Influence of Initial Preform Geometries on Densification of Sintered AISI 4150 P/M Steel during Hot Upset Forging

摘要

Present investigation attempts to evaluate the densification behaviour of sintered and subsequently hot upset forged AISI 4150 Powder Metallurgy (P/M) steel using three different initial aspect ratios, namely, 0. 59, 0. 94, and 1. 29. The compacts of above aspect ratios were prepared using suitable die assembly on the 1. 0 MN Capacity Universal Testing Machine with initial preform density of 87±1 percent theoretical by applying pressures in the range of 530±10 MPa. These preforms were sintered at 1150±10℃ for a period of 90 min in an electrical muffle furnace with protective ceramic coating. The sintered preforms were axially hot upset forged to different height strains on a friction screw press of 1. 0 MN capacity at the sintering temperature itself. The experimental data and the calculated parameters were critically analyzed and yielded the various empirical relationships relating fractional theoretical density, height strain, diameter strain, Poisson's ratio and bulging.