Swirling of molten weld puddle 

Many forces acts on the weld puddle with different welding conditions.

Swirling motion of weld puddle can be more often seen precisely with autogenous arc welding process.

This swirling motion ensures proper fusion of edges of the weld joint.

This can be more observed in PAW and GTAW process.

https://pagead2.googlesyndication.com/pagead/js/adsbygoogle.js?client=ca-pub-4084239029012850