ABSTRACT
Metal forming (working, mechanical shaping) is the processing of solid metals by means of mechanical forces and proceeds under the assumption that metal retains the shape imposed when the stress declines below that for yielding (except for elastic changes). The shaping can be considered from the industrial, mechanical, computational, and microstructural aspects, which are distinct but interlocking (Figure 2.1) [1]. Under industrial processing, the machinery, tooling, and lubrication are selected to produce the object of desired shape [2-9]. The feedstock with speci‰ed pretreatment is processed in a manner to control the ‰nal product properties [10-19]. The operation is managed to maximize productivity while minimizing defects, thus achieving suitable economy [7,11,20]. Primary forming usually causes extensive shape changes to large rough workpieces, often as-cast; to reduce loads with the large machinery required, hot working is employed to lower the §ow stress and improve the ductility [10-16]. For secondary processing to near-net shape, cold, lubricated, cleaned objects are formed with smooth tooling and die lubrication to operate with moderate forces, limited ductility, and products with good surface ‰nish and improved properties [2,3]. Cold deformation to a ‰nal shape results in improved surface tolerances and greater strength owing to strain hardening (Chapter 10) [19]. If high total reductions are required, notably in rolling, it may be necessary to interpose annealing to cause recrystallization to new smaller grains (Chapter 11) [19].
