Handbook-Welding Cast Iron

13 Once the weld has been completed, reheat the entire weld with the torch until it glows faintly. Then place the welded specimen between sheets of asbestos paper to allow it to cool as slowly as possible. After the weld has cooled completely, wire brush the surface of the weld on both sides, and examine it carefully. Note particularly the appearance of the underside. If thorough fusion between the bottom edges of the vee has not been obtained, the defect can be clearly seen. The bottom of a good weld will show little round beads of weld metal protruding through. Test your weld by clamping the specimen in a large vise, with the centerline of the weld flush with the tip of the jaws. Strike the upper part of the specimen with a heavy hammer until the part breaks. If you have made a good weld, the break will probably occur in the base metal, not in the weld. If it breaks through the weld, examine the fracture carefully for inclusions, gaps, or blowholes. If the break occurs in the base metal, remove the specimen from the vise, nick it with a hacksaw, on both sides of the weld zone, then return it to the vise and break it across the weld. Examine the fractured weld metal carefully to see whether it appears sound, with no slag or oxide inclusions or blowholes.