A study on the barrelling of sintered iron preforms during hot upset forging

Upset forging tests on iron preforms of cylindrical shape with different initial aspect ratios, forged at the temperature of 1150°C suggest that the experimentally determined theoretical density ratio has a straight-line relationship with the new strain parameter (eεz−εθ) and the geometrical parameter ratio [(h0/hf)(3D02/(2Db2+Dc2))]. The barrel-radius curvature fits a circular arc. This shows that the bulged and contact diameters and height can be related to the theoretical density ratio. Also, an attempt has been made to establish the relationship between the measured barrel radius and the stress ratio parameters namely σθ/σz, σz/σm, and σθ/σ̄, and Poisson’s ratio.