308806 Lecture Notes - Lecture 7: Hot Working, Simulation Software, Friction

• School: Curtin University
• Department: Mechanical Engineering
• Course: 308806
• Professor: Alokesh Pramanik

Document Summary

Introduction: definition of metal forming; stresses in forming processes. General parameters in metal forming: material characteristics, friction, lubrication. Utilizes a remarkable property of metals (and alloys), their ability to flow plastically in the solid state without deterioration of properties. Plastic deformation: permanent deformation, non-recoverable after unloading, involves permanent atomic displacements. In metal forming, the tool, usually called a die, applies stresses that exceed the yield strength of the metal. The metal takes a shape determined by the geometry of the die. Stresses used in metal forming to plastically deform the metal are usually compressive; typical examples are rolling, forging and extrusion. Extrusion: triaxial compression wire & tube drawing: biaxial compression and tension. Deep drawing: biaxial tension & compression and simple uniaxial tension. The mechanical properties of materials desirable in metal forming processes are: Low yield strength: allow for lower deformation forces. Values of strain hardening exponent n appropriate: high n is better in shearing, low n better in cold rolling.