Some aspects on geometric and matrix work-hardening characteristics of sintered cold forged copper alloy preforms

Powder metallurgy (P/M) material subjected to plastic deformation results into densification, however the extended deformation would not only enhance the densification also supplements the strain hardening. Unlike fully dense material that would only undergo strain hardening while plastic deformation, the P/M material leads to pore closure as well; this phenomenon complicates the work hardening mechanism. The present study revealed that both strain and density configures strengthening of P/M preform, which respectively termed as matrix and geometric work hardening. An attempt has been made to delineate some aspects of work hardening behaviour with the influence of different aspect ratios of sintered and cold deformed copper alloy preforms. The preforms were initially prepared through conventional P/M route and finally subjected to cold upsetting under dry friction condition. A statistical analysis has also been introduced to study the quantitative impact of strain and density in the presence of aspect ratio on work hardening rate characteristics.