Author Contributions
Conceptualization, H.G. and Z.L.; methodology, H.G.; software, H.G.; validation, H.G. and Z.L.; formal analysis, H.G.; investigation, H.G.; resources, H.G.; data curation, H.G.; writing—original draft preparation, H.G. and Z.L.; writing—review and editing, H.G. and J.T.; visualization, H.G. and Z.L.; supervision, H.G.; project administration, H.G. and J.T.; funding acquisition, J.T. All authors have read and agreed to the published version of the manuscript.
Figure 1.
Dimensional drawings of the double-cell thin-walled tube interface: (
a) Cross-sectional dimensions (mm); (
b) Schematic of the extruded workpiece profile (from Ref. [
28]).
Figure 1.
Dimensional drawings of the double-cell thin-walled tube interface: (
a) Cross-sectional dimensions (mm); (
b) Schematic of the extruded workpiece profile (from Ref. [
28]).
Figure 2.
Schematic diagram of the dimensions of tensile specimens (mm).
Figure 2.
Schematic diagram of the dimensions of tensile specimens (mm).
Figure 3.
Schematic diagram of crush performance testing: (a) Crush test rig configuration; (b) Specimen morphology in the crushed state.
Figure 3.
Schematic diagram of crush performance testing: (a) Crush test rig configuration; (b) Specimen morphology in the crushed state.
Figure 4.
Schematic diagram of metallographic sampling locations.
Figure 4.
Schematic diagram of metallographic sampling locations.
Figure 5.
The macro-morphology (near-peak-aged state) of the three Al-Mg-Si alloy thin-walled profiles after crush testing: (a) 6xxx-1(1.6Mg/Si) profile; (b) 6xxx-2(1.33Mg/Si) profile; (c) 6xxx-3(1.14Mg/Si) profile.
Figure 5.
The macro-morphology (near-peak-aged state) of the three Al-Mg-Si alloy thin-walled profiles after crush testing: (a) 6xxx-1(1.6Mg/Si) profile; (b) 6xxx-2(1.33Mg/Si) profile; (c) 6xxx-3(1.14Mg/Si) profile.
Figure 6.
Displacement-load curves and crushing energy-absorption curves during axial crushing of the three Al-Mg-Si alloy thin-walled profiles (at near-peak-aged state): (a) Displacement-load curves; (b) Energy-absorption curves.
Figure 6.
Displacement-load curves and crushing energy-absorption curves during axial crushing of the three Al-Mg-Si alloy thin-walled profiles (at near-peak-aged state): (a) Displacement-load curves; (b) Energy-absorption curves.
Figure 7.
Displacement-load curves and crushing energy-absorption curves during axial crushing of the three Al-Mg-Si alloy thin-walled profiles in different ageing states: (a,c,e) Displacement-load curves of profiles 6xxx-1(1.6Mg/Si), 6xxx2, and 6xxx-3(1.14Mg/Si); (b,d,f) Energy-absorption curves of profiles 6xxx-1(1.6Mg/Si), 6xxx2, and 6xxx-3(1.14Mg/Si).
Figure 7.
Displacement-load curves and crushing energy-absorption curves during axial crushing of the three Al-Mg-Si alloy thin-walled profiles in different ageing states: (a,c,e) Displacement-load curves of profiles 6xxx-1(1.6Mg/Si), 6xxx2, and 6xxx-3(1.14Mg/Si); (b,d,f) Energy-absorption curves of profiles 6xxx-1(1.6Mg/Si), 6xxx2, and 6xxx-3(1.14Mg/Si).
Figure 8.
Metallographic organization of the three Al-Mg-Si alloy thin-walled profiles in the near-peak-aged state: (a) Profile 6xxx-1(1.6Mg/Si); (b) Profile 6xxx-2(1.33Mg/Si); (c) Profile 6xxx-3(1.14Mg/Si).
Figure 8.
Metallographic organization of the three Al-Mg-Si alloy thin-walled profiles in the near-peak-aged state: (a) Profile 6xxx-1(1.6Mg/Si); (b) Profile 6xxx-2(1.33Mg/Si); (c) Profile 6xxx-3(1.14Mg/Si).
Figure 9.
Tensile fracture surface morphology of the three Al-Mg-Si alloy thin-walled profiles in different aging states: (a–c) 175 °C/10 h, 175 °C/16 h, 205 °C/6 h, 6xxx-1(1.6Mg/Si) profile; (d–f) 175 °C/10 h, 175 °C/16 h, 205 °C/6 h, 6xxx-2(1.33Mg/Si) profile; (g–i) 175 °C/10 h, 175 °C/16 h, 205 °C/6 h, 6xxx-3(1.14Mg/Si) profile.
Figure 9.
Tensile fracture surface morphology of the three Al-Mg-Si alloy thin-walled profiles in different aging states: (a–c) 175 °C/10 h, 175 °C/16 h, 205 °C/6 h, 6xxx-1(1.6Mg/Si) profile; (d–f) 175 °C/10 h, 175 °C/16 h, 205 °C/6 h, 6xxx-2(1.33Mg/Si) profile; (g–i) 175 °C/10 h, 175 °C/16 h, 205 °C/6 h, 6xxx-3(1.14Mg/Si) profile.
Figure 10.
Bending macro-morphology of the three Al-Mg-Si alloy thin-walled profiles in different aging states: (a–c) 175 °C/10 h, 175 °C/16 h, 205 °C/6 h, 6xxx-1(1.6Mg/Si) profile; (d–f) 175 °C/10 h, 175 °C/16 h, 205 °C/6 h, 6xxx-2(1.33Mg/Si) profile; (g–i) 175 °C/10 h, 175 °C/16 h, 205 °C/6 h, 6xxx-3(1.14Mg/Si) profile.
Figure 10.
Bending macro-morphology of the three Al-Mg-Si alloy thin-walled profiles in different aging states: (a–c) 175 °C/10 h, 175 °C/16 h, 205 °C/6 h, 6xxx-1(1.6Mg/Si) profile; (d–f) 175 °C/10 h, 175 °C/16 h, 205 °C/6 h, 6xxx-2(1.33Mg/Si) profile; (g–i) 175 °C/10 h, 175 °C/16 h, 205 °C/6 h, 6xxx-3(1.14Mg/Si) profile.
Figure 11.
SEM images of second-phase particles of the three Al-Mg-Si alloy thin-walled profiles in different aging states: (a–c) 175 °C/10 h, 175 °C/16 h, 205 °C/6 h, 6xxx-1(1.6Mg/Si) profile; (d–f) 175 °C/10 h, 175 °C/16 h, 205 °C/6 h, 6xxx-2(1.33Mg/Si) profile; (g–i) 175 °C/10 h, 175 °C/16 h, 205 °C/6 h, 6xxx-3(1.14Mg/Si) profile.
Figure 11.
SEM images of second-phase particles of the three Al-Mg-Si alloy thin-walled profiles in different aging states: (a–c) 175 °C/10 h, 175 °C/16 h, 205 °C/6 h, 6xxx-1(1.6Mg/Si) profile; (d–f) 175 °C/10 h, 175 °C/16 h, 205 °C/6 h, 6xxx-2(1.33Mg/Si) profile; (g–i) 175 °C/10 h, 175 °C/16 h, 205 °C/6 h, 6xxx-3(1.14Mg/Si) profile.
Figure 12.
TEM images of intragranular precipitation in of the three thin-walled profiles of Al-Mg-Si alloys in different aging states: (a–c) 175 °C/10 h, 175 °C/16 h, 205 °C/6 h, 6xxx-1(1.6Mg/Si) profile; (d–f) 175 °C/10 h, 175 °C/16 h, 205 °C/6 h, 6xxx-2(1.33Mg/Si) profile; (g–i) 175 °C/10 h, 175 °C/16 h, 205 °C/6 h, 6xxx-3(1.14Mg/Si) profile.
Figure 12.
TEM images of intragranular precipitation in of the three thin-walled profiles of Al-Mg-Si alloys in different aging states: (a–c) 175 °C/10 h, 175 °C/16 h, 205 °C/6 h, 6xxx-1(1.6Mg/Si) profile; (d–f) 175 °C/10 h, 175 °C/16 h, 205 °C/6 h, 6xxx-2(1.33Mg/Si) profile; (g–i) 175 °C/10 h, 175 °C/16 h, 205 °C/6 h, 6xxx-3(1.14Mg/Si) profile.
Figure 13.
TEM images of grain boundary precipitation of 6xxx-1(1.6Mg/Si) profile after different aging process treatments: (a) 175 °C/10 h; (b) 175 °C/16 h; (c) 205 °C/6 h.
Figure 13.
TEM images of grain boundary precipitation of 6xxx-1(1.6Mg/Si) profile after different aging process treatments: (a) 175 °C/10 h; (b) 175 °C/16 h; (c) 205 °C/6 h.
Table 1.
Chemical compositions of the three cast rod alloys (wt. %).
Table 1.
Chemical compositions of the three cast rod alloys (wt. %).
Serial Number | Si | Fe | Cu | Mn | Mg | Cr | Al | Mg/Si | Mg + Si |
---|
6xxx-1(1.6Mg/Si) | 0.55 | 0.17 | 0.20 | 0.14 | 0.90 | 0.01 | Bal. | 1.60 | 1.45 |
6xxx-2(1.33Mg/Si) | 0.81 | 0.18 | 0.21 | 0.15 | 1.08 | 0.01 | Bal. | 1.33 | 1.85 |
6xxx-3(1.14Mg/Si) | 0.59 | 0.19 | 0.20 | 0.15 | 0.67 | 0.01 | Bal. | 1.14 | 1.26 |
Table 2.
Axial crushing properties of the three types of Al-Mg-Si alloy thin-walled profiles in different aging states.
Table 2.
Axial crushing properties of the three types of Al-Mg-Si alloy thin-walled profiles in different aging states.
Profile Number | Aging Process | Peak Load (KN) | Total Energy Absorption during Crushing (KJ) | Effective Energy Absorption during Crushing (KJ) | Cracked/Not Cracked |
---|
6xxx-1(1.6Mg/Si) | 175 °C/10 h | 362.5 | 31.02 | 22.21 | Yes |
175 °C/16 h | 402.75 | 30.9 | 16.55 | Yes |
205 °C/6 h | 380.3 | 30.61 | 30.61 | No |
6xxx-2(1.33Mg/Si) | 175 °C/10 h | 425 | 18.93 | 9.55 | Yes |
175 °C/16 h | 449.95 | 16.17 | 5.28 | Yes |
205 °C/6 h | 397.75 | 21.88 | 21.88 | No |
6xxx-3(1.14Mg/Si) | 175 °C/10 h | 312.45 | 25.43 | 13.82 | Yes |
175 °C/16 h | 383.2 | 27.26 | 10.87 | Yes |
205 °C/6 h | 358.85 | 28.19 | 28.19 | No |
Table 3.
Average grain size in the near-peak-aged state of the three kinds of Al-Mg-Si alloy thin-walled profiles.
Table 3.
Average grain size in the near-peak-aged state of the three kinds of Al-Mg-Si alloy thin-walled profiles.
Profile Number | 6xxx-1(1.6Mg/Si) | 6xxx-2(1.33Mg/Si) | 6xxx-3(1.14Mg/Si) |
---|
Average grain size (µm) | 63.6 | 154.9 | 92.1 |
Table 4.
Tensile properties of the three Al-Mg-Si alloy thin-walled profiles (at near-peak-aged state).
Table 4.
Tensile properties of the three Al-Mg-Si alloy thin-walled profiles (at near-peak-aged state).
Profile Number | Yield Strength (MPa) | Tensile Strength (MPa) | Elongation (%) |
---|
6xxx-1(1.6Mg/Si) | 294 | 305 | 11.1 |
6xxx-2(1.33Mg/Si) | 355 | 367 | 8.2 |
6xxx-3(1.14Mg/Si) | 273 | 288 | 11.2 |
Table 5.
Tensile properties of the three Al-Mg-Si alloy thin-walled profiles with different aging states.
Table 5.
Tensile properties of the three Al-Mg-Si alloy thin-walled profiles with different aging states.
Profile Number | Aging Process | Yield Strength (MPa) | Tensile Strength (MPa) | Elongation (%) |
---|
6xxx-1 | 175 °C/10 h | 252 | 270 | 15.3 |
175 °C/16 h | 294 | 305 | 11.1 |
205 °C/6 h | 273 | 287 | 14.6 |
6xxx-2 | 175 °C/10 h | 342 | 355 | 11.7 |
175 °C/16 h | 355 | 367 | 8.2 |
205 °C/6 h | 302 | 317 | 11.1 |
6xxx-3 | 175 °C/10 h | 232 | 272 | 13.3 |
175 °C/16 h | 273 | 288 | 11.2 |
205 °C/6 h | 258 | 272 | 13.7 |
Table 6.
Bending properties of the three Al-Mg-Si alloy thin-walled profiles in different aging states.
Table 6.
Bending properties of the three Al-Mg-Si alloy thin-walled profiles in different aging states.
Profile Number | Aging Process | Specimen Thickness d1 (mm) | Measured Bending Angle α1 (°) | 2 mm Equivalent Bending Angle α2 (°) |
---|
6xxx-1(1.6Mg/Si) | 175 °C/10 h | 2.66 | 96 | 81 |
175 °C/16 h | 2.66 | 91 | 77 |
205 °C/6 h | 2.65 | 83 | 102 |
6xxx-2(1.33Mg/Si) | 175 °C/10 h | 2.65 | 51 | 59 |
175 °C/16 h | 2.65 | 36 | 45 |
205 °C/6 h | 2.66 | 60 | 69 |
6xxx-3(1.14Mg/Si) | 175 °C/10 h | 2.64 | 46 | 57 |
175 °C/16 h | 2.64 | 47 | 54 |
205 °C/6 h | 2.66 | 48 | 60 |
Table 7.
Chemical composition of the second-phase particles (wt%) of the three Al-Mg-Si alloy thin-walled profiles.
Table 7.
Chemical composition of the second-phase particles (wt%) of the three Al-Mg-Si alloy thin-walled profiles.
Placement | Al | Mg | Cu | Fe | Mn | Si |
---|
a1 | 88.03 | 0.69 | 0.49 | 6.66 | 1.23 | 2.88 |
a2 | 86.50 | 0.69 | 0.38 | 7.07 | 1.96 | 3.40 |
d1 | 67.82 | -- | -- | 21.83 | 4.22 | 6.12 |
d2 | 83.09 | 0.43 | -- | 11.38 | 1.29 | 3.81 |
f1 | 65.07 | -- | 1.01 | 19.70 | 7.22 | 6.99 |
f2 | 74.35 | 0.36 | 0.63 | 14.17 | 5.08 | 5.41 |
g1 | 76.29 | -- | -- | 20.23 | 0.91 | 6.47 |
g2 | 76.51 | -- | -- | 16.52 | 0.86 | 5.74 |
Table 8.
Area fractions of the second phase for the three Al-Mg-Si alloy thin-walled profiles.
Table 8.
Area fractions of the second phase for the three Al-Mg-Si alloy thin-walled profiles.
Profile Number | Aging Process | Area Fraction of Second Phase (%) |
---|
6xxx-1(1.6Mg/Si) | 175 °C/10 h | 1.74 |
175 °C/16 h | 1.66 |
205 °C/6 h | 1.71 |
6xxx-2(1.33Mg/Si) | 175 °C/10 h | 2.02 |
175 °C/16 h | 1.85 |
205 °C/6 h | 1.96 |
6xxx-3(1.14Mg/Si) | 175 °C/10 h | 1.58 |
175 °C/16 h | 1.45 |
205 °C/6 h | 1.48 |