The invention provides an apparatus and process to cast continuously high quality hollow round steel billets or tubes. The hollow round steel billets are produced by a compact, high production casting machine incorporating a rotating hypocycloidal mandrel for inside cooling and deformation of the solidified steel. The outside cooling is by traditional mold and spray cooling. The adjustable rolling movement of the mandrel controls the uniform heat extraction from the inner annulus as well as the deformation and deformation rate of the as-cast steel to increase the ductility. The inside of the hollow round billet so formed is substantially round and the inside surface is smooth to facilitate high quality and further processing to finished pipes in conventional high production machinery.
Provided is a hot-top type continuous casting machine for stably producing hot metal hollow billets having a high quality, which comprises: (a) a molten metal holding part fed therein with molten metal; (b) a ring mold arranged being connected to the molten metal holding part; and (c) a core inserted in the hollow mold from thereabove, and composed of a low heat-conductive upper core and a high heat-conductive lower core to be cooled by coolant circulating therethrough.
An alloy material 4 received in a melting hearth 1 is melted by high-density energy supplied from a heat source 5. The molten alloy is transferred to a forced-cooled die 3 having a cavity 2 defining the profile of a product, and quenched to an amorphous state. The alloy has the composition represented by the general formula of Zr.sub.100-a-b-c A.sub.a B.sub.b C.sub.c (wherein the mark A represents one or more elements selected from Ti, Hf, Al and Ga, the mark B represents one or more elements selected from Fe, Co, Ni and Cu, the mark C represents one or more elements selected from Pd, Pt, Au and Ag, and the marks a-c represent the atomic ratios of respective elements A-C under the conditions of a=5-20, b=15-45, c.ltoreq.10 and a+b+c=30-70. The differential temperature region .DELTA.T (=T.sub.x -T.sub.g) in the supercooled liquid phase of the Zr alloy represented by the difference between the crystallization point T.sub.x and the glass transition point T.sub.g, is preferably 100 K or more. The obtained amorphous alloy has a rod-shaped or tubular profile having a large cross section and being excellent in plastic workability.
An alloy material 4 received in a melting hearth 1 is melted by high-density energy supplied from a heat source 5. The molten alloy is transferred to a forced-cooled die 3 having a cavity 2 defining the profile of a product, and quenched to an amorphous state. The alloy has the composition represented by the general formula of Zr.sub.100-a-b-c A.sub.a B.sub.b C.sub.c, wherein the mark A represents one or more elements selected from Ti, Hf, Al and Ga, the mark B represents one or more elements selected from Fe, Co, Ni and Cu, the mark C represents one or more elements selected from Pd, Pt, Au and Ag, and the marks a-c represent the atomic ratios of respective elements A-C under the conditions of a=5-20, b=15-45, c.ltoreq.10 and a+b+c=30-70. The differential temperature region .DELTA.T (=T.sub.x -T.sub.g) in the supercooled liquid phase of the Zr alloy represented by the difference between the crystallization point T.sub.x and the glass transition point T.sub.g is preferably 100 K or more. The obtained amorphous alloy has a rod-shaped or tubular profile having a large cross section and being excellent in plastic workability.
