CASTING METHOD FOR JOINED PART OF SHAFTLIKE CASTING JOINED WITH DISSIMILAR METAL IN AXIAL DIRECTION

摘要

PURPOSE:To obtain desirable width and quality of diffused layers formed in the mixed areas in the joined parts between a base material and a joining material by specifying the temp. on the surface of the molten base material, the charging temp. and speed of the molten joining metal and cooling conditions for casting and casting the molten metal. CONSTITUTION:A molten base material A is bottom charged through a pipe 1 into a casting mold consisting of a top mold 5 disposed with chillers 3 of which the front sides in the joining parts are formed of a cushioning medium 4, etc. In order to prevent the oxidation of the surface of said molten metal, the molten metal B for joining at 40-80 deg.C higher than the liquidus line is top charged at 8-15/sec charging speed after waiting until the temp. of the molten metal A attains 10-50 deg.C higher than the liquidus line under stirring. Here if the temp. of the molten metal A is too high, the mixing with the metal B is excessive, and if said temp. is too low, nonmetallic inclusions do not float, and the characteristic over the entire part of the diffused layer in the joined parts is degraded. If the temp. of the metal B is too high, the mixing with the base material is excessive and if said temp. is too low, the required width of the diffused layers is not obtained and the structure in the joined parts is made nonuniform. If the charging speed is too low, the stirring of the metals A and B is insufficient and the floating of the nonmetallic inclusions is difficult. If the speed is too high, the mixing is excessive and casting defects are apt to arise.