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.