Metallographic Observations to Illustrate Fundamental Principles and Applications of Deformation Processing

To honor the 50th anniversary of the Henry Clifton Sorby Award, this lecture is based on results from undergraduate laboratory experiments in courses on metal forming operations and engineering design as well as on graduate student research. Deformation processing operations, e.g. rolling, forging, drawing, extrusion, etc., inherently involve applications of non-uniform strain files. Metallographic results are presented to illustrate how controlled applications of non-uniform deformation during plane-strain compression and the principles of slip-line field theory correlate with light optical macroscopic observations of cold-deformed and subsequently recrystallized microstructures in a 99.95 wt.% continuous cast copper ingot. Measured forming pressures during plain-strain punching of the continuously cast ingot, which initially possessed a large columnar grain structure, are also characterized with a single parameter, D, which describes the deformation zone geometry, defined as the ratio of the height to mean width of the deformation zone. Example applications of the fundamental principles illustrated here include the formation of fine-grained surface layers in cold drawn and annealed 302 stainless steel wire for enhanced cold-heading response and the creation of award-winning artistic images in brass.