Study on densification behaviour of sintered AISI 4135 steel through hot upset forging

Abstract

Present investigation is to assess the densification behaviour of sintered AISI 4135 steel through hot upset forging. Powder blend of AISI 4135 steel was prepared by using elemental powders in required proportions of iron, carbon, chromium, silicon, manganese and molybdenum by blending them in pot mill. The compacts initial aspect ratios of 0.59, 0.94, and 1.29 were prepared using suitable die assembly on the 1.0 MN Capacity Universal Testing Machine with initial preform density of 87±1 percent theoretical. These preforms were sintered at 1150±10°C 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 to study the densification behaviour. The experimental analysis of data and the calculated parameters were critically analyzed. Fractional theoretical density, height strain, diameter strain, Poisson’s ratio and bulging ratio parameters were derived many empirical relationships. These empirical relationships were tested with respect to initial preform geometry.