Warm-forming of pre-aged Al-Zn-Mg-Cu alloy sheet

Österreicher, Johannes A.; Tunes, Matheus A.; Grabner, Florian; Arnoldt, Aurel; Kremmer, Thomas; Pogatscher, Stefan; Schlögl, Carina M.

doi:10.1016/j.matdes.2020.108837

Cited by 35 publications

(9 citation statements)

References 41 publications

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“…As the deformation continues, the intensity of work hardening declines. Dynamic softening occurs, which facilitates the annihilation of dislocation, slows down the dislocation interaction, and results in a decrease in dislocation density [ 29 ]. As a result, the strength effect of work hardening deteriorates.…”

Section: Resultsmentioning

confidence: 99%

Deformation Behavior of an Extruded 7075 Aluminum Alloy at Elevated Temperatures

Ye,

Xia,

Qiu

et al. 2024

Materials

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Hot compression tests were conducted to explore the deformation behavior of an extruded 7075 aluminum alloy bar at elevated temperatures. Specimens with 0°, 45°, and 90° angles along the extrusion direction were prepared. The compression temperatures were 300 and 400 °C, and the strain rates ranged from 0.001 to 0.1 s−1. The corresponding microstructures were characterized via OM and TEM, and the macroscopic texture was tested using XRD. The results indicated that the strength of the 7075 alloy decreases with higher compression temperatures and is in a proportional relationship with respect to the strain rate. During high-temperature compression, it is easier to stimulate atomic diffusion in the matrix, which can improve thermal activation abilities and facilitate dynamic recovery and dynamic recrystallization. In addition, the coarsening of precipitates also contributed to dynamic softening. When compressed at 300 °C, the stress levels of the 0° specimens ranked first, and those for the 45° specimens were the lowest. When compressed at 400 °C, the flow stresses of the specimens along three directions were comparable. The anisotropic mechanical behavior can be explained by the fiber grains and brass {011} <211> texture component. However, higher temperature deformation leads to recrystallization, which can weaken the anisotropy of mechanical properties.

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Section: Resultsmentioning

confidence: 99%

Deformation Behavior of an Extruded 7075 Aluminum Alloy at Elevated Temperatures

Ye,

Xia,

Qiu

et al. 2024

Materials

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“…Tensile testing. Miniaturized tensile tests (smooth, notched, and smiley shear -see Figure 3) at various strain rates and temperatures were conducted in triplicate using a Bähr DIL 805 A/D deformation dilatometer (see Figure 4 and [2]). The smiley shear specimen was adapted from Gorji et al [11].…”

Section: Methodsmentioning

confidence: 99%

“…Long et al [9] showed that the ultimate tensile strength of warm-formed 7xxx parts after paint bake is reduced as a function of warm-forming temperature and time. Österreicher et al [2] found differences in the differential scanning calorimetry dissolution peak temperatures of hardening precipitates in AA7075 warm-formed at different temperatures; these results indicate different grades of coarsening of the hardening precipitates as a function of warm-forming temperature. Rader et al [10] reported extensive warm tensile test data for AA7075 at various warm-forming temperatures, strain rates, and holding times.…”

Section: Introductionmentioning

confidence: 99%

A Materials Science-Based Approach to Finite Element Simulation of Warm-Forming of Al-Mg-Zn Alloys

Grabner

Österreicher

2022

KEM

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Warm deep-drawing of pre-aged (under-aged) blanks of 7xxx series aluminum alloys (Al-Zn-Mg) at moderate temperatures of roughly 120–230°C is a promising route for producing parts with considerable geometrical complexity, good paint bake hardening response, and, thus, excellent final mechanical properties. Furthermore, oil-based lubricants can be used, eliminating the need for elaborate cleaning routines. However, finite element (FE) simulation of the process is challenging: time-temperature regimes during coupon testing for material cards should closely follow the real conditions in the press because the material undergoes significant changes at warm-forming temperatures, such as recovery and precipitation/coarsening/reversion of hardening phases. When convective heating is used for Nakajima or tensile testing, heating rates are usually too low to adequately represent real process conditions (where inductive or contact heating may be used). Here we present a method for establishing FE material cards and calibrating the GISSMO damage model using miniaturized tensile specimens for a dilatometer with inductive heating. The simulations are compared with warm deep-drawing experiments of pre-aged 7xxx and good agreement of minimum draw temperature for two alloys is achieved. The findings are discussed with regards to transmission electron microscopy investigations and final mechanical properties published earlier. It was found that warm-forming is suitable to produce complex 7xxx parts with high final strength. Conditions in the press can be represented by using miniaturized tensile specimens and inductive heating for calibration of material cards/damage models.

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“…In contrast to greater aging temperatures, lesser aging temperatures have produced the highest hardness (S1), as can be shown (S2 and S3). This is explained by a rise in intermediate zones during precipitation, a rise in finer intermetallic, and a decline in interparticle distances [33][34][35] . After peak aging circumstances, the hardness value declines because of excessive aging, which causes precipitates to coarsen.…”

Section: Hardnessmentioning

confidence: 99%

Implication of Pre-Aged Three Step T6 Treatment on the Properties of Granite and Silicon Nitride Particulates Reinforced Al7075 Matrix Composite

Sowrabh,

Gurumurthy,

Shivaprakash

et al. 2023

Mat. Res.

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In the current research Al7075 (Al-5.4Zn-2.6Mg) alloy and composite prepared by dispersing 2 wt.% granite powder and 3 wt.% Si 3 N 4 in Al7075 are subjected to peak aging treatment at 100, 120 and 150 0 C to obtain the maximum induced hardness by solid solution strengthening. In succession, by the results of peak aging treatment the alloy and composite are pre aged and heat treated by three step aging conditions. The results indicated that pre aged three step aging has resulted in enhanced alloy hardness of 185.6 VHN as compared to peak hardness of 142.9 at 100 0 C resulting in 29.88% improvement. Moreover, the composite subjected to pre-aged three step aging has resulted in improved hardness to 197.6 VHN as compared to peak hardness of 153.5 at 100 0 C resulting in 28.72% improvement. Also, the alloy and composite in this condition showed an improvement of 21.38% and 16.34% respectively in the UTS. Also, particularly composite displayed excellent wear characteristics as compared to as cast alloy. An interesting fact noticed in this work is that in three step aging the last step having higher temperature and longer duration of aging has resulted always a better hardness and hence has improved mechanical properties. This may be due to increased aging kinetics during heat treatment. The novel approach developed in this study will reduce the longer duration of conventional aging heat treatment and the energy consumption.

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Warm-forming of pre-aged Al-Zn-Mg-Cu alloy sheet

Cited by 35 publications

References 41 publications

Deformation Behavior of an Extruded 7075 Aluminum Alloy at Elevated Temperatures

Deformation Behavior of an Extruded 7075 Aluminum Alloy at Elevated Temperatures

A Materials Science-Based Approach to Finite Element Simulation of Warm-Forming of Al-Mg-Zn Alloys

Implication of Pre-Aged Three Step T6 Treatment on the Properties of Granite and Silicon Nitride Particulates Reinforced Al7075 Matrix Composite

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