Spannungsverläufe Nach Wechseln der Verformungsgeschwindigkeit an Metalleinkristallen

Abstract

The general relations between the change in effective stressΔτ _v and the extrapolated valueΔτ _A deduced in the preceding parts are applied to various experimental conditions. ThusΔτ _v =Δτ _A is valid in the first stage of hardening curve, if the active sources are of the multiplicative type and the recovery is negligible. For higher strains, the variations are of the yield point type. Assuming the Gaussian form of the source distribution function, the expression for the ratioΔτ _v /Δτ _A is deduced and the condition of its strain independence specified.Δτ _v is equal to the extrapolated valueΔτ _B (extrapolation ofτ from the transient region to the strain of the rate change) only under special assumptions about the activity of dislocation sources.

The stress variations of the yield point type and the magnitude of the transient strain intervalΔa _u are discussed also for other commonly occurring cases. Different recovery processes, i.e. recovery of short and long range obstacles, cross slip and climb of dislocations, can be characterized by the type of strain dependence of the ratioΔτ _v /Δτ _A .