| 摘要 |
PURPOSE:To improve the single crystallinity, crystal direction and internal direction of a single crystal formed and to increase the rate of production in unidirectional solidification by drawing from a casting mold by dividing thermally and vertically a heating body for heating the mold and increasing the temp. gradient at the solidification boundary near the lower part. CONSTITUTION:A nickel superalloy of a columnar crystal or single crystal is adequately used for the moving vane of a gas turbine, etc. The production thereof is accomplished by pouring a molten metal into a casting mold 1 on a water-cooled molding board 2 and a polycrystal part 5 is first solidified and is then made into a single crystal part 7 by a crystal limiting circuit 6. The mold 1 is covered with heating bodies 3a, 10 for heating the mold to maintain the molten metal at a specified temp. A heat insulating material 18 is inserted into the boundary between the lower part 12 and upper part 3a thereof to prevent the transmission of the high temp. in the lower part of the upper part as far as possible. The gradient of the heating temp. near the solidification boundary 8 is steepened, by which the temp. gradient at the solidification boundary is increased. The upper part is maintained at a constant temp., by which the single crystallinity, crystal direction and internal quality of the moving vane of the turbine is improved and productivity is made higher. |
