After sample preparation, a sample was investigated under the optical microscope. Figure 4 presents the micrographs obtained from rebar sample. Micrographs in (a) and (c) illustrated a homogeneous microstructure, comparing between core and case area, that refer to a general hot-rolled rebar. The microstructure constructed with ferrite and pearlite, corresponding with a white phase and a lamellar phase respectively as presented in Figure 5.