The base metal is the existing metal structure that receives the weld, as opposed to the filler metal added to the joint. Its chemical composition, thickness, and thermal properties determine the required preheat, heat input, and welding process. Inspectors check it for laminations or surface defects before welding begins.
Make sure you grind the mill scale off the base metal before you strike an arc.
Welders often blame the filler metal for a bad weld, but poor base metal preparation is the culprit most of the time.
Also heard as
- parent metal
Related terms
Filler metal
The rod, wire, strip or electrode metal melted into a joint to build up a weld or braze.
HAZ
Heat-affected zone: base metal next to a weld whose structure changed from the heat but did not melt.
Heat input
Energy delivered to a weld per unit length, calculated from amps, volts and travel speed.