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

Upset forging tests on iron preforms of cylindrical shape with different in itial aspect ratios, forged at the temperature of 1150 degrees C suggest th at the experimentally determined theoretical density ratio has a straight-l ine relationship with the new strain parameter (e(epsilon z-epsilon 0)) and the geometrical parameter ratio [(h(0)/h(f))(3D(0)(2)/(2D(b)(2) + D-c(2))) ]. The barrel-radius curvature fits a circular are. This shows that the bul ged and contact diameters and height can be related to the theoretical dens ity ratio. Also, an attempt has been made to establish the relationship bet ween the measured barrel radius and the stress ratio parameters namely sigm a(theta)/sigma(z), sigma(z)/sigma(m), and sigma(theta)/<(sigma)over bar>, a nd Poisson's ratio. (C) 2000 Elsevier Science S.A. All rights reserved.