The effect of deformation-zone geometry on split-ends formation in plane-strain rolling

Mechanism and model is proposed for split-ends defects formation in plane-strain rolling. An upper bound method has been chosen for this analysis and a rigid body uni-triangular rotational velocity field was assumed for the deformation zone. Two solutions were obtained for rolling process; for sound flow and split-ends pattern. By comparing power requirements for these cases, the whole range of rolling parameters has been divided into safe and split-ends zone. Both perfectly plastic and strain-hardening materials are studied. It has been found that split-ends formation (crocodiling) is more likely to occur in thick plates and sheets when slight reduction is applied. Comparison of analytically developed criteria with data from experimental rolling of aluminium specimens shows generally good agreement.