4.1. Results of metallurgical analysis
4.1.1. Macro analysis
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.