Strain hardening behaviour in forming of sintered iron-0.35% carbon powder metallurgy preform during cold upsetting

摘要

A complete experimental investigation on the instantaneous strain-hardening behaviour of powder metallurgy preforms of Fe-0.35%C was carried out. The strain hardening behaviour of the above-mentioned P/M sintered steel preforms with aspect ratio of 0.4 and 0.6, respectively, under triaxial stress state condition was determined by cold upsetting under nilo and graphite lubricant conditions. The instantaneous strain hardening value (n i), strength coefficient (Ki), and the stress as a function of strain and densification were obtained and analyzed. Further, a relation is obtained from a semi-log plot of stress against relative density. This was analyzed to study the hardening behaviour due to the densification as applied stress is a function of induced strain as well as of densification in the powder metallurgy materials.