# Local Deformation and Texture of Cold-Rolled AA6061 Aluminum Alloy

^{1}

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^{3}

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## Abstract

**:**

_{0}, t

_{0}and t are the thicknesses of the AA6061 sheet before and after the cold rolling, respectively). The volume fraction of total deformation texture is relatively independent of the thickness reduction for Δt/t

_{0}≤ 30%, and becomes an approximately linearly increasing function of the thickness reduction for Δt/t

_{0}> 30%. Increasing the thickness reduction causes the increase of the Vickers hardness of the cross-section of the cold-rolled sheets, which exhibits a similar increase trend to the volume fraction of total deformation texture for Δt/t

_{0}> 30%. A simple relation between the Vickers hardness and the thickness reduction is established and is used to curve-fit the experimental results.

## 1. Introduction

## 2. Materials and Methods

_{0}= 10%, t

_{0}and t are the thicknesses of the AA6061 sheet before and after the cold rolling) was achieved per rolling pass. Five different thickness reductions of 10%, 30%, 50%, 70%, and 90% were achieved. It took nine rolling passes to reach 90% thickness reduction. The resultant thickness reductions are 10%, 30%, 50%, 70%, and 90%, corresponding to the thicknesses of 5.72, 4.45, 3.18, 1.91 and 0.64, respectively.

_{4}and 950 mL DI water (deionized water) at a DC voltage of 18 V for 60 s. After the etching, the grain structures of the specimens were analyzed on an optical microscope (BX53M, Olympus Corp., Tokyo, Japan) under polarized light. A scanning electron microscope (SEM) (JEOL 5900 LV) was used to observe the particle structures in the specimens.

_{α}radiation for each specimen. The alpha rotation angle was in a range of 15–90° with the angle increment of 5°. The Tex Tools software (ResMat Corporation, Barcelona, Spain) was used to calculate the 3D ODFs (orientation distribution functions) and the volume fractions of texture components. A triple of Euler angles (φ

_{1}, Φ, φ

_{2}) was used to represent the orientation intensity, following Bunge’s notation.

## 3. Results and Discussion

_{2}Si), and the other consists of Al, Fe and Si (bright particles, Al(Fe,Mn)Si).

#### 3.1. Texture Analysis

#### 3.2. Indentation Deformation

_{0}, as shown in Figure 4. With the increase of the cold rolling, the number of grains with less internal stresses (dislocation density) decreases, and there are more and more grains with large internal stresses (dislocation density) in the Al alloy.

_{V}, which represents the resistance to local plastic deformation, can be calculated as:

_{0}> 30%. For Δt/t

_{0}≤ 30%, the trends are different. Such behavior may imply the possible connection between the deformation texture and the dislocation density, i.e., the variation of the deformation texture (Copper, S and Brass components) may be associated with the increase of the dislocation density (the rate of work hardening) and the dislocation motion in FCC (face-centered cubic) metals with severe deformation.

_{0}is the flow stress at the reference state of ε

_{eff}= 0, ε

_{eff}is the effective strain, α is a constant, μ is the shear modulus, n is strain exponent, and b is the magnitude of Burgers vector. For a cold-rolled AA6061 Al sheet, the effective strain can be calculated from the thickness reduction as:

_{0}being the thickness at the state of ε

_{eff}= 0, and ∆t/t

_{0}being the thickness reduction. Substituting Equation (3) into (2) and using the relationship of H

_{V}= 3σ, we obtain:

_{plastic}, as:

_{max}is the maximum indentation depth, δ

_{r}is the residual indentation depth, and F

_{un}is the normal load applied to the indenter for the unloading process.

_{plastic}is a nonlinear decreasing function of Δt/t

_{0}. The specimen with Δt/t

_{0}= 0 has the largest energy dissipation and ductility, and the cold-rolled specimen of 90% in the thickness reduction has the least energy dissipation and ductility. Such a result is due to that plastic deformation causes the increase in dislocation density. The larger the thickness reduction, the more severe is the plastic deformation, and the higher is the dislocation density. Note that plastic deformation is a function of the microstructure (internal stress) in the materials, which needs to be considered in the calculation of the energy dissipation for the plastic deformation of crystallized metals.

## 4. Conclusions

_{0}likely due to the compression deformation of grains during the rolling. A slight difference in the grain sizes exist between the material near the free surface and the material around the center portion for a small reduction in the thickness. Increasing the thickness reduction (plastic deformation) leads to the decrease of the volume fraction of the recrystallization texture and the Cube component as well as the increase of the volume fraction of the deformation texture due to the transform of the Cube component and random texture to the components of the deformation texture.

## Author Contributions

## Funding

## Acknowledgments

## Conflicts of Interest

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**Figure 1.**Optical metallographs of the as-annealed and cold-rolled AA6061 alloy; (

**A**) surface region, and (

**B**) center portion; (

**a**) as-annealed, (

**b**) Δt/t

_{0}= 10%, (

**c**) Δt/t

_{0}= 30%, (

**d**) Δt/t

_{0}= 50%, (

**e**) Δt/t

_{0}= 70%, and (

**f**) Δt/t

_{0}= 90%.

**Figure 2.**SEM images of the as-annealed and cold-rolled AA6061 alloy showing the dark and bright particles; (

**A**) surface region, and (

**B**) center portion; (

**a**) as-annealed, (

**b**) Δt/t

_{0}= 10%, (

**c**) Δt/t

_{0}= 30%, (

**d**) Δt/t

_{0}= 50%, (

**e**) Δt/t

_{0}= 70%, and (

**f**) Δt/t

_{0}= 90%.

**Figure 3.**Three-dimensional ODF of the as-annealed and cold-rolled specimens; (

**a**) as-annealed; (

**b**) Δt/t

_{0}= 10%; (

**c**) Δt/t

_{0}= 30%; (

**d**) Δt/t

_{0}= 50%; (

**e**) Δt/t

_{0}= 70%; and (

**f**) Δt/t

_{0}= 90%.

**Figure 5.**Load–displacement curves for indentations of the as-annealed and cold-rolled AA6061 alloy at a normal load of 200 mN.

**Figure 6.**Dependence of the Vickers hardness on the thickness reduction for the indentation of the as-annealed and cold-rolled specimens at the normal load of 200 mN.

**Figure 7.**Dependence of Vickers hardness on effective strain for the as-annealed and cold-rolled specimens with the indentations performed at the normal load of 200 mN.

**Figure 8.**Plastic energy dissipated in the indentation of the as-annealed and cold-rolled specimens at the normal load of 200 mN.

Sample | Mg | Si | Fe | Cu | Cr | Al |
---|---|---|---|---|---|---|

AA6061 | 1.0 | 0.6 | 0.34 | 0.27 | 0.2 | Bal. |

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**MDPI and ACS Style**

Zhou, D.; Du, W.; Wen, X.; Qiao, J.; Liang, W.; Yang, F.
Local Deformation and Texture of Cold-Rolled AA6061 Aluminum Alloy. *Materials* **2018**, *11*, 1866.
https://doi.org/10.3390/ma11101866

**AMA Style**

Zhou D, Du W, Wen X, Qiao J, Liang W, Yang F.
Local Deformation and Texture of Cold-Rolled AA6061 Aluminum Alloy. *Materials*. 2018; 11(10):1866.
https://doi.org/10.3390/ma11101866

**Chicago/Turabian Style**

Zhou, Diaoyu, Wenwen Du, Xiyu Wen, Junwei Qiao, Wei Liang, and Fuqian Yang.
2018. "Local Deformation and Texture of Cold-Rolled AA6061 Aluminum Alloy" *Materials* 11, no. 10: 1866.
https://doi.org/10.3390/ma11101866