Deformation Behavior of a 70/30 Alpha Brass in Plane Stress/plane Strain

Generally a simple power law ~ = K E" (where K and n are empirical constants called the strength coefficient and the work hardening coefficient respectively) is used to describe plastic stress-strain dependence of deformable metals (1,2). This equation was employed by Low (3) to describe the uniaxial tensile behavior of an annealed 70/30 brass. The slope of the corresponding double logarithmic true stress-true strain plot gives a single value of n. However, this fit is not always adequate. Geil and Carwile (4) reported a deviation in the linearity of the double logarithmic plot for steel. Two sets of K and n values were used to describe the stress-strain relationship in a spheroidized hypo-eutectoid steel by Wilson and Konnan (5). Various reasons, such as grain size effects, cementite particle distribution, cell formation, stacking fault energy, etc. were proposed to rationalize the double-n behavior (6-9). Ollilainen reported a triple-n behavior for a decarburized steel (10).