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

Abstract

This paper gives a set of formulae for measuring strain hardening exponentn in different typical deforming routes by using experimental parametersp (forming load),v (velocity of cross-head) andI (gauge length of specimen). With them the uniform method for measuringn _ε (strain hardening exponent at constant strain rate),n _v (strain hardening exponent under constant velocity) andn _p (strain hardening exponent under constant load) is established when ε,v orp is constant distinctively. Furthermore, the deviation amongn 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 ofn _ε,n _v , andn _p obtained with different sets of constant ε,v orp 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 ofn _ε,n _v andn _p is reached and the parametern is more subtly analyzed by experiment.