The influence of plastic instabilities on the mechanical properties of a high-manganese austenitic FeMnC steel

Abstract

The influenceofp lasticinstabilitieson the mechanicalp ropertiesof ahigh-manganese austeniticF eMnCsteelThe serrationsobserved on the stress-strain curvesof a Fe-22Mn-0.6Cwt.% steel presentall the phenomenological featuresassociated withd ynamicstrain ageing,including negativestrain ratesensitivity and thermalactivation. We showt hatt he activation energyis,however,inexplicably lowand thatt he dynamicstrain ageing contribution to work-hardening islimited,i. e. mechanicaltwinning ist he dominants train hardening mechanism. Finally,novel insitu experiments areused tostudyt he dynamicb ehaviour of intensestrain localisation bandsw hichf ormo ntensile samples.Inspiteo fthe localisation behaviour seen in tensile tests,stamped parts do notpresentanysurfacedefects.

TWIP Effect and Plastic Instability Condition in an Fe^|^ndash;Mn^|^ndash;C Austenitic Steel

“…Dynamic stain aging was reported to be significant but had less effect on work hardening compared to deformation twinning. 16,31,33) Considering that deformation twinning dominates the work hardening, and that an increase in the work hardening rate is often observed when dynamic strain aging occurs, we speculate that there is an important interaction between dynamic strain aging and deformation twinning. In recent papers, dynamic strain aging has been reported to arise from an interaction between carbon and the point defects in stacking faults 14) and an interaction between carbon and trailing partials.…”

Deformation Twinning Behavior of Twinning-induced Plasticity Steels with Different Carbon Concentrations – Part 2: Proposal of Dynamic-strain-aging-assisted Deformation Twinning

“…The negative strain rate sensitivity of flow stress is widely accepted as strong evidence for the occurrence of DSA. 17,[35][36][37] Because strain aging is controlled by carbon motion, DSA is suppressed at low temperature and promoted at high temperature in a specific temperature range. Accordingly, serrations associated with DSA appear and disappear in low and high temperatures, corresponding to the experimental facts obtained in this study.…”

Influence of Dislocation Separation on Dynamic Strain Aging in a Fe–Mn–C Austenitic Steel

“…5,11) The dynamic strain aging behavior has been discussed using the diffusion speed of solute atoms and the dislocation velocity. 5,6,8,12) The diffusion speed of interstitial atoms depends on the type of solute atoms and deformation temperature, and the dislocation velocity depends on the strain rate, dislocation density, tensile direction, and the Burgers vector. On discussions of dynamic strain aging in FCC metals, the Burgers vector is implicitly assumed to be a=2h110i, irrespective of stacking fault energy.…”