8-Mechanical Behavior

Necking occurs when the specimen develops a localized

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Unformatted text preview: decrease in cross sectional area. Engineering stress decreases with further strain until fracture occurs. Engineering stress uses original area. PERCENT ELONGATION Provides a measure of the ductility Reported for a given gauge length % elongation = l f − lo × 100 lo where: lf is the final gage length lo is the original gage length PERCENT REDUCTION IN AREA Provides a measure of the ductility % reduction in area = Ao − A f Ao × 100 where: Ao is the original cross-sectional area Af is the final cross-sectional area Hardness Testing A measure of the resistance of a metal to permanent (plastic) deformation. Determined by forcing an indenter into the metal surface. COMMON HARDNESS TESTS Brinell Vickers Knoop Rockwell Hardness is related to strength Engineering Stress-strain versus True Stress-strain Plastic Deformation Consider the permanent deformation of a single crystal stressing beyond its elastic limit. Slip Planes: Slip or shear deformation of metal atoms on...
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This document was uploaded on 02/27/2014 for the course NANO 108 at UCSD.

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