HIGH STRENGTH METALLIC PARTS AND ITS MANUFACTURE

PURPOSE:To manufacture metallic parts of a single crystal excellent in tensile strength, creep strength or the like by pouring a metallic molten metal into a main mold and a bypass mold, subjecting it to unidirectional solidification and also subjecting the molten metal in the bypass mold to unidirectional solidification at the same speed. CONSTITUTION:A main mold 2 is fixed on a water-cooled copper chill 1, which is set in a heater 3 to heat the mold 2. An alloy molten metal is cast in the mold 2, then the water-cooled copper chill 1 is pulled out in the lower direction and unidirection al solidification is executed. At first, many crystals are formed by a starter 4 at the lower end of the mold 2, but, in the process of progressing the solidification, the crystals are narrowed down to one crystal by a selector 5 into a single crystal. Furthermore, in an expanding part, it is converted into a large one, and the solidifica tion progresses, e.g. to the bolt thread part 7 and bolt head 8 of the casting. The lower end of the bolt head 8 and the position in the lower end of the bolt are con nected by a bypass mold 9, and the molten metal in the bypass mold 9 is subjected to unidirectional solidification at the same speed as that in the molten metal in the mold 2. The crystalline direction on the whole of the casting can be made same, by which metallic parts such as a high strength bolt or the like can efficiently be manufactured.