Welding Inspection & Metallurgy API ICP Self Study Notes

Knowledge of cast structures is important since the welding process is
somewhat akin to making a casting in a foundry. Because of the similarity in
the shape of its grains, a weld can be considered a small casting. A solidified
weld may have a structure that looks very much like that of a cast piece of
equipment. However, the thermal conditions that are experienced during
welding produce a cast structure with characteristics unique to welding.