1 Introduction
2 Material and methods
2.1 Material
Material | Material properties | Alloy composition | ||||
---|---|---|---|---|---|---|
YS | UTS |
\(A_{80}\)
| Mn | Mg | Si | |
MPa | % | wt% | ||||
AA 6016 | 120 |
\(>250\)
| 24 | 0.2 | 0.2 | 0.2 |
2.2 Process sequence and sample geometry
2.3 Manufacturing of reinforcements and testing
Parameter | Value |
---|---|
Scanning speed (mm/min) | 2500 |
Power (W) | 800 |
Powder mass flow (g/min) | 2.3 |
Thickness of single layer (mm) | 0.3–0.4 |
2.4 Microstructure and hardness
2.5 Hole flanging experiments
2.6 Functionalizing and testing
3 Results
3.1 Mechanical properties and microstructure
3.1.1 Mechanical properties
-
The elongation at break is reduced by around 50% for all the reinforcement specimens.
-
The tensile strength is reduced the range of 210–230 MPa, while the double layered reinforcement outperforms the single layered one, which is an indication of the rather random heating and cooling behavior in the reinforcement processing.
YS (MPa) | UTS (MPa) |
---|---|
Not reinf. T4 | |
142 | 258 |
127 | 264 |
134 | 264 |
Not reinf. T6 | |
247 | 295 |
242 | 294 |
242 | 294 |
Reinf. on T4 | |
132 | 215 |
130 | 212 |
130 | 207 |
Reinf. on T4 + T6 | |
228 | 265 |
213 | 250 |
213 | 249 |
Uniform elong. (%) | Fracture elong. (%) |
---|---|
Not reinf. T4 | |
23.7 | 27.1 |
23.2 | 27.3 |
23.4 | 26.4 |
Not reinf. T6 | |
16 | 20.5 |
12.3 | 16 |
13.2 | 15.6 |
Reinf. on T4 | |
196 | 260 |
20 | 21.5 |
16 | 22 |
Reinf. on T4 + T6 | |
8.4 | 12.2 |
8.1 | 12.2 |
8.3 | 12.7 |
3.1.2 Microstructure
3.2 Forming forces
3.3 Forming limits of reinforced blanks
3.4 Part geometry
3.5 Rip off tests of reinforced flanges
4 Discussion
4.1 Tensile test properties
4.2 Microstructure and hardness
4.3 Functionalizing and testing
Number of layers | 1 | 2 | 3 |
---|---|---|---|
Additional mass | \(1.4\%\) | \(2.88\%\) | \(4.32\%\) |
Force after reinf. | \(14\%\) | \(71\%\) | \(164\%\) |
Force after subs. hardening | \(196\%\) | \(260\%\) | \(380\%\) |
5 Conclusion
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The material can be used for additive reinforcements via LMD. Additive layers with no detectable porosity, no bonding defects but slight short cracks near the surface can be achieved. Hereby, a single layer can be manufactured in roughly 20 s.
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The reinforced blanks can be hole-flanged with no alterations of the tooling equipment. The forming limits in terms of HER are comparable to conventional material. However, the hardenability of the reinforced material is not given in the same extend as for the base material.
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The mechanical properties change through the reinforcement process but stays in controllable margins. A drop in tensile elongation of about 5% in the T6 state was observed in the reinforced sheets compared to the base material sheets.
-
The reinforcement enables functionalizing of formed parts to achieve optimal lightweight performance.