Determination of Flow Curves for Bulk Metal Forming

摘要: In the simplest case flow curve is obtained by measuring force F and elongation A L in tensile test. range of strain below uniform it assumed that stress constant over cross-section specimen. The ratio F/A where actual called σf: $$ {\sigma _f} = \frac{F}{A}$$ (2.1) For plastic deformation most metals condition volume conservation fulfilled with good accuracy. Therefore can be calculated from measured elongation: $$A \frac{{\pi r_0^2{L_0}}}{{{L_0} + \Delta L}} $$ (2.2) where L0 initial gage length test piece. Flow plotted vs. \phi In\frac{{{L_0} L}}{{{L_0}}}$$ (2.3) The function _t} _f}\left(\phi\right) $$ (2.4) is curve. It indicates required for to occur under uniaxial stress. relation between an a multiaxial state described concepts equivalent strain. So general triaxial Eq. (2.4) φ must replaced φ.