PSI - Issue 33

Elvira Wahyu Arum Fanani et al. / Procedia Structural Integrity 33 (2021) 3–10 Fanani et al / Structural Integrity Procedia 00 (2019) 000–000

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composite it is known that the forged workpiece has a more uniform particle distribution (Hanamantraygouda et al., 2018) it represents the recovery and recrystallization process of Al-SiC. Matrix grains are 8-55 µm in the close die forging and 7-46 µm in the open die forging (Khemraj et al., 2018). Based on research conducted by Hanamantraygouda et al. It can be seen that the distribution of the reinforcement particles of the composite as a result of cold forging is the same as that of the as-cast composite (Hanamantraygouda. and Shivakumar, 2015). In line with this, observations under the optical microscope also show that some of the number of resolvable pores is reduced and some particle cracking has been taken place in the forged specimens thus making the particle size more uniform (Özdemir et al., 2000). Based on research conducted by Shi et al. where he examined the effect of differences in forging reduction and found that at a deformation level of 40% localized strain occurred, and the hardness level of the matrix was low and the matrix was easily pinched in voids between the broken whiskers. When forging at a degree of 60% the local strain increases, the matrix is harder, and the matrix is not easily squeezed into the voids to fill them, which in the new type of voids. At this degree of forging, cracking damage and debonding have not occurred on the interface. Forging with a reduction of 70%, there was a higher local strain and the hardening of the matrix resulted in debonding and crack damage (Shi et al., 2014). In specimens that are subjected to a forging process with a different % reinforcement, it is known that as-cast specimens have a higher porosity when compared to forged specimens, but when the % reinforcement is more than 17% vol, the porosity will increase drastically (Özdemir et al., 2000). Kapoor et al. conducted a study MDF where the specimens passed 0, 3, 6, and 9 pass Al samples. Based on this research, it is known that when a specimen passes 0 passes (annealed) shows large grains, when 3 passes it is known that the specimen shows a large number of sub-grain boundaries, after 6 and 9 passes the prior large grain boundaries were not discernable and only ultrafine sub-grains and grains were seen (Kapoor et al., 2013).

Forging direction of last pass

Figure 2. Macrostructures of work piece forged with different passes: (a) 2; (b) 3; (c) 6; (d) 12; (e) 15; (f) 24 passes (Zhu et al., 2014).

Grain size change with the increase of the forging passes as shown in Figure 2 presented by Zhu et al. show that the size of grains in the center of samples (Zhu et al., 2014), it decreases with increasing the forging passes to 12 but it does not further refine the grains with more than 12 passes, shown in Table 2. In general, an increase of forging pass will increase the cumulative strain. The recrystallized grains become finer with increasing the forging passes.

Table 2. Grain size in sample center change with forging passes (Zhu et al., 2014). Forging Passes

Grain Size (µm)

2 3 6

450 270 120 110 100 110 110

12 16 20 24