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A review of sheet warm forming methods for high-strength 7xxx aluminum alloys

  
Sep 20, 2025

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Figure 1

Graphic diagram of the warm forming process (own drawing).
Graphic diagram of the warm forming process (own drawing).

Figure 2

Schematic diagram of the warm forming process in the form of a temperature–time graph (own drawing).
Schematic diagram of the warm forming process in the form of a temperature–time graph (own drawing).

Figure 3

True stress–strain curves of AA7075 at elevated temperatures [11].
True stress–strain curves of AA7075 at elevated temperatures [11].

Figure 4

(a) True stress–strain curves of AA7075 at 220°C and (b) strain rate sensitivity parameter (m) [11].
(a) True stress–strain curves of AA7075 at 220°C and (b) strain rate sensitivity parameter (m) [11].

Figure 5

(a) True stress–strain curves and (b) true tensile/yield strength of AA7075 [13].
(a) True stress–strain curves and (b) true tensile/yield strength of AA7075 [13].

Figure 6

The true stress–strain curves of the AA7075-T6 alloy under (a) different temperatures with a strain rate of 0.1 s−1 and (b) different strain rates with a temperature of 300°C [15].
The true stress–strain curves of the AA7075-T6 alloy under (a) different temperatures with a strain rate of 0.1 s−1 and (b) different strain rates with a temperature of 300°C [15].

Figure 7

Influence of the forming temperature on the formability in the warm and hot forming of (a) EN AW7022-T6 and (b) EN AW7075-T6 [16].
Influence of the forming temperature on the formability in the warm and hot forming of (a) EN AW7022-T6 and (b) EN AW7075-T6 [16].

Figure 8

(a) YS, (b) peak stress, (c) true uniform strain, and (d) true fracture strain of AW-7020-T6 [10].
(a) YS, (b) peak stress, (c) true uniform strain, and (d) true fracture strain of AW-7020-T6 [10].

Figure 9

Influence of forming temperature on strength AA7075 T6 taking into account the sheet thickness (own drawing).
Influence of forming temperature on strength AA7075 T6 taking into account the sheet thickness (own drawing).

Figure 10

Influence of forming temperature on strength AA7020 T6 taking into account the heating time (own drawing).
Influence of forming temperature on strength AA7020 T6 taking into account the heating time (own drawing).

Figure 11

Geometry of shaping tools in tests (a) LDH and (b) LDR (own drawing).
Geometry of shaping tools in tests (a) LDH and (b) LDR (own drawing).

Figure 12

Dependence of (a) LDH and (b) LDR of forming temperature (the dashed horizontal line indicates the alloy AA5182-O that has the best workability at ambient temperature) [11].
Dependence of (a) LDH and (b) LDR of forming temperature (the dashed horizontal line indicates the alloy AA5182-O that has the best workability at ambient temperature) [11].

Figure 13

(a) Erichsen values of 7075-T6 as a function of test temperatures and (b) Vickers hardness of 7075 (PB – paint baking) [13].
(a) Erichsen values of 7075-T6 as a function of test temperatures and (b) Vickers hardness of 7075 (PB – paint baking) [13].

Figure 14

LDR and LDD value at elevated temperature [10].
LDR and LDD value at elevated temperature [10].

Figure 15

Visual inspection of the part sidewall isothermally formed at 204°C for (a) Fuchs, (b) PTFE Spray, (c) OKS, and (d) at 233°C utilizing the Fuchs lubricant [9].
Visual inspection of the part sidewall isothermally formed at 204°C for (a) Fuchs, (b) PTFE Spray, (c) OKS, and (d) at 233°C utilizing the Fuchs lubricant [9].

Figure 16

Peak values during isothermal cup drawing at 170°C utilizing different lubricants [9].
Peak values during isothermal cup drawing at 170°C utilizing different lubricants [9].

Figure 17

Comparison of perimeter (a) and draw-in length and (b) of cups drawn under isothermal conditions utilizing different lubricants [9].
Comparison of perimeter (a) and draw-in length and (b) of cups drawn under isothermal conditions utilizing different lubricants [9].

Figure 18

CAD model of car bracket [14].
CAD model of car bracket [14].

Figure 19

FEM of a formed B-pillar (a) thickness deformation and (b) temperature distribution [18].
FEM of a formed B-pillar (a) thickness deformation and (b) temperature distribution [18].

Figure 20

Mechanical properties of the drawpiece manufactured (a) conventionally and (b) by accelerated heating [18].
Mechanical properties of the drawpiece manufactured (a) conventionally and (b) by accelerated heating [18].

Figure 21

Model of the formed component (B-pillar) [15].
Model of the formed component (B-pillar) [15].

Figure 22

Mechanical properties of warm-stamped components [15].
Mechanical properties of warm-stamped components [15].

Figure 23

U-profile (a) geometric dimension and (b) forming tools [9].
U-profile (a) geometric dimension and (b) forming tools [9].

Figure 24

Force evolution as a function of the punch stroke for isothermal warm forming of the structural U-profile at 204°C utilizing different lubricants [9].
Force evolution as a function of the punch stroke for isothermal warm forming of the structural U-profile at 204°C utilizing different lubricants [9].

Figure 25

Visual inspection of the part sidewall isothermally formed at 204°C for (a) Fuchs, (b) PTFE Spray, (c) OKS, and (d) at 233°C utilizing the Fuchs lubricant [9].
Visual inspection of the part sidewall isothermally formed at 204°C for (a) Fuchs, (b) PTFE Spray, (c) OKS, and (d) at 233°C utilizing the Fuchs lubricant [9].

Figure 26

Model of manufactured elements (a) U-shape profile and (b) the B-pillar’s foot [17].
Model of manufactured elements (a) U-shape profile and (b) the B-pillar’s foot [17].

Figure 27

The influence of the heating strategy on the strength of the U-profile (a) front, (b) flange, and (c) lateral [17].
The influence of the heating strategy on the strength of the U-profile (a) front, (b) flange, and (c) lateral [17].

Figure 28

Shape deviations measured in the cross-section of the U-shape (a) second strategy and (b) third strategy [17].
Shape deviations measured in the cross-section of the U-shape (a) second strategy and (b) third strategy [17].

Figure 29

The influence of the heating strategy on the stress–strain curves of different areas of the B-pillar’s foot [17].
The influence of the heating strategy on the stress–strain curves of different areas of the B-pillar’s foot [17].

Figure 30

The influence of the sheet metal heating method on (a) hardness and (b) stress–strain curves, FH – conventional sheet heating, CH – contact heating, PB – paint baking [19].
The influence of the sheet metal heating method on (a) hardness and (b) stress–strain curves, FH – conventional sheet heating, CH – contact heating, PB – paint baking [19].

Figure 31

Precipitation size distribution after (a) CH200 and (b) FH200 treatment [19].
Precipitation size distribution after (a) CH200 and (b) FH200 treatment [19].

Figure 32

TEM images of samples (a) CH200 + PB and (b) FH200 + PB [19].
TEM images of samples (a) CH200 + PB and (b) FH200 + PB [19].

Chemical composition of typical aluminum alloys_

Alloy Zn Mg Cu Fe Cr Si Mn Ti Zr
7075 5.1–6.1 2.1–2.9 1.2–2 ≤0.5 0.18–0.28 ≤0.4 ≤0.3 ≤0.2 0.08–0.25
7020 4–5 1–1.4 ≤0.2 ≤0.4 0.1–0.35 ≤0.35 0.05–0.5 ≤0.25 0.12
7xxx_1 7–8 1.2–1.8 1.3–2 0.08 0.04 0.06 0.04 0.06 0.08–0.15

Mechanical properties of typical aluminum alloys_

Alloy Density (kg/m3) R m (MPa) R p0.2 (MPa) A 50 (%) Hardness (HV1)
7075 T6 2,810 540–580 460–500 8–12 180–198
7020 T6 2,780 350–380 280–310 8–10 108–115
7xxx_1 2,800 517–525 486 11–16 127–155