KR101698533B1 - Aluminium wrought alloy - Google Patents

Abstract

The present invention provides an aluminum wrought alloy not deformed in a solution process and a press water quenching (PWQ) process. According to the present invention, the aluminum wrought alloy comprises: 5.5-6.0 wt% of Zn; 2.0-2.5 wt% of Mg; 0.2-0.6 wt% of Cu; 0.1-0.2 wt% of Cr; 0.2 wt% or less (greater than 0 wt%) of Fe; 0.2 wt% or less (greater than 0 wt%) of Mn; 0.2 wt% or less (greater than 0 wt%) of Si; 0.1 wt% or less (greater than 0 wt%) of Ti; 0.05 wt% or less (greater than 0 wt%) of Sr; and the remainder consisting of Al.

Description

[0001] Aluminum wrought alloy [0002]

BACKGROUND OF THE INVENTION 1. Field of the Invention [0001] The present invention relates to an alloy of a body material, and more particularly to an aluminum body material alloy.

Aluminum extruded materials have been applied to increase the strength of automobile bumpers, structural materials, smart phones and IT parts. Although a 7000 series aluminum alloy is used as such an aluminum extruded material, the extrudability is low, resulting in a problem of a sectional shape and a decrease in productivity.

That is, since the 7000 series aluminum alloy has a yield strength of 500 MPa or more after T6 heat treatment, it is widely used from aerospace parts to automobile and smartphone case, but has a problem of low extrudability due to high rigidity of material, There is a problem that deformation occurs. In the case of conventional structural materials, the deformation can be controlled through final processing. However, in case of additional processing of smartphone and various precision extruded products, the manufacturing cost is increased and the price competitiveness is lowered. Also, when the continuous casting method is used to produce a billet, when a sudden volume change occurs at 0.3% or more near the solid carrier, cracks are generated in the manufacturing process of the billet. Therefore, there is a need to develop a material capable of securing a yield strength of 500 MPa or more after heat treatment, in which cracks are not generated when the billet is produced by the continuous casting method, the extrudability is excellent, the deformation is small during the T6 heat treatment, have.

An object of the present invention is to provide a 7000 series aluminum alloy capable of securing an extrusion speed of 1 mm / s or more while having a strength of 500 MPa or more in yield strength, It is an object of the present invention to provide an aluminum body material alloy which does not cause deformation during press water quenching. Another object of the present invention is to provide an automobile bumper, a structural material, and a smartphone case, which comprise the aluminum body material alloy as a material. However, these problems are exemplary and do not limit the scope of the present invention.

According to one aspect of the present invention, there is provided an aluminum body material alloy comprising: 5.5 to 6.0% by weight of Zn; 2.0 wt% to 2.5 wt% of Mg; 0.2 wt% to 0.6 wt% of Cu; 0.1% to 0.2% Cr by weight; 0.2 wt% or less (more than 0 wt%) of Fe; Mn not more than 0.2% by weight (more than 0% by weight); 0.2 wt% or less (more than 0 wt%) of Si; 0.1 wt% or less (more than 0 wt%) of Ti; 0.05% by weight or less (more than 0% by weight) of Sr; And the balance of Al;

According to another aspect of the present invention, there is provided an aluminum body material alloy comprising: 5.5 to 6.0% by weight of Zn; 2.0 wt% to 2.5 wt% of Mg; 0.2 wt% to 0.6 wt% of Cu; 0.1% to 0.2% Cr by weight; 0.2 wt% or less (more than 0 wt%) of Fe; Mn not more than 0.2% by weight (more than 0% by weight); 0.2 wt% or less (more than 0 wt%) of Si; 0.1 wt% or less (more than 0 wt%) of Ti; And the balance of Al;

An aluminum body material alloy according to another aspect of the present invention, wherein Zn is contained in an amount of 5.5 wt% or more and less than 6.0 wt%; 2.0 wt% to 2.5 wt% of Mg; 0.2 wt% to 0.6 wt% of Cu; 0.1% to 0.2% Cr by weight; 0.2 wt% or less (more than 0 wt%) of Fe; Mn not more than 0.2% by weight (more than 0% by weight); 0.2 wt% or less (more than 0 wt%) of Si; 0.1 wt% or less (more than 0 wt%) of Ti; 0.05% by weight or less (more than 0% by weight) of Sr; 0.2 wt% to 0.8 wt% Ag; And the balance of Al;

In the aluminum body material alloy, strictly, Cu may be contained in an amount of 0.4 to 0.6% by weight.

Strictly, from 2.0 wt% to 2.25 wt% Mg in the aluminum body alloy.

According to another aspect of the present invention, an automobile bumper, a structural material, or a smartphone case can be provided. The automobile bumper, the structural material or the smartphone case may include the above-described aluminum body material alloy.

According to some embodiments of the present invention, as the 7000 series aluminum alloy, an extrusion speed of 1 mm / s or more can be secured while having a strength of 500 MPa or more in yield strength, and a deformation Aluminum alloy can be realized. Of course, the scope of the present invention is not limited by these effects.

FIG. 1 is a photograph showing an aspect of an aluminum body alloy according to a comparative example of the present invention in accordance with an extrusion speed.
FIG. 2 is a graph showing a phase fraction of an aluminum body alloy according to a comparative example of the present invention when analyzed by T6 heat treatment. FIG.
3 is a photograph showing the microstructure of an aluminum body alloy according to an embodiment of the present invention.
FIG. 4 is a photograph showing the shape of a corner of an aluminum body alloy in an extrusion process according to an embodiment of the present invention. FIG.
FIG. 5 is a graph showing changes in the volume change ratio in the solidus according to the Zn content in the aluminum body alloy according to the experimental example of the present invention. FIG. FIG. 7 is a graph showing an experimentally measured yield strength according to the Zn content in an aluminum body alloy according to an experimental example of the present invention, and FIG. 8 is a graph showing an experiment FIG. 2 is a graph showing an experimentally measured change in the extrusion rate according to the Zn content in the aluminum general material alloy according to the example. FIG.
FIG. 9 is a graph showing changes in the volume change ratio in the solidus depending on the Mg content in the aluminum body alloy according to the experimental example of the present invention. FIG. 11 is a graph showing an experimentally measured yield strength according to the Mg content in an aluminum body alloy according to an experimental example of the present invention. This graph shows the experimentally measured changes in the extrusion speed depending on the Mg content in the whole-body alloy.
FIG. 13 is a graph showing changes in ratio of T prime depending on the Cu content in the aluminum body material alloy according to the experimental example of the present invention, and FIG. 14 is a graph showing the change in the Cu content in the aluminum body alloy according to the experimental example of the present invention FIG. 15 is a graph for analyzing a change in the ratio of the GP zone according to the Cu content in the aluminum body alloy according to the experimental example of the present invention, and FIG. 16 is a graph showing the change in the ratio of S prime depending on the Cu content in the aluminum body alloy according to the experimental example of the present invention. FIG. 18 is a graph plotting the change in theta prime phase ratio, and FIG. 18 is a graph showing the variation of Cu content in an aluminum body alloy according to the experimental example of the present invention. And, Figure 19 is a graph of measuring the yield strength of the Cu content in the experimental jeonsinjae aluminum alloy according to the experimental example of the present invention.
FIG. 20 is a graph showing changes in the ratio of T prime according to the Mg content in the aluminum body material alloy according to the experimental example of the present invention, and FIG. 21 is a graph showing changes in the Mg content in the aluminum body alloy according to the experimental example of the present invention FIG. 22 is a graph for analyzing a change in the ratio of the GP zone according to the Mg content in the aluminum body alloy according to the experimental example of the present invention, and FIG. 23 is a graph showing changes in the ratio of S prime depending on the Mg content in the aluminum body alloy according to the experimental example of the present invention, and FIG. 24 is a graph showing the change in the S prime ratio according to the Mg content in the aluminum body alloy according to the experiment of the present invention. FIG. 25 is a graph plotting changes in theta prime phase ratio, and FIG. 25 is a graph showing an experiment in which strain measurement according to the Mg content was tested in an aluminum body alloy according to an experimental example of the present invention. And, Figure 26 is a measure of the yield strength of the Mg content in the experimental jeonsinjae aluminum alloy according to the experimental example of the present invention graph.
FIG. 27 is a graph showing a change in ratio of T prime depending on the Zn content in the aluminum body material alloy according to the experimental example of the present invention, and FIG. 28 is a graph showing the change in the Zn content in the aluminum body material alloy according to the experimental example of the present invention FIG. 29 is a graph showing an analysis of the change in the ratio of the GP zone according to the Zn content in the aluminum body alloy according to the experimental example of the present invention, and FIG. 29 30 is a graph showing the change of the ratio of S prime according to the Zn content in the aluminum body alloy according to the experimental example of the present invention. FIG. 31 is a graph showing the change of the S prime ratio according to the Zn content in the aluminum body alloy according to the experimental example of the present invention. FIG. 32 is a graph showing an analysis of a change in theta prime phase ratio, and FIG. 32 is a graph showing an experimental result of strain measurement according to the Zn content in an aluminum- And, Figure 33 is measured by the experiments the yield strength of the Zn content in the aluminum alloy according to jeonsinjae experimental example of the present invention graph.
FIG. 34 is a graph illustrating a phase fraction of an aluminum body alloy according to an exemplary embodiment of the present invention during T6 heat treatment. FIG.
35 is a photograph showing the microstructure of an aluminum body alloy according to another embodiment of the present invention.
FIG. 36 is a photograph showing the shape of a corner of an aluminum body alloy in an extrusion process according to another embodiment of the present invention. FIG.
FIG. 37 is a graph showing an experimentally measured yield strength according to the Ag content in the aluminum body material alloy according to the experimental example of the present invention, and FIG. 38 is a graph showing the change in the extrusion speed according to the Ag content in the aluminum body material alloy according to the experiment example of the present invention It is a graph measured by an experiment.

Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings. It should be understood, however, that the invention is not limited to the disclosed embodiments, but may be embodied in many different forms and should not be construed as limited to the embodiments set forth herein. Rather, these embodiments are provided so that this disclosure will be thorough and complete, Is provided to fully inform the user. Also, for convenience of explanation, the components may be exaggerated or reduced in size.

FIG. 1 is a photograph showing an aspect of an aluminum body alloy according to a comparative example of the present invention in accordance with an extrusion speed.

The aluminum antimicrobial alloy (A7075) provided as a comparative example of the present invention contains 5.1 wt% to 6.1 wt% of Zn; 2.1 to 2.9 wt% Mg; 1.2 wt% to 2.0 wt% of Cu; 0.18 wt.% To 0.28 wt.% Cr; 0.5% by weight or less of Fe; Mn is not more than 0.3% by weight; 0.4 wt% or less of Si; 0.2% by weight of Ti; And the remainder being Al;

Among aluminum alloy products, so-called 7000 series alloys have a yield strength of 500 MPa or more after T6 heat treatment, and are widely used from aviation to automobiles and smartphone cases. However, the problem is that the extrudability is low due to the high stiffness of the material. For example, in FIG. 1 (b), when the extrusion rate is 0.2 mm / s, there is no edge peeling phenomenon. In FIG. 1 (a), the extrusion rate is 0.5 mm / s, can confirm.

For reference, in the aluminum body alloy according to the comparative example of the present invention, the yield strength was about 103 MPa, the tensile strength was about 288 MPa, and the elongation was about 10% in the O tempering heat treatment , The yield strength at T6 annealing was about 503 MPa, the tensile strength was about 572 MPa, and the elongation was about 11%.

FIG. 2 is a graph showing a phase fraction of an aluminum body alloy according to a comparative example of the present invention when analyzed by T6 heat treatment. FIG.

Referring to FIG. 2, the aluminum alloy body according to the comparative example of the present invention is formed by solution treatment at 450 ° C and artificial aging at 125 ° C. The phases with the highest fraction are the T prime phase and the Eta Prime phase. These two awards are stable and do not change in accordance with the prescription or be transformed into another one. Therefore, it contributes to the increase of yield strength after T6 heat treatment.

The GP zone, the S prime phase and theta prime phase also contribute to the strength enhancement, but because of the quasi-steady state annealing during the annealing process or the transformation into other phases, the T6 heat treatment It is a major factor in the transformation of time.

Since the aluminum alloy according to the comparative example of the present invention has a relatively high fraction of the metastable phases, the present invention intends to control the fraction of these phases as an additive element.

The aluminum body material alloy provided as one embodiment of the present invention has a Zn content of 5.5 wt% to 6.0 wt%; 2.0 wt% to 2.5 wt% of Mg; 0.2 wt% to 0.6 wt% of Cu; 0.1% to 0.2% Cr by weight; 0.2 wt% or less (more than 0 wt%) of Fe; Mn not more than 0.2% by weight (more than 0% by weight); 0.2 wt% or less (more than 0 wt%) of Si; 0.1 wt% or less (more than 0 wt%) of Ti; 0.05% by weight or less (more than 0% by weight) of Sr; And the remaining unavoidable impurities and Al.

As a result, the yield strength and the elongation were about 243 MPa, 399 MPa, and 15.1%, respectively, in the F tempering heat treatment. The yield strength of the aluminum alloy was about 515 MPa , A tensile strength of about 565 MPa, and an elongation of about 10.7%.

3 is a photograph showing the microstructure of an aluminum body alloy according to an embodiment of the present invention.

3 (a) shows the low-magnification (X50) microstructure after the F tempering heat treatment in the extruded material of the aluminum body alloy according to the embodiment of the present invention. FIG. 3 (b) (X200) microstructure after F tempering heat treatment in an extruded material of an aluminum body alloy according to an embodiment of the present invention, and FIG. 3 (c) shows an aluminum body product alloy according to an embodiment of the present invention (X50) microstructure after the T6 heat treatment in the extruded material of FIG. 3, and FIG. 3 (d) shows the high magnification (X200) microstructure after the T6 heat treatment in the extruded material of the aluminum body alloy according to the embodiment of the present invention described above.

FIG. 4 is a photograph showing the shape of a corner of an aluminum body alloy in an extrusion process according to an embodiment of the present invention. FIG.

Referring to FIG. 4, it can be seen that the aluminum body material alloy according to one embodiment of the present invention does not exhibit edge peeling even when the extrusion speed is 1.0 mm / s. Furthermore, it was confirmed that deformation did not occur during PWQ (press water quenching) processing.

Hereinafter, the reason why the alloying elements controlling the extrudability in the aluminum body alloy according to one embodiment of the present invention is determined and the compositional range of the alloying elements is limited will be described with reference to experimental examples to help understand the present invention. It should be understood, however, that the present invention is not limited to the following examples.

The present inventors have found that the extrudability is drastically lowered when the shear modulus exceeds 19 GPa in the aluminum body alloy. The premise of this premise was that the shear rate of the A6061 alloy was calculated to be about 18.8 GPa at an extrusion rate of 1.2 mm / s and an extrusion temperature of 445 DEG C, and the extrusion rate was 0.2 mm / s and the extrusion temperature was 450 DEG C, And the shear rate of the alloy was calculated to be about 19.16 GPa.

Control alloy elements for improving extrudability: Zinc (Zn)

FIG. 5 is a graph showing changes in the volume change ratio in the solidus according to the Zn content in the aluminum body alloy according to the experimental example of the present invention. FIG. FIG. 7 is a graph showing an experimentally measured yield strength according to the Zn content in an aluminum body alloy according to an experimental example of the present invention, and FIG. 8 is a graph showing an experiment FIG. 2 is a graph showing an experimentally measured change in the extrusion rate according to the Zn content in the aluminum general material alloy according to the example. FIG.

The aluminum body material alloy according to the present example had a composition of Zn of 2.0 wt% to 2.5 wt%; 0.2 wt% to 0.6 wt% of Cu; 0.1% to 0.2% Cr by weight; 0.2 wt% or less (more than 0 wt%) of Fe; Mn not more than 0.2% by weight (more than 0% by weight); 0.2 wt% or less (more than 0 wt%) of Si; 0.1 wt% or less (more than 0 wt%) of Ti; 0.05% by weight or less (more than 0% by weight) of Sr; And the balance of unavoidable impurities and Al.

Referring to FIG. 5, it is preferable that the Zn content is limited to 6.5 wt% or less from the viewpoint of preventing cracking in the process of continuous casting into billets. Referring to FIG. 6, in the case of Zn, To 8.5% by weight. From the viewpoint of yield strength, the yield strength before the heat treatment is reduced to 5.5% by weight or more, and the yield strength after the heat treatment is improved according to the content of Zn , And referring to FIG. 8, it is analyzed that, in the case of the extrusion rate, 5 wt% to 6 wt% have the best properties.

Table 1 summarizes the change of the characteristic value according to the Zn content in the aluminum body alloy according to the experimental example of the present invention.

Zn content Shear Modulus
(GPa) Volumetric change of solid body line
(%) Yield strength F
(MPa) Yield strength T6
(MPa) Extrusion speed
(mm / s) 5 18.89 0.2 230 487 1.2 5.5 18.88 0.23 243 515 1.1 6 18.87 0.27 235 523 1.15 6.5 18.86 0.31 227 527 0.8 7 18.83 0.35 216 531 0.7 7.5 18.81 0.41 214 536 0.6 8 18.71 0.48 210 540 0.6 8.5 18.75 0.51 211 540 0.5

Referring to Table 1, it is advantageous to increase the Zn composition to about 8 wt% in terms of the amount of Zn in terms of the shear stage water, but it is not more than 0.3 wt% in terms of volume change in the vicinity of the solid- It is necessary to limit it to 6% by weight or less. In the F state of the billet, 5.5% by weight is the highest yield strength in terms of yield strength, and the strength after T6 heat treatment increases with the Zn content, It is necessary to not exceed 6% by weight in the aspect of aspect ratio. Therefore, in consideration of the volume change, shear rate, yield strength, and extrusion rate, the aluminum content of the aluminum alloy according to one embodiment of the present invention is 5.5% It is evaluated that it is preferable to limit it to 6.0 wt%.

Control alloy element for improving extrudability: Magnesium (Mg)

FIG. 9 is a graph showing changes in the volume change ratio in the solidus depending on the Mg content in the aluminum body alloy according to the experimental example of the present invention. FIG. 11 is a graph showing an experimentally measured yield strength according to the Mg content in an aluminum body alloy according to an experimental example of the present invention. This graph shows the experimentally measured changes in the extrusion speed depending on the Mg content in the whole-body alloy.

The aluminum body material alloy according to this Experiment Example changed the composition of Mg to an arbitrary composition and contained 5.5 wt% to 6.0 wt% of Zn; 0.2 wt% to 0.6 wt% of Cu; 0.1% to 0.2% Cr by weight; 0.2 wt% or less (more than 0 wt%) of Fe; Mn not more than 0.2% by weight (more than 0% by weight); 0.2 wt% or less (more than 0 wt%) of Si; 0.1 wt% or less (more than 0 wt%) of Ti; 0.05% by weight or less (more than 0% by weight) of Sr; And the balance of unavoidable impurities and Al.

Referring to FIG. 9, it is preferable that the Mg content is limited to 2% by weight or more in view of prevention of cracking in the process of continuous casting into billets. Referring to FIG. 10, in the case of Mg, 2.25 11, the yield strength after the heat treatment is continuously improved in accordance with the Mg content. However, when the data before the heat treatment affecting the extrudability are checked, it is limited to 2.5% by weight or less And it is analyzed that it is preferable to limit the rate of the extrusion rate to 2 wt% to 2.5 wt% with reference to FIG.

Table 2 summarizes the changes of the characteristic values according to the Mg content in the aluminum body alloy according to the experimental example of the present invention.

Mg content Shear Modulus
(GPa) Volumetric change of solid body line
(%) Yield strength F
(MPa) Yield strength T6
(MPa) Extrusion speed
(mm / s) 1.5 18.66 0.1 199 505 0.9 1.75 18.63 0.30 203 510 0.9 2 18.81 0.27 234 508 1.2 2.25 18.95 0.22 243 515 1.1 2.5 19.09 0.16 250 533 0.7 2.75 19.26 0.11 253 532 0.4 3 19.33 0.21 259 536 0.2

Referring to Table 2, the optimum Mg composition is advantageously less than 2.25 wt% in terms of the shear rate, and 1.5 to 3 wt% is preferable in terms of the volume change. As the Mg content increases in terms of yield strength, Considering the volume change, shear rate, yield strength, and extrusion rate, the Mg content of the aluminum body alloy according to an embodiment of the present invention is 2.0 wt% or more, To 2.5% by weight, and strictly, from 2.0% to 2.25% by weight Mg.

T6 Heat Treatment Deformation Control and Yield Strength Factor: Copper (Cu)

FIG. 13 is a graph showing changes in ratio of T prime depending on the Cu content in the aluminum body material alloy according to the experimental example of the present invention, and FIG. 14 is a graph showing the change in the Cu content in the aluminum body alloy according to the experimental example of the present invention FIG. 15 is a graph for analyzing a change in the ratio of the GP zone according to the Cu content in the aluminum body alloy according to the experimental example of the present invention, and FIG. 16 is a graph showing the change in the ratio of S prime depending on the Cu content in the aluminum body alloy according to the experimental example of the present invention. FIG. 18 is a graph plotting the change in theta prime phase ratio, and FIG. 18 is a graph showing the variation of Cu content in an aluminum body alloy according to the experimental example of the present invention. And, Figure 19 is a graph of measuring the yield strength of the Cu content in the experimental jeonsinjae aluminum alloy according to the experimental example of the present invention.

The aluminum body material alloy according to this Experiment Example changed the composition of Cu to an arbitrary composition and contained Zn in an amount of 5.5 wt% to 6.0 wt%; 2.0 wt% to 2.5 wt% of Mg; 0.1% to 0.2% Cr by weight; 0.2 wt% or less (more than 0 wt%) of Fe; Mn not more than 0.2% by weight (more than 0% by weight); 0.2 wt% or less (more than 0 wt%) of Si; 0.1 wt% or less (more than 0 wt%) of Ti; 0.05% by weight or less (more than 0% by weight) of Sr; And the balance Al.

Referring to FIG. 13, it is preferable to limit the Cu content to 0.8% by weight or less because it converges from 0.8% by weight Cu in the case of T prime depending on the Cu content. Referring to FIG. 14, Therefore, it is analyzed that the Eta Prime phase is continuously increased, and it is analyzed that it is advantageous to increase the Cu content. Referring to FIG. 15, the GP zone is stable in the range of 1.6 wt% to 1.7 wt% 16, the fraction of S prime increases proportionally with the Cu content, so that the Cu fraction of not more than 1% by weight is not more than 0.8% by weight Referring to FIG. 17, the proportion of theta prime phase is increased according to the Cu content. However, when the Cu content is less than 1.4% by weight, the fraction is considerably low. Is the side on the prime theta (theta prime) is preferable to limit the Cu to less than 1.4% by weight, and 18, in terms of deformation is evaluated as preferable to limit the Cu content to less than 0.8% by weight.

Referring to FIG. 19, the yield strength after heat treatment is proportional to the Cu content but is constantly converged from 0.6% by weight. The F-state yield strength before heat treatment is preferably 250 MPa or less in terms of extrudability Therefore, it is analyzed that it is preferable to limit the Cu content to 0.6 wt% or less in terms of the yield strength.

Accordingly, it has been found that in view of T prime phase, Eta Prime phase, GP zone phase, S prime phase, theta prime phase, strain and yield strength, Cu It is estimated that the content is most preferably limited to 0.2 wt% to 0.6 wt%.

Table 3 summarizes changes in the phase fraction and the like according to the Cu content in the aluminum body alloy according to the experimental example of the present invention.

Cu content T '% η '% GP% S '% θ '% transform
mm / 200mm Yield strength
F
(MPa) Yield strength
T6
(MPa) 0.2 4.1 3.22 1.66 0.19 0  0.05 238 466 0.4 4.23 3.49 1.65 0.43 0.00614 0.05 239 492 0.6 4.29 3.76 1.64 0.69 0.0416 0.06 243 515 0.8 4.33 4.03 1.63 0.95 0.1 0.10 245 519 1.0 4.35 4.3 1.61 1.22 0.18 0.13 249 523 1.2 4.36 4.56 1.6 1.49 0.27 0.17 252 522 1.4 4.37 4.72 1.6 1.65 0.33 0.20 253 527 1.6 4.37 4.73 1.61 1.65 0.33 0.20 262 526 1.8 4.37 4.79 1.62 1.71 0.35 0.21 251 531 2.0 4.37 5.03 1.6 1.99 0.46 0.23 249 525

In summary, the composition of Cu contributes to the improvement of the strength of the solution heat treatment as the content increases, and it is analyzed that the proportion of the stable phase Al ₂ Mg ₃ Zn ₃ T 'and MgZn 2 η' is increased. 2000 series alloy, the Cu content is more affected by the GP zone fraction, whereas in the case of 7000 series, the α-phase zeolite zone (GP zone) in which the Cu, Mg, ), And the effect on the GP zone was not significant depending on the content of Cu due to the high artificial aging temperature. It was found that the effect of the T6 heat treatment on the strength GP, S '(Al ₂ CuMg) and θ' (Al ₂ Cu) but is greater in effect of the GP zone, S 'and θ' phase there was found that the rapid increase in more than 0.8% by weight. Therefore, it is considered that it is most advantageous to limit the Cu content in the range of 0.2 wt% to 0.6 wt% in view of the phase analysis result, the dimensional change and the strength in heat treatment.

T6 Heat Treatment Deformation Control and Yield Strength Factor: Magnesium ( Mg )

FIG. 20 is a graph showing changes in the ratio of T prime according to the Mg content in the aluminum body material alloy according to the experimental example of the present invention, and FIG. 21 is a graph showing changes in the Mg content in the aluminum body alloy according to the experimental example of the present invention FIG. 22 is a graph for analyzing a change in the ratio of the GP zone according to the Mg content in the aluminum body alloy according to the experimental example of the present invention, and FIG. 23 is a graph showing changes in the ratio of S prime depending on the Mg content in the aluminum body alloy according to the experimental example of the present invention, and FIG. 24 is a graph showing the change in the S prime ratio according to the Mg content in the aluminum body alloy according to the experiment of the present invention. FIG. 25 is a graph plotting changes in theta prime phase ratio, and FIG. 25 is a graph showing an experiment in which strain measurement according to the Mg content was tested in an aluminum body alloy according to an experimental example of the present invention. And, Figure 26 is a measure of the yield strength of the Mg content in the experimental jeonsinjae aluminum alloy according to the experimental example of the present invention graph.

The aluminum body material alloy according to this Experiment Example changed the composition of Mg to an arbitrary composition and contained 5.5 wt% to 6.0 wt% of Zn; 0.2 wt% to 0.6 wt% of Cu; 0.1% to 0.2% Cr by weight; 0.2 wt% or less (more than 0 wt%) of Fe; Mn not more than 0.2% by weight (more than 0% by weight); 0.2 wt% or less (more than 0 wt%) of Si; 0.1 wt% or less (more than 0 wt%) of Ti; 0.05% by weight or less (more than 0% by weight) of Sr; And the balance Al.

20, the Mg content was limited to 1.75% by weight to 3% by weight before and after 2 to 2.25% by weight, which is the optimum composition of the former extrudability evaluation factor. As a result, T prime), it is possible to add up to 3% by weight of Mg in terms of T prime. Referring to FIG. 21, from the viewpoint of Eta Prime, 22%, it is preferable to limit the Mg content to 2.75% by weight or less in order not to exceed 2% by weight in the GP zone. Referring to FIG. 23, (S prime) phase was estimated to maintain the fraction of 0.6 wt% to 0.7 wt% irrespective of the Mg content, and Mg content was judged to have no significant influence.

Referring to FIG. 24, theta prime phase was analyzed to have a small amount of decrease according to the Mg content, and it was evaluated that there was no significant influence on the Mg content. Referring to FIG. 25, 26, the yield strength after heat treatment is proportional to the Mg content. However, since the F-state yield strength before heat treatment is preferably 250 MPa or less in terms of extrudability, the Mg content It is judged that it is preferable to limit it to less than 2.5% by weight in terms of the yield strength.

  Therefore, in view of T prime phase, Eta Prime phase, GP zone phase, S prime phase, theta prime phase, strain and yield strength, Mg content Is most preferably limited to a range of 2 wt% to 2.25 wt%.

Table 4 summarizes changes in the phase fraction and the like according to the Mg content in the aluminum body alloy according to the experimental example of the present invention.

Mg content T '% η '% GP% S '% θ '% transform
(mm / 200 mm) Yield strength
F
(MPa) Yield strength
T6
(MPa) 1.75 3.48 3.36 1.32 0.68 0.0532 0.04 203 510 2 3.84 3.70 1.46 0.68 0.0481 0.05 234 508 2.25 4.29 3.76 1.64 0.69 0.0416 0.06 243 515 2.5 4.73 3.81 1.81 0.69 0.0355 0.11 250 533 2.75 5.13 3.85 1.96 0.69 0.0298 0.20 253 532 3 5.46 3.89 2.11 0.69 0.0246 0.32 259 536

As shown in Table 4, when the content of Mg is increased, the strength is improved by increasing the T 'and η' phases. However, the difference from Cu is not affected by S 'and θ' Zone may be preferable to be limited to about 2 to 2.3% by weight since the proper amount of the GP Zone, 1.7% or more, starts to exceed the Mg content of 2.4% by weight and the generation of the strain is increased during the heat treatment.

T6 Heat Treatment Deformation Control and Yield Strength Factor: Zinc (Zn)

FIG. 27 is a graph showing a change in ratio of T prime depending on the Zn content in the aluminum body material alloy according to the experimental example of the present invention, and FIG. 28 is a graph showing the change in the Zn content in the aluminum body material alloy according to the experimental example of the present invention FIG. 29 is a graph showing an analysis of the change in the ratio of the GP zone according to the Zn content in the aluminum body alloy according to the experimental example of the present invention, and FIG. 29 30 is a graph showing the change of the ratio of S prime according to the Zn content in the aluminum body alloy according to the experimental example of the present invention. FIG. 31 is a graph showing the change of the S prime ratio according to the Zn content in the aluminum body alloy according to the experimental example of the present invention. FIG. 32 is a graph showing an analysis of a change in theta prime phase ratio, and FIG. 32 is a graph showing an experimental result of strain measurement according to the Zn content in an aluminum- And, Figure 33 is measured by the experiments the yield strength of the Zn content in the aluminum alloy according to jeonsinjae experimental example of the present invention graph.

The aluminum body material alloy according to the present example had a composition of Zn of 2.0 wt% to 2.5 wt%; 0.2 wt% to 0.6 wt% of Cu; 0.1% to 0.2% Cr by weight; 0.2 wt% or less (more than 0 wt%) of Fe; Mn not more than 0.2% by weight (more than 0% by weight); 0.2 wt% or less (more than 0 wt%) of Si; 0.1 wt% or less (more than 0 wt%) of Ti; 0.05% by weight or less (more than 0% by weight) of Sr; And the balance Al.

Referring to FIG. 27, the Zn content was limited to 5 to 6.5% by weight in the range of 5.5 to 6% by weight in terms of the control of the extrusion rate, and 0.5% by weight, respectively. Accordingly, it is continuously increased in the case of T prime, and it is estimated that it is possible to add up to 6.5 wt% of Zn in terms of T prime. Referring to FIG. 28, in the case of Eta Prime, It is estimated that the addition of up to 6.5% by weight is possible. Referring to FIG. 29, it is preferable to limit the Zn content to 6% by weight or less so that the GP zone does not exceed 2%. Referring to FIG. 30, The S prime phase is estimated to maintain a 0.6-0.7% fraction irrespective of the Zn content, so that the Zn content is considered to have no significant influence. Referring to FIG. 31, theta prime phase has a Zn content , 32, it is preferable that the Zn content is limited to 5.5 to 6% by weight in terms of deformation, and referring to FIG. 33, it is preferable that the yield after the heat treatment The strength was proportional to the Zn content and the F-state yield strength before heat treatment was also found to be insignificantly influenced by all ranges of 250 MPa or less. However, the above-mentioned T prime phase, Eta Prime Considering both the GP zone, the S prime zone, the theta prime zone, the deformation and the yield strength, the Zn content is limited to 5.5 to 6 wt% It is evaluated to be preferable.

Table 5 summarizes changes in the phase fraction and the like according to the Zn content in the aluminum body alloy according to the experimental example of the present invention.

Zn content T '% η '% GP% S '% θ '% transform
(mm / 200 mm) Yield strength
F
(MPa) Yield strength
T6
(MPa) 5 4.16 3.47 1.35 0.69 0.0439 0.05 230 487 5.5 4.29 3.76 1.64 0.69 0.0416 0.06 243 515 6 4.41 4.06 1.93 0.69 0.04 0.17 235 523 6.5 4.51 4.35 2.21 0.69 0.0384 0.26 227 527

As shown in Table 5, when the content of Zn is increased, the strength is enhanced by the increase of T 'and η', which is the same as that of Mg and Cu, and is different from that of Cu. However, since the GP zone starts to exceed the appropriate value of 1.7% or more from 6% and the strain rate is increased during the heat treatment, the Zn content is advantageous in terms of controlling the heat treatment strain rate in the range of 5% to 6% Is analyzed.

FIG. 34 is a graph illustrating a phase fraction of an aluminum body alloy according to an exemplary embodiment of the present invention during T6 heat treatment. FIG.

Referring to FIG. 34, the aluminum alloy body according to an embodiment of the present invention is formed by solution-treating at 450.degree. C., followed by artificial aging at 125.degree. The phases with the highest fraction are the T prime phase and the Eta Prime phase. These two awards are stable and do not change in accordance with the prescription or be transformed into another one. Therefore, it contributes to the increase of yield strength after T6 heat treatment. In addition, the GP zone, S prime phase and theta prime phase contribute to the strength enhancement, but have a problem of coarsening or transforming into another phase during quenching .

As described above, the 7000 series alloy contributes to a fraction on the T prime phase, the Eta Prime phase, the GP zone phase, the S prime phase, and theta prime phase Cu, Mg and Zn were confirmed by analysis and experiment. It was confirmed that the composition of these elements could be originally controlled by limiting the composition of these elements.

Meanwhile, the aluminum body material alloy provided in another embodiment of the present invention contains 5.5 to 6.0% by weight of Zn; 2.0 wt% to 2.5 wt% of Mg; 0.2 wt% to 0.6 wt% of Cu; 0.1% to 0.2% Cr by weight; 0.2 wt% or less (more than 0 wt%) of Fe; Mn not more than 0.2% by weight (more than 0% by weight); 0.2 wt% or less (more than 0 wt%) of Si; 0.1 wt% or less (more than 0 wt%) of Ti; And the remaining unavoidable impurities and Al;

Elements contributing to fractions on the T prime phase, Eta Prime phase, GP zone phase, S prime phase and theta prime phase in this alloy are Cu, Mg and Zn, and it was confirmed that the content of these metastable phases can be originally controlled by limiting the composition of these elements within the above range.

In another embodiment of the present invention, the aluminum body material alloy contains 5.5 to 6.0% by weight of Zn; 2.0 wt% to 2.5 wt% of Mg; 0.2 wt% to 0.6 wt% of Cu; 0.1% to 0.2% Cr by weight; 0.2 wt% or less (more than 0 wt%) of Fe; Mn not more than 0.2% by weight (more than 0% by weight); 0.2 wt% or less (more than 0 wt%) of Si; 0.1 wt% or less (more than 0 wt%) of Ti; 0.05% by weight or less (more than 0% by weight) of Sr; 0.1 wt% to 0.8 wt% Ag; And the balance Al.

As a result, the yield strength was about 208 MPa, the tensile strength was about 350 MPa, and the elongation was about 12.9% in the F tempering heat treatment in the aluminum tempered alloy, and the yield strength was about 573 MPa , The tensile strength was about 618 MPa, and the elongation was about 10.9%.

35 is a photograph showing the microstructure of an aluminum body alloy according to another embodiment of the present invention.

35 (a) shows a low magnification (X50) microstructure after F tempering heat treatment in an extruded material of an aluminum body alloy according to another embodiment of the present invention, and FIG. 35 (b) 35 (c) shows a high magnification (X200) microstructure after the F tempering heat treatment in the extruded material of the aluminum body alloy according to another embodiment of the present invention, and FIG. 35 (c) (X50) microstructure after the T6 heat treatment in the extruded material of the aluminum body material alloy, and FIG. 35 (d) shows the high magnification (X200) fine structure after the T6 heat treatment in the extruded material of the aluminum body alloy according to the yet another embodiment of the present invention Organization.

FIG. 36 is a photograph showing the shape of a corner of an aluminum body alloy in an extrusion process according to another embodiment of the present invention. FIG.

Referring to FIG. 36, it can be seen that edge extrusion does not occur even when the extrusion speed is 1.4 mm / s in the aluminum body alloy according to another embodiment of the present invention. Furthermore, it was confirmed that deformation did not occur during PWQ (press water quenching) processing.

Hereinafter, to understand another alloy element (Ag) controlling the extrudability in the aluminum body alloy according to another embodiment of the present invention and to limit the composition range of Ag, Together. It should be understood, however, that the following examples are for illustrative purposes only and are not intended to limit the scope of the present invention.

FIG. 37 is a graph showing an experimentally measured yield strength according to the Ag content in the aluminum body material alloy according to the experimental example of the present invention. FIG. 38 shows the change in the extrusion speed according to the Ag content in the aluminum body material alloy according to the experiment example of the present invention It is a graph measured by an experiment.

The aluminum body material alloy according to this Experiment Example changed the Ag to an arbitrary composition and contained Zn in an amount of 5.5 wt% to 6.0 wt%; 2.0 wt% to 2.5 wt% of Mg; 0.2 wt% to 0.6 wt% of Cu; 0.1% to 0.2% Cr by weight; 0.2 wt% or less (more than 0 wt%) of Fe; Mn not more than 0.2% by weight (more than 0% by weight); 0.2 wt% or less (more than 0 wt%) of Si; 0.1 wt% or less (more than 0 wt%) of Ti; 0.05% by weight or less (more than 0% by weight) of Sr; And the balance Al. Concretely, it is preferable to use an alloy containing Al as the remainder and containing Cr: 0.15, Cu: 0.6, Fe: 0.1, Mg: 2.25, Mn: 0.1, Si: 0.1, Sr: 0.01, Ti: 0.05, have.

Referring to FIG. 37, when Ag is added to the aluminum body alloy according to the embodiment of the present invention described above, the yield strength after the heat treatment is continuously increased, while the yield strength before the heat treatment is 250 MPa or less And the Ag content is increased from 1% by weight to the yield strength before heat treatment, so that it is judged that it is preferable to limit Ag to 1% by weight or less in terms of yield strength. 38, it is advantageous to limit the Ag content to 1 wt% or less in terms of the yield strength, and it is advantageous to limit the Ag content to 0.8 wt% or less in terms of the extrusion speed and economy. From the viewpoint of the yield strength, it is preferable that the Ag content is limited to 0.1 to 0.8% by weight.

Table 6 summarizes the changes in the yield strength and the extrusion speed depending on the Ag content in the aluminum body alloy according to the experimental example of the present invention.

Ag content Yield strength F
(MPa) Yield strength T6
(MPa) Extrusion speed
(mm / s) 0.1 240 510 1.0 0.2 220 523 1.2 0.3 215 531 1.3 0.4 215 537 1.3 0.5 212 541 1.4 0.6 210 560 1.4 0.7 208 573 1.4 0.8 205 565 1.5 0.9 204 568 1.4 1.0 201 570 1.5 1.1 210 573 1.3 1.2 223 576 1.2 1.3 237 575 1.1 1.4 246 577 1.1

In summary, referring to Table 6, when Ag is added to the aluminum body material alloy according to the embodiment of the present invention described above with reference to FIG. 3, up to 0.1% by weight is not significantly effective in terms of yield strength and extrusion speed, From 0.2 to 1.4 wt%, the yield strength continuously increases after the T6 heat treatment. In the case of the extrusion rate, the extrusion rate is continuously increased from 0.2 to 1.0 wt% to 1.5 mm / s, but from 1.1 wt% . Although it is advantageous to increase the amount of Ag in terms of the strength after the T6 heat treatment, it is preferable to limit the content of Ag to 0.2 to 1.0% by weight from the viewpoints of economy and extrudability.

Various embodiments of an aluminum alloy having a yield strength of 500 MPa or more and a productivity of more than 1 mm / s at an extrusion rate and no deformation during solution treatment and PWQ treatment have been described with 7000 series alloys so far.

The phases that improve the mechanical properties after the T6 heat treatment in the conventional A7075 are phases such as θ ', S', η ', T' and GP zones, among which GP zones, θ 'and S' In the present invention, among the phases contributing to the improvement of strength, the GP zones, θ 'and S', which cause deformation during heat treatment, are lowered and η 'and T 'To secure the stable fraction of the phases that did not change thermally. In addition, a small amount of Ag which can contribute to the strength improvement by forming Al-Ag beta phase without reacting with Zn, Mg and Cu which are major addition elements in 7000 series alloy without extrusion rate and thermal deformation can be obtained and yield strength and tensile strength .

The above-described alloys of the present invention have an extrusion speed of at least 1 mm / s of 7000 series aluminum aluminum alloy, 5 times faster than conventional A7075 alloy, no deformation during solution and PWQ, a strength of 500 MPa or more in yield strength, And can be applied not only to structural materials such as automobile body and chassis parts such as automobile bumpers but also as a case material for smart phones and IT parts.

While the present invention has been described with reference to exemplary embodiments, it is to be understood that the invention is not limited to the disclosed exemplary embodiments, but, on the contrary, is intended to cover various modifications and equivalent arrangements included within the spirit and scope of the invention. Accordingly, the true scope of the present invention should be determined by the technical idea of the appended claims.

Claims (8)

delete delete At least 5.5 wt% and less than 6.0 wt% of Zn; 2.0 wt% to 2.5 wt% of Mg; 0.2 wt% to 0.6 wt% of Cu; 0.1% to 0.2% Cr by weight; 0.2 wt% or less (more than 0 wt%) of Fe; Mn not more than 0.2% by weight (more than 0% by weight); 0.2 wt% or less (more than 0 wt%) of Si; 0.1 wt% or less (more than 0 wt%) of Ti; 0.05% by weight or less (more than 0% by weight) of Sr; 0.2 wt% to 0.8 wt% Ag; And the balance Al;
Extrusion speed during extrusion 1. Extrusion is possible within a range of 2 to 1.5 mm / s,
Having a yield strength in the range of 523 to 565 MPa after T6 heat treatment after extrusion,
Aluminum body alloy. The method of claim 3,
0.4% to 0.6% by weight of Cu. The method of claim 3,
And from 2.0% to 2.25% by weight of Mg. An automobile bumper comprising the aluminum body material alloy according to any one of claims 3 to 5 as a material. A structural material comprising the aluminum body material alloy according to any one of claims 3 to 5 as a material. 6. A smartphone case comprising the aluminum body material alloy according to any one of claims 3 to 5 as a material.

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