Nonuniformity of strain and stress distribution over the width of rolled powder strip

Abstract

1. The appearance of cracks on the edges or in the central part of green powder strip is due to non-uniformity in density across the strip, with substantial overdensification of the powder at some points, which leads to uneven elongation. Forced equalization of elongation sets up additional tensile stresses which are high enough to produce rupture. 2. Edge cracking in the rolling of powders and granules can be prevented, firstly, by providing a pass in the rolls, which ensures that the edge strain is equal to the strain of the central part, and, secondly, by choosing the most suitable thermomechanical conditions of rolling, as a result of which the mechanical properties of the strip are increased. In rolling between plain rolls control must be exercized over the distribution of reduction over the strip width: Reduction is increased by supplying extra powder in those places where dangerous tensile stresses are set up.