Features of Fusion Welded Joint

A typical fusion weld joint consists of fusion zone, weld interface, heat affected zone and unaffected base metal zone.

Fusion zone: a mixture of filler metal and base metal melted together homogeneously due to convection as in casting. Epitaxial grain growth (casting)

Weld interface – a narrow boundary immediately solidified after melting.

Heat Affected Zone (HAZ) – below melting but substantial microstructural change even though the same chemical composition as base metal (heat treating) – usually degradation in mechanical properties

Unaffected base metal zone (UBMZ) – high residual stress

Welders | Hobart | Lincoln | Miller | Tig | Mig