Graphite nodulizing additives that transform graphite in cast iron into spherical shapes are referred to as "nodulizing agents." The primary component of nodulizing agents is the nodulizing element, such as Mg, Ce, or Ca. The spherical graphite in ductile iron is formed through the spheroidizing treatment of cast iron melt, making it stronger than gray cast iron and more ductile than malleable cast iron, while still retaining the advantages of gray cast iron. However, the nodulizing agent used in the melting and casting of ductile iron can increase the tendency to produce "white mouth" and hardened structures in the weld, leading to cracks in the weld and heat-affected zone (especially the fusion zone). Therefore, the nodulizing agent for ductile iron casting...Weldability of iron is worse than that of gray cast iron.