanadium (V). Specifically, the high-strength aluminum alloy rolled sheet may include silicon (Si) 0 to 0.1, iron (Fe) 0 to 0.15, titanium (Ti) 0 to 0.1, vanadium (V) 0 to 0.05% by weight.

According to an embodiment, the content of copper (Cu) and magnesium (Mg) of the high-strength aluminum alloy rolled sheet may be added in a ratio that satisfies the following relational expression 1.

[Relationship 1]

7.5 ≤ [Cu]/[Mg] ≤ 9.5

(In the above relational expression 1, [Cu] is the weight% of copper (Cu), and [Mg] is the weight% of magnesium (Mg).)

As described above, when the ratio of the copper to the magnesium ([Cu]/[Mg]) is less than 7.5, the content of the copper (Cu) is excessively reduced compared to the magnesium (Mg), resulting in a sufficient amount of precipitation of the omega (Ω) phase. can decrease This causes the strength of the high-strength aluminum alloy rolled sheet to be reduced. Conversely, when the ratio of the copper to the magnesium ([Cu]/[Mg]) exceeds 9.5, the content of the magnesium (Mg) is excessively reduced compared to the copper (Cu), and the precipitation amount of the omega (Ω) phase is also reduced. As a result, mechanical properties may deteriorate.

For this reason, the ratio of the copper to the magnesium ([Cu]/[Mg]) is preferably 7.5 to 9.5, more preferably 7.7 to 8.2.

The composition of the high-strength aluminum alloy rolled sheet material according to an embodiment of the present invention has been described above. Hereinafter, a method of manufacturing a high-strength aluminum alloy rolled sheet will be described with reference to FIG. 1.

1 is a process chart for explaining a manufacturing method of a high-strength aluminum alloy rolled sheet according to an embodiment of the present invention.

Referring to Figure 1, the high-strength aluminum alloy rolled sheet according to an embodiment of the present invention is a) by weight, copper (Cu) 5.1 to 5.9, magnesium (Mg) 0.6 to 0.9, manganese (Mn) 0.25 to 0.6, silver (Ag) 0.15 to 0.25, zirconium (Zr) 0.07 to 0.13, silicon (Si) 0 to 0.1, iron (Fe) 0 to 0.15, titanium (Ti) 0 to 0.1, vanadium (V) 0 to 0.05 and the balance aluminum Melting an aluminum alloy material composed of alloy (Al) and unavoidable impurities, b) casting the molten aluminum alloy, c) homogenizing the cast alloy, d) homogenizing the homogenized aluminum alloy Reheating, e) hot rolling the reheated aluminum alloy, f) solution heat treating the hot rolled aluminum alloy, g) cold rolling the solution heat treated aluminum rolled sheet, h) The cold-rolled rolled aluminum sheet may be subjected to a first aging treatment and i) the step of performing a second aging treatment on the first aged aluminum rolled sheet.

First, step a) is a step for preparing a material for manufacturing the above-described high-strength aluminum alloy rolled sheet. The high-strength aluminum alloy rolled sheet is, by weight%, copper (Cu) 5.1 to 5.9, magnesium (Mg) 0.6 to 0.9, manganese (Mn) 0.25 to 0.6, silver (Ag) 0.15 to 0.25, zirconium (Zr) 0.07 to 0.13 , Silicon (Si) 0 to 0.1, iron (Fe) 0 to 0.15, titanium (Ti) 0 to 0.1, vanadium (V) 0 to 0.05, and the balance aluminum alloy (Al) and unavoidable impurities. It can be.

According to an embodiment, in step a), the ratio of copper (Cu) and magnesium (Mg) may be prepared in a range that satisfies relational expression 1.

[Relationship 1]

7.5 ≤ [Cu]/[Mg] ≤ 9.5

(In the above relational expression 1, [Cu] is the weight% of copper (Cu), and [Mg] is the weight% of magnesium (Mg).)

According to an embodiment, the high-strength aluminum alloy rolled sheet material made of the above-described composition ratio may be melted at 700 to 800 ° C. in a melting furnace.

Next, an aluminum alloy slab may be manufactured by casting and then cooling the molten alloy through step b). Specifically, the molten aluminum alloy may be cast using a commercial DC casting method. At this time, the casting temperature is preferably performed at 650 to 750 ° C. If the casting temperature is less than 650 ° C., the fluidity of the melt may decrease and a problem may occur in filling the casting mold, and the casting temperature exceeds 750 ° C. If it does, the shrinkage rate increases during solidification and cracks may occur. Thereafter, an aluminum alloy slab can be manufactured by a DC casting method through continuous supply of molten metal.

Next, fine segregation and residual stress inside the slab structure formed in the casting process through step c) may be homogenized and removed. Specifically, by holding at 480 to 550 ° C for 10 to 30 hours and then slowly cooling, the high-solute elements segregated at the grain boundaries diffuse into the base and uniformly re-precipitate, securing rollability in the subsequent processing process. Cracking during the secondary cooling of the slab can be prevented through mitigation. If the homogenization treatment temperature in step c) is less than 480° C., the high-solute elements at the grain boundaries cannot sufficiently diffuse, so that the solute segregation at the grain boundaries can cause brittleness and cause cracks during hot rolling. Conversely, if the homogenization treatment temperature exceeds 550 ° C., surface blisters may be formed due to high-temperature oxidation and local dissolution of the surface portion may occur. For this reason, the homogenization treatment temperature is preferably 480 to 550°C.

In addition, in step c), it is preferable to maintain at 480 to 550 ° C. for 10 to 30 hours. If the holding time is less than 10 hours, elements with a low diffusion coefficient may not sufficiently diffuse into the matrix, and if the holding time exceeds 30 hours, similarly, grain coarsening and high temperature oxidation due to long exposure at high temperatures Since the problem of may occur, the step c) requires maintaining a temperature of 480 to 550 ° C. for 10 to 30 hours.

In step d), the aluminum alloy slab can be reheated to secure a uniform temperature distribution in the thickness direction and to impart an additional homogenization treatment effect. Specifically, the aluminum alloy slab at 450 to 500 ° C. It can be reheated for 10 to 15 hours.

If the reheating temperature in step d) is less than 450 ° C, there is a problem that the high-temperature flow stress of the slab is relatively high, the rollability is lowered, and non-uniform residual stress is formed inside the finally manufactured rolled sheet. This may cause deformation even during the manufacturing process of the high-strength aluminum alloy rolled sheet or in a finished product state, and an additional heat treatment process may be performed to remove the residual stress, thereby reducing productivity.

Conversely, when the reheating temperature exceeds 500° C., the high-temperature flow stress of the slab is significantly reduced, and cracks and cracks may occur during rolling. For this reason, the reheating temperature is preferably 450 to 500°C.

In addition, step d) is preferably maintained at 450 to 500 ° C for 10 to 15 hours. If the holding time is less than 10 hours, the additional homogenization treatment effect of the slab may be significantly reduced. Conversely, if the holding time exceeds 15 hours, grain coarsening may occur due to exposure to high temperatures for a long time, thereby reducing final strength. For this reason, in step d), it is preferable to maintain a temperature of 450 to 500 ° C. for 10 to 15 hours.

In step e), the reheated aluminum alloy slab may be hot rolled. Specifically, the hot rolling may be performed by rolling rolls at 200 to 300 °C.

At this time, the hot rolling is preferably performed at a reduction ratio of 60 to 90%. If the reduction ratio is less than 60%, it is difficult to completely destroy the casting structure of the slab and it is difficult to effectively improve the strength of the final plate. On the other hand, if the reduction ratio is 60% or more, it is possible to sufficiently destroy the casting structure in the initial slab to manufacture an aluminum alloy hot-rolled sheet having a thickness of 20 to 100 mm. However, when the reduction ratio exceeds 90%, the number of rolling passes through which the rolling rolls stretch the aluminum alloy slab increases. This results in an increase in the manufacturing time for performing the rolling, and additional processing such as reheating is required because the hot rolling temperature must be maintained according to the increased time. For this reason, the hot rolling is preferably performed at a reduction ratio of 60 to 90%.

Step f) is a step of solution heat treating the high-strength aluminum alloy rolled sheet hot-rolled through step e). Specifically, it may be performed by maintaining the hot-rolled high-strength aluminum alloy rolled sheet at 500 to 550 ° C for 0.5 to 10 hours.

If the solution heat treatment temperature is less than 500° C., there is a problem in that a supersaturated solid solution is not sufficiently formed during the solution heat treatment, and thus the effect of the aging treatment is difficult to implement. Conversely, when the solution heat treatment temperature exceeds 550° C., the solid solution may overgrow and become coarse, and as a result, the strength may be significantly reduced. For this reason, the solution heat treatment temperature is preferably 500 to 550°C.

In addition, the time for performing the solution heat treatment may be variably adjusted according to the thickness of the hot-rolled sheet material, and more preferably may be increased as the thickness of the hot-rolled sheet material becomes thicker. However, if the time for performing the solution heat treatment exceeds 10 hours, high-temperature oxidation may occur, and crystal grains may excessively grow, resulting in reduced mechanical properties. In addition, if the time for performing the solution heat treatment is less than 0.5 hour, sufficient time is not given for solute atoms to diffuse into the matrix and become dissolved, making it difficult to realize the effect of the solution heat treatment. For this reason, it is preferable that the solution heat treatment be carried out for 0.5 to 10 hours.

Step g) is a step of cold rolling the aluminum alloy rolled sheet material subjected to solution heat treatment through step f). Specifically, the cold rolling may be performed in a cold rolling reduction range of 1.5 to 20%. If the cold rolling reduction ratio is less than 1.5%, the effect on the improvement of physical properties is insignificant, and if the cold rolling reduction ratio exceeds 20%, the strength increases but the elongation ratio is excessively reduced, resulting in deterioration in marketability. For this reason, it is preferable that the cold rolling reduction ratio is 1.5 to 20%.

According to an embodiment, step g) is preferably performed within 72 hours after step f), more preferably within 3 hours.

Referring to FIG. 2, it can be seen that the aluminum alloy rolled sheet subjected to the solution heat treatment through step f) undergoes rapid precipitation behavior immediately after the solution heat treatment, so that the yield strength rapidly increases. This may reduce productivity by requiring an excessive load in the cold rolling step to be described later. In particular, after solution heat treatment, if 72 hours are exceeded, the yield strength increases excessively, causing shear deformation and crack formation.

To prevent this, step g) is preferably performed within 72 hours after step f), more preferably within 3 hours after step f).

Steps h) and i) are steps of aging the aluminum alloy rolled sheet material cold-rolled through step g). At this time, steps h) and step i) are preferably performed in different temperature ranges, specifically, step h) may be performed at 20 to 40 ° C, and step i) may be performed at 160 to 200 ° C. can Hereinafter, the aging process performed at 20 to 40 ° C is defined as the first aging treatment, and the aging process performed at 160 to 200 ° C is defined as the second aging treatment.

The first aging treatment may be performed to enhance strength and provide a uniform nucleation site during the second aging treatment by precipitating fine precipitates inside the aluminum alloy rolled sheet before performing the second aging treatment to be described later.

As described above, the first aging treatment may be performed at 20 to 40 ° C. and may be performed for 20 to 200 hours.

If the first aging treatment is performed for less than 20 hours, the aging treatment time is insufficient and it is difficult to expect the effect, and if the first aging treatment exceeds 200 hours, the aging treatment effect is saturated and unnecessary process time may increase. . For this reason, the first aging treatment may be performed for 20 to 200 hours.

Thereafter, a second aging treatment may be performed by raising the aluminum alloy rolled sheet material to 160 to 200 ° C. The second aging treatment may be performed by maintaining the range of 1 to 20 hours at 160 to 200 ℃.

If the temperature of the second aging is less than 160° C. or less than 1 hour, it is difficult to expect an effect of increasing mechanical strength by the second aging, and conversely, if the second aging treatment exceeds 200° C. or 20 hours, precipitation phase Due to overaging, the growth of major precipitates and the distance between precipitates may increase. This causes a significant decrease in the mechanical strength of the aluminum alloy rolled sheet.

Finally, after the second aging treatment, the aluminum alloy rolled sheet may be cooled in air to complete the manufacturing process.

Hereinafter, the high-strength aluminum alloy rolled sheet and manufacturing method according to the present invention will be described in more detail through examples. However, the following examples are only one reference for explaining the present invention in detail, but the present invention is not limited thereto, and may be implemented in various forms.

Also, unless defined otherwise, all technical and scientific terms have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs. The terminology used in the description herein is merely to effectively describe specific embodiments and is not intended to limit the present invention. In addition, the unit of additives not specifically described in the specification may be % by weight.

go. Check physical property change immediately after solution heat treatment

Prior to manufacturing a high-strength aluminum alloy rolled sheet according to an embodiment of the present invention, the following experiment was performed to confirm the degree of change in physical properties after solution heat treatment.

By weight, copper (Cu) 5.8% by weight, magnesium (Mg) 0.75% by weight, manganese (Mn) 0.44% by weight, silver (Ag) 0.18% by weight, zirconium (Zr) 0.11% by weight, silicon (Si) 0.06% by weight , 0.14% by weight of iron (Fe), 0.04% by weight of titanium (Ti), 0.03% by weight of vanadium (V), and the balance of aluminum alloy (Al) and 2xxx series aluminum alloy materials consisting of unavoidable impurities were prepared.

The aluminum alloy material was melted at 750 ° C in a melting furnace, and then the molten aluminum molten metal was cast at 700 ° C using a DC casting method to manufacture an aluminum alloy slab. The cast aluminum alloy slab was maintained at 500 ° C. for 20 hours and then slowly cooled to perform homogenization treatment.

Thereafter, the aluminum alloy slab was reheated at 470° C. for 13 hours and then hot-rolled at a reduction rate of 70% of the initial thickness using a rolling roll having a temperature of 250° C.

The hot-rolled aluminum alloy rolled sheet was solution-treated at 530 ° C. for 2 hours, and the yield strength was measured for 100 days, and the results are shown in FIG. 2.

Referring to FIG. 2, it can be seen that the yield strength of the high-strength aluminum alloy rolled sheet is improved by a predetermined amount immediately after solution heat treatment. Specifically, the high-strength aluminum alloy rolled sheet immediately after solution heat treatment had a yield strength of 180.5 MPa, but the yield strength increased over time, and the yield strength increased to 242.9 MPa after 3 hours.

In addition, it increased to 285.2 MPa after 24 hours and 299.6 MPa after 72 hours, and after exceeding 72 hours, the yield strength was maintained constant at a level exceeding 300 MPa. Through this, it can be confirmed that the rapid precipitation behavior of the rolled aluminum sheet proceeds immediately after the solution heat treatment, so that the yield strength rapidly increases. This adversely affects the quality and productivity of the high-strength aluminum rolled sheet. For this reason, it is preferable to perform cold rolling within 72 hours after the solution heat treatment, more preferably within 3 hours.

me. Check the effect of cold working and first aging treatment during processing heat treatment

[Example 1]

Checking the influence of cold rolling and first aging treatment conditions on the mechanical properties of aluminum alloy during processing heat treatment (solution heat treatment - cold rolling - first aging treatment - second aging treatment) of high-strength aluminum alloy rolled sheet To this end, a 2xxx-based aluminum alloy material was prepared with the same composition as in Preparation Example 1 in Table 1 below.

The aluminum alloy material was melted at 700 ° C. in a melting furnace, and then, a number of aluminum alloy slabs having a width of 320 mm, a thickness of 110 mm, and a length of 1200 mm were manufactured using the molten aluminum alloy using a pilot-class DC casting facility. Thereafter, the prepared slab was cooled after homogenization treatment to remove microsegregation and residual stress during casting.

To manufacture a rolled sheet, the slab was reheated at 480° C. for 13 hours, and hot-rolled at a reduction rate of 70% of the initial thickness using a rolling roll having a temperature of 200° C.

The hot-rolled aluminum alloy rolled sheet was subjected to solution heat treatment at 530 ° C. for 2 hours, then cold rolling was performed at a cold rolling reduction of 15% within 3 hours, and a first aging treatment was performed at 30 ° C. for 72 hours.

[Example 2]

All processes were performed in the same manner as in Example 1 except that cold rolling was performed at a cold rolling reduction of 11%.

[Example 3]

All processes were performed in the same manner as in Example 1 except that cold rolling was performed at a cold rolling reduction of 7%.

[Example 4]

A 2xxx-based aluminum alloy material was prepared with the same composition as in Preparation Example 2 of Table 1, and all processes were performed in the same manner as in Example 1 except that cold rolling was performed at a cold rolling reduction of 10%.

[Comparative Example 1]

Except for omitting the cold rolling process, all processes were performed in the same manner as in Example 1.

[Comparative Example 2]

All processes were performed in the same manner as in Example 1 except that the cold rolling process was omitted and the first aging treatment was performed for 3 hours.

[Comparative Example 3]

All processes were performed in the same manner as in Example 1 except that cold rolling was performed at a cold rolling reduction of 1%.

[Comparative Example 4]

All processes were performed in the same manner as in Example 1 except that cold rolling was performed at a cold rolling reduction of 23%.

[Comparative Example 5]

All processes were performed in the same manner as in Example 1 except that cold rolling was performed at a cold rolling reduction of 11% and the first aging treatment was performed for 15 hours.

[Comparative Example 6]

All processes were performed in the same manner as in Example 1 except that cold rolling was performed at a cold rolling reduction of 11% and the first aging treatment was performed for 240 hours.

[Comparative Example 7]

A 2xxx-based aluminum alloy material was prepared with the same composition as Comparative Preparation Example 2 in Table 1, and all processes were performed in the same manner as in Example 1 except that cold rolling was performed at a cold rolling reduction of 10%.

[Comparative Example 8]

A 2xxx-based aluminum alloy material was prepared with the same composition as Comparative Preparation Example 2 in Table 1, and a conventional high-strength aluminum alloy rolled sheet manufacturing method including a cold stretching process rather than cold rolling was applied.

Cu Mg Mn Ag Zr Si Fe Ti V Preparation Example 1 5.8 0.75 0.44 0.18 0.11 0.06 0.14 0.04 0.03 Preparation Example 2 5.56 0.68 0.42 0.16 0.12 0.04 0.09 0.02 0.02 Comparative Preparation Example 1 5.11 0.68 0.28 0.14 - 0.03 0.08 0.02 0.11 Comparative Preparation Example 2 4.76 0.6 0.32 0.15 - 0.05 0.09 0.08 0.02 Comparative Preparation Example 3 4.91 0.61 0.33 0.17 - 0.05 0.09 0.09 0.02

The tensile strength, yield strength and elongation at room temperature were measured as shown in Table 2 below using a tensile tester for the high-strength aluminum alloy rolled sheets prepared in Examples 1 to 4 and Comparative Examples 1 to 8.

Furtherance cold rolling reduction
(%) 1st aging treatment
time (h) The tensile strength
(MPa) yield strength
(MPa) elongation rate
(%) Example 1 Preparation Example 1 15 72 518.9 426.7 8.8 Example 2 11 499.8 397.4 10.5 Example 3 7 489.8 372.9 12.7 Example 4 Preparation Example 2 10 491.1 384.5 12.3 Comparative Example 1 Preparation Example 1 - 72 468.3 299.6 19.5 Comparative Example 2 3 432.0 242.9 20.7 Comparative Example 3 1.0 72 469.3 201.2 19.7 Comparative Example 4 23 521.4 429.0 6.7 Comparative Example 5 11 15 491.0 385.9 10.9 Comparative Example 6 240 501.1 400.3 10.2 Comparative Example 7 Comparative Preparation Example 2 10 72 440.3 338.8 13.2 Comparative Example 8 - 397.4 310.9 23.8

Referring to Table 2, it can be seen that the high-strength aluminum alloy rolled sheets prepared in Examples 1 to 4 commonly have a yield strength of 370 MPa or more, a tensile strength of 480 MPa or more, and an elongation of 8% or more.

On the other hand, Comparative Example 8, in which a rolled sheet material was manufactured through a conventional stretching method without performing cold rolling, has a tensile strength of 397.4 MPa, a yield strength of 310.9 MPa, and an elongation of 23.8%. This exhibited lower tensile and yield strength compared to Examples 1 to 4 in which cold working and first aging treatment were performed, and even when compared to Comparative Example 7 in which all processes were the same except for 10% cold rolling, a lower strength level was obtained. indication can be seen. That is, in manufacturing a high-strength aluminum alloy rolled sheet, it can be confirmed that the cold working and the first aging treatment contribute to strengthening the strength.

In addition, on the other hand, the tensile strength of Comparative Example 1 in which only the first aging treatment was performed without cold working was 468.3 MPa and the yield strength was 299.6 MPa. It can be seen that the tensile strength is 21.5 to 50.6 MPa and the yield strength is 73.3 to 127.1 MPa lower than that of the rolled sheets prepared in Examples 1 to 3 having the same composition. This means that the cold working performed in the cold rolling reduction range of 1.5 to 20.0% improved the tensile strength of the aluminum alloy rolled sheet by 4.6 to 10.8% and the yield strength by 24.5 to 42.4%.

In addition, when comparing Examples 1 to 3 and Comparative Examples 3 to 4, it can be seen that the tensile strength and yield strength increase as the cold rolling reduction ratio increases under the same conditions.

However, comparing Example 1 in which the cold rolling reduction is 15% and Comparative Example 3 in which the cold rolling reduction is less than 1.5%, it can be seen that when the cold rolling reduction is less than 1.5%, the yield strength is reduced by 225.5 MPa and the tensile strength is reduced by 49.6 MPa. Comparing Example 1 in which the cold reduction ratio is 15% and Comparative Example 4 in which the cold reduction ratio exceeds 20%, the tensile strength and yield strength increase with the cold reduction ratio when the cold reduction ratio exceeds 20%. Although the increase in strength-to-width ratio is not large, it can be seen that the elongation decreases by about 2.1% from 8.8% to 6.7%.

Based on the above results, it can be confirmed that the cold reduction ratio is 1.5 to 20% of critical significance.

Comparing Example 2 and Comparative Example 5, Example 2 in which the first aging treatment was performed for 72 hours under the same conditions has a tensile strength of 499.8 MPa and a yield strength of 397.4 MPa. On the other hand, Comparative Example 5 in which the first aging treatment was performed for 15 hours had a tensile strength of 491 MPa and a yield strength of 385.9 MPa, which was 8.8 MPa and 11.1 MPa lower in yield strength than Example 2. In the case of Comparative Example 6 in which the first aging treatment was performed for 240 hours, the tensile strength was 501.1 MPa and the yield strength was 400.3 MPa, showing slightly higher tensile and yield strength than Example 2, but the increase in tensile and yield strength compared to Example 2 is 1.3 MPa and 2.9 MPa, respectively, and it can be seen that the increase in strength is not large even if the first aging treatment exceeds 200 hours.

This is because, as described above, when the first aging treatment is performed for less than 20 hours, the aging treatment time is insufficient and it is difficult to expect the effect, and when the first aging treatment exceeds 200 hours, the effect is saturated.

On the other hand, comparing Examples 2, 4, and Comparative Example 7, in which the cold reduction ratio and the first aging treatment time are similar, Example 2 and Example 4 have a tensile strength of 490 MPa or more and a yield strength of 380 MPa or more, It can be seen that Comparative Example 7 has a tensile strength of 440.3 MPa and a yield strength of 338.8 MPa. It is expected that the above difference is realized due to the difference in composition, more specifically, the difference in the content of copper (Cu) and zirconium (Zr). In fact, Examples 2 and 4 contain 5.56 to 5.8% by weight of copper (Cu) and 0.11 to 0.12% by weight of zirconium (Zr), so that the volume fraction of the main reinforcing phase is increased, and the crystal grains of the rolled sheet are refined, The zirconium (Zr) has an effect of increasing strength by suppressing local deformation or slip at grain boundaries.

all. Confirmation of 2nd aging treatment conditions

In order to confirm the influence of the second aging treatment condition on the mechanical properties of the aluminum alloy during the processing heat treatment (solution heat treatment - cold rolling - first aging treatment - second aging treatment) of aluminum alloy rolled sheet, the following example Alternatively, a high-strength aluminum alloy rolled sheet was manufactured according to Manufacturing Example.

[Example 5]

After manufacturing a high-strength aluminum alloy rolled sheet in the same manner as in Example 1, a second aging treatment was performed at a holding time of maximum tensile strength at 180 ° C, and the second aging treatment was completed at room temperature. It was air-cooled until it fell.

[Example 6]

All processes were performed in the same manner as in Example 5 except that a high-strength aluminum alloy rolled sheet was manufactured in the same manner as in Example 2.

[Example 7]

All processes were performed in the same manner as in Example 5 except that a high-strength aluminum alloy rolled sheet was manufactured in the same manner as in Example 3.

[Example 8]

All processes were performed in the same manner as in Example 5 except for cold rolling at a cold rolling reduction of 5.6%.

[Example 9]

All processes were performed in the same manner as in Example 5 except that cold rolling was performed at a cold rolling reduction of 1.5%.

[Example 10]

After manufacturing a high-strength aluminum alloy rolled sheet in the same manner as in Example 4, all processes were performed in the same manner as in Example 5 except for cold rolling at a cold rolling reduction of 15%.

[Example 11]

All processes were performed in the same manner as in Example 10 except for cold rolling at a cold rolling reduction of 10%.

[Example 12]

All processes were performed in the same manner as in Example 10 except for cold rolling at a cold rolling reduction of 5%.

[Comparative Example 9]

All procedures were performed as in Example 6 except that the second aging treatment was performed at 150 ° C.

[Comparative Example 10]

All procedures were performed as in Example 6 except that the second aging treatment was performed at 210 ° C.

[Comparative Example 11]

All processes were performed in the same manner as in Example 5 except for preparing a high-strength aluminum alloy rolled sheet in the same manner as in Comparative Example 1.

[Comparative Example 12]

A 2xxx-based aluminum alloy material was prepared with the same composition as Comparative Preparation Example 1 in Table 1, and all processes were performed in the same manner as in Example 5 except that cold rolling was performed at a cold rolling reduction of 1.84%.

[Comparative Example 13]

All processes were performed in the same manner as in Example 6 except that a high-strength aluminum alloy rolled sheet was manufactured in the same manner as in Comparative Example 7.

[Comparative Example 14]

All processes were performed in the same manner as in Comparative Example 13 except for cold rolling at a cold rolling reduction of 5%.

[Comparative Example 15]

All processes were performed in the same manner as in Comparative Example 13 except for cold rolling at a cold rolling reduction of 15%.

[Comparative Example 16]

A high-strength aluminum alloy rolled sheet was manufactured in the same manner as in Comparative Example 8, and all processes were performed in the same manner as in Example 5 except that the cold stretching method was applied instead of cold rolling.

[Comparative Example 17]

A 2xxx-based aluminum alloy material was prepared with the same composition as Comparative Manufacturing Example 3 in Table 1, and all processes except that a conventional high-strength aluminum alloy rolled sheet manufacturing method including a cold stretching process other than cold rolling were applied were applied. The same procedure as in 16 was performed.

The tensile strength, yield strength and elongation at room temperature were measured as shown in Table 3 below using a tensile tester for the high-strength aluminum alloy rolled sheets prepared in Examples 5 to 12 and Comparative Examples 9 to 17.

Furtherance cold rolling reduction
(%) Second aging treatment
Temperature (℃) The tensile strength
(MPa) yield strength
(MPa) elongation rate
(%) Example 5 Preparation Example 1 15 180 573 547 6.6 Example 6 11 558 530 7.9 Example 7 7 544 512 8.5 Example 8 5.6 545 515 8.1 Example 9 1.5 539.6 497.2 8.9 Example 10 Preparation Example 2 15 552 523 10.5 Example 11 10 533 495 8.0 Example 12 5 518 482 11.8 Comparative Example 9 Preparation Example 1 11 150 506 475 8.2 Comparative Example 10 11 210 532 485 7.7 Comparative Example 11 - 180 509 451 7.0 Comparative Example 12 Comparative Preparation Example 1 1.84 506 463 8.7 Comparative Example 13 Comparative Preparation Example 2 10 498 474 9.6 Comparative Example 14 5 490 461 10.2 Comparative Example 15 15 511 476 5.0 Comparative Example 16 - 500 477 8.6 Comparative Example 17 Comparative Preparation Example 3 - 501 489 10.1

First, processing heat treatment (solution heat treatment - cold rolling - first aging treatment - second aging treatment) was performed according to Comparative Examples 16 and 17 in which rolled sheets were manufactured through a conventional stretching method and an embodiment of the present invention. Examples 5 to 12 can be compared.

Specifically, the high-strength aluminum alloy rolled sheet according to an embodiment of the present invention has a tensile strength of 518 to 573 MPa, a yield strength of 482 to 547 MPa, a tensile strength of 500 to 501 MPa, and a yield strength of 477 to 489 MPa. It was confirmed that a high-strength high-strength aluminum alloy rolled sheet material could be manufactured compared to the above.

In addition, referring to FIG. 3, the high-strength aluminum alloy rolled sheet (FIG. 3 (a)) prepared in Example 5 of the present invention has an even surface condition and has no defects, but the high-strength aluminum produced in Comparative Example 16 of the present invention Severe orange peel was observed on the surface of the alloy rolled sheet (Fig. 3 (b)). Surface roughness It can also be seen that Example 5 has a relatively even surface roughness of 0.292 μm, whereas Comparative Example 16 has a rough surface roughness of 2.079 μm.

This difference is considered to be due to the general stretching method receiving tensile stress at both ends of the aluminum alloy rolled sheet, increasing the grains to become coarse, and forming anisotropy between grains. On the other hand, the aluminum alloy rolled sheet according to the embodiment of the present invention has an excellent surface condition because there is no stretching process, and the strength can be further strengthened through cold rolling and first and second aging treatments.

This time, it is possible to compare the change in physical properties according to the second aging treatment temperature. Specifically, Examples 5 to 12 subjected to the second aging treatment at 160 to 200 ° C according to an embodiment of the present invention can implement a yield strength of 482 MPa or more and a tensile strength of 518 MPa or more. At the same time, elongation of 6.5% or more was secured. This is because, through the second aging treatment, the supersaturated solid solution of the aluminum alloy rolled sheet material is sufficiently precipitated and the aging treatment implements the desired mechanical properties.

On the other hand, Comparative Example 9 having a second aging treatment temperature of less than 160° C. has a tensile strength of 506 MPa and a yield strength of 475 MPa, so it can be seen that it does not secure sufficient strength compared to Examples 5 to 12. In addition, Comparative Example 10 in which the second aging treatment was performed at 210 ° C. had a tensile strength of 532 MPa and a yield strength of 485 MPa. This is because, as described above, the distance between precipitates increased due to overaging of the high-strength aluminum alloy rolled sheet.

In addition, it can be confirmed that the effect of the second aging treatment is implemented differently depending on the cold rolling reduction ratio. Specifically, in Examples 5 to 12 having similar compositions and second aging treatment conditions, it can be seen that the strength increases as the cold reduction ratio increases.

On the other hand, referring to FIG. 4, when the composition of the aluminum alloy is the same as in Preparation Example 1 and the second aging treatment is performed at 180° C., not only the strength is remarkably improved as the amount of cold rolling reduction increases, but also the maximum tensile strength. It can be seen that the arrival time is significantly shortened. This suggests that the plate material manufacturing method according to the embodiment of the present invention has a great advantage not only in terms of high strength but also in terms of productivity improvement.

In addition, in FIG. 4, the plate material having the same composition as in Preparation Example 1 was rolled at a 10% cold reduction rate (a graph marked 'Δ' in FIG. 4) and the plate material having the same composition as in Comparative Preparation Example 2 was cold The rolling conditions (a graph marked with '☆' in FIG. 4) can be compared with the reduction ratio.

In FIG. 4, comparing the graph marked with '△' and the graph marked with '☆', when the degree of aging treatment and cold working are similar, the graph marked with '△' is compared to the condition with the marked '☆'. It can be seen that the strength is significantly improved. This means that when the plate material having the same composition as Preparation Example 1 is rolled at the same cold reduction rate as the plate material having the same composition as Comparative Preparation Example 2, the strength can be significantly improved.

The aforementioned difference in strength is due to copper (Cu) and zirconium (Zr) contents. Specifically, the graph marked '△' contains 0.11% by weight of zirconium (Zr) and has an effect of increasing strength, but the graph marked '☆' does not contain zirconium (Zr) and performs the same cold rolling. There is also a difference in tensile strength and yield strength.

In addition, in order to more specifically analyze the difference in strength according to the presence or absence of zirconium (Zr), the microstructure of the high-strength aluminum alloy rolled sheet was photographed.

Referring to Figure 5, according to Example 5 (Fig. 5 (a)), Example 6 (Fig. 5 (b)) and Example 7 (Fig. 5 (c)) including zirconium (Zr) It can be seen that the manufactured high-strength aluminum alloy rolled sheet has a relatively fine grain size. This is evidence that crystal grain refinement is performed by zirconium (Zr) attached in the high-strength aluminum alloy rolled sheet material, thereby affecting mechanical strength improvement.

On the other hand, in Comparative Example 12 (FIG. 6(a)) and Comparative Example 17 (FIG. 6(b)) in which zirconium (Zr) was not added, it can be confirmed that the crystal grains were relatively coarsened.

It can be confirmed that the size difference of these crystal grains contributes decisively to the formation of strength during sample processing, and as a result, high-strength characteristics are realized.

Finally, after preparing a test piece having an area of 300 x 400 mm and a thickness of 30.20 mm (error range ± 0.04) by the methods of Examples 5 to 7 and Comparative Examples 16 to 17, a ballistic test was performed. The bulletproof test was conducted according to the MIL-STD-662F standard, and specifically, two partial penetration tests and two complete penetration tests were conducted. The results are disclosed in Table 4 below.

specimen thickness
(mm) Velocity (m/s) protection limit speed
V ₅₀ (㎧) speed range
(㎧) Partial Penetration (PP) Full Penetration (CP) One 2 3 4 Example 5 30.20 754.9 764.9 770.4 768.9 764.6 15.5 Example 6 30.15 774.9 765.7 768.9 770.4 770.0 17.5 Example 7 30.17 758.3 751.1 768.1 768.6 761.5 17.5 Comparative Example 16 30.19 750.9 742.9 754.4 751.0 749.8 11.5 Comparative Example 17 30.27 740.4 737.9 751.2 751.3 745.2 13.4

Referring to Table 4, the high-strength aluminum alloy rolled sheets prepared in Examples 5 to 7 have a protection limit speed (V ₅₀ ) of 761.5 to 770.0 m/s and Comparative Examples 16 to 17 high-strength aluminum alloys prepared by a conventional stretching process It can be confirmed that 11.7 to 24.8 ㎧ is improved compared to the plate material.

That is, the high-strength aluminum alloy rolled sheet according to an embodiment of the present invention is subjected to processing heat treatment (solution heat treatment - cold rolling - first aging treatment - using rolling equipment that can utilize existing rolling and heat treatment equipment instead of the usual stretching process). The aluminum alloy rolled sheet material is manufactured through the second aging treatment), but strength characteristics at high speed deformation as well as strength and elongation can be secured by adjusting the conditions of cold rolling, first aging treatment and second aging treatment.

Although the present invention has been described through specific details and limited examples as described above, this is only provided to help a more general understanding of the present invention, the present invention is not limited to the above examples, and the present invention belongs Various modifications and variations from these descriptions are possible to those skilled in the art.

Therefore, the spirit of the present invention should not be limited to the described embodiments, and it will be said that not only the claims to be described later, but also all modifications equivalent or equivalent to these claims belong to the scope of the present invention. .

Claims (13)

a) In weight percent, copper (Cu) 5.1 to 5.9, magnesium (Mg) 0.6 to 0.9, manganese (Mn) 0.25 to 0.6, silver (Ag) 0.15 to 0.25, zirconium (Zr) 0.07 to 0.13, silicon (Si) Melting an aluminum alloy material consisting of 0.04 to 0.1, iron (Fe) 0.09 to 0.15, titanium (Ti) greater than 0 and less than 0.1, vanadium (V) 0.02 to 0.05, and the balance aluminum (Al) and unavoidable impurities;
b) casting the molten aluminum alloy;
c) homogenizing the cast alloy;
d) reheating the homogenized aluminum alloy;
e) hot rolling the reheated aluminum alloy;
f) subjecting the hot-rolled aluminum alloy to a solution heat treatment;
g) cold-rolling the solution heat-treated aluminum rolled sheet;
h) subjecting the cold-rolled rolled aluminum sheet to a first aging treatment; and
Including; i) second aging treatment of the aluminum rolled sheet subjected to the first aging treatment;
Step h) is performed at 20 to 40 ° C. for 20 to 200 hours,
In step i),
(i-1) maintaining at 160 to 200° C. for 1 to 20 hours; and
(i-2) A method for producing a high-strength aluminum rolled sheet material comprising the step of air-cooling the sheet material having performed step i-1). According to claim 1,
Step d) is a method for producing a high-strength aluminum rolled sheet, characterized in that carried out at 450 to 500 ℃ for 10 to 15 hours. According to claim 1,
Step e) is characterized in that carried out at a reduction ratio of 60 to 90%, a method for producing a high-strength aluminum rolled sheet. According to claim 1,
Step f) is characterized in that maintained at 500 to 550 ℃ for 0.5 to 10 hours, a method for producing a high-strength aluminum rolled sheet. According to claim 1,
Step g) is characterized in that carried out at a cold rolling reduction of 1.5 to 20%, a method for producing a high-strength aluminum rolled sheet. According to claim 1,
Step g) is characterized in that carried out within 72 hours immediately after step f), a method for producing a high-strength aluminum rolled sheet. According to claim 6,
Step g) is a method for producing a high-strength aluminum rolled sheet, characterized in that performed within 3 hours immediately after step f). delete delete By weight%, copper (Cu) 5.1 to 5.9, magnesium (Mg) 0.6 to 0.9, manganese (Mn) 0.25 to 0.6, silver (Ag) 0.15 to 0.25, zirconium (Zr) 0.07 to 0.13, silicon (Si) 0.04 to 0.04 0.1, iron (Fe) 0.09 to 0.15, titanium (Ti) greater than 0 and less than 0.1, vanadium (V) 0.02 to 0.05, and the balance consisting of aluminum (Al) and unavoidable impurities,
The content of copper (Cu) and magnesium (Mg) satisfies the following relational expression 1,
Characterized in that it is produced by performing a first aging treatment performed at 20 to 40 ° C. for 20 to 200 hours and a second aging treatment performed at 160 to 200 ° C. for 1 to 20 hours and air-cooled, high-strength aluminum rolled sheet.
[Relationship 1]
7.5 ≤ [Cu]/[Mg] ≤ 9.5
(In the above relational expression 1, [Cu] is the weight% of copper (Cu), and [Mg] is the weight% of magnesium (Mg).) According to claim 10,
Characterized in that the elongation of the aluminum rolled sheet is 6.5% or more, high-strength aluminum rolled sheet. According to claim 10,
Characterized in that the yield strength of the aluminum rolled sheet is 480 to 600 MPa, high-strength aluminum rolled sheet. According to claim 11,
Characterized in that the tensile strength of the aluminum rolled sheet is 510 to 700 MPa, high-strength aluminum rolled sheet.

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