Improving the Hydromechanical Deep-Drawing Process Using Aluminum Tailored Heat Treated Blanks

doi:10.1007/s40195-015-0347-0

Abstract

Abstract:

The present work demonstrates the effectiveness of combining the hydromechanical deep-drawing process with the Tailored Heat Treated Blank (THTB) technique. In the hydromechanical deep-drawing process, the fluid pressure is used for postponing the fracture occurrence in the blank, while the THTB technique allows to create a material property gradient through a suitable a.jpgicial aging treatment carried out prior to the forming process. Since the number of process variables is large, in the present work the authors propose an optimization loop for the determination of the parameters controlling the extension of the blank regions to be subjected to the aging treatment and the temperature levels to be set during the heat treatment. The proposed methodology couples a simple finite element model (Abaqus) with a multi-objective optimization platform (modeFRONTIER). A preliminary experimental campaign was carried out for determining the effect of the aging treatment on the mechanical (through tensile tests) and deformative (through formability tests) behavior of the AC170PX aluminum alloy. Optimization results prove the effectiveness of the adopted methodology and put in evidence that the adoption of properly aged blanks in the hydromechanical deep drawing allows to increase the limit drawing ratio and to simplify the process since it is conducted at room temperature.

Key words: Aluminum alloy, Aging, Hydromechanical deep drawing, Finite element analysis, Mechanical characterization, Formability

Antonio Piccininni, Gabriella Di Michele, Gianfranco Palumbo, Donato Sorgente, Luigi Tricarico. Improving the Hydromechanical Deep-Drawing Process Using Aluminum Tailored Heat Treated Blanks[J]. Acta Metallurgica Sinica (English Letters), 2015, 28(12): 1482-1489.

Figures/Tables 15

Table 1 Chemical composition of AC170PX alloy (in wt%)

Si	Fe	Cu	Mn	Mg	Cr	Zn	Ti	Al
0.6	0.16	0.14	0.06	0.7	0.0	0.0	0.0	Bal.

Fig.1 a Experimental setup for tensile tests on aged specimens; b stochastic pattern created on the specimen surface (unit: mm)

Fig.2 Summary of results from the mechanical characterization of aged specimens in terms of percentage yield stress (YS%) a and percentage ultimate tensile strength (UTS%) b

Fig.3 Formability test: a equipment; b FLCs concerning specimens subjected to different aging temperatures

Fig.4 a FE model; b adopted pressure and punch stroke profiles

Fig.5 a Temperature map superimposed to the blank for simulating the behavior of the THTB; b definition of the parameter FLDCRT

Table 2 Ranges of variation of the adopted input parameters

Input variable	Lower value	Upper value
L₁ (mm)	10	19
L₂ (mm)	10	14
T₁ (°C)	200	400
T₂ (°C)	200	400

Fig.6 Flowchart of the optimization loop

Fig.7 Distribution of the initial population within the design space for the parameters: a T1 and T2; b L1 and L2

Fig.8 History charts of the two input variables related to the aging temperatures T1 a and T2 b

Fig.9 Contour plot of the output variable punch stroke

Fig.10 History plots of the two input variables L1 a and L2 b related to the extension of the aged regions

Table 3 List of numerical simulations to define the optimal value of the parameter L2

Run	L₁ (mm)	L₂ (mm)	T₁ (°C)	T₂ (°C)
No. 1	19	10	200	400
No. 2	19	14	200	400
No. 3	19	12	200	400

Fig.11 Distribution of the parameters sheet thickness (STH) and FLDCRT along the radial direction

Fig.12 STV and maximum FLDCRT value according to L2

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