Experimental measurement and elaborate analysis of strain hardening exponent in tensile deformation

This paper gives a set of formulae for measuring strain hardeningexponent n in different typical deforming routes by using experimental parameters p (forming load), v (velocity of cross-head) and l (gauge length of specimen). With them the uniform method for measuring n (strain hardening exponent at constant strain rate), nv (strain hardening exponent under constant velocity) and np (strain hardening exponent under constant load) is established when , v or p is constant distinctively. Furthermore, the deviation among n values via different typical deformation route is analyzed. The results indicate that there exists structural sensitivity under superplastic and plastic deformation. In addition, the experimental results also prove that the values of n, nv and np obtained with different sets of constant , v or p curves are different too, even if the formulae are the same. Thus a more profound understanding of the relation between the experimental results and the mathematic expressions of n, nv and np is reached and the parameter n is more subtly analyzed by experiment.