The invention relates to an overlaying
welding technology of an iron
casting, in particular to an overlaying
welding technology of a ductile
cast iron roller. The technology comprises the following steps: (1), post-
welding preparation: a, detecting cracks; b, controlling a welding material; and c, selecting a welding beveling; (2), welding: a, preheating the beveling within a range of 120mm to 180mm at a temperature range of 130 DEG C to 170 DEG C; b, adopting a DC reverse-connected
arc welding machine for welding, using welding rods with the
diameter of 3.2mm for welding a first-layer welding line and using welding rods with the
diameter of 4mm for welding lines on subsequent
layers; and (3), post-welding detection. The invention adopting the technologies, such as small currents, a plurality of stages, sectional welding, welding line hammering after welding,
cooling speed reduction, and the like prevents welding line cracks and fusion region cracks from generating, prolongs the service life of products, obtains favorable
economic benefits and solves the problems for the overlaying welding of mid-small cracks, and the like on the surface of the ductile
cast iron roller.