Spheroidized carbide
Spheroidized carbides are spherically shaped cementite particles derived from lamellar pearlite through a targeted annealing process (spheroidizing). This microstructure improves the machinability of high-carbon steels.
You get spheroidized carbides by soft annealing. After heating, you let the steel cool very slowly so the carbon in the structure forms into spheres instead of lamellae. That makes the material softer and easier to machine, but also tougher. When welding, you have to watch out: the heat input can change the structure again, and there's a risk of cracking. If you cool the part slowly after welding and maybe stress-relieve anneal it, you stay on the safe side. Cooling too fast leads back to hard, lamellar structure that breaks more easily.