Showing papers by "Shiro Kobayashi published in 1979"

Ductile Fracture in Axisymmetric Extrusion and Drawing—Part 1: Deformation Mechanics of Extrusion and Drawing

Abstract: Abstract : This investigation applies theories on flow and fracture in metalworking processes to prediction of workability of materials in axisymmetric bar extrusion and drawing, with special reference to central bursting. Part 1 deals with the determination of deformation mechanics in extrusion and drawing. The matrix method is used as the method of analysis and is shown to be an efficient numerical method which provides useful information on the detailed deformation characteristics for various process variables. In part 2 the validity of a theory on ductile fracture was examined by experimental data found in the literature. Then, combining the formulation of fracture criteria with the deformation mechanics found in Part 1, the workability of materials in extrusion and drawing was determined. Workability in extrusion was examined for aluminum alloy 2024-T351, using data found in the literature, and experiments of workability in drawing were attempted for SAE 1144 colddrawn steel to test the prediction. The results of validation were inconclusive. Conclusive validation of the present workability theory in extrusion and drawing awaits more extensive and systematic experimental investigations, as well as theoretical calculations. (Author)