Granular pearlite
A microstructural constituent consisting of a ferritic matrix with globular carbide precipitates, which emerges from lamellar pearlite through thermal post-treatment. It is characterized by a favorable balance between formability and strength.
Granular pearlite forms when you heat-treat lamellar pearlite in a controlled way. The fine carbide lamellae break down and ball up into small spheres in the ferritic matrix. This makes the material tougher and more formable without losing too much strength. When welding, you mainly need to watch the heat input. If the zone gets too hot or you cool too fast, hard, brittle structure can form again or the grain can coarsen. Clean, controlled cooling after welding is therefore key to keep the desired spheroidal structure in the base material. In practice: keep the interpass temperature low, weld with as little heat as possible, and let the part cool slowly in air after welding. If you stress-relieve the weld afterwards, you'll restore the structure in the HAZ reasonably well.