9.4 Effect of d-factor with strain triaxiality ratio

Figure 11 shows a plot between d-factor and strain triaxiality ratio for all sheets tested. As the strain triaxiality ratio increase, the d-factor also increased. As the d-factor increased, the formability of the sheet decreased and vice versa.

The d-factor was found to be lowest for the metal sheet annealed at 350°C indicating formability property compared to the sheets annealed at different temperatures.

Figure 12. d-factor vs. mean strain (εm) at various annealing temperatures.

Figure 13. Void area fraction (Va) vs. strain triaxiality factor (To) at various annealing temperatures.

In the case of sheet annealed at 350°C, the ligament thickness was lowest and exhibited the best formability among the sheets tested. As the stress state moved from tension-compression to tension-tension region, the ligament thickness decreased. Similar behaviour was observed for all grades of aluminium sheets selected. The sheets annealed between these temperature show the corresponding changes recorded in the ligament thickness, which confirms with the prediction of Narayanasamy et al. [2].

showed higher value of Va (Figure 13) which was in close agreement with the

The L/W ratio of voids was correlated with various shear stresses calculated from Mohr's circle like γ12, γ13, γ<sup>23</sup> and γ12/ε<sup>m</sup> at all annealing temperature conditions which has been shown in Figures 14–16. For sheets annealed at 350°C, negative sloped curves were obtained due to high L/W ratio, whereas the sheet annealed at

L/W ratio of void vs. shear strains at various annealing temperatures for Al 1145 alloy.

L/W ratio of void vs. shear strains at various annealing temperatures for Al1350 alloy.

findings of Narayanasamy et al. [2].

Aluminium and Its Interlinking Properties DOI: http://dx.doi.org/10.5772/intechopen.86553

Figure 15.

Figure 16.

47

9.7 Effect of L/W ratio of voids and shear strains

#### 9.5 Effect of d-factor with mean strain

The relationship between the hydrostatic/mean strain and the d-factor has been shown in Figure 12. The d-factor linearly increase as the hydrostatic strain increases for all sheets tested. Even for a large mean strain developed during forming, the d-factor value was less. The rate of change was in good agreement with the findings of Narayanasamy et al. [1], whereas the d-factor was found to be the highest for sheet annealed at 200°C due to the presence of Si and poor recovery in processing.

#### 9.6 Effect of void area fraction and strain triaxiality ratio

It has been observed that the void size of the sheet annealed at 350°C was approximately 8.21–12.9 μm, whereas for the sheets annealed at 250 and 300°C, the void size was 3–6 μm. The larger void size may be due to good recrystallization, and smaller void size may be due to poor formability at lower annealing temperature. The sheets annealed at 200°C possessed low Va and sheets annealed at 350°C

Figure 14. L/W ratio of voids vs. shear strains at various annealing temperatures for Al alloys: (a) γ12, (b) γ13, (c) γ23, (d) γ12/εm.

### Aluminium and Its Interlinking Properties DOI: http://dx.doi.org/10.5772/intechopen.86553

In the case of sheet annealed at 350°C, the ligament thickness was lowest and exhibited the best formability among the sheets tested. As the stress state moved from tension-compression to tension-tension region, the ligament thickness decreased. Similar behaviour was observed for all grades of aluminium sheets selected. The sheets annealed between these temperature show the corresponding changes recorded in the ligament thickness, which confirms with the prediction of

The relationship between the hydrostatic/mean strain and the d-factor has been

shown in Figure 12. The d-factor linearly increase as the hydrostatic strain increases for all sheets tested. Even for a large mean strain developed during forming, the d-factor value was less. The rate of change was in good agreement with the findings of Narayanasamy et al. [1], whereas the d-factor was found to be the highest for sheet annealed at 200°C due to the presence of Si and poor recovery in

It has been observed that the void size of the sheet annealed at 350°C was approximately 8.21–12.9 μm, whereas for the sheets annealed at 250 and 300°C, the void size was 3–6 μm. The larger void size may be due to good recrystallization, and smaller void size may be due to poor formability at lower annealing temperature. The sheets annealed at 200°C possessed low Va and sheets annealed at 350°C

L/W ratio of voids vs. shear strains at various annealing temperatures for Al alloys: (a) γ12, (b) γ13, (c) γ23,

9.6 Effect of void area fraction and strain triaxiality ratio

Narayanasamy et al. [2].

Aluminium Alloys and Composites

processing.

Figure 14.

(d) γ12/εm.

46

9.5 Effect of d-factor with mean strain

showed higher value of Va (Figure 13) which was in close agreement with the findings of Narayanasamy et al. [2].
