Changes in the longitudinal flow and apparent plastic poisson’s ratio of a porous metal strip during hot densification rolling

Abstract

Analytical relationships between the longitudinal flow and the thickness deformation, and between the apparent plastic Poisson’s ratio and the relative density of a porous metal strip during hot rolling have been derived from geometrical considerations. Experimental data obtained from the hot rolling of porous copper strips of relative density of 0.4 have been shown to agree well with the results predicted from analytical relationships. Changes in the longitudinal flow and the apparent plastic Poisson’s ratio can be divided as taking place in three distinct stages of densification. Stage I,i.e., the densification up to the relative density of 0.70, involves the densification of the strip merely by decreasing the pore channel widths without closing them. Stage II,i.e., the densification from the relative density from 0.70 to that of 0.95, is associated with the patching of pore channels at some points, the number of which increases as the thickness deformation given to the strip increases. Stage III,i.e., the densification of the strip from the relative density of 0.95 and onward, involves the elimination of the newly formed closed porosity by shearing.