A
casting defect repairing method is characterized by comprising the following steps of drilling or tapping a threaded bottom hole capable of covering a defect of a
casting according to the size of the defect of the
casting, boring a pin hole in the upper portion of the threaded bottom hole of the casting,
polishing the bottom of the casting and conducting chamfering by 45 degrees by a bench worker, manufacturing a
plug in interference fit with the casting, placing the
plug in liquid nitrogen to be cooled for at least half an hour, plugging the plug into the casting to be in
interference fit with the casting after the plug is cooled,
welding the bottom of the casting and the lower end of the bottom of the plug through a
welding rod, knocking out puffy surfaces on the surface of the casting after
welding of each layer is finished, detecting whether cracks exist or not, continuing to weld the next layer if no crack exists, stopping welding until the welding area is 3-5 mm higher than the bottom of the casting, and
polishing protruding portions of the top end of the pin hole of the casting and the bottom of the casting by the bench worker. The
casting defect repairing method has the beneficial effects of guaranteeing the quality and shape of a sand core, solving the problem that complex sand cores are difficult to produce, simplifying manual operation and improving working efficiency.