擬 HIP による鉄系予備焼結体の圧縮特性

抄録

Consolidation behavior in pseudo-HIP ( known also as Ceracon) is experimentally investigated using pre-sintered iron-based alloy as a specimen. Pressure transmitting medium is spherical powder of alumina mixed with 5 wt% graphite. Heating temperature is 800-1200°C and pressure of upper punch is 34.7-347 MPa. Obtained results are as follows : Transmitting ratio of applied pressure in the pressure transmitting medium is low and the pressure applied on a specimen is about 1/2 of the applied pressure by upper punch. Maximum density of a specimen achieved is 99.2%. In the range of less than this value, consolidation behavior can be described by the pressure-density equation presented by Shapiro et al. The achieved density in pseudo-HIP is nearly equal to that in HIP, but according to the observation in SEM, the matrix of the cross section of the specimen in pseudo-HIP seems to be less purified than that in HIP. This is because of the difference of consolidating time between in both processes, that is, as the consolidating time in pseudo-HIP is shorter than in HIP, the diffusion of atoms in pseudo-HIP seems to contribute hardly to the increase of the density. Finally, in order to produce a consolidated part of high accurate dimension and good shape, precise setting of a specimen in the die is important.