Morphologies and characteristics of deformation induced martensite during low cycle fatigue behaviour of austenitic stainless steel

Abstract

Quantification, formation and nucleation micro-mechanisms of deformation induced martensite during low cycle fatigue behaviour of austenitic stainless steel have been investigated at various strain amplitudes tested at ambient temperature. The evolutionary deformation induced martensite has been quantified through magnetic measurement technique. It has been found that as strain amplitude increases, the volume fraction of deformation induced martensite increases. Extensive analytical transmission electron microscopy studies showed more than one nucleation site for martensitic transformation and the transformation micro-mechanisms have been observed to be: γ (fcc) → (hcp), γ (fcc) → α′ (bcc), γ (fcc) → deformation twins → α′ (bcc) and γ (fcc) → (hcp) → α′ (bcc).