The macro graphs for the specimens 2 and 3 are presented in Figs. 2 and 3, respectively.
From the macro graphs (Figs. 2 and 3), the weld is distinct with solidification lines clearly visible. The center line mark indicates the fused mass of materials. The inner diameter side is having more plastic bonded zone compared to outer diameter side.
4.1.2. Micro analysis From the micrographs (Figs. 4 and 5) it is observed that no distinct HAZ or fusion line is visible. It is merged with the weld metal due to higher rate of heating (instantaneous higher heat input) and subsequent higher rate of cooling (due to very low weld cycle, i.e.,about 25 s for the sample) and narrow HAZ. During heating the overheating area is formed in the spots of the burning welding arc.