Abstract: The cyclic deformation characteristics and microstructural changes of high manganese nonmagnetic steel have been studied. It was found that the experimental material showed cyclic softening at room temperasture but cyclic hardening at low tempertures when the strain amplitudes were relatively low(1/2Δεt =0.25%),0.5%, but only cyclic hardening was showed at room or low temperatures when the strain amplitude was relatively high(1/2Δεt =1.0%).The cyclic softening of the experimental material consisted with the softening which was resulted in by the decomposition of IS complexes. The cyclic hardening was due to the formation of deformation-induced martensite, and the effect of distocation hardening of the austenite martrix under relatively high strain amplitude.

Key words: Cycle deformation, High manganese steel, Nonmagnetic steel