ANALYSIS AND EXPERIMENT ON YIELD CRITERION FOR SINTERED POWDER MATERIALS

摘要

Plastic deformation is an important process to improve properties and obtain final products made of sintered powder materials. Sintered ferrous material is widely used in many engineering departments and its deformation characteristics are typical for most sintered powder materials. Factors such as deformation strengthening, instantaneous and initial relative densities, etc, on the subsequent yield strength are studied, and an approach to determine the plastic stress coefficient and hardening exponent is derived, which is based on the yield criterion and the strengthening laws of plastic deformation of sintered powder materials as well as on a uni-axial compression experiment of a sintered ferrous cylinder specimen. A unified form of the yield criterion function is obtained, in which the initial and the subsequent yields of sintered powder materials are expressed.