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

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) → ɛ (hcp), γ (fcc) → α′ (bcc), γ (fcc) → deformation twins → α′ (bcc) and γ (fcc) → ɛ (hcp) → α′ (bcc).

► Extensive LCF tests have been done at various strain amplitudes.
► Quantification of deformation induced martensite has been done by using magnetic measurement.
► Nucleation micromechanisms of martensite have been understood through analytical TEM studies.
► The sites of martensite formation have been clearly identified by analysing extensive TEM-SAD pattern.