MANUFACTURE OF HOOP-STATE METAL BODY FROM METAL POWDER

PURPOSE:To manufacture a hoop-state metal body having excellent quality free from inner bore with a simple process by rolling metal powder into the hoop-state compact body, passing it through a continuous sintering furnace to make the hoop-state sintered body and also hot-rolling this in the cooling zone in the continuous sintering furnace. CONSTITUTION:The powder of high speed tool steel, etc., is rolled and compacted to plate-state and successively, sintered in the continuous annealing furnace under non-oxidize atmosphere to make hoop-state sintered body. This is hot-rolled at 10-30% draft by utilizing temp. held in the sintered body itself in the cooling zone in the continuous annealing furnace and the bore existing in the sintered body is crushed and this is worked into the hoop-state metal material without any defect of inner oxidation, etc., due to open-bore. After coiling this at Ms point-300 deg.C, resintering treatment is executed with a batch furnace maintained under reducing atmosphere. Successively, cold-rolling is executed at >=40% draft including the annealing. The hoop-state metal body without any bore defect is manufactured with simple process by using the metal powder as the raw material.