PSI - Issue 14

Sandeep Das et al. / Procedia Structural Integrity 14 (2019) 119–126 Sandeep Das et al. / Structural Integrity Procedia 00 (2018) 000–000

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current ( I p ) of 4A and at pulse width ( T on ) of 331, 400, 468, 536 µs provides uniform alloying on the work surface, while at the same peak current, but at other pulse widths such as 296, 570, 605 and 673 µs, non- uniform alloying on the surface was noticed. During the EDA process, arcing phenomenon was also observed at high working time (alloying time). Arcing is not observed at low frequency and less working time. After the experiments elemental characterization was carried out. The value of surface roughness for the sample before alloying was 0.60 µm. The surface roughness was found to be 5 µm. Cross sectional Analysis of alloyed layer after EDA is shown in Figure 6. It shows that an alloyed layer of thickness 90µm is successfully formed for a working (discharge/machining) time of 5 min. Locations of EDX spectrums on the cross section of alloyed layer are shown in Figure 7. Figure 8 shows EDX spectrum at location 4. It can be seen that titanium, boron, silicon, carbon and aluminium have been deposited in the electric discharge processed region. The transfer of boron was found to be negligible. This can be attributed to the availability of free electrons which is very less in non-metals. The weight (%) of various elements transferred in the surface during alloying at four different locations 3, 4, 5 and 6 are presented in the Table 3.

Fig. 4. Images of uniform alloyed region on aluminium samples. (a) Pulse on time 536 µs, I P 4A; (b) Pulse on time 468 µs, I P 4A; (c) Pulse on time 400 µs, I P 4A; (d) Pulse on time 331 µs, I P 4A.