**3. Aluminum alloy behavior during deep drawing process**

The drawing of metal or "deep drawing" is the process by which a punch force is applied to sheet metal to flow between the surfaces of a punch die. By this, the sheet is formed into cylindrical, conic, or box-shaped parts. The development of the deep drawing process has paralleled scientific development, particularly in the aircraft and automotive industries. This process is more popular because of its swift press cycle times. Complex axisymmetric geometries and certain nonaxisymmetric geometries can be produced with a few operations. With respect to the functional perspective, the deep drawing process produces high-strength and lightweight parts as well as geometries unattainable with some other manufacturing processes [20]. A schematic illustration of these deep drawing processes is shown in **Figure 1**. This design is made in such a way that thickness reduction of the workpiece material has been avoided completely (**Figure 1**). For this process, the basic tools are the punch, the drawing die ring, and the blank holder.

**Figure 2** shows the important process parameters involved in the deep drawing process. In addition, material properties such as the strain hardening coefficient (n) and normal anisotropy (R) affect the deep drawing operation.

Instead of tool temperatures, forming temperature curves (FTCs) were characterized from AA5754-O as a workpiece temperature at the warm deep drawing (WDD) process. The distinctive behavior of these curves was examined under nonisothermal WDD of AA 5754-O. The process parameters were considered such as FTC, blank holder force, and punch velocity to assure deep drawability. Optimum conditions were investigated by evaluating the cup volume and springback parameters. In the findings, 330°C in the flange-die radius region and 100°C in the cup wall-punch bottom region were the ideal optimum temperatures for the warm deep drawing process [21]. The stress-strain response of AA2014, AA5052, and AA6082 aluminum alloys at four temperatures: 303, 423, 523 and 623 K, and three strain rates: 0.0022, 0.022, and 0.22 s<sup>−</sup><sup>1</sup> was evaluated through uniaxial tensile tests. It was found that the Cowper-Symonds model was not a robust constitutive model, and failed to predict the flow behavior. A comparative study was followed for modeling of three aluminum alloys under the mentioned strain rates and temperatures. For comparison, the capability of Johnson-Cook model, modified models

**155**

*Aluminum Alloys Behavior during Forming DOI: http://dx.doi.org/10.5772/intechopen.86077*

constitutive equation.

*Significant variables in deep drawing [20].*

**Figure 2.**

limiting strains as damage model [23].

and stamping speed 50 mm s<sup>−</sup><sup>1</sup>

of Zerilli-Armstrong and Arrhenius and artificial neural network were considered for constitutive behavior. Better formability of the materials was observed at an elevated temperature of 623 K in terms of cup height and maximum safe strains by conducting cylindrical cup deep drawing experiments under two different punch speeds of 4 and 400 mm/min [22]. Tensile tests of AA5754-H22 aluminum alloy were carried out at five different temperatures and three different strain rates to investigate the deformation behavior correlating with the Cowper-Symonds

When punch and die were heated to 200°C, the forming limit strain and dome

Deep drawing of aluminum alloy AA6111 at elevated temperatures was analyzed

[25]. Tailor friction stir welded blanks (TFSWBs) of

height were improved. Significant enhancement was noted when the die and punch temperatures were maintained at 200 and 30°C, respectively, in deep drawn cup depth. Using a thermo-mechanical FE model, the forming behavior at different isothermal and nonisothermal conditions was predicted. In the FE model, temperature-dependent properties in Barlat-89 yield criterion and coupled with Cowper-Symonds hardening model were used. The validation had taken place using thinning/failure location in deformed cups by implementing the experimental

with the effect of friction coefficient through experiments and finite element method. Results indicated that the friction coefficient and lubrication position influence the minimum thickness, the thickness deviation, and the failure mode of the formed parts. During the hot forming process, the failure modes were draw mode, stretch mode, and equi-biaxial stretch mode. Fracture occurred at the center of cup bottom or near the cup corner in a ductile mode or ductile brittle mixed mode [24]. Simulations of deep drawing tests at elevated temperatures were carried out with experimental validation on aluminum alloy 7075. For stamping operations, some of the important parameters such as blank holder force, stamping speed, blank temperature, and friction coefficient were considered. During the experimentation, stamping tests were performed at temperature between 350 and 500°C, 0 and 10 kN blank holding force, 50 and 150 mm/s stamping speed, and 0.1 and 0.3 frictional coefficient. At lower values of temperature, blank holder force and friction coefficient improvement were seen in thickness homogeneity whereas formability was improved with the well lubricated blank at about 400°C temperature

AA5754-H22 and AA5052-H32 sheet metals were fabricated using a tool with optimized design along with optimized process parameters. For optimization to design the friction stir welding experiments, Taguchi L9 orthogonal array was used. For

**Figure 1.** *Schematic illustration of deep drawing process [20].*

*Aluminum Alloys Behavior during Forming DOI: http://dx.doi.org/10.5772/intechopen.86077*

*Aluminium Alloys and Composites*

its values under dry conditions [19].

the drawing die ring, and the blank holder.

three strain rates: 0.0022, 0.022, and 0.22 s<sup>−</sup><sup>1</sup>

*Schematic illustration of deep drawing process [20].*

that it had three stages such as stage I: the lubricant is applied excessively and the IHTC is plateaued, stage II: in which the lubricant diminishes during sliding and the IHTC decreases, and stage III: lubricant breakdown occurs and the IHTC is equal to

The drawing of metal or "deep drawing" is the process by which a punch force is applied to sheet metal to flow between the surfaces of a punch die. By this, the sheet is formed into cylindrical, conic, or box-shaped parts. The development of the deep drawing process has paralleled scientific development, particularly in the aircraft and automotive industries. This process is more popular because of its swift press cycle times. Complex axisymmetric geometries and certain nonaxisymmetric geometries can be produced with a few operations. With respect to the functional perspective, the deep drawing process produces high-strength and lightweight parts as well as geometries unattainable with some other manufacturing processes [20]. A schematic illustration of these deep drawing processes is shown in **Figure 1**. This design is made in such a way that thickness reduction of the workpiece material has been avoided completely (**Figure 1**). For this process, the basic tools are the punch,

**Figure 2** shows the important process parameters involved in the deep drawing process. In addition, material properties such as the strain hardening coefficient (n)

Instead of tool temperatures, forming temperature curves (FTCs) were characterized from AA5754-O as a workpiece temperature at the warm deep drawing (WDD) process. The distinctive behavior of these curves was examined under nonisothermal WDD of AA 5754-O. The process parameters were considered such as FTC, blank holder force, and punch velocity to assure deep drawability. Optimum conditions were investigated by evaluating the cup volume and springback parameters. In the findings, 330°C in the flange-die radius region and 100°C in the cup wall-punch bottom region were the ideal optimum temperatures for the warm deep drawing process [21]. The stress-strain response of AA2014, AA5052, and AA6082 aluminum alloys at four temperatures: 303, 423, 523 and 623 K, and

tests. It was found that the Cowper-Symonds model was not a robust constitutive model, and failed to predict the flow behavior. A comparative study was followed for modeling of three aluminum alloys under the mentioned strain rates and temperatures. For comparison, the capability of Johnson-Cook model, modified models

was evaluated through uniaxial tensile

**3. Aluminum alloy behavior during deep drawing process**

and normal anisotropy (R) affect the deep drawing operation.

**154**

**Figure 1.**

**Figure 2.** *Significant variables in deep drawing [20].*

of Zerilli-Armstrong and Arrhenius and artificial neural network were considered for constitutive behavior. Better formability of the materials was observed at an elevated temperature of 623 K in terms of cup height and maximum safe strains by conducting cylindrical cup deep drawing experiments under two different punch speeds of 4 and 400 mm/min [22]. Tensile tests of AA5754-H22 aluminum alloy were carried out at five different temperatures and three different strain rates to investigate the deformation behavior correlating with the Cowper-Symonds constitutive equation.

When punch and die were heated to 200°C, the forming limit strain and dome height were improved. Significant enhancement was noted when the die and punch temperatures were maintained at 200 and 30°C, respectively, in deep drawn cup depth. Using a thermo-mechanical FE model, the forming behavior at different isothermal and nonisothermal conditions was predicted. In the FE model, temperature-dependent properties in Barlat-89 yield criterion and coupled with Cowper-Symonds hardening model were used. The validation had taken place using thinning/failure location in deformed cups by implementing the experimental limiting strains as damage model [23].

Deep drawing of aluminum alloy AA6111 at elevated temperatures was analyzed with the effect of friction coefficient through experiments and finite element method. Results indicated that the friction coefficient and lubrication position influence the minimum thickness, the thickness deviation, and the failure mode of the formed parts. During the hot forming process, the failure modes were draw mode, stretch mode, and equi-biaxial stretch mode. Fracture occurred at the center of cup bottom or near the cup corner in a ductile mode or ductile brittle mixed mode [24]. Simulations of deep drawing tests at elevated temperatures were carried out with experimental validation on aluminum alloy 7075. For stamping operations, some of the important parameters such as blank holder force, stamping speed, blank temperature, and friction coefficient were considered. During the experimentation, stamping tests were performed at temperature between 350 and 500°C, 0 and 10 kN blank holding force, 50 and 150 mm/s stamping speed, and 0.1 and 0.3 frictional coefficient. At lower values of temperature, blank holder force and friction coefficient improvement were seen in thickness homogeneity whereas formability was improved with the well lubricated blank at about 400°C temperature and stamping speed 50 mm s<sup>−</sup><sup>1</sup> [25]. Tailor friction stir welded blanks (TFSWBs) of AA5754-H22 and AA5052-H32 sheet metals were fabricated using a tool with optimized design along with optimized process parameters. For optimization to design the friction stir welding experiments, Taguchi L9 orthogonal array was used. For

the multi-objective optimization to maximize the weld strength and total elongation reducing the surface roughness and energy consumption, the gray relational analysis was applied. The formability was evaluated and compared with TFSWBs and parent materials using LDR tests. The analysis had proved that TFSWBs were comparable with parent materials more specifically without any failure in the weld zone area. For improvement in the LRD, a modified conical tractrix die was proposed and 27% improvement was observed.

Simulations of cylindrical cup drawing were carried out with experimental validation on AA6111 aluminum alloy at elevated temperatures. The influence of four important process parameters, namely, punch velocity, blank holder force (BHF), friction coefficient, and initial forming temperature of blank on drawing characteristics was investigated using design of experiments (DOE), analysis of variance (ANOVA), and analysis of mean (ANOM). Based on the results of ANOVA, the BHF had the greatest influence on minimum thickness. The significance of punch velocity for thickness deviation, BHF, friction coefficient, and initial forming temperature of blank was 44.35, 24.88, 15.77, and 14.995% respectively. Further, the effect of each factor on forming characteristics was analyzed by ANOM [26].

A design optimization problem was constructed to identify the formability window, in which the punch stroke was maximized subject to wrinkling and tearing. For this, the formability window of a difficult-to-draw material AA 5402 was explained with the pulsating blank holder force (PBHF) and the variable blank holder force (VBHF). Some parameters in the VBHF and PBHF were included and taken as the design variables. A sequential approximate optimization (SAO) using a radial basis function (RBF) network was used to determine the optimal parameter of PBHF and VBHF. From numerical simulation coupled with the SAO using the RBF network using the PBHF and VBHF, formability window was observed. It was identified that the proposed approach was highly useful for clarifying the formability window of a difficult-to-draw material [27]. The tailored heat treated blank (THTB) technique was demonstrated to create a material property gradient through a suitable artificial aging treatment carried out prior to the forming process on the effectiveness of combining the hydromechanical deep-drawing process. This method was coupled with a simple finite element model and a multi-objective optimization platform. For determining the effect of the aging treatment on the mechanical and deformative behavior of the AC170PX aluminum alloy, a preliminary experimental campaign was carried out. The adoption of aged blanks in the hydromechanical deep drawing allows to increase the limit drawing ratio and to simplify the process proved from the optimization results [28].

For increasing the drawability of AA1200 aluminum alloy cylindrical cups, one technique was developed. For optimal process design, effects of die and punch along with fillet radius of die and punch on LDR, drawing load with respect to punch stroke and strain of the cup wall was investigated numerically. To determine the optimum LDR form numerical analysis, a commercial finite element simulation package, ANSYS 14.0, was used. The effects of the original blank on the various LDR and punch load were numerically investigated. This process successfully produced cylindrical cups with considerable drawing ratio [29]. The effect of pulsating blankholder system was investigated on improving the formability of aluminum 1050 alloy. Using ABAQUS6.7 software, the deep drawing process was simulated for cylindrical cup of AA 1050. Later on, experimental and numerical analyses were compared for depth of cup, tearing, and thickness distribution. The results indicated that with proper frequency and gap, the cup depth and thickness distribution can be improved by using the pulsating blankholder system. Further, good agreement was observed between simulation and experimental results [30]. An analytical model was proposed for the nonuniform fluid pressure distribution

**157**

**Figure 3.**

*Aluminum Alloys Behavior during Forming DOI: http://dx.doi.org/10.5772/intechopen.86077*

current density of 21.7 A/mm<sup>2</sup>

formability was evaluated [33–37].

and square in cross section will be formed [39].

*Incremental forming of an aluminum sheet on CNC milling machine [34].*

in the cavity and for the hydrodynamic flow of the fluid film between the blank and die for AA5086 aluminum alloy. From Reynolds equation solution, the hydrodynamic flow was calculated and model was implemented in ABAQUS/Explicit, finite element software. The approach was validated and investigated for the influences of the blank holder force and the fluid pressure on the formability of the blank metal. The results exhibited that the choice of an appropriate blank holder force reduced the strain in the blank and prevented the risk of fracture [31]. A study was made on deep drawing of SiCp/2024Al composite sheets by considering the effect of pulse current on heating performance and thermal. The high-intensity pulse current flows through the sheet and generates the tremendous Joule heat. The specimen temperature was kept around 673 K at a rate of 13.5 K/s under the

by inserting the stainless-steel inserts. Besides, the SiCp/2024Al composite was successfully deep drawn with good surface quality [32]. Deep drawing process characteristics of AA 6xxx alloy sheet were discussed under different process parameters such as punch force, lubrication, fillet radius, punch speed etc., and the

Incremental sheet forming (ISF) is a flexible process in which a sheet of metal is formed by a progression of localized deformation. This process does not require any specialized tool; a simple tool moves over the surface of the sheet metal by which localized plastic deformation is initiated. Hence, many shapes can be formed by designing a proper path to a tool. The main motto of this process is to form a sheet metal without any manufacturing of specialized dies [38]. **Figure 3** shows an example of the incremental forming. In this **Figure 3**, according to computer numerical control (CNC) machine program instructions, the ball tool moves on the sheet to form the required shape. Hence, the process is in CNC machine; the program can be edited as per the requirement. From the shown **Figure 3**, the hollow

A few observations are made and discussed on incremental forming process. Incremental forming behavior of 6111-T4 an alloy was investigated for exterior body panel applications. Tensile testing data were used to simulate the incremental forming

**4. Aluminum alloy behavior during incremental forming**

. The temperature difference was reduced by 73.3%

#### *Aluminum Alloys Behavior during Forming DOI: http://dx.doi.org/10.5772/intechopen.86077*

*Aluminium Alloys and Composites*

posed and 27% improvement was observed.

simplify the process proved from the optimization results [28].

For increasing the drawability of AA1200 aluminum alloy cylindrical cups, one technique was developed. For optimal process design, effects of die and punch along with fillet radius of die and punch on LDR, drawing load with respect to punch stroke and strain of the cup wall was investigated numerically. To determine the optimum LDR form numerical analysis, a commercial finite element simulation package, ANSYS 14.0, was used. The effects of the original blank on the various LDR and punch load were numerically investigated. This process successfully produced cylindrical cups with considerable drawing ratio [29]. The effect of pulsating blankholder system was investigated on improving the formability of aluminum 1050 alloy. Using ABAQUS6.7 software, the deep drawing process was simulated for cylindrical cup of AA 1050. Later on, experimental and numerical analyses were compared for depth of cup, tearing, and thickness distribution. The results indicated that with proper frequency and gap, the cup depth and thickness distribution can be improved by using the pulsating blankholder system. Further, good agreement was observed between simulation and experimental results [30]. An analytical model was proposed for the nonuniform fluid pressure distribution

the multi-objective optimization to maximize the weld strength and total elongation reducing the surface roughness and energy consumption, the gray relational analysis was applied. The formability was evaluated and compared with TFSWBs and parent materials using LDR tests. The analysis had proved that TFSWBs were comparable with parent materials more specifically without any failure in the weld zone area. For improvement in the LRD, a modified conical tractrix die was pro-

Simulations of cylindrical cup drawing were carried out with experimental validation on AA6111 aluminum alloy at elevated temperatures. The influence of four important process parameters, namely, punch velocity, blank holder force (BHF), friction coefficient, and initial forming temperature of blank on drawing characteristics was investigated using design of experiments (DOE), analysis of variance (ANOVA), and analysis of mean (ANOM). Based on the results of ANOVA, the BHF had the greatest influence on minimum thickness. The significance of punch velocity for thickness deviation, BHF, friction coefficient, and initial forming temperature of blank was 44.35, 24.88, 15.77, and 14.995% respectively. Further, the effect of each factor on forming characteristics was analyzed by ANOM [26]. A design optimization problem was constructed to identify the formability window, in which the punch stroke was maximized subject to wrinkling and tearing. For this, the formability window of a difficult-to-draw material AA 5402 was explained with the pulsating blank holder force (PBHF) and the variable blank holder force (VBHF). Some parameters in the VBHF and PBHF were included and taken as the design variables. A sequential approximate optimization (SAO) using a radial basis function (RBF) network was used to determine the optimal parameter of PBHF and VBHF. From numerical simulation coupled with the SAO using the RBF network using the PBHF and VBHF, formability window was observed. It was identified that the proposed approach was highly useful for clarifying the formability window of a difficult-to-draw material [27]. The tailored heat treated blank (THTB) technique was demonstrated to create a material property gradient through a suitable artificial aging treatment carried out prior to the forming process on the effectiveness of combining the hydromechanical deep-drawing process. This method was coupled with a simple finite element model and a multi-objective optimization platform. For determining the effect of the aging treatment on the mechanical and deformative behavior of the AC170PX aluminum alloy, a preliminary experimental campaign was carried out. The adoption of aged blanks in the hydromechanical deep drawing allows to increase the limit drawing ratio and to

**156**

in the cavity and for the hydrodynamic flow of the fluid film between the blank and die for AA5086 aluminum alloy. From Reynolds equation solution, the hydrodynamic flow was calculated and model was implemented in ABAQUS/Explicit, finite element software. The approach was validated and investigated for the influences of the blank holder force and the fluid pressure on the formability of the blank metal. The results exhibited that the choice of an appropriate blank holder force reduced the strain in the blank and prevented the risk of fracture [31]. A study was made on deep drawing of SiCp/2024Al composite sheets by considering the effect of pulse current on heating performance and thermal. The high-intensity pulse current flows through the sheet and generates the tremendous Joule heat. The specimen temperature was kept around 673 K at a rate of 13.5 K/s under the current density of 21.7 A/mm<sup>2</sup> . The temperature difference was reduced by 73.3% by inserting the stainless-steel inserts. Besides, the SiCp/2024Al composite was successfully deep drawn with good surface quality [32]. Deep drawing process characteristics of AA 6xxx alloy sheet were discussed under different process parameters such as punch force, lubrication, fillet radius, punch speed etc., and the formability was evaluated [33–37].
