Abstract: The flow curves were measured for the stable austenitic steels 304L and 304LN by means of tensile test at room temperature, which are described by the models σ=K1εn1+Exp(K2+n2ε),σ=Kεn1+n2lnε andσ=σo+Kεn (where, K1, K2, n1 and n2; K, n1 and n2; σo, K and n are constant). The comparison of the maximum deviations and the consideration of the variation of the work hardening rate with true strain show that the flow curves for the austenitic steels 304L and 304LN can be described by the model σ=Kεn1+n2lnε at higher recision. The derivatives of the models σ=Kεn1+exp(K2+n2ε) andσ=K1εn1+n2lnε with respect to true strain, exhibit the extreme at low true strain. This inherent character indicates that both models are unsuitable to describe the part of the work hardening rate curve at low true strain.

Key words: Flow curve, Mathematical model, Work hardening rate