Formulation Of The Limiting Ductility In Metalworking Processes

摘要

The concepts of workability in metalworking processes are examined. The most common limitation is pore formation and coalescence to form internal cracks in the absence of a free surface and cracks at free surfaces. Pore coalescence in technical alloys occurs largely by microinstabilities rather than by reducing the ligament to zero cross-sectional area by plastic flow. The mechanism of ductile fracture is examined, including homogeneous and heterogeneous nucleation, and nucleation by the hydrodynamic separation phenomenon. The effect of a hydrostatic pressure is examined along with factors controlling ductility at elevated temperatures. The two most important variables affecting ductile fracture are the volume fraction of the second-phase particles and the hydrostatic pressure component.