The formability curves of AZ31B magnesium and 5083 aluminum alloy sheets were constructed using the pneumatic stretching test at two different sets of forming conditions. The test best resembles the conditions encountered in actual hydro/pneumatic forming operations, such as the superplastic forming (SPF) and quick plastic forming (QPF) techniques. Sheet samples were deformed at (400 °C and 1 × 10−3 s−1) and (450 °C and 5 × 10−3 s−1), by free pneumatic bulging into a set of progressive elliptical die inserts. The material in each of the formed domes was forced to undergo biaxial stretching at a specific strain ratio, which is simply controlled by the geometry (aspect ratio) of the selected die insert. Material deformation was quantified using circle grid analysis (CGA), and the recorded planar strains were used to construct the forming limit curves of the two alloys. The aforementioned was carried out with the sheet oriented either along or across the direction of major strains in order to establish the relationship between the material’s rolling direction and the corresponding limiting strains. Great disparities in limiting strains were found in the two orientations for both alloys; hence, a “composite FLD” is introduced as an improved means for characterizing material formability limits.

References

References
1.
Engelhart
,
D.
, and
Moedel
,
C.
, 1999, “
Die Entwicklung des Audi A2-ein neues Fahrzeugkonzept in der Kompaktwagenklasses
,”
Proceedings of Technologien um das 3l-Auto
,
Brunswick
,
Germany
, Nov. 16–18.
2.
Dick
,
M.
, 1999, “
Das 3-Liter Lupo—Technologien für den Minimalen Verbrauch
,”
Proceedings of Technologien um das 3l-Auto
,
Brunswick
,
Germany
, Nov. 16–18.
3.
Cole
,
G.
, and
Sherman
,
A.
, 1995, “
Lightweight Materials for Automotive Applications
,”
Mater. Charact.
,
35
(
1
), pp.
3
9
.
4.
Jambor
,
A.
, and
Beyer
,
M.
, 1997, “
New Cars—New Materials
,”
Mater. Des.
,
18
(
4–6
), pp.
203
209
.
5.
Luo
,
A.
, 2002, “
Magnesium: Current and Potential Automotive Applications
,”
JOM
,
54
(
2
), pp.
42
48
.
6.
Mordike
,
B.
, and
Ebert
,
T.
, 2001, “
Magnesium Properties—Applications—Potential
,”
Mater. Sci. Eng. A
,
302
, pp.
37
45
.
7.
Doege
,
E.
, and
Dröder
,
K.
, 2001, “
Sheet Metal Forming of Magnesium Wrought Alloys—Formability and Process Technology
,”
J. Mater. Process. Technol.
,
115
, pp.
14
19
.
8.
Verma
,
R.
, and
Carter
,
J.
, 2006, “
Quick Plastic Forming of a Decklid Inner Panel With Commercial AZ31 Magnesium Sheet
,” SAE Paper No. 2006-01-0525.
9.
Abu-Farha
,
F.
, and
Khraisheh
,
M.
, 2007, “
Analysis of Superplastic Deformation of AZ31 Magnesium Alloy
,”
J. Adv. Eng. Mater.
,
9
(
9
), pp.
777
783
.
10.
Carter
,
J.
,
Krajewski
,
P.
, and
Verma
,
R.
, 2008, “
Hot Blow Forming of AZ31 Mg Sheet: Formability Assessment and Application Development
,”
JOM
,
60
, pp.
77
81
.
11.
Taleff
,
E.
,
Hector
, Jr.,
L.
,
Bradley
,
J.
,
Verma
,
R.
, and
Krajewski
,
P.
, 2009, “
The Effect of Stress State on High-Temperature Deformation of Fine-Grained Aluminum–Magnesium Alloy AA5083 Sheet
,”
Acta Mater.
,
57
, pp.
2812
2822
.
12.
Hector
, Jr.,
L.
,
Krajewski
,
P.
,
Taleff
,
E.
, and
Carter
,
J.
, 2010, “
High Temperature Forming of a Vehicle Closure Component in Fine-Grained Aluminum Alloy AA5083 and Magnesium AZ31: Finite Element Simulations and Experiments
,”
Key Eng. Mater.
,
433
, pp.
197
210
.
13.
Agnew
,
S.
, and
Duygulu
,
O.
, 2003, “
A Mechanistic Understanding of the Formability of Magnesium: Examining the Role of Temperature on the Deformation Mechanisms
,”
Mater. Sci. Forum
,
419–422
, pp.
177
188
.
14.
Doege
,
E.
, and
Dröder
,
K.
, 1997, “
Processing of Magnesium Sheet Metals by Deep Drawing and Stretch Forming
,”
Materiaux etTechniques
,
7–8
, pp.
19
23
.
15.
Krajewski
,
P.
, and
Schroth
,
J.
, 2007, “
Overview of Quick Plastic Forming Technology
,”
Mater. Sci. Forum
,
551–552
, pp.
3
12
.
16.
Rashid
,
M.
,
Kim
,
C.
,
Ryntz
,
E.
,
Saunders
,
F.
,
Verma
,
R.
, and
Sooho
,
K.
, 2001, “
Quick Plastic Forming of Aluminum Alloy Sheet Metal
,” US Patent 6-253-588.
17.
Keeler
,
S.
, and
Backofen
,
W.
, 1963, “
Plastic Instability and Fracture in Sheets Stretched Over Rigid Punches
,”
Trans. Am. Soc. Metals
,
56
, pp.
25
48
.
18.
18
Marciniak
,
Z.
,
Duncan
,
J.
, and
Hu
,
S.
, 2002,
Mechanics of Sheet Metal Forming
,
2nd ed.
,
Butterworth-Heinemann
,
Oxford, UK
.
19.
ASTM E 2218-02 (2008), Standard Test Method for Determining Forming Limit Curves.
20.
Marciniak
,
Z.
, and
Kuczynski
,
Z.
, 1967, “
Limit Strains in the Processes of Stretch-Forming Sheet Metal
,”
Int. J. Mech. Sci.
,
9
, pp.
609
620
.
21.
Nakazima
,
K.
,
Kikuma
,
T.
, and
Asuka
,
K.
, 1971, “
Study on the Formability of Steel Sheet
,” Yawata Technical Report No. 264, pp.
678
680
.
22.
ISO 12004: 1997, Metallic Materials—Guidelines for the Determination of Forming Limit Diagrams.
23.
Naka
,
T.
,
Torikai
,
G.
,
Hino
,
R.
, and
Yoshida
,
F.
, 2001, “
The Effects of Temperature and Forming Speed on the Forming Limit Diagram for Type 5083Aluminum-Magnesium Alloy Sheet
,”
J. Mater. Process. Technol.
,
113
, pp.
648
653
.
24.
Li
,
D.
, and
Ghosh
,
A.
, 2004, “
Biaxial Warm Forming Behavior of Aluminum Sheet Alloys
,”
J. Mater. Process. Technol.
,
145
, pp.
281
293
.
25.
Hsu
,
E.
,
Carsley
,
J.
, and
Verma
,
R.
, 2008, “
Development of Forming Limit Diagrams of Aluminum and Magnesium Sheet Alloys at Elevated Temperatures
,”
J. Mater. Eng. Perform.
,
17
(
3
), pp.
288
296
.
26.
Geiger
,
M.
, and
Merklein
,
M.
, 2003, “
Determination of Forming Limit Diagrams—A New Analysis Method for Characterization of Materials Formability
,”
CIRP Ann.-Manuf. Technol.
,
52
, pp.
213
216
.
27.
Giuliano
,
G.
,
Carrino
,
L.
, and
Franchitti
,
S.
, 2005, “
Formability of Superplastic PbSn60 Alloy
,”
Mater. Lett.
,
59
, pp.
2156
2158
.
28.
Siegert
,
K.
,
Jäger
,
S.
, and
Vulcan
,
M.
, 2003, “
Pneumatic Bulging of Magnesium AZ31 Sheet Metals at Elevated Temperatures
,”
CIRP Ann.
,
52
, pp.
241
244
.
29.
Chan
,
C.
, and
Chow
,
K.
, 2002, “
Analysis of Hot Limit Strains of a Superplastic 5083 Aluminum Alloy Under Biaxial Tension
,”
Int. J. Mech. Sci.
,
44
, pp.
1467
1478
.
30.
Banabic
,
D.
,
Vulcan
,
M.
, and
Siegert
,
K.
, 2005, “
Bulge Testing under Constant and Variable Strain Rates of Superplastic Aluminum Alloy
,”
CIRP Ann.-Manuf. Technol.
,
54
, pp.
205
208
.
31.
Luo
,
Y.
,
Miller
,
C.
,
Luckey
,
G.
,
Friedman
,
P.
, and
Peng
,
Y.
, 2007, “
On Practical Forming Limits in Superplastic Forming of Aluminum Sheet
,”
J. Mater. Eng. Perform.
,
16
, pp.
274
283
.
32.
Kulas
,
M.
,
Krajewsky
,
P.
,
Bradley
,
J.
, and
Taleff
,
E.
, 2007, “
Forming Limit Diagrams for Hot-Forming of AA5083 Aluminum Sheet: Continuously Cast Material
,”
J. Mater. Eng. Perform.
,
16
, pp.
308
313
.
33.
Kulas
,
M.
,
Krajewsky
,
P.
,
Bradley
,
J.
, and
Taleff
,
E.
, 2007, “
Forming Limit Diagrams for AA5083 Under SPF and QPF Conditions
,”
Mater. Sci. Forum
,
551–552
, pp.
129
134
.
34.
Abu-Farha
,
F.
,
Shuaib
,
N.
,
Khraisheh
,
M.
, and
Weinmann
,
K.
, 2008, “
Limiting Strains of Sheet Metals Obtained by Pneumatic Stretching at Elevated Temperatures
,”
CIRP Ann.-Manuf. Technol.
,
57
, pp.
275
278
.
35.
Abu-Farha
,
F.
,
Hector
,
L.
, and
Krajewski
,
P.
, 2011, “
Forming Limit Curves for the AA5083 Alloy Under Quick Plastic Forming Conditions
,” SAE Paper No. 2011-01-0235.
36.
Banabic
,
D.
,
Balan
,
T.
, and
Comsa
,
D.
, 2001, “
Closed Form Solution for Bulging Through Elliptical Dies
,”
J. Mater. Process. Technol.
,
115
, pp.
83
86
.
You do not currently have access to this content.