Comparison of workability strain and stress parameters of powder metallurgy steels AISI 9840 and AISI 9845 during cold upsetting

A complete experimental investigation on the workability behaviour of nickel–chromium–molybdenum steel grades namely AISI 9840 and AISI 9845 of powder metallurgy preforms was performed. Cold upsetting of aforesaid composites with different aspect ratios namely 0.42, 0.63 and 0.93 was carried out with graphite lubricant and the formability behaviour of the preforms under triaxial stress-state condition was determined. A new formability strain parameter was proposed, evaluated and compared with formability stress parameter for all the above said preforms. The characteristics of various stress and strain ratio parameters with respect to relative density were also analyzed and presented for comparison.