Characterization of the mechanical properties of low-nickel austenitic stainless steels

The tensile properties of 6 low-nickel austenitic stainless steels were investigated. The Ludwigson model was shown to be adequate in describing the flow behaviour of stable, low stacking fault energy austenitic alloys in the entire strain regime of a conventional tensile test. Nitrogen was found to be the most effective element in increasing the lattice friction stress σ0, while C was the most effective alloying element in increasing the efficiency of grain boundary strengthening (ky). The combined effect of N + C resulted in high-sustained work hardening rates and a delay in the onset of dynamic softening. The addition of Cu and Ni, two elements which are known to increase the stacking fault energy had the opposite effect. High work hardening rates were accompanied by a strong rotated brass {1 1 0}〈1 1 1〉 texture development. While α′-martensite was shown to nucleate inside ɛ-martensite clusters, nucleation directly from γ could not be excluded. The development of α′-martensite resulted in a strong increase in the work hardening rate in uniaxial tension.