HOT HYDROSTATIC PRESSURIZING METHOD USING VISCOPLASTIC PRESSURE MEDIUM

摘要

PURPOSE:To accelerate the denseness increase of metallic powder by HIP molding by sealing the metallic powder into a case, sealing a heated billet into a container and subjecting the billet to isotropic compression and axial compressive deformation. CONSTITUTION:The metallic powder M is sealed in the case 1 and the preheated billet 2 is contained in the container 5. The viscoplastic pressure medium 3 consisting of a heat-resistant grease, etc. is filled to the outside of the billet 2. The medium 3 is then pressurized and the isotropic high pressure is acted to the entire outside circumference of the billet 2; at the same time, a stem 6 is pushed to exert axially the compression to the billet 2. The top end of the stem 6 contacts with the top surface of the billet 2 when the stem advances. The pressure p1 is generated under the contact pressure sigma1, by which the billet 2 is radially compressed and the denseness of the powder M in the billet 2 is increased. The contact pressure rises to p2 when the contact pressure rises to sigma2 on further press advancing of the stem 6. The strain by the axial compression is then applied to the powder by which the denseness of the powder is much increased.